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1
Norton, MR, R. Murison, ICR Holford e GG Robinson. "Rotation effects on sustainability of crop production: the Glen Innes rotation experiment". Australian Journal of Experimental Agriculture 35, n. 7 (1995): 893. http://dx.doi.org/10.1071/ea9950893.
Testo completoAbstract (sommario):
This study, which commenced in 1921, is the longest running crop rotation experiment in the summer rainfall region of Australia. The 7 rotation treatments comprise various frequencies and combinations of maize and spring oat crops with and without autumn oats and red clover ley. The maize and oat yields are analysed separately using principles described by Paterson (1964). Spline regressions are used to describe the trends of yields with time and to make comparisons amongst the rotations. Yield performance of maize and oats was improved as legume ley duration increased, although as maize cropping became more frequent this effect was reduced. Autumn-sown oats benefited both maize and spring oat yields, independent of the presence of a legume ley. Crop yields were generally maintained in those rotations containing a grazed clover ley. After alteration of ley management in the mid 1960s so that clover crops were subsequently removed as hay, crop yields in these rotations declined. The benefits of clover ley to crop productivity were considered to be primarily due to the maintenance of those soil chemical, physical, and biological properties associated with sustainable crop production.
2
Bhathal, J. S., e R. Loughman. "Ability of retained stubble to carry-over leaf diseases of wheat in rotation crops". Australian Journal of Experimental Agriculture 41, n. 5 (2001): 649. http://dx.doi.org/10.1071/ea00134.
Testo completoAbstract (sommario):
Increasingly, wheat rotations on sand-plain soils in Western Australia are being managed with stubble retention practices for reasons of moisture and soil conservation. A major concern in stubble retention practices is an associated increase in risk from septoria nodorum blotch (Phaeosphaeria nodorum) and yellow spot (Pyrenophora tritici-repentis). These pathogens frequently occur together in the region and survive in crop surface residues. The amount of disease carry-over on stubble is an important determinant of the severity of leaf diseases during the entire crop season. To provide a rationale for wheat leaf disease management in stubble retention rotation systems the extent to which retained wheat stubble induces disease in rotated crops was investigated. The frequency with which wheat stubble, which had been retained through a 1-year rotation, induced significant disease in seedling wheat was low (14%) over the 4-year period of study. While disease carry-over from wheat stubble retention in rotations is possible, it appears to be uncommon. The small proportion (1–8%) of retained wheat stubble that remained after germination of the return wheat crop in typical Western Australian farming systems further indicates that in general retained wheat stubble is not a significant source of disease carry-over in rotation wheat crops in this environment.
3
Schultz, JE. "Crop production in a rotation trial at Tarlee, South Australia". Australian Journal of Experimental Agriculture 35, n. 7 (1995): 865. http://dx.doi.org/10.1071/ea9950865.
Testo completoAbstract (sommario):
A crop rotation trial was established in 1977 on a hard-setting red-brown earth at Tarlee, South Australia, to monitor the long-term effect of intensive and traditional rotations on soil properties and crop production. The rotations involve wheat alternating with cereals, grain legumes, pasture, and fallow. There are 3 stubble + tillage treatments: remove stubble + cultivate, retain stubble + cultivate, retain stubble + no tillage. Three rates of nitrogen (0,40, 80 kg N/ha as ammonium nitrate) are applied to the wheat. Grain yield varied with seasonal conditions, and water use efficiencies were up to 10 kg/ha. mm. In the more productive rotations, wheat grain yields expressed as a percentage of potential yield tended to increase over time. The best wheat yields were always in rotations that included a grain legume or legume pasture, with additional yield increases in all rotations coming from the use of N fertiliser. By comparison with rotation and N fertiliser effects, there was little effect of the stubble + tillage treatments on grain yield. Most of the yield variations were related to differences in tiller density or grains per ear, with grain weight remaining relatively constant over all seasons. There was a tendency for grain legume yields to decrease over the latter years of the trial, and this was attributed to the build-up of plant diseases through growing the same species on the same plot every second year. Overall, faba beans were the highest yielding grain legume, and the wheat-beans rotation, with 80 kg N/ha on the wheat, gave highest total grain production. Data for residue remaining after harvest indicate that in some years there is less than the desired minimum levels to give adequate protection against erosion, so any grazing of the residues must be carefully managed.
4
Ewing, MA, AD Bathgate, RJ French e CK Revell. "The role of crop and pasture legumes in rotations on duplex soils". Australian Journal of Experimental Agriculture 32, n. 7 (1992): 971. http://dx.doi.org/10.1071/ea9920971.
Testo completoAbstract (sommario):
Duplex soils are prominent in southern Australia and are generally low in fertility. Their agricultural performance is, therefore, suboptimal in most circumstances without an exogenous source of nitrogen. This is often supplied by legumes which are grown in rotation with non-leguminous crops. Both crop and pasture legumes are now widely used in southern Australia and the contribution that they make to the non-legume phase of rotations is through nitrogen fixation and through other mechanisms such as cereal disease breaks. We use a mathematical programming model, MIDAS (Model of an Integrated Farming Dryland Agricultural System), to investigate the role of legumes in the low rainfall wheatbelt of Western Australia. The impact of legumes on farm profitability is assessed with a special focus on the contribution of legumes grown on a duplex soil. By using the model, the sensitivity of rotation choice on this duplex soil to changes in biological and economic parameters is explored. We conclude that crop legumes, in particular, have a firmly established role on sandy-surfaced duplex soils in low rainfall regions and that substantial increases in both the productivity and legume content of pasture would be required to outperform rotations which include crop legumes.
5
Turner, NC. "Crop production on duplex soils: an introduction". Australian Journal of Experimental Agriculture 32, n. 7 (1992): 797. http://dx.doi.org/10.1071/ea9920797.
Testo completoAbstract (sommario):
Duplex or texture-contrast soils occur over about 60% of the agricultural areas of south-west Western Australia. Annual crops of wheat, barley, oats, and lupins predominate on these soils, grown in rotation with annual pastures. The climate is characterised by cool, wet winters and hot, dry summers. Crop production is restricted to the winter and spring and is limited by waterlogging in the wet winter months and by water shortage during grain filling in spring. Research on crop production on duplex soils has been undertaken for the past 8 years by a collaborative team from the CSIRO Dryland Crops andyoils Program and the Western Australian Department of Agriculture. This research has been focussed on 3 sites at which processes limiting crop production on duplex soils have been highlighted. This special issue was initiated to summarise that research and to put it in its regional and national perspective. Additionally, opportunity was taken to compare and contrast experiences both within Western Australia and throughout Australia, and to draw out management options for crop production on duplex soils.
6
Bell, Lindsay W., Andrew T. James, Mary Ann Augustin, Artur Rombenso, David Blyth, Cedric Simon, Thomas J. V. Higgins e Jose M. Barrero. "A Niche for Cowpea in Sub-Tropical Australia?" Agronomy 11, n. 8 (19 agosto 2021): 1654. http://dx.doi.org/10.3390/agronomy11081654.
Testo completoAbstract (sommario):
Pulses have emerged as important rotation crops in Australia. Some are in demand in agricultural production systems due to their high potential market value, because of their roles as grain or forage crops, their nitrogen fixation capability, and because they provide a disease break or improve soil health. While several pulse crops have been identified for winter-season cropping, there are few adapted legumes apart from mungbean that are appropriate for dryland summer cropping. Currently, short-duration crops of mungbean are commonly used, but yields are highly variable and susceptible to drought. Here, we propose that cowpea has the potential to become an alternative rotation crop in dryland summer cropping zones, providing a competitive and profitable alternative pulse crop option where its drought tolerance could enable better performance under inconsistent in-crop rainfall. We demonstrate that cowpea has nutritional properties and putative uses that could prove valuable in emerging plant-based protein and aquaculture markets.
7
Hulugalle, N. R., e F. Scott. "A review of the changes in soil quality and profitability accomplished by sowing rotation crops after cotton in Australian Vertosols from 1970 to 2006". Soil Research 46, n. 2 (2008): 173. http://dx.doi.org/10.1071/sr07077.
Testo completoAbstract (sommario):
In agricultural systems, soil quality is thought of in terms of productive land that can maintain or increase farm profitability, as well as conserving soil resources so that future farming generations can make a living. Management practices which can modify soil quality include tillage systems and crop rotations. A major proportion of Australian cotton (Gossypium hirsutum L.) is grown on Vertosols (~75%), of which almost 80% is irrigated. These soils have high clay contents (40–80 g/100 g) and strong shrink–swell capacities, but are frequently sodic at depth and prone to deterioration in soil physical quality if incorrectly managed. Due to extensive yield losses caused by widespread deterioration of soil structure and declining fertility associated with tillage, trafficking, and picking under wet conditions during the middle and late 1970s, a major research program was initiated with the objective of developing soil management systems which could improve cotton yields while concurrently ameliorating and maintaining soil structure and fertility. An outcome of this research was the identification of cotton–winter crop sequences sown in a 1 : 1 rotation as being able to sustain lint yields while at the same time maintaining soil physical quality and minimising fertility decline. Consequently, today, a large proportion (~75%) of Australian cotton is grown in rotation with winter cereals such as wheat (Triticum aestivum L.), or legumes such as faba bean (Vicia faba L.). A second phase of research on cotton rotations in Vertosols was initiated during the early 1990s with the main objective of identifying sustainable cotton–rotation crop sequences; viz. crop sequences which maintained and improved soil quality, minimised disease incidence, facilitated soil organic carbon sequestration, and maximised economic returns and cotton water use efficiency in the major commercial cotton-growing regions of Australia. The objective of this review was to summarise the key findings of both these phases of Australian research with respect to soil quality and profitability, and identify future areas of for research. Wheat rotation crops under irrigated and dryland conditions and in a range of climates where cotton is grown can improve soil quality indicators such as subsoil structure, salinity, and sodicity under irrigated and dryland conditions, while leguminous crops can increase available nitrogen by fixing atmospheric nitrogen, and by reducing N volatilisation and leaching losses. Soil organic carbon in most locations has decreased with time, although the rate of decrease may be reduced by sowing crop sequences that return about 2 kg/m2.crop cycle of residues to the soil, minimising tillage and optimising N inputs. Although the beneficial effects of soil biodiversity on quality of soil are claimed to be many, except for a few studies on soil macrofauna such as ants, conclusive field-based evidence to demonstrate this has not been forthcoming with respect to cotton rotations. In general, lowest average lint yields per hectare were with cotton monoculture. The cotton–wheat systems generally returned higher average gross margins/ML irrigation water than cotton monoculture and other rotation crops. This indicates that where irrigation water, rather than land, is the limiting resource, cotton–wheat systems would be more profitable. Recently, the addition of vetch (Vicia villosa Roth.) to the cotton–wheat system has further improved average cotton yields and profitability. Profitability of cotton–wheat sequences varies with the relative price of cotton to wheat. In comparison with cotton monoculture, cotton–rotation crop sequences may be more resilient to price increases in fuel and fertiliser due to lower overall input costs. The profitability of cotton–rotation crop sequences such as cotton–wheat, where cotton is not sown in the same field every year, is more resilient to fluctuations in the price of cotton lint, fuel and nitrogen fertiliser. This review identified several issues with respect to cotton–rotation crop sequences where knowledge is lacking or very limited. These are: research into ‘new’ crop rotations; comparative soil quality effects of managing rotation crop stubble; machinery attachments for managing rotation crop stubble in situ in permanent bed systems; the minimum amount of crop stubble which needs to be returned per cropping cycle to increase SOC levels from present values; the relative efficacy of C3 and C4 rotation crops in relation to carbon sequestration; the interactions between soil biodiversity and soil physical and chemical quality indicators, and cotton yields; and the effects of sowing rotation crops after cotton on farm and cotton industry economic indicators such as the economic incentives for adopting new cotton rotations, farm level impacts of research and extension investments, and industry- and community/catchment-wide economic modelling of the impact of cotton research and extension activities.
8
Cox, H. W., R. M. Kelly e W. M. Strong. "Pulse crops in rotation with cereals can be a profitable alternative to nitrogen fertiliser in central Queensland". Crop and Pasture Science 61, n. 9 (2010): 752. http://dx.doi.org/10.1071/cp09352.
Testo completoAbstract (sommario):
Empirical and simulation results from three crop rotations incorporating cereals, pulses and nitrogen (N) fertiliser application were examined over 4 years in a subtropical environment, central Queensland, Australia. The hypothesis was that pulse crops in rotation with cereals would be a viable alternative to applying N fertilisers and would improve farm business economic performance provided the yield potential of pulses were not compromised by planting into very low soil water situations. Empirical data and simulations with the Agricultural Production Systems Simulator model were used to give insights into the N contribution, yield benefit to cereals and overall economic performance of the inclusion of pulses into the rotation. The field trial rotations included: rotation 1: sorghum and wheat in an opportunity crop rotation (called cereals-only), rotation 2; cereals grown following a fallow with a pulse crop immediately after (called cereal double-cropped pulse) and rotation 3, pulses grown following a fallow with a cereal crop immediately after (called pulse double-cropped cereal). Empirical and simulated results indicated that the cereal double-cropped pulse rotation produced the highest average annual gross margins using prices at that time. In the simulations, when pulse crops were included in the rotation, no additional N fertiliser was required and the lowest chance of negative gross margins was obtained. The cereal double-cropped pulse rotation produced the largest trial and simulated gross margins. The pulse double-cropped cereal rotation produced greater gross margins than the N-deficient cereals-only rotation but significantly lower than the cereal double-cropped pulse rotation. Simulations indicated that the cereals-only rotation could be made profitable when the soil was ‘topped-up’ to 100 kg available N/ha before planting, or by 40 kg N/ha to each cereal crop. Chickpea and mungbean contributed an average of 35 and 29 kg N/ha, respectively, in the field trial. A minimum of 100 mm of the stored soil water at planting was needed to reduce the risk of negative returns. By planting only when the soil contained adequate water, the cereal double-cropped pulse rotation may provide a valuable supplement to farm income while simultaneously reducing the need for N fertilisers on the cereals. Alternatively, in a rotation with cereals only, modest amounts of fertiliser N will maintain profitability with minimal levels of financial risk.
9
Lawes, Roger, e Michael Renton. "The Land Use Sequence Optimiser (LUSO): A theoretical framework for analysing crop sequences in response to nitrogen, disease and weed populations". Crop and Pasture Science 61, n. 10 (2010): 835. http://dx.doi.org/10.1071/cp10026.
Testo completoAbstract (sommario):
The break crop effect, where a non-cereal crop provides relief from soil pathogens, may increase soil nitrogen reserves for a cereal and help minimise populations of herbicide resistant weeds. It is widely used in agriculture to maximise the economic return and yield of cereal crops. In Western Australia, cereal crops are being grown with increasing frequency, at the expense of less profitable break crops and we have developed a land use sequence optimiser (LUSO) to analyse strategic break crop decisions across a suite of price, yield, nitrogen fertiliser cost, soil borne disease load and weed load thresholds. The model is flexible and can easily be parameterised for a wide range of economic, edaphic and biotic parameters. We demonstrate its use in a strategic sense to determine economic and biotic thresholds that force a rotation change in a typical Western Australian cropping system.
10
Hulugalle, Nilantha R., Bruce McCorkell, Viliami F. Heimoana e Lloyd A. Finlay. "SHORT COMMUNICATION: Soil Properties Under Cotton-Corn Rotations in Australian Cotton Farms". Journal of Cotton Science 20, n. 4 (2016): 294–98. http://dx.doi.org/10.56454/fsng2773.
Testo completoAbstract (sommario):
During the past decade sowing corn (Zea mays L.) in rotation with cotton (Gossypium hirsutum L.) has gained popularity among many Australian cotton growers. Research on cotton-corn rotations in Australia is sparse, although anecdotal evidence suggests that subsequent cotton yields are increased. Our objective was to quantify the impact of sowing a corn rotation crop on soil properties of Vertisols under cotton-based farming systems on 18 farms within Australian cotton-growing regions. Each site had either corn or cotton sown during the preceding summer. Soil was sampled in transects from the surface 0.3 m. Soil organic carbon concentrations and storage were higher, and exchangeable cation concentrations lower after corn than after cotton but soil structure was not significantly affected. The yield increases reported by cotton growers are, therefore, unlikely to have been caused by the soil properties measured in this study. Enhanced cycling of nutrients such as N and P through higher soil organic matter and microbial activity cannot, however, be ruled out.
11
Armstrong, E. L., D. P. Heenan, J. S. Pate e M. J. Unkovich. "Nitrogen benefits of lupins, field pea, and chickpea to wheat production in south-eastern Australia". Australian Journal of Agricultural Research 48, n. 1 (1997): 39. http://dx.doi.org/10.1071/a96054.
Testo completoAbstract (sommario):
Nitrogen balances of narrow leaf lupin (Lupinus angustifolius L.), albus lupin (L. albus L.), field pea (Pisum sativum L.), chickpea (Cicer arietinum L.), and barley (Hordeum vulgare L.) sown over a range of dates were examined in 1992 in a rotation study at Wagga Wagga, NSW. Each N budget included assessment of dependence on fixed as opposed to soil N, peak aboveground biomass N, and N removed as grain or returned as unharvested aboveground crop residues. N balances of wheat sown across the plots in 1993 were assessed similarly in terms of biomass and grain yield. Yields, N2 fixation, and crop residue N balances of the legumes were markedly influenced by sowing time, and superior performance of lupins over other species was related to higher biomass production and proportional dependence on N2 fixation, together with a poorer harvest index. Residual N balances in aboveground biomass after harvest of the 1992 crops were significantly correlated with soil mineral N at 1993 sowing and with biomass and grain N yields of the resulting wheat crop. Best mean fixation and grain N yield came from albus lupin. Wheat grain N yields following the 2 lupins were some 20% greater than after fiield pea and chickpea and 3 times greater than after barley. Net soil N balance based solely on aboveground returns of N of legumes in 1992 through to harvest of wheat in 1993 was least for narrow leaf lupin-wheat ( –20 kg N/ha), followed by albus lupin-wheat ( –44), chickpea-wheat ( –74), and field pea-wheat ( –96). Corresponding combined grain N yields (legume+wheat) from the 4 rotations were 269, 361, 178, and 229 kg N/ha, respectively. The barley-wheat rotation yielded a similarly computed soil N deficit of 67 kg/ha. Data are discussed in relation to other studies on legume-based rotations.
12
Vu, D. T., C. Tang e R. D. Armstrong. "Tillage system affects phosphorus form and depth distribution in three contrasting Victorian soils". Soil Research 47, n. 1 (2009): 33. http://dx.doi.org/10.1071/sr08108.
Testo completoAbstract (sommario):
Major changes in tillage practices have occurred over the past 2 decades across the diverse range of soil types and rainfall zones that characterise cropping systems in southern Australia. However, there has been little corresponding change in the management of nutrients, especially phosphorus (P). This study investigated the effects of tillage and crop rotations on the stratification and transformation of P in soil profiles from 3 tillage/rotation trials encompassing 3 agro-ecological zones of southern Australia. Soil samples were collected from field trials at Longerenong (Vertosol, average rainfall 420 mm), Walpeup (Calcarosol, rainfall 325 mm), and Rutherglen (Chromosol, rainfall 650 mm) in Victoria. Soil samples from various depths were sequentially analysed for organic and inorganic P fractions. Phosphorus accumulated in the surface soil (0–0.1 m) across all sites and tillage practices/rotations studied but the proportion of P in different chemical fractions varied markedly among soil types and tillage practice/rotation. In the sandy Calcarosol, a greater proportion of fertiliser P was transformed into labile (resin-P) forms, whereas it tended to accumulate in non-labile pools in the finer textured Vertosol and Chromosol. The effects of tillage and crop rotation were generally confined to the topsoil with P strongly stratified in the topsoil in direct-drill and zero-tillage treatments compared with conventional tillage. The implications for management of P fertilisers in Victorian cropping systems are discussed.
13
McDonald, GK. "The contribution of nitrogen fertiliser to the nitrogen nutrition of rainfed wheat crops in Australia: a review". Australian Journal of Experimental Agriculture 29, n. 3 (1989): 455. http://dx.doi.org/10.1071/ea9890455.
Testo completoAbstract (sommario):
Very little nitrogen (N) fertiliser is applied to wheat crops in Australia. Currently, about 105 t of N fertiliser (less than 20% of Australia's total consumption) are used annually at an average rate of 2-3 kg Nha. This scant use of N fertiliser over much of the Australian wheat belt N is because the N derived from a legume-dominant pasture ley is thought to provide a wheat crop's N requirement. However, trends in the grain protein content of Australian wheat and some other indices of soil fertility suggest that legume-based pastures have not always been able to supply all the N required for adequate nutrition of the wheat crop and that there has been some occasional need for extra N from applications of fertiliser. Recent declines in the productivity and quality of pastures has further increased the need for supplementary applications of N fertiliser. The increase in grain legume production also has been partly based on the presumption that grain legumes contribute to the N economy of the following wheat crop. Many experiments throughout the wheat belt show a yield advantage of wheat grown after a grain legume, but these rotation trials also show that the level of productivity of the grain legume has little effect on the yield of the following wheat crop. A review of these experiments suggests that grain legumes, directly, contribute little to the N nutrition of a following wheat crop and their benefit may be from the legume acting as a disease break or providing the opportunity to control grassy weeds.
14
Marcroft, S. J., S. J. Sprague, S. J. Pymer, P. A. Salisbury e B. J. Howlett. "Crop isolation, not extended rotation length, reduces blackleg (Leptosphaeria maculans) severity of canola (Brassica napus) in south-eastern Australia". Australian Journal of Experimental Agriculture 44, n. 6 (2004): 601. http://dx.doi.org/10.1071/ea03087.
Testo completoAbstract (sommario):
Due to the large increase of canola production in Australia, current blackleg cultural control recommendations (extended rotation length and isolation distance from canola stubble) are not adhered to by farmers in many canola-producing regions. Canola crops are increasingly being sown in short rotation and, in many instances, adjacent to paddocks containing canola stubble. In this study, the level of disease in commercial canola crops was determined for different rotations and distances from canola stubble. There was a strong relationship between the presence of canola stubble from the previous year (6-month-old stubble) and distance to current canola crops, but no relationship between the presence of older (18–42 month old) stubble and distance to current canola crops. Blackleg severity was highest where canola crops had been sown adjacent to 6-month-old canola stubble, with the level of blackleg severity decreasing markedly in the first 100 m. Disease severity then generally declined up to 500 m. Plants 500–1000 m from 6-month-old stubble had similar levels of blackleg infection. Blackleg severity was similar between canola crops sown into 18-month-old canola stubble (short rotation) and crops sown into paddocks that had no history of canola for at least the previous 3 years (long rotation). Based on these findings, we recommend that canola crops should be sown at distances greater than 100 m and preferably 500 m from last season's canola stubble, rather than extending rotation length between crops.
15
Whish, J. P. M., P. Castor e P. S. Carberry. "Managing production constraints to the reliability of chickpea (Cicer arietinum L.) within marginal areas of the northern grains region of Australia". Australian Journal of Agricultural Research 58, n. 5 (2007): 396. http://dx.doi.org/10.1071/ar06179.
Testo completoAbstract (sommario):
The poor reliability of chickpea yield produced in the marginal (<600 mm rainfall) areas of the northern cropping zone is a constraint to the wide adoption of the crop. Chickpea is a valuable rotation crop and is currently the only viable winter grain legume suitable to this region. This paper uses results from in-crop monitoring and crop simulation, to identify practical management strategies to improve the reliability of chickpea crops in this region. APSIM-Chickpea successfully simulated the commercial yields of chickpea crops monitored during the study. Soil water at sowing and sowing date were identified as key determinants of yield. A ‘rule of thumb’ was derived, which showed that crops sown with a starting plant-available water of ~100 mm at sowing had an 80% probability of producing a better than break-even yield for the majority of the region and this was independent of the soil’s plant-available water capacity or crop sowing date. The probability of accumulating 100 mm of stored water in this western region is 90% following harvest of a May–sown wheat crop. Increased plant population improved crop yields in 60% of years, but this only translated to improved returns in ~50% of those years. The use of these simple management approaches will improve the reliability of chickpea production and ensure that these marginal areas have the option of a viable winter grain legume in their rotations.
16
Thomson, C. J., C. K. Revell, N. C. Turner, M. A. Ewing e I. F. Le Coultre. "Influence of rotation and time of germinating rains on the productivity and composition of annual pastures in Western Australia". Australian Journal of Agricultural Research 49, n. 2 (1998): 225. http://dx.doi.org/10.1071/a94082.
Testo completoAbstract (sommario):
A long-term rotation experiment located in south-western Australia was used to measure the effect of rotation and time of germinating rains on the productivity and botanical composition of grazed annual pastures in 2 contrasting seasons in an environment with an average annual rainfall of 325 mm. The density of self-regenerating seedlings of subterranean clover (Trifolium subterraneum), capeweed (Arctotheca calendula), and grasses (Lolium rigidum, Hordeum leporinum, Bromus diandrus) was greatly increased (approx. 3 times the density) when there was a second year of pasture after crop compared with the first year after crop. The lower plant density resulted in first-year pastures having only about 33% of the autumn biomass accumulation of second-year pastures. This difference in early pasture growth had no effect on total pasture production in 1992, but in 1993 total pasture production was 30% greater in second-year pastures compared with first-year pastures. Botanical composition varied between and within seasons with the percentage of subterranean clover increasing throughout the season and the percentage of capeweed decreasing throughout the season. Grasses comprised <20% of the biomass in all seasons and treatments. Production of subterranean clover seed in 1993 was higher in a 1 : 2 crop-pasture rotation than in a 1 : 1 crop-pasture rotation and direct drilling in the cropping phase increased seed set compared with conventional tillage in both 1 : 1 and 1 : 2 crop-pasture rotations. Capeweed seedlings emerged in large numbers after rainfall between February and May and subsequently showed a relative growth rate twice that of subterranean clover and the grasses, but exclusion of rainfall until June resulted in a significant reduction in the emergence of capeweed seedlings. Additionally, capeweed had a lower rate of seedling survival compared with other pasture species, and this is contrary to observations by other researchers that capeweed is highly resistant to moisture stress during early growth.
17
Sadras, Victor O., Jeff A. Baldock, Jim W. Cox e W. D. Bellotti. "Crop rotation effect on wheat grain yield as mediated by changes in the degree of water and nitrogen co-limitation". Australian Journal of Agricultural Research 55, n. 6 (2004): 599. http://dx.doi.org/10.1071/ar04012.
Testo completoAbstract (sommario):
Theoretically, growth of stressed plants is maximised when all resources are equally limiting. The concept of co-limitation could be used to integrate key factors affected by crop rotation. This paper tested the hypothesis that the effect of crop rotation on the yield of wheat is partially mediated by changes in the degree of co-limitation between nitrogen and water. Four rotations were established on a sodic, supracalcic, red chromosol in a Mediterranean-type environment of southern Australia. Rotations included wheat grown after (a) faba bean harvested for grain, (b) faba bean incorporated as green manure, (c) ryegrass pasture, or (d) medic pasture; barley was grown after wheat in all cases. The response of wheat to the rotations during 3 growing seasons was analysed in terms of nitrogen and water co-limitation, and the response of barley was taken as a measure of the persistence of rotation effects. Daily scalars quantifying water and nitrogen stress effects on tissue expansion were calculated with a crop simulation model. These scalars were integrated in a series of seasonal indices to quantify the intensity of water (SW ) and nitrogen stress (SN ), the aggregated intensity of water and nitrogen stress (SWN ), the degree of water and nitrogen co-limitation (CWN ), and the integrated effect of stress and co-limitation (SCWN 25 CWN/SWN ). The expectation is that grain yield should be inversely proportional to stress intensity and directly proportional to degree of co-limitation, thus proportional to SCWN . Combination of rotations and seasons generated a wide variation in the amount of water and inorganic nitrogen in the 1-m soil profile at the time of wheat sowing. Plant-available water ranged from 33 to 107 mm, and inorganic nitrogen from 47 to 253 kg N/ha. Larger amounts of nitrogen were found after green-manured faba bean, and smaller after grass pasture. There was a consistent effect of rotation on wheat yield and grain protein content, which persisted in subsequent barley crops. Measured grain yield of wheat crops ranged from 2.5 to 4.8 t/ha. It was unrelated to water or nitrogen stresses taken individually, inversely related to the aggregated stress index SWN , and directly related to the CWN index of co-limitation. The combination of stress and co-limitation in a single index SCWN accounted for 65% of the variation in measured crop yield. This is a substantial improvement with respect to the stress effect quantified with SWN , which accounted for 43% of yield variation. It is concluded that rotation effects mediated by changes in the relative availability of water and nitrogen can be partially accounted for by degree of resource co-limitation.
18
Kalkhoran, Sanaz Shoghi, David Pannell, Tas Thamo, Maksym Polyakov e Benedict White. "Optimal lime rates for soil acidity mitigation: impacts of crop choice and nitrogen fertiliser in Western Australia". Crop and Pasture Science 71, n. 1 (2020): 36. http://dx.doi.org/10.1071/cp19101.
Testo completoAbstract (sommario):
Many agricultural soils are naturally acidic, and agricultural production can acidify soil through processes such as nitrogen (N) fixation by legumes and application of N fertiliser. This means that decisions about mitigation of soil acidity (e.g. through application of lime), crop rotation and N fertiliser application are interdependent. This paper presents a dynamic model to determine jointly the optimal lime application strategies and N application rates in a rainfed cropping system in Western Australia. The model accounts for two crop rotations (with and without a legume break crop), for the acid tolerance of different crop types, and for differences in the acidifying effect of different N fertilisers. Results show that liming is a profitable strategy to treat acidic soils in the study region, but that there are interactions between N and acidity management. Choice of fertiliser affects optimal lime rates substantially, with the use of a more acidifying ammonium-based fertiliser leading to higher lime rates. The optimal liming strategy is also sensitive to inclusion of a legume crop in the rotation, because its fixed N can be less acidifying than fertiliser, and it allows a reduction in fertiliser rates. Higher rainfall zones have greater N leaching, which contributes to a higher optimal rate of lime. We find that injection of lime into the subsoil increases profit. Optimal lime rates in the absence of subsoil incorporation are higher than usual current practice, although the economic gains from increasing rates are small.
19
Hill, Matthew P., Sarina Macfadyen e Michael A. Nash. "Broad spectrum pesticide application alters natural enemy communities and may facilitate secondary pest outbreaks". PeerJ 5 (19 dicembre 2017): e4179. http://dx.doi.org/10.7717/peerj.4179.
Testo completoAbstract (sommario):
BackgroundPesticide application is the dominant control method for arthropod pests in broad-acre arable systems. In Australia, organophosphate pesticides are often applied either prophylactically, or reactively, including at higher concentrations, to control crop establishment pests such as false wireworms and earth mite species. Organophosphates are reported to be disruptive to beneficial species, such as natural enemies, but this has not been widely assessed in Australian systems. Neither has the risk that secondary outbreaks may occur if the natural enemy community composition or function is altered.MethodsWe examine the abundance of ground-dwelling invertebrate communities in an arable field over successive seasons under rotation; barley, two years of wheat, then canola. Two organophosphates (chlorpyrifos and methidathion) were initially applied at recommended rates. After no discernible impact on target pest species, the rate for chlorpyrifos was doubled to elicit a definitive response to a level used at establishment when seedling damage is observed. Invertebrates were sampled using pitfalls and refuge traps throughout the experiments. We applied measures of community diversity, principal response curves and multiple generalised linear modelling techniques to understand the changes in pest and natural enemy communities.ResultsThere was large variability due to seasonality and crop type. Nevertheless, both pest (e.g., mites and aphids) and natural enemy (e.g., predatory beetles) invertebrate communities were significantly affected by application of organophosphates. When the rate of chlorpyrifos was increased there was a reduction in the number of beetles that predate on slug populations. Slugs displayed opposite trends to many of the other target pests, and actually increased in numbers under the higher rates of chlorpyrifos in comparison to the other treatments. Slug numbers in the final rotation of canola resulted in significant yield loss regardless of pesticide application.DiscussionOrganophosphates are a cost-effective tool to control emergent pests in broad-acre arable systems in Australia. We found risks associated with prophylactic application in fields under rotation between different crop types and significant changes to the community of pests and natural enemy. Disrupting key predators reduced effective suppression of other pests, such as slugs, and may lead to secondary outbreaks when rotating with susceptible crops such as canola. Such non-target impacts are rarely documented when studies focus on single-species, rather than community assessments. This study represents a single demonstration of how pesticide application can lead to secondary outbreaks and reinforces the need for studies that include a longer temporal component to understand this process further.
20
Mielenz, Henrike, Peter J. Thorburn, Robert H. Harris, Sally J. Officer, Guangdi Li, Graeme D. Schwenke e Peter R. Grace. "Nitrous oxide emissions from grain production systems across a wide range of environmental conditions in eastern Australia". Soil Research 54, n. 5 (2016): 659. http://dx.doi.org/10.1071/sr15376.
Testo completoAbstract (sommario):
Nitrous oxide (N2O) emissions from Australian grain cropping systems are highly variable due to the large variations in soil and climate conditions and management practices under which crops are grown. Agricultural soils contribute 55% of national N2O emissions, and therefore mitigation of these emissions is important. In the present study, we explored N2O emissions, yield and emissions intensity in a range of management practices in grain crops across eastern Australia with the Agricultural Production Systems sIMulator (APSIM). The model was initially evaluated against experiments conducted at six field sites across major grain-growing regions in eastern Australia. Measured yields for all crops used in the experiments (wheat, barley, sorghum, maize, cotton, canola and chickpea) and seasonal N2O emissions were satisfactorily predicted with R2=0.93 and R2=0.91 respectively. As expected, N2O emissions and emissions intensity increased with increasing nitrogen (N) fertiliser input, whereas crop yields increased until a yield plateau was reached at a site- and crop-specific N rate. The mitigation potential of splitting N fertiliser application depended on the climate conditions and was found to be relevant only in the southern grain-growing region, where most rainfall occurs during the cropping season. Growing grain legumes in rotation with cereal crops has great potential to reduce mineral N fertiliser requirements and so N2O emissions. In general, N management strategies that maximise yields and increase N use efficiency showed the greatest promise for N2O mitigation.
21
Hulugalle, N. R., P. C. Entwistle, F. Scott e J. Kahl. "Rotation crops for irrigated cotton in a medium-fine, self-mulching, grey Vertosol". Soil Research 39, n. 2 (2001): 317. http://dx.doi.org/10.1071/sr00035.
Testo completoAbstract (sommario):
Many cotton growers sow rotation crops after irrigated cotton (Gossypium hirsutum L.), assuming that they will improve soil quality and maintain profitability of cotton. Wheat (Triticum aestivum L.) is the most common rotation crop, although more recently, legumes such as faba bean (Vicia Faba L.) and chickpea (Cicer arietinum L.) have come into favour. This paper reports data on soil quality (organic C, nitrate-N, soil structure), yield (cotton lint and rotation crop grain yield, fibre quality), economic returns (gross margins/ha, gross margins/ML irrigation water), and management constraints from an experiment conducted from 1993 to 1998 near Wee Waa, north-western New South Wales, Australia. The soil is a medium-fine, self-mulching, grey Vertosol. The cropping sequences used were cotton followed by N-fertilised wheat (urea at 140 kg N/ha in 1993; 120 kg N/ha thereafter), unfertilised wheat, and unfertilised grain legumes (chickpea in 1993; faba bean thereafter), which were either harvested or the grain incorporated during land preparation. Soil organic C in the 0—0.6 m depth was not affected by the rotation crop, although variations occurred between times of sampling. Regression analysis indicated that there had been no net gain or loss of organic C between June 1993 and October 1998. Sowing leguminous rotation crops increased nitrate-N values. A net increase in root-zone nitrate-N reserves occurred with time (from June 1993 to October 1998) with all rotation crops. Soil compaction (measured as specific volume of oven-dried soil) was lower with wheat by October 1998. A net decrease in soil compaction occurred in the surface 0.15 m with all rotation crops between 1993 and 1998, whereas it increased in the 0.15–0.60 m depth. Cotton lint yield and quality, and gross margins/ha and gross margins/ML, were always higher where wheat was sown, with highest gross margins occurring when N fertiliser was applied. Applying N fertiliser to wheat did not significantly increase cotton lint yield and fibre quality, but increased gross margins of the cotton–wheat sequence due to higher wheat yield and protein percentage. Lint yield and fibre quality were decreased by sowing leguminous rotation crops. Management constraints such as lack of effective herbicides, insect damage, harvesting damage, and availability of suitable marketing options were greater with legumes than with wheat. Overall, wheat was a better rotation crop than grain legumes for irrigated cotton.
22
Roget, DK, e AD Rovira. "The relationship between incidence of infection by the take-all fungus (Gaeumannomyces graminis var. tritici), rainfall and yield of wheat in South Australia". Australian Journal of Experimental Agriculture 31, n. 4 (1991): 509. http://dx.doi.org/10.1071/ea9910509.
Testo completoAbstract (sommario):
. This paper describes results obtained from an 8-year field trial on a calcareous sandy loam in South Australia. Different crop rotations resulted in varying percentages of plants with take-all [caused by Gaeumannomyces graminis var. tritici (Ggt)]. The results demonstrated that in a wheat-grass/medic pasture rotation, take-all caused an average annual yield loss in wheat of 29%. These yield losses were strongly correlated with disease incidence and rainfall in September (r2 = 0.91, P = 0.07) but only moderately correlated to disease incidence alone (r2 = 0.44, P = 0.09). The level of early infection (at 10 weeks) by Ggt was influenced by spring rainfall in the previous season. A regression model was developed to predict the incidence of take-all in a wheat crop from the incidence of take-all and the August-September rainfall the previous season (r2 = 0.96, P = 0.007) for a wheat-grass/medic pasture rotation (successive host plants).
23
Siddique, K. H. M., e J. Sykes. "Pulse production in Australia past, present and future". Australian Journal of Experimental Agriculture 37, n. 1 (1997): 103. http://dx.doi.org/10.1071/ea96068.
Testo completoAbstract (sommario):
Summary. Several cool- and warm-season pulse crops (grain legumes) are grown in rotation with cereals and pasture forming sustainable farming systems in Australia. Australian pulse production has increased rapidly over the past 25 years to about 2 x 106 t/year, mainly because of the increase in the area and yield of lupin production for stockfeed purposes. Pulses currently comprise only 10% of the cropping areas of Australia and this could be expanded to 16% as there are large areas of soil types suitable for a range of pulse crops and new better-adapted pulse varieties are becoming available. Cool-season pulses will continue to dominate pulse production in Australia and the majority of the expansion will probably come from chickpea and faba bean industries. There appears to be no major constraint to pulse production in Australia that cannot be addressed by breeders, agronomists and farmers. Of the current major pulse crops, field pea faces the most number of difficulties, in particular the lack of disease management options. A recent strategic plan of the Australian pulse industry predicts the production of 4 x 106 t/year by 2005 but this will largely depend upon export demand and pulse prices. It is predicted that the growth in pulse production will come from increased productivity in the existing areas, from 1.0 to 1.4 t/ha, through improvements in crop management and the development of superior varieties. The area of pulse production will also expand by an additional 1.2 x 106 ha probably yielding 1.0 t/ha. If trends in grazing stock prices continue, the increased area under pulse production will mostly come at the expense of those areas under unimproved pasture and continuous cereal cropping.
24
Osler, Graham H. R., Petra C. J. van Vliet, Craig S. Gauci e Lynette K. Abbott. "Changes in free living soil nematode and micro-arthropod communities under a canola - wheat - lupin rotation in Western Australia". Soil Research 38, n. 1 (2000): 47. http://dx.doi.org/10.1071/sr99050.
Testo completoAbstract (sommario):
Diversification of the crops used in wheat production systems provides alternative sources of income and can interrupt wheat pathogen lifecycles. Two important alternative crops in Western Australia are canola and lupins, which may both improve growth of following wheat. Improved growth of wheat following canola may be the consequence of biofumigation or increased root penetration by the wheat. Available nitrogen may be increased following lupins. We examined free-living soil fauna in a canola–wheat–lupin rotation near Moora, Western Australia, to determine the effects of these crops on the soil fauna. Each crop in the rotation was sampled in June, August, and October 1998. Nematodes were sorted into functional groups and arthropods were sorted to order level. Prostigmatid mites were the dominant arthropod group and they were sorted to morphospecies. An active and abundant faunal community was present under all crops, demonstrating that the canola variety in this study, Pinnacle TT, did not eliminate the free-living fauna. The structure of the mite communities changed throughout the year and the changes were different under the 3 crops. The soil arthropod communities were distinctly different under lupins compared with the other crops at the end of the growing season in 2 ways. First, 5 times more animals were present under the lupins than under wheat or canola, primarily due to an increase in the numbers of a tydeid and a tarsonemid mite species. Second, the tarsonemid species was always the second most abundant species under lupins but was infrequently the second ranked species under the other 2 crops. The soil arthropod communities were also different at the start of the growing season when the prostigmatid community under canola was dominated by a rhagidiid species, whilst under lupins and wheat a caligonellid and eupodid species dominated. The canola followed a lupin crop and therefore the difference in June may be attributed to the preceding lupins. Mite data from the lupin plots were consistent with a previously described succession from another environment. We hypothesise that if net nutrient mineralisation rates are greatest at the start of a succession then net mineralisation rates under lupins may be rapid at the end of the lupin crop and slow when the next crop is planted in the remaining lupin stubble. The difference between lupins and canola in their mite communities would then imply that net mineralisation rates are a factor creating differences between the effects of break crops on the following wheat crop.
25
Ward, P. R. "Predicting the impact of perennial phases on average leakage from farming systems in south-western Australia". Australian Journal of Agricultural Research 57, n. 3 (2006): 269. http://dx.doi.org/10.1071/ar04137.
Testo completoAbstract (sommario):
Rising watertables and dryland salinity in southern Australia are due to excess groundwater recharge after the replacement of native vegetation by annual crops and pastures. The inclusion of perennial plants into agricultural systems has been proposed as a possible method of recharge reduction, through the creation of a buffer (extra water storage capacity generated by the perennial in comparison with an annual crop or pasture). However, the role of perennial phases under conditions of highly episodic leakage is not well understood. In this paper, a simple Leakage/Buffer Model (LeBuM) was developed to determine the effect of perennial phases on long-term average annual leakage, incorporating episodic events. Mechanistic modelling studies on contrasting soil types were used to demonstrate that leakage for any given May–December period was directly related to soil water storage at 1 May. From this finding, it follows that leakage from a phase rotation can be calculated if the size of the buffer, and the leakage quantity in the absence of a buffer, are known for each stage of the rotation. LeBuM uses a long-term sequence of leakage values in the absence of a buffer as input, and the maximum buffer size, its rate of development, and the length of perennial and annual phases are specified as parameters. LeBuM was applied to leakage data modelled for 5 contrasting soil types over 100 years at 24 sites in the Western Australian wheatbelt. Phase rotations on duplex, waterlogging duplex, or loamy sand soils reduced leakage by >90% for regions with <380 mm annual rainfall, but were less effective in wetter regions and on deep sands or acid loamy sands. Nevertheless, phase rotations if adopted widely could delay the onset of salinity by as much as several decades.
26
Baker, Jeanine, e Christopher Preston. "Canola (Brassica napus L.) seedbank declines rapidly in farmer-managed fields in South Australia". Australian Journal of Agricultural Research 59, n. 8 (2008): 780. http://dx.doi.org/10.1071/ar07436.
Testo completoAbstract (sommario):
Canola is an important crop in southern Australia, where it is used as part of the crop rotation to manage cereal diseases, improve wheat yields, and assist in integrated weed management programs. The potential release of herbicide-tolerant transgenic cultivars into Australia has raised concerns that volunteer canola may itself become an uncontrollable weed. This study examined the persistence of the canola seedbank in farmer-managed fields in 3 geographical areas of the South Australian cropping region for up to 3.5 years after the last canola crop was grown. In total, 66 fields from minimum- and no-tillage farms were sampled for number of canola seed/m2 and the percentage of those that germinated. ANOVA analysis indicated that time since the last harvest and cultivation method were both significant factors affecting the number of seed/m2 present. Neither time since harvest nor cultivation method was significant for number of germinated canola seeds, although time since harvest approached significance at the 5% level. This demonstrates that the canola seedbank and the number of volunteers decline rapidly in managed cropping systems in southern Australia. Therefore, it is unlikely that herbicide-tolerant canola will become a major weed if volunteers are managed carefully.
27
Robertson, Fiona, Roger Armstrong, Debra Partington, Roger Perris, Ivanah Oliver, Colin Aumann, Doug Crawford e David Rees. "Effect of cropping practices on soil organic carbon: evidence from long-term field experiments in Victoria, Australia". Soil Research 53, n. 6 (2015): 636. http://dx.doi.org/10.1071/sr14227.
Testo completoAbstract (sommario):
Despite considerable research, predicting how soil organic carbon (SOC) in grain production systems will respond to conservation management practices, such as reduced tillage, residue retention and alternative rotations, remains difficult because of the slowness of change and apparent site specificity of the effects. We compared SOC stocks (equivalent soil mass to ~0–0.3 m depth) under various tillage, residue management and rotation treatments in three long-term (12-, 28- and 94-year-old) field experiments in two contrasting environments (Mallee and Wimmera regions). Our hypotheses were that SOC stocks are increased by: (1) minimum tillage rather than traditional tillage; (2) continuous cropping, rather than crop–fallow rotations; and (3) phases of crop or pasture legumes in rotations, relative to continuous cropping with cereals. We found that zero tillage and stubble retention increased SOC in some circumstances (by up to 1.5 Mg C ha–1, or 8%) but not in others. Inclusion of bare fallow in rotations reduced SOC (by 1.4–2.4 Mg C ha–1, or 8–12%) compared with continuous cropping. Including a pulse crop (field pea, where the grain was harvested) in rotations also increased SOC in some instances (by ~6–8 Mg C ha–1, or 29–35%) but not in others. Similarly, leguminous pasture (medic or lucerne) phases in rotations either increased SOC (by 3.5 Mg C ha–1, or 21%) or had no significant effect compared with continuous wheat. Inclusion of a vetch green manure or unfertilised oat pasture in the rotation did not significantly increase SOC compared with continuous wheat. The responses in SOC to these management treatments were likely to be due, in part, to differences in nitrogen and water availability (and their effects on carbon inputs and decomposition) and, in part, to other, unidentified, interactions. We conclude that the management practices examined in the present study may not reliably increase SOC on their own, but that significant increases in SOC are possible under some circumstances through the long-term use of multiple practices, such as stubble retention + zero tillage + legume N input + elimination of fallow. The circumstances under which increases in SOC can be achieved require further investigation.
28
Moore, Andrew D. "Opportunities and trade-offs in dual-purpose cereals across the southern Australian mixed-farming zone: a modelling study". Animal Production Science 49, n. 10 (2009): 759. http://dx.doi.org/10.1071/an09006.
Testo completoAbstract (sommario):
Dual-purpose cereals are employed in the high-rainfall zone of southern Australia to provide additional winter forage. Recently there has been interest in applying this technology in the drier environments of South and Western Australia. It would therefore be useful to gain an understanding of the trade-offs and risks associated with grazing wheat crops in different locations. In this study the APSIM (Agricultural Production Systems Simulator) crop and soil simulation models were linked to the GRAZPLAN pasture and livestock models and used to examine the benefits and costs of grazing cereal crops at 21 locations spanning seven of the regions participating in the Grain & Graze research, development and extension program. A self-contained part of a mixed farm (an annual pasture–wheat rotation plus permanent pastures) supporting a breeding ewe enterprise was simulated. At each location the consequences were examined of: (i) replacing a spring wheat cultivar with a dual-purpose cultivar (cv. Wedgetail or Tennant) in 1 year of the rotation; and (ii) either grazing that crop in winter, or leaving it ungrazed. The frequency of early sowing opportunities enabling the use of a dual-purpose cultivar was high. When left ungrazed the dual-purpose cultivars yielded less grain on average (by 0.1–0.9 t/ha) than spring cultivars in Western Australia and the Eyre Peninsula but more (by 0.25–0.8 t/ha) in south-eastern Australia. Stocking rate and hence animal production per ha could be increased proportionately more when a dual-purpose cultivar was used for grazing; because of the adjustments to stocking rates, grazing of the wheat had little effect on lamb sale weights. Across locations, the relative reduction in wheat yield caused by grazing the wheats was proportional to the grazing pressure upon them. Any economic advantage of moving to a dual-purpose system is likely to arise mainly from the benefit to livestock production in Western Australia, but primarily from grain production in south-eastern Australia (including the Mallee region). Between years, the relationship between increased livestock production and decreased grain yield from grazing crops shifts widely; it may therefore be possible to identify flexible grazing rules that optimise this trade-off.
29
Angus, J. F., A. F. van Herwaarden, D. P. Heenan, R. A. Fischer e G. N. Howe. "The source of mineral nitrogen for cereals in south-eastern Australia". Australian Journal of Agricultural Research 49, n. 3 (1998): 511. http://dx.doi.org/10.1071/a97125.
Testo completoAbstract (sommario):
The relative importance of soil mineral nitrogen (N) available at the time of sowing ormineralised during the growing season was investigated for 6 crops of dryland wheat. The soil mineral N in the root-zone was sampled at sowing and maturity and the rate of net mineralisation in the top 10 cm was estimated by sequential sampling throughout the growing season, using an in situ method. Mineralisation during crop growth was modelled in relation to total soil N, ambient temperature, andsoil water content. Mineral N accumulated before sowing varied by a factor of 3 between the sites (from 67 to 195 kgN/ha), while the net mineralisation during crop growth varied by a factor of 2 (from 43 to 99 kgN/ha). The model indicated that 0·092% of total N was mineralised per day when temperature and water were not limiting, with rates decreasing for lower temperatures and soil water contents. When tested with independent data, the model predicted the mineralisation rate of soil growing continuous wheat crops but underestimated mineralisation of soil in a clover-wheat rotation. For crops yielding <3 t/ha, the supply of N was mostly from mineralisation during crop growth and the contribution from mineral N accumulated before sowing was relatively small. For crops yielding >4 t/ha, thesupply of N was mostly from N present in the soil at the time of sowing. The implication is that for crops to achieve their water-limited yield, they must be supplied with an amount of N greater than can be expected from mineralisation during the growing season, either from fertiliser or from mineral N accumulated earlier.
30
Borger, C. P. D., G. P. Riethmuller e A. Hashem. "Emergence, survival and seed production of Enteropogon ramosus in a pasture - wheat rotation or continuous pasture rotation in the wheatbelt of Western Australia". Crop and Pasture Science 61, n. 8 (2010): 601. http://dx.doi.org/10.1071/cp10135.
Testo completoAbstract (sommario):
Enteropogon ramosus is a native, perennial, C4 grass species found within the wheatbelt of Western Australia. Emergence, survival, seed production and seed dormancy of E. ramosus was investigated in a continuous pasture rotation, a pasture–minimum tillage wheat rotation, and a pasture–minimum tillage wheat rotation where a cultivation event at the beginning of the pasture year was used to kill all E. ramosus plants. The results indicated that E. ramosus could germinate throughout the year, although plant density (ranging annually from 0 to 17 plants m−2) was lowest in conditions of low rainfall (summer–autumn drought). Seed production (estimated from seed head production, r = 91.7, P < 0.001) ranged from 0 to 2274 m–2 and was greatest in spring, in the continuous pasture rotation. Seed germinability reached 80–89%, following an initial 3 months of dormancy directly after seed production. Cultivation at the beginning of the pasture-crop rotation killed all plants, reduced emergence and prevented seed production for the 2-year period of the experiment. Soil disturbance from minimum tillage crop sowing reduced but did not eliminate E. ramosus plants. As a result, E. ramosus grew throughout the year in the minimum tillage cropping system. Further research is required to determine the competitive effect of E. ramosus on crop growth.
31
Oliver, DP, JE Schultz, KG Tiller e RH Merry. "The effect of crop rotations and tillage practices on cadmium concentration in wheat grain". Australian Journal of Agricultural Research 44, n. 6 (1993): 1221. http://dx.doi.org/10.1071/ar9931221.
Testo completoAbstract (sommario):
The cadmium concentrations in wheat grain were determined from three crop rotation x tillage experiments in South Australia. Generally, the concentrations in grain were highest in wheat grown after lupins and lowest in wheat grown after cereal. The high cadmium concentrations in grain from wheat/lupins plots could not be explained solely by acidification, thus indicating involvement of other processes in cadmium availability. While cadmium concentration in grain also increased with increasing rates of nitrogenous fertilizers, the results of cultivation practices were generally too inconsistent to allow conclusions to be drawn. Cadmium concentrations exceed the maximum permissible concentration (MPC) of 0.05 mg kg-1 set by the National Health and Medical Research Council (NHWIRC) for unspecified foods in only one of the three tillage experiments. This study indicates that crop rotation is an important factor affecting cadmium uptake. Under certain soil conditions and with particular wheat varieties, the cadmium concentration in grain may exceed the MPC as the result of the crop rotation used.
32
Anderson, W. K., M. A. Hamza, D. L. Sharma, M. F. D'Antuono, F. C. Hoyle, N. Hill, B. J. Shackley, M. Amjad e C. Zaicou-Kunesch. "The role of management in yield improvement of the wheat crop—a review with special emphasis on Western Australia". Australian Journal of Agricultural Research 56, n. 11 (2005): 1137. http://dx.doi.org/10.1071/ar05077.
Testo completoAbstract (sommario):
Modern bread wheat (Triticum aestivum) has been well adapted for survival and production in water-limited environments since it was first domesticated in the Mediterranean basin at least 8000 years ago. Adaptation to various environments has been assisted through selection and cross-breeding for traits that contribute to high and stable yield since that time. Improvements in crop management aimed at improving yield and grain quality probably developed more slowly but the rate of change has accelerated in recent decades. Many studies have shown that the contribution to increased yield from improved management has been about double that from breeding. Both processes have proceeded in parallel, although possibly at different rates in some periods, and positive interactions between breeding and management have been responsible for greater improvements than by either process alone. In southern Australia, management of the wheat crop has focused on improvement of yield and grain quality over the last century. Adaptation has come to be equated with profitability and, recently, with long-term economic and biological viability of the production system. Early emphases on water conservation through the use of bare fallow, crop nutrition through the use of fertilisers, crop rotation with legumes, and mechanisation, have been replaced by, or supplemented with, extensive use of herbicides for weed management, reduced tillage, earlier sowing, retention of crop residues, and the use of ‘break’ crops, largely for management of root diseases. Yields from rainfed wheat crops in Western Australia have doubled since the late 1980s and water-use efficiency has also doubled. The percentage of the crop in Western Australia that qualifies for premium payments for quality has increased 3–4 fold since 1990. Both these trends have been underpinned by the gradual elimination or management of the factors that have been identified as limiting grain yield, grain quality, or long-term viability of the cropping system.
33
Monjardino, M., D. J. Pannell e S. B. Powles. "The economic value of pasture phases in the integrated management of annual ryegrass and wild radish in a Western Australian farming system". Australian Journal of Experimental Agriculture 44, n. 3 (2004): 265. http://dx.doi.org/10.1071/ea03050.
Testo completoAbstract (sommario):
Most cropping farms in Western Australia must deal with the management of herbicide-resistant populations of weeds such as annual ryegrass (Lolium rigidum Gaudin) and wild radish (Raphanus raphanistrum�L.). Farmers are approaching the problem of herbicide resistance by adopting integrated weed management systems, which allow weed control with a range of different techniques. One important question in the design of such systems is whether and when the benefits of including pasture in rotation with crops exceed the costs. In this paper, the multi-species resistance and integrated management model was used to investigate the value of including pasture phases in the crop rotation. The most promising of the systems examined appears to be so-called 'phase farming', involving occasional 3-year phases of pasture rather than shorter, more frequent and regular pasture phases. This approach was competitive with the best continuous cropping rotation in a number of scenarios, particularly where herbicide resistance was at high levels.
34
Coventry, DR. "Acidification problems of duplex soils used for crop-pasture rotations". Australian Journal of Experimental Agriculture 32, n. 7 (1992): 901. http://dx.doi.org/10.1071/ea9920901.
Testo completoAbstract (sommario):
The acidification of duplex soils used for crop-pasture rotations has been reported widely in Australia in the winter dominant rainfall regions. At some locations induced soil acidity limits crop and pasture yield. The rate of soil acidification is affected by soil properties, agricultural management and rainfall. Rates of acid addition of 0.6-6 kmol H+/ha.year have been measured from long term crop pasture rotation experiments; these rates are comparable with values reported from pastoral studies in higher rainfall areas. Components of both the carbon and nitrogen cycles contribute to this acid addition, with loss of nitrate nitrogen below the rooting depth of these predominantly annual plant systems likely to be the main cause of acidification. Lime application has been recommended as a means of correcting acidification and improving crop and pasture yield. There is little information on the longevity of any beneficial effects of lime, the movement of lime in the soil and re-acidification of the soil in crop-pasture systems. A long term experimental site with rotation, deep tillage and lime treatments has been soil sampled throughout a 9-year period for changes in soil pH and aluminium. Soil pH decreased with increasing time after lime application. At lower lime rates (0.5-1.0 t/ha) there was no difference in pH or exchangeable A1 after 9 years, compared with the unlimed soil. At the higher lime rates there was downward movement of the neutralising effect of lime with time, as well as acidification of the soil. However, the yield responses obtained with all of the lime rates were maintained 9 years after 1 application of lime, even though the soil was strongly acid according to the measures used. Strategies for countering soil acidificaton may require an initial application of lime if acidity factors are restricting yield. Management systems which increase the permeability of the B horizon of duplex soils and which promote plant growth and a deep root system are essential for countering acidity in a croppasture rotation.
35
Li, Guangdi D., Rajinder P. Singh, John P. Brennan e Keith R. Helyar. "A financial analysis of lime application in a long-term agronomic experiment on the south-western slopes of New South Wales". Crop and Pasture Science 61, n. 1 (2010): 12. http://dx.doi.org/10.1071/cp09103.
Testo completoAbstract (sommario):
Management of Acid Soils Through Efficient Rotations (MASTER) is a long-term agronomic experiment commenced in 1992. There were 3 fundamental treatment contrasts in this experiment: (a) annual systems v. perennial systems; (b) limed v. unlimed treatments; and (c) permanent pastures v. pasture–crop rotations. The soil was acidic to depth with pH (in CaCl2) below 4.5 and exchangeable Al above 40% at 0.10–0.20 m when the experiment started. Lime was applied every 6 years to maintain soil pHCa at 5.5 in the 0–0.10 m soil depth. A financial analysis was undertaken to estimate potential benefits and costs involved in liming acid soils on the south-western slopes of New South Wales, based on data from the MASTER experiment. The most important finding from the current study is that liming pastures on soils that have a subsurface acidity problem is profitable over the long-term for productive livestock enterprises. The pay-back period for liming pastures, grazed by Merino wethers, was 14 years for both annual and perennial pastures. More profitable livestock enterprises, such as prime lambs or growing-out steers, were estimated to reduce the pay-back period. This gives farmers confidence to invest in a long-term liming program to manage highly acid soils in the traditional permanent pasture region of the high-rainfall zone (550–800 mm) of south-eastern Australia. Results from the current study also confirmed that the total financial return from liming is greater if the land is suitable for operation of a pasture–crop rotation system. The positive cash flows generated from cropping in a relatively short time can significantly shorten the pay-back period for the investment in lime. But cropping without liming on soils with subsurface acidity was worse than grazing animals. Crop choice is crucial for the perennial pasture–crop rotation. Inclusion of high-value cash crops, such as canola or a wheat variety with high protein, would lead to a rise in the aggregate benefits over time as the soil fertility improved and soil acidity was gradually ameliorated.
36
Ridley, A. M., B. Christy, F. X. Dunin, P. J. Haines, K. F. Wilson e A. Ellington. "Lucerne in crop rotations on the Riverine Plains. 1. The soil water balance". Australian Journal of Agricultural Research 52, n. 2 (2001): 263. http://dx.doi.org/10.1071/ar99165.
Testo completoAbstract (sommario):
Dryland salinity, caused largely by insufficient water use of annual crops and pastures, is increasing in southern Australia. A field experiment in north-eastern Victoria (average annual rainfall 600 mm) assessed the potential for lucerne grown in rotation with crops to reduce the losses of deep drainage compared with annual crops and pasture. Soil under lucerne could store 228 mm of water to 1.8 m depth. This compared with 84 mm under continuous crop (to 1.8 m depth), except in 1997–98 where crop dried soil by 162 mm. Between 1.8 and 3.25 m depth lucerne was able to create a soil water deficit of 78 mm. The extra water storage capacity was due to both the increased rooting depth and increased drying abiliy of lucerne within the root-zone of the annual species. Large drainage losses occurred under annuals in 1996 and small losses were calculated in 1997 and 1999, with no loss in 1998. Averaged over 1996–1999, drainage under annual crops was 49 mm/year (maximum 143 mm) and under annual pastures 35 mm/year (maximum 108 mm). When the extra soil water storage under lucerne was accounted for, no drainage was measured under this treatment in any year. Following 2 years of lucerne, drainage under subsequent crops could occur in the second crop. However, with 3 or 4 years of lucerne, 3–4 crops were grown before drainage loss was likely. Our calculations suggest that in this environment drainage losses are likely to occur under annual species in 55% of years compared with 6% of years under lucerne. In wet years water use of lucerne was higher than for crops due to lucerne’s ability to use summer rainfall and dry soil over the summer–autumn period. During the autumn–winter period crop water use was generally higher than under lucerne. The major period of increased soil water extraction under lucerne was from late spring to midsummer, with additional drying from deeper layers until autumn. Under both lucerne and crops, soil dried progressively from upper to lower soil layers. Short rotations of crops and lucerne currently offer the most practical promise for farmers in cropping areas in southern Australia to restore the water balance to a level which reduces the risk of secondary salinity.
37
Chan, K. Y., M. K. Conyers, G. D. Li, K. R. Helyar, G. Poile, A. Oates e I. M. Barchia. "Soil carbon dynamics under different cropping and pasture management in temperate Australia: Results of three long-term experiments". Soil Research 49, n. 4 (2011): 320. http://dx.doi.org/10.1071/sr10185.
Testo completoAbstract (sommario):
In addition to its important influence on soil quality and therefore crop productivity, soil organic carbon (SOC) has also been identified as a possible C sink for sequestering atmospheric carbon dioxide. Limited data are available on the impact of management practices on the rate of SOC change in agricultural soils in Australia. In this paper, results of three long-term trials (13–25 years) located near Wagga Wagga in temperate Australia were used to assess C dynamics under different tillage and stubble management practices, and under cropping intensities in pasture/crop rotations. Experimental results confirm the importance of management practices and pasture in determining first the steady-state SOC concentrations that are characteristic of given rotations and crop management systems, and second the rates of change of SOC concentrations as they approach steady-state concentrations in agricultural soils of this agro-ecological zone. A long-term crop/pasture experiment at a site with initial high SOC showed that the rate of SOC change in different treatments ranged from –278 to +257 kg C/ha.year over 0–0.3 m soil depth. Under continuous cropping, even under conservation agriculture practices of no-tillage, stubble retention, and crop rotation, the high initial SOC stock (0–0.3 m) present after a long-term pasture phase was, at best, maintained but tended to decrease with increased tillage or stubble burning practices. The effect of tillage was greater than that of stubble management. Increases in SOC were observed only in rotations incorporating a pasture phase. Our results suggest that improved soil nutrient and grazing management of permanent pasture can lead to an increase of 500–700 kg C/ha.year where the initial SOC concentrations are well below steady-state concentrations that could be expected after long periods of improved management. No difference was found between perennial pasture and annual pasture to the depth measured (0–0.3 m). Our results suggest that pasture holds the key to maintaining, and even increasing, SOC under crop/pasture in this environment.
38
Xu, R. K., D. R. Coventry, A. Farhoodi e J. E. Schultz. "Soil acidification as influenced by crop rotations, stubble management, and application of nitrogenous fertiliser, Tarlee, South Australia". Soil Research 40, n. 3 (2002): 483. http://dx.doi.org/10.1071/sr00104.
Testo completoAbstract (sommario):
Soil acidification, as influenced by N fertiliser, stubble management, and crop rotations, was investigated using soil samples from a long-term rotation trial at Tarlee, South Australia. With the effects of combination of treatment inputs (wheat–lupin, stubble retention and N-fertiliser application), the pHCa (0–10 cm depth) declined from the starting value of 6.12 to 4.50 after a 14-year period. All of the treatments caused the soil pH to decrease. The mean acidification rates for the period 1978–1992 varied from 0.5 to 2.22 kmol H+/ha.year for different treatments. Although the rainfall at Tarlee (483 mm) is not sufficient to cause regular drainage events, it is likely that downward movement of NO3– in the soil profile has caused acidification in the surface soil. Also the retention of stubble caused more acidification than where there was regular stubble burning or removal. The acidification resulted in an increase in soil exchangeable Al and Mn and extractable Al and Mn, and the decrease in soil exchangeable base cations. The values for soluble Al (extracted in CaCl2) in 1992 were 1.58 and 2.45 mg/kg (0–10 cm depth) for the wheat–bean and wheat–lupin rotations, but the percentage of Al in the ECEC was low. It is not known whether this acidity has any impact on yields of field crops at this stage. But with soluble Al and the percentage of Al in ECEC increasing, it is possible that Al toxicity may occur in the high input-output cropping soils in South Australia. acidity, pH, aluminium, manganese.
39
Lawes, R. A., P. R. Ward e D. Ferris. "Pasture cropping with C4 grasses in a barley–lupin rotation can increase production". Crop and Pasture Science 65, n. 10 (2014): 1002. http://dx.doi.org/10.1071/cp13442.
Testo completoAbstract (sommario):
In southern Australia, intercropping, pasture cropping and overcropping have evolved as techniques to address environmental problems such as dryland salinity and wind erosion and to utilise soil water outside the conventional winter-dominant growing season. We paired three winter-dormant pastures, including two subtropical C4 perennial species (Rhodes grass, Chloris gayana; Gatton panic, Megathyrsus maximus) and the summer-active perennial C3 legume siratro (Macroptilium atropurpureum), with a conventional barley (Hordeum vulgare)–lupin (Lupinus angustifolius) rotation to explore the extent to which different summer-active species reduced crop yields. We also examined whether the competition for resources could be altered by supplying increased nitrogen to the crop and changing the row spacing of the pasture. Under high-input conditions, pasture reduced cereal crop yields by up to 26% and lupin yields by up to 29%. Under low-input conditions, pasture cropping did not significantly reduce crop yield, and frequently increased crop yields. With low inputs, barley yield increases in 2011 ranged from 23% to 31%. In lupins under low-input conditions, yield increases ranged from 91% to 106% in 2010 and from –6% to +39% in 2012. The impact of the crop on the pasture was less pronounced, where the timing of pasture growth was delayed by the crop, but absolute levels of production were not influenced by the crop. Row spacing altered the temporal dynamic of pasture production; initially, the pasture produced less than the narrow spaced equivalent, but after 2 years, production exceeded that in the narrow row. Across all pasture species in 2009 and 2012, winter pasture production reduced crop yield by 0.32 and 0.4 t grain/ha pasture biomass produced, implying that moderate yield losses occurred because pasture production was also moderate. In the other two years, winter pasture production did not affect crop yield, suggesting that the pasture was able to utilise resources surplus to crop requirements. In this environment, with this combination of crops and summer-active pastures, higher levels of inputs did not enhance crop yield in a pasture-cropping system. We suggest that grain yield losses are lower in the low-input system and this implies that, at some level, competition between the species was reduced in a nitrogen-limited environment and the extent of the competition depended on season.
40
McCown, RL. "Being realistic about no-tillage, legume ley farming for the Australian semi-arid tropics". Australian Journal of Experimental Agriculture 36, n. 8 (1996): 1069. http://dx.doi.org/10.1071/ea9961069.
Testo completoAbstract (sommario):
There is a long tradition of expectation that, in time, land use in the better-endowed areas of Australia's semi-arid tropics would intensify from beef production on grassy woodlands to broadacre production of dryland crops. However, successive development attempts have yet to result in a substantial field crop industry. This paper reflects on a recent 20-year research and development episode in which ley farming, so successful in the wheat-sheep zone of southern Australia, was adapted and trialed in the tropical north. The system tested in the tropics was one which featured (i) coarse grain crops in rotation with legume leys and (ii) cattle grazing native pasture in the crop growing season and ley and crop residues in the dry season. It can be concluded that this system is technically successful. But compared with the ley system in southern Australia, the benefits of pasture legumes are less efficiently captured, both in the animal and the crop production enterprises. In addition, in this climate and on these soils, pastures with the high legume composition needed to substantially substitute for nitrogen fertiliser in the crop phase pose a serious threat of soil acidification. In contrast to legume leys, the advantage of no-tillage, mulch farming practices over conventional cultivation is much greater in this semi-arid tropical region than in temperate or Mediterranean areas: by slowing evaporation, mulch is often crucial in reducing high temperature injury or impedance to emerging seedlings as well as reducing the deleterious effects of intensive summer rainfall. But even with this improvement the climatic risks in dryland grain cropping remain a strong deterrent to crop industry development. Today, the findings from past experimentation, accrued farming experience, and new information products combine to provide what seem to be more realistic expectations for agriculture in this region. Even with the 'best' technology, this region suffers comparative disadvantage with respect to dryland field crop production and marketing. However, the region enjoys comparative advantages in the production of several other types of commodities, and a more realistic approach to 'Research and Development' includes a shift of resources toward activities with production and marketing advantages.
41
Monjardino, M., D. J. Pannell e S. B. Powles. "The economic value of haying and green manuring in the integrated management of annual ryegrass and wild radish in a Western Australian farming system". Australian Journal of Experimental Agriculture 44, n. 12 (2004): 1195. http://dx.doi.org/10.1071/ea03144.
Testo completoAbstract (sommario):
Most cropping farms in Western Australia must deal with the management of herbicide-resistant populations of weeds such as annual ryegrass (Lolium rigidum) and wild radish (Raphanus raphanistrum). Farmers are approaching the problem of herbicide resistance by adopting integrated weed management systems, which allow weed control with a range of different techniques. These systems include non-herbicide methods ranging from delayed seeding and high crop seeding rates to the use of non-cropping phases in the rotation. In this paper, the Multi-species RIM (resistance and integrated management) model was used to investigate the value of including non-cropping phases in the crop rotation. Non-crop options investigated here were haying and green manuring. Despite them providing excellent weed control, it was found that inclusion of these non-cropping phases did not increase returns, except in cases of extreme weed numbers and high levels of herbicide resistance.
42
Postlethwaite, Yvonne L., e David R. Coventry. "Using grain sorghum for crop rotation in southern Australia: a farm approach to system development". Agriculture, Ecosystems & Environment 95, n. 2-3 (maggio 2003): 629–37. http://dx.doi.org/10.1016/s0167-8809(02)00199-8.
Testo completo
43
Owen, K. J., T. G. Clewett, K. L. Bell e J. P. Thompson. "Wheat biomass and yield increased when populations of the root-lesion nematode (Pratylenchus thornei) were reduced through sequential rotation of partially resistant winter and summer crops". Crop and Pasture Science 65, n. 3 (2014): 227. http://dx.doi.org/10.1071/cp13295.
Testo completoAbstract (sommario):
The root-lesion nematode, Pratylenchus thornei, can reduce wheat yields by >50%. Although this nematode has a broad host range, crop rotation can be an effective tool for its management if the host status of crops and cultivars is known. The summer crops grown in the northern grain region of Australia are poorly characterised for their resistance to P. thornei and their role in crop sequencing to improve wheat yields. In a 4-year field experiment, we prepared plots with high or low populations of P. thornei by growing susceptible wheat or partially resistant canaryseed (Phalaris canariensis); after an 11-month, weed-free fallow, several cultivars of eight summer crops were grown. Following another 15-month, weed-free fallow, P. thornei-intolerant wheat cv. Strzelecki was grown. Populations of P. thornei were determined to 150 cm soil depth throughout the experiment. When two partially resistant crops were grown in succession, e.g. canaryseed followed by panicum (Setaria italica), P. thornei populations were <739/kg soil and subsequent wheat yields were 3245 kg/ha. In contrast, after two susceptible crops, e.g. wheat followed by soybean, P. thornei populations were 10 850/kg soil and subsequent wheat yields were just 1383 kg/ha. Regression analysis showed a linear, negative response of wheat biomass and grain yield with increasing P. thornei populations and a predicted loss of 77% for biomass and 62% for grain yield. The best predictor of wheat yield loss was P. thornei populations at 0–90 cm soil depth. Crop rotation can be used to reduce P. thornei populations and increase wheat yield, with greatest gains being made following two partially resistant crops grown sequentially.
44
Hollaway, G. J., T. W. Bretag e T. V. Price. "The epidemiology and management of bacterial blight (Pseudomonas syringae pv. pisi) of field pea (Pisum sativum) in Australia: a review". Australian Journal of Agricultural Research 58, n. 11 (2007): 1086. http://dx.doi.org/10.1071/ar06384.
Testo completoAbstract (sommario):
Bacterial blight caused by Pseudomonas syringae pv. pisi is an important, but sporadic, disease of field peas (Pisum sativum) in Australia. The presence of P. syringae pv. pisi reduces the profitability of peas due to yield loss and, in some cases, it also limits Australia’s export of peas to some countries. Pseudomonoas syringae pv. pisi is primarily a seed-borne pathogen, but infected pea trash can be an important source of inoculum. Alternative hosts and soil are not regarded as epidemiologically important sources of inoculum. P. syringae pv. pisi survives, multiplies and spreads epiphytically in pea crops. Epiphytic populations of P. syringae pv. pisi only become pathogenic following crop damage caused by frost or severe weather conditions. Frost damage is especially important because the ice nucleating activity of P. syringae pv. pisi initiates frost damage at higher temperatures than occurs in the absence of the bacterium. In addition early-sown crops are more prone to damage from bacterial blight than crops sown later in the season. Pseudomonas syringae pv. pisi consists of seven identified races. One of these (Race 6) lacks all avirulence genes and is common around the world and in Australia. Globally, Race 2 and Race 6 predominate; however, in Australia, Race 3 predominates due to the widespread cultivation of cultivars susceptible to Race 3, but resistant to Race 2. Resistance to Race 6 within P. sativum has not been found but attempts are being made to incorporate a race non-specific resistance identified from P. abyssinicum into field pea. Bacterial blight can be successfully controlled using an integrated disease management strategy incorporating crop rotation, pathogen-free seed, avoidance of planting in areas prone to frequent frosts or extreme wet weather, crop hygiene and avoiding early sowing. Seed treatment and application of foliar bactericides have limited use in control of this disease.
45
Walker, S. R., I. N. Taylor, G. Milne, V. A. Osten, Z. Hoque e R. J. Farquharson. "A survey of management and economic impact of weeds in dryland cotton cropping systems of subtropical Australia". Australian Journal of Experimental Agriculture 45, n. 1 (2005): 79. http://dx.doi.org/10.1071/ea03189.
Testo completoAbstract (sommario):
In dryland cotton cropping systems, the main weeds and effectiveness of management practices were identified, and the economic impact of weeds was estimated using information collected in a postal and a field survey of Southern Queensland and northern New South Wales. Forty-eight completed questionnaires were returned, and 32 paddocks were monitored in early and late summer for weed species and density. The main problem weeds were bladder ketmia (Hibiscus trionum), common sowthistle (Sonchus oleraceus), barnyard grasses (Echinochloa spp.), liverseed grass (Urochloa panicoides) and black bindweed (Fallopia convolvulus), but the relative importance of these differed with crops, fallows and crop rotations. The weed flora was diverse with 54 genera identified in the field survey. Control of weed growth in rotational crops and fallows depended largely on herbicides, particularly glyphosate in fallow and atrazine in sorghum, although effective control was not consistently achieved. Weed control in dryland cotton involved numerous combinations of selective herbicides, several non-selective herbicides, inter-row cultivation and some manual chipping. Despite this, residual weeds were found at 38–59% of initial densities in about 3-quarters of the survey paddocks. The on-farm financial costs of weeds ranged from $148 to 224/ha.year depending on the rotation, resulting in an estimated annual economic cost of $19.6 million. The approach of managing weed populations across the whole cropping system needs wider adoption to reduce the weed pressure in dryland cotton and the economic impact of weeds in the long term. Strategies that optimise herbicide performance and minimise return of weed seed to the soil are needed. Data from the surveys provide direction for research to improve weed management in this cropping system. The economic framework provides a valuable measure of evaluating likely future returns from technologies or weed management improvements.
46
Robertson, Michael, e Clinton Revell. "Perennial pastures in cropping systems of southern Australia: an overview of present and future research". Crop and Pasture Science 65, n. 10 (2014): 1084. http://dx.doi.org/10.1071/cp14040.
Testo completoAbstract (sommario):
Addressing the opportunities and challenges for integrating perennial forages and shrubs into the mixed crop–livestock farming systems of southern Australia has been the focus of the Future Farm Industries Cooperative Research Centre EverCrop project. This overview discusses the use of perennial plants in cropping landscapes in terms of the concepts of ‘rotation, separation and integration’ and highlights the contribution of papers in this special issue of Crop and Pasture Science across a range of biophysical and socioeconomic factors. Drivers for the inclusion of perennial forage plants include salinity management, groundcover maintenance and filling seasonal feed gaps, and this need will continue as mixed crop–livestock systems evolve in the context of managing business risk and a requirement for better natural resource management outcomes.
47
Armstrong, R. D., R. Perris, M. Munn, K. Dunsford, F. Robertson, G. J. Hollaway e G. J. O. Leary. "Effects of long-term rotation and tillage practice on grain yield and protein of wheat and soil fertility on a Vertosol in a medium-rainfall temperate environment". Crop and Pasture Science 70, n. 1 (2019): 1. http://dx.doi.org/10.1071/cp17437.
Testo completoAbstract (sommario):
Fundamental changes in farming systems occurred throughout the medium-rainfall zone of southern Australia during the late 1990s. Pulse and canola crops replaced pastures and long-fallowing, and minimal-tillage practices were increasingly adopted. An experiment was established in 1998 to examine long-term effects of these changes on crop productivity and soil fertility. Nine rotation–tillage treatments based on 3- and 6-year cycles were compared by using wheat (Triticum aestivum) as a bioassay crop over 2001–17. Seasonal conditions during the study ranged from the Millennium Drought to the top rainfall decile. Averaged across the 17 seasons, wheat yields were significantly lower in rotations based on continuous wheat (1.73t/ha) or 3 years of perennial lucerne (Medicago sativa) (1.93t/ha) and highest after traditional long-fallow (2.92t/ha) or vetch (Vicia sativa) green manure (2.57t/ha). Wheat yields following a pulse (2.23t/ha) or canola (Brassica napus) (2.21t/ha) were intermediate. Whereas rotation effects varied with seasonal rainfall, there was a long-term trend for relative yields in continuous wheat rotations to decline and those following a green manure or fallow to differ increasingly from other treatments. Compared across the same rotation (canola–wheat–pulse), average wheat yields under no-tillage (2.09t/ha) were significant lower (P<0.05) than under reduced (2.22t/ha) and conventional (2.29t/ha) tillage. By contrast, grain protein concentration increased with increasing proportion and type of legumes (green manure and pasture>pulse) in the rotation via their effect on soil mineral nitrogen (N). Lowest protein was recorded in continuous wheat and highest where at least one-third of the rotation contained a non-pulse legume, i.e. vetch green manure, lucerne or annual medic (Medicago truncatula). Soil-borne cereal fungal pathogens and nematodes generally had little effect on grain yields. Soil organic carbon (SOC) and total N stocks declined in all treatments over time, except in the lucerne and green manure treatments, where total N was maintained. Greatest declines in SOC and total N occurred in the fallow treatment. Results from the first 20 years of experimentation suggest that differences in grain yield (and protein) of wheat were most likely the result of treatment (rotation and tillage practice) effects on soil nitrate and water (growing-season rainfall and fallow storage) rather than disease. We found no evidence that current farming systems based on use of pulses, canola and reduced tillage are less able to maintain intervening cereal yields than traditional systems. On the contrary, practices such as long-fallowing are expected to have increasing negative influence on productivity in the longer term via decreased soil C and N fertility.
48
Yunusa, I. A. M., W. D. Bellotti, A. D. Moore, M. E. Probert, J. A. Baldock e S. M. Miyan. "An exploratory evaluation of APSIM to simulate growth and yield processes for winter cereals in rotation systems in South Australia". Australian Journal of Experimental Agriculture 44, n. 8 (2004): 787. http://dx.doi.org/10.1071/ea03121.
Testo completoAbstract (sommario):
The Agricultural Production Systems Simulator (APSIM) suite of models was used to predict dynamics in water and nitrogen in soil, as well as the growth and yield of sequential crops of wheat and barley in pasture–wheat–barley rotations, between 1995 and 1997 at Roseworthy, South Australia. The NWHEAT model satisfactorily predicted above-ground dry matter, leaf area index and grain yields for both crops in rotations with either grassy (Grass) or medic (Medic) pastures, including the lack of significant response of yield to nitrogen fertiliser applied to wheat at sowing. Simulation data for soil water, from SOILWAT2, was consistent with measured data. Simulation with SOILN2, however, largely underestimated soil nitrogen, due to excessive uptake by the simulated wheat during the season when nitrogen was abundant and water supply readily available. Thus, the soil nitrate had to be reset at sowing for the following barley crop; simulated soil nitrate agreed with the measured data in this season when this nutrient was low. For most variables of crop growth and soil water, the simulated data were mostly within 2 standard errors of the measured means. Prediction of grain protein was underestimated in all cases, including where nitrogen in the shoot was overestimated. This was possibly due to inadequate remobilisation of nitrogen from the straw and roots to the grain by the simulated crop. A satisfactory prediction of dry matter, grain yield and grain weight was obtained for wheat when the models were extended to other trials at Roseworthy (Lower North), Minnipa (Upper Eyre Peninsula) and Wunkar (Murray Mallee), based on limited soil data. Long-term simulations of wheat yields showed that, with early sowing in the Lower North, median wheat yield increased by 50 kg/ha for every kilogram of nitrogen applied at sowing, up to a maximum nitrogen rate of 50 kg/ha. In the drier districts of the Upper Eyre Peninsula and the Murray Mallee, nitrogen fertiliser of no more than 25 kg/ha, applied at sowing, was enough to achieve yield benefits in any given season. At these drier sites, crop failures occurred in 5% (Upper Eyre Peninsula) and 10% (Murray Mallee) of the seasons simulated. Median sowing dates from these simulations were 15 May for the Lower North, 30 May for the Upper Eyre Peninsula and 24 May for Murray Mallee. This suggested that sowing could be conducted at least a week earlier than currently practised in the 3 environments. This study demonstrated the capability of APSIM to predict growth and grain yield of wheat and barley, as well as the associated dynamics of soil water in the main cereal belts of South Australia.
49
Roget, DK. "Decline in root rot (Rhizoctonia solani AG-8) in wheat in a tillage and rotation experiment at Avon, South Australia". Australian Journal of Experimental Agriculture 35, n. 7 (1995): 1009. http://dx.doi.org/10.1071/ea9951009.
Testo completoAbstract (sommario):
Studies of a tillage x rotation field experiment begun in 1978 at Avon, South Australia, have demonstrated a decline in rhizoctonia root rot of wheat. In direct-drilled treatments the severity of rhizoctonia root rot culminated in 1983, with patches of poor plant growth accounting for up to 46% of the crop area, and then declined to negligible levels by 1990. Disease severity was significantly less in cultivated than direct-drilled treatments. In cultivated treatments the onset of decline was more difficult to determine, but by 1990 there was negligible rhizoctonia root rot in either tillage treatment, with no increase in disease from 1990 to 1994. Decline in rhizoctonia root rot occurred largely independent of rotation, although there were significant differences in root damage and patch area between rotations, with disease generally being more severe in wheat following pasture than following peas, medic, or wheat. When inoculum of R. solani was added to soil collected from the experimental site in 1985, wheat grown in soil from direct-drilled plots had significantly less disease than wheat grown in soil from cultivated treatments, indicating a possible development of suppression.
50
Silsbury, JH. "Grain yield of wheat in rotation with pea, vetch or medic grown with three systems of management". Australian Journal of Experimental Agriculture 30, n. 5 (1990): 645. http://dx.doi.org/10.1071/ea9900645.
Testo completoAbstract (sommario):
Pea (Pisum sativum L. cv. Alma), vetch (Vicia sativa L. cv. Languedoc) and annual medic (Medicago truncatula Gaertn. cv. Paraggio) were grown at Brinkworth, South Australia, in 1987 in large (0.75 ha) plots and subjected to 3 systems of management: (i) ploughing in at flowering as a green manure crop, (ii) harvesting for grain and ploughing in the dry residues, and (iii) harvesting for grain and removing the residues. A wheat crop was sown over the whole area in the following season (1988) and the effects of type of legume and management on grain yield and grain protein content were measured. The management system imposed on the legume had a highly significant (P<0.01) effect on the grain yield of the following wheat crop, but there were no significant differences between the 3 legumes in their effects on wheat yield or on grain protein content. Ploughing in the legumes as a green manure crop at flowering added about 100 kg/ha more nitrogen (N) to the soil than allowing the legumes to mature, harvesting for seed, and removing residues. Incorporating the dry residues rather than removing them added about 26 kg N/ha. The green manure crop significantly increased subsequent wheat yield (by 49%; P<0.001) and protein content of the grain (by 13%; P<0.05) compared with the treatment in which the legumes were harvested for grain and all residues removed; incorporating the dry residues increased yield by 10%. It is concluded that the amount of N added during the legume phase in a rotation is more important than the kind of legume from which the N is derived. The occasional use of a dense legume crop as a green manure may rapidly add a large amount of N to a soil to be slowly exploited by following grain crops.