Dissertations / Theses on the topic 'Hedgerow intercropping'

Thesis (M.S.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 3, 2008) Includes bibliographical references.

If upland rice production is to be sustained on sloping land, soil erosion and fertility decline must be addressed. Where soil profiles are deep, hedgerows of Gliricidia sepium and Cassia spectabilis, planted on the contour, reduce soil erosion by promoting terrace formation and overcome fertility depletion by providing nutrient rich biomass. G. sepium and C. spectabilis established by seed survived better than by cuttings. Although increased hedgerow biomass was initially obtained when both species were intercropped, intense competition was observed in established hedgerows. Consequently, mixing both species at high planting density is not recommended as C. spectabilis, a non-fixing legume, may deplete soil-N reserves. In acid soils, biomass production of G. sepium was significantly increased when lime (6 t/ha) was applied. On 18 to 30% slopes, upland rice and maize production improved along fertility and moisture gradients. Rice yields were increased when biomass of G. sepium was incorporated into the soil, up to an optimum level equivalent to 40 kg N/ha. Mulching C. spectabilis increased maize productivity during the drought prone second season. Competition was observed at the hedgerow-crop interface particularly at the upper one as a result of terracing. Although green manuring increased crop yield, broadleaf weeds, seedling maggot, stemborer and blast also increased. Strategies to manage hedgerow biomass that minimize these problems need to be developed.

The potential of agroforestry to alleviate problems related to scarcities of arable land, water, food and fuel wood is subject to understanding system functioning and implementing and managing an efficiently designed system. The objectives of this study were to understand interactions and productivity of a hedgerow intercropping system with reference to water and radiation use, and analyse system design and management scenarios in order to enhance returns. Field trials monitoring soil water, solar radiation and plant productivity were conducted during 2006-2008 at Ukulinga Research Farm (KwaZulu Natal, South Africa) using a Jatropha-Kikuyu (Pennisetum clandestinum) hedgerow intercropping system as case study. In order to extrapolate results, a process-based hedgerow intercropping model was developed by building intercropping and tree growth into the SWB-2D model. Data collected from the field trials were used to parameterise and evaluate the model, which was used to analyse hedgerow orientation and spacing to determine income scenarios of virtual system and to help develop design criteria. Allometric relationships of Jatropha using basal stem diameter and crown width as predictor variables were found to be very reliable. Stem diameter was linearly related with wood and branch proportions and inversely proportional to foliage. Neither below-ground (BG) interspecies competition nor tree spacing had any significant effects on allometry. Allometric equations were proven valid for accurate, non-destructive and rapid predictions of tree growth under various growing and non-destructive canopy management conditions. When interspecies competition was present, none of the tree spacing/arrangement options tested resulted in consistently highest tree relative growth rates (RGR). Treatments had no effect on tree RGR when high water availability and kikuyu dormancy coincided. The single-row treatment (SR) produced the shortest trees, but generally had the highest stem RGR during low rainfall periods. The standard-spacing treatment (SS) had the highest RGR during the spring and summer seasons. Jatropha-only treatment (JO) trees were the tallest and biggest. Treatments affected post-pruning tree height increase, even when rainfall was high. Length of tree-crop interface (TCI) generally decreased tree yield, especially as trees matured toward their maximum-yield age (4-5 years). SR trees showed slow response to pruning due to a high TCI. They, however, exhibited compensatory growth during May to August, when competition for water with grass was low. BG competition reduced tree nut yield more than tree biomass. Tree spacing/arrangements had no effect on tree harvest index. Soil water varied among treatments and was asymmetrically distributed across tree hedgerows. System ET was generally the highest in SR and lowest in the double-row treatment (DR). Differences were mainly due to transpiration. Treatments affected tree root distribution, which was inferred using correlations between tree RGR and soil water deficit (SWD). In JO and SR, fine tree roots were asymmetrically distributed. Their distribution in DR was essentially symmetrical. Strong vegetative RGR-SWD correlations during the 2007/08 season indicated that tree growth was mainly water-limited. Though DR and SR had comparable tree RGRs, DR produced less grass than SR. This implied DR had more intensive BG competition than SR. Interspecific competition was severe due to a lack of temporal complementarity between Jatropha and kikuyu and a shallow soil profile (0.6 m). Tree water uptake predominantly came from the 0.2 – 0.6 depth, which had about 8.6% of the total root biomass in the profile. There was no clear relationship between intercrop growth and root distribution. Radiation use efficiency of kikuyu decreased towards tree hedgerows possibly due to preceding interaction of the irradiance with tree canopy reducing photosynthetically active radiation. The effect of radiation distribution on tree-crop (T-C) interactions was mainly to magnify effects of water. Finally, tree spacing/arrangement could be manipulated to optimise radiation and soil water distribution and intercrop growth. Predictions of solar radiation distribution, profile water content and tree water use were quite accurate. In general, intercrop productivity simulations were acceptable. Intercrop growth was overestimated when rainfall was high and underestimated when rainfall was low. During model calibration, tree woody biomass, leaf area index, crown width and nut yield were predicted adequately, while leaf dry mass was overestimated. During model validation, woody biomass and crown width were simulated reasonably well. However, foliage biomass, leaf area index and nut yield were overestimated. Overall, adequacy of the model for simulating tree productivity was established. Using scenario modelling, model capabilities to facilitate design/planning and management of hedgerow intercropping systems and interpretation of model outputs were demonstrated. The model can be used to determine the T-C trade-off that yields maximum income. By selecting best-case row orientation and spacing scenarios using the model, and keeping in mind values of tree and intercrop yields, system returns can be maximised. Tree crown growth can also be predicted in order to decide on the extent and timing of pruning. The present model is applicable to any potential tree-intercrop combination. It should be linked to a nutrient simulator of SWB, its component, and appraised further by considering shade-intolerant and shade-loving crop species, along with evergreen and deciduous tree species. This provides model users with numerous T-C combinations to choose from. Various tree spacing/arrangement options can also be explored using the model in order to realise the full potential and implications of the experimental findings of this study and others.
Thesis (PhD)--University of Pretoria, 2012.
gm2014
Plant Production and Soil Science
unrestricted

Thesis (M.S.) University of Missouri-Columbia, 2006.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 20, 2007) Vita. Includes bibliographical references.

Two studies were carried out in the Morgan Arboretum of McGill University to explore the agroforestry potential of some native tree species of Southern Quebec. In the first study, soil chemical characteristics under basswood (Tilia americana L.), white ash (Fraxinus americana L.) and bitternut hickory (Carya cordiformis Wang. K. Koch) in relation to sugar maple (Acer saccharum Marsh.) were assessed in natural stands. Soil pH was highest under white ash and was lowest under bitternut hickory. Soil NO$ sb3 sp-$ was low under basswood compared to white ash. Soil pH and exchangeable soil Ca$ sp{2+}$ and Mn$ sp{2+}$ decreased with an increase in basal area and exchangeable soil K$ sp+$ decreased (p = 0.07) with an increase in the proportion of sugar maple relative to total basal area.
In the second study, the effects of black walnut (Juglans nigra L.) on growth and nutrient content of lettuce (Lactuca sativa L.), kale (Brussica oleracea L.), parsley (Petroselinum crispum) and Swiss chard (Beta vulgaris L.) in an alley cropping system were determined. The experiment was carried out in a randomized complete block design with repeated measures. All vegetables survived in the black walnut plantation and in the open field. The order of sensitivity to growth under black walnut was Swiss chard $>$ kale $>$ lettuce $>$ parsley. Low light intensity in the plantation likely decreased plant dry weights and nutrient content. Generally plant N, P and K concentrations were higher in the plantation while Ca, Mg and Mn concentrations were higher in the open field, possibly due to an antagonistic effect of high soil K$ sp+$ content in the plantation and to inhibitory effects of black walnut.

[Truncated abstract] Removal of native vegetation to facilitate traditional agriculture practices has been shown to reduce ecosystem health, and restricts the native habitat. The subsequent change in the predominant vegetation water use patterns has altered the catchment water balance, and hydrology which results in land degradation through such processes of salinisation and water logging. More recently, moves toward more sustainable farming practices have been taken to help re-establish catchment hydrological equilibrium and improve catchment ecosystem services. Agroforestry is one such vehicle for this reestablishment. Perennial native vegetation has been shown to have a significant effect on catchment processes, mitigating any further degradation of the land. The effect of alternating native perennial tree belts with traditional broad acre agriculture in the alleys, referred to as alley farming, is investigated in this thesis due to the potential environmental and economic benefits that can result. This thesis investigates the impact of tree belts upon the water table and aims to gauge the ability of alley farming at controlling recharge within the low-medium rainfall zone on the valley floor. The basis of this research is the analysis of data collected from the Toolibin Alley Faring Trial. This experiment was established in 1995 to assess the viability of alley farming and incorporates different combinations of belt width, alley width and revegetation density. Transects of piezometers within each design have been monitored from October 1995 to January 2008. The piezometers were sporadically monitored over this period on a total of 39 dates. ... To further understand the response observed in the water table data, in depth hydrograph analysis of the control piezometer water levels was conducted. The statistical analysis demonstrates that the belts are having a very limited impact on the water table morphology, this is associated with the restricted use of groundwater by the perennial tree belts due to the poor quality, has been applied. This explains why there is limited signature of increased water table depth in the statistical analysis; there is evidence that alley farming as a means of reducing recharge may work however the overriding control on the trial are the rainfall trends rather than perennial growth. The low perennial biomass production at the site is an effect of limited water resources; however a significant distinction can be made between the water table depth and variability beneath high and low biomass belts. There are three main controls at the site; climate, development of perennial biomass and development of perennial root systems (both vertically and laterally). The regional climatic trends will influence water table levels creating a greater soil water storage capacity; therefore the contribution of soil water to transpiration rates will enable the tree belts to have some impact on recharge. Of the alley farming designs tested, the optimal planting density and belt/alley design, from an economic perspective, is identified as having a 4m belt width which generated the greatest biomass. As a means of controlling recharge at the site the effectiveness of alley farming is limited due the shallow saline water table limiting perennial growth.

[Truncated abstract] Insufficient water use by annual crop and pasture species leading to costly rises in saline watertables has prompted research into potentially profitable deep-rooted perennial species in the Western Australian wheatbelt. Native mallee eucalypts are currently being developed as a short-rotation coppice crop for production of leaf oils, activated carbon and bio-electricity for low rainfall areas (300—450 mm) too dry for many of the traditional timber and forage species. The research in this study was aimed at developing a knowledge base necessary to grow and manage coppiced mallee eucalypts for both high productivity and salinity control. This firstly necessitated identification of suitable species, climatic and site requirements favourable to rapid growth, and understanding of factors likely to affect yield of the desirable leaf oil constituent, 1,8-cineole. This was undertaken using nine mallee taxa at twelve sites with two harvest regimes. E. kochii subsp. plenissima emerged as showing promise in the central and northern wheatbelt, particularly at a deep acid sand site (Gn 2.61; Northcote, 1979), so further studies focussed on physiology of its resprouting, water use and water-use efficiency at a similar site near Kalannie. Young E. kochii trees were well equipped with large numbers of meristematic foci and adequate root starch reserves to endure repeated shoot removal. The cutting season and interval between cuts were then demonstrated to have a strong influence on productivity, since first-year coppice growth was slow and root systems appeared to cease in secondary growth during the first 1.5—2.5 years after cutting. After decapitation, trees altered their physiology to promote rapid replacement of shoots. Compared to uncut trees, leaves of coppices were formed with a low carbon content per unit area, and showed high stomatal conductance accompanied by high leaf photosynthetic rates. Whole-plant water use efficiency of coppiced trees was unusually high due to their fast relative growth rates associated with preferential investments of photosynthates into regenerating canopies rather than roots. Despite relatively small leaf areas on coppice shoots over the two years following decapitation, high leaf transpiration rates resulted in coppices using water at rates far in excess of that falling as rain on the tree belt area. Water budgets showed that 20 % of the study paddock would have been needed as 0—2 year coppices in 5 m wide twin-row belts in order to maintain hydrological balance over the study period. Maximum water use occurred where uncut trees were accessing a fresh perched aquifer, but where this was not present water budgets still showed transpiration of uncut trees occurring at rates equivalent to 3—4 times rainfall incident on the tree belt canopy. In this scenario, only 10 % of the paddock surface would have been required under 5 m wide tree belts to restore hydrological balance, but competition losses in adjacent pasture would have been greater

Thesis (M. Sc. Agriculture (Agronomy)) -- University of Limpopo, 2019
Pigeonpea (Cajanus cajan (L) Millsp.) is an important grain legume crop in tropical and subtropical countries, where it provides a cheap source of protein. Smallholder farmers in Limpopo Province cultivate landraces of pigeonpea, which are characterised with late maturity, low grain yield and being sensitive to photoperiod. To increase the productivity of the cropping system involving pigeonpea, several earlymedium maturity varieties have been introduced. However, performance of the varieties has not been tested in strip intercropping in Limpopo Province. Farmers plant these landraces by using mixed intercropping without definite row arrangement. This practice does not optimise plant density; it hinders farm inputs application and is characterised producing low yields. Therefore, the inclusion of early maturing varieties of pigeonpea in an intercrop will enable farmers to select the best variety for planting in future and thus enhance their output as well as their productivity. The objectives of this study were to assess the agronomic performance of five pigeonpea varieties in pigeonpea-maize strip intercropping, to determine the effect of strip intercropping on maize yield and establish the effect of location and season variations on the performance of both component crops under the intercropping system. Experiments were conducted at the University of Limpopo Experimental Farm (UL Farm) and Ga-Thaba village during the 2015/16 and 2016/17 season. Five improved early-medium maturing pigeonpea varieties (ICEAP 001284, ICEAP 00604, ICEAP 87091, ICEAP 00661 and ICEAP 01101-2) from ICRISAT were evaluated under strip intercropping with maize cultivar PAN 6479. The varieties were selected as earlymedium maturing varieties from previous pigeonpea trials. The trials were laid in a split plot design. The main plot comprised cropping systems (intercrop and monocrop), while the subplot comprised the varieties with three replications. Data collected on pigeonpea were number of days to 50% flowering and 90% maturity number of primary branches; plant height (cm); number of pods per plant; pod length (cm); number of seed per pod; hundred seed weight (g); and grain yield (kg ha-1), whereas on maize, number of days to 50% tasselling and silking; plant height (cm); cob length (cm); cob per plant; grain yields (kg ha-1); and stover (kg ha-1) were recorded. LER was calculated to determine intercropping productivity. Data analysis was done using Statistic 10.0; and Least Significance Difference (LSD) was used to separate the means that showed significant differences at an alpha level of 0.05. The results revealed significant differences in nearly all pigeonpea variables expect (pod length, number of seed per pod and hundred seed weight). Variables that showed significant differences in maize were plant height, cob length, grain yields and stover. Number of days to 50% flowering and 90% physiological maturity differed significantly (P ≤ 0.05) among varieties at the UL Farm and Ga-Thaba. Varieties (ICEAP 001284 and ICEAP 00604) exhibited the shortest number of days to 50% flowering and 90% maturity in both locations during both seasons. The interaction between variety x season (V x S) showed significant (P ≤ 0.05) differences in pigeonpea grain yield. The top yielders during 2015/16 at the UL Farm were ICEAP 01101-2 (1555 kg ha-1) and ICEAP 001284 (1280 kg ha-1), while during the 2016/17 season, they were ICEAP 001284 (937 kg ha-1) and ICEAP 01101-2 (912 kg ha-1). High yielder at Ga-Thaba during the 2016/17 season were ICEAP 001284 and ICEAP 01101-2 with grain yields of 671 kg ha-1 and 627 kg ha-1, respectively. Furthermore, varieties that obtained high yields during the 2015/16 season were ICEAP 001284 (504 kg ha-1) and ICEAP 00604 (541 kg ha-1). Most of the varieties during both seasons at the UL Farm and Ga-Thaba yielded more than 500 kg ha-1 under strip intercropping as compared to mixed intercropping, which obtained yields averages of below 400 kg ha-1. The highest maize grain yields of 1450 kg ha-1 were recorded during 2015/16 as compared to 958 kg ha1 during the 2016/17 season at the UL Farm. The calculated total Land Equivalent Ratio (LER) for the two crops in both locations gave positive and higher than 1 values, which suggests a favourable grain yield advantage for maize-pigeonpea strip intercrop over mixed intercropping. Key words: Cajanus cajan, maize, cropping system, maturity, grain yields, land equivalent ratio

"June 2001"
Bibliography: p. 165-183.
xxviii, 250 p. : ill., plates (col.), maps (col.) ; 30 cm.
The aims of this study were to develop models for predicting groundwater recharge from alley farming systems in the Murray Basin and for designing alley farms that will result in a prescribed recharge reduction. --p. 158.
Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy and Farming Systems, 2002

"June 2001"
Bibliography: p. 165-183.
xxviii, 250 p. : ill., plates (col.), maps (col.) ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
The aims of this study were to develop models for predicting groundwater recharge from alley farming systems in the Murray Basin and for designing alley farms that will result in a prescribed recharge reduction. --p. 158.
Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy and Farming Systems, 2002

Alleycropping is an agroforestry technology of planting crops between rows of trees, preferable legumes to promote an interaction among them with positive benefits in terms of improving soil fertility and hence good crop yields. The technology has been tested with a variety of trees/shrubs species in association with crops (alleycropping) or with grasses (alleygrazing), sometimes with encouraging results and sometimes not, in a wide range of environmental conditions around the world. Research in alleycropping started in late 1970s and sinc~ then many publications have been released. However, little or nothing has been reported about this technology using black wattle and the fever tree, two nitrogen-fixing trees common in South Africa and reported as fast-growing species which produce a considerable amount of biomass within a short period of time. Due to that fact, a two-year trial was established in 2003 at the Ukulinga research farm, Pietermaritzburg, South Africa to evaluate the potential of the two tree species under alleycropping with maize and cowpeas as joint intercrops, under alleycropping with pumpkin, and under alleygrazing with Eragrostis curvula and with Panicum maximum. The trial assessed the crop yields and the biomass production from all the components, and their fodder digestibility using Neutral Detergent Fibre (NDF) and Acid Detergent Fibre (ADF) determinations. Additionally the changes in tree grovlth vaa."'i.ables (difu~eter, total height, total \lollhl1e and biomass) were mortitored to produce regression equations to predict those variables, one from another, using regression analysis. The diameter was taken at ground level (dgl) and at the height of 1.3 m, normally called diameter at breast height (dbh). The results showed that tree growth and biomass production were better in black wattle alleycropping than in association with the fever tree. The average dgl of black wattle after 12 months was 48mm and the average dbh was 36mlll. Over the same period the total tree height was about 406cm. A tree pruning was done to one-year old black wattle in the whole trial and the prunings produced about 5.6t/ha of fresh foliage biomass in the association with maize and cowpea and 4.5t/ha in the association with pumpkin. In alleygrazing the growth variables were similar to those obtained in alleycropping but the biomass production was considerably different. The prunings produced about 7.66t/ha of fresh foliage biomass. The dry matter biomass from the prunings was 1.96t/ha, 1.58t/ha and 2.68t/ha in the association with maize and cowpeas, pumpkin and E. curvula respectively. The dry matter was obtained from 4days- oven-dried samples and it was 35% of the fresh foliage biomass and 60% of the fresh woody biomass. The fever tree did not grow significantly during the study period and due to that fact, the species was discarded from the study. Similarly, because after several endeavours using different seed lots, P. maximum had germinated very unevenly, and this grass was excluded from the experimentation. Values ofNDF and ADF less than 35% are considered good, between 35% and 60% fair and poor if greater than 50%. Using is classification the NDF and ADF values from this study were good in pumpkin (30.5% and 29.9%) and cowpeas (36.5% and 46.9%) biomass, fair in E. curvula (41.9% and 39.9%) and maize stover (53.6% and 42.1%) and poor in black wattle (76.58% and 68.1%) foliage. If black wattle is to be used as fodder, it must be mixed with highly digestible fodder like P. maximum, Digitaria sp., and other legume plants, to increase animal intake and to avoid any risk of it becoming an animal hazard due to tannin effects. The regression equations produced linear relationships between dgl and age, and biomass and dbh. The other interactions were not linear. The best equations were obtained in the interaction between dgl and age (dgl= 4.8*Age -7.03; R2 =0.86; SE= 6.6), dgl and height (h= -0.03dg12 + 10.5dgl - 21.25; R2= 0.96, SE= 42.9, h= height), biomass and dbh (lny = 2.409*lndbh; R2=0.99, SE=O.O, Y= tree foliage biomass). During the study, monkeys, cattle, birds and bushbucks posed a threat to the success of the study due to damage they caused to the crops. It was possible to keep the damage below the critical levels, although at high cost.
Thesis (M.Env.Dev.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.