Gotowa bibliografia na temat „Deep-placed fertiliser”

Much of our knowledge of plant growth in response to soil nutrient supply comes from studies under homogeneous soil conditions. However, the adoption of reduced or nil tillage and shallow banding of fertilisers at the time of seeding causes spatially variable distribution and availability of soil nutrients in agricultural lands. Soil available nutrients, particularly the poorly mobile ones such as phosphorus (P), potassium (K), zinc (Zn), manganese (Mn), and copper (Cu), stratify within the fertilised topsoil. In water-limited environments where the topsoil is prone to drying, soil nutrient stratification may influence nutrient availability and plant uptake because of impeded root growth or reduced diffusion of immobile nutrients to the root surface, or more likely a combination of both factors. Placing fertilisers deeper in the soil profile could increase nutrient acquisition and utilisation by plants as fertiliser nutrients are in the moist soil for a longer part of the growing season. However, the effectiveness of deep placement of fertilisers may also be determined by soil texture, tillage, fertilising history, nutrient mobility, and crop species. In Mediterranean-type climates of southern Australia, a yield response of winter crops to deep fertiliser mostly occurs on infertile sandy soils in low rainfall regions. This contrasts with the responses of winter and summer crops in northern Australia on soils with optimum-to-high nutrients but subjected to rapid and frequent drying of topsoil because of high temperatures and high evaporation demand during the growing season. The pattern of nutrient accumulation by crop species (indeterminate v. determinate) and the mobility of mineral nutrients in the phloem would also modify the effectiveness of deep-placed nutrients under drought. The complexity of plant responses to subsoil nutrition may suggest that before adopting deep fertiliser practice in a paddock it is essential to understand the effects of edaphic and climatic conditions, soil management, and plant–soil interactions in order to achieve maximum yield benefit.

Much of the fertiliser nitrogen (N) used in agriculture is lost to the atmosphere as nitric oxide and nitrogen dioxide (collectively referred to as NOx), ammonia (NH3), and nitrous oxide (N2O). The lost N is not only an economic problem for the farmer; it also contaminates the environment and affects human health. Because the values obtained for NOx and NH3 loss to the atmosphere from agriculture in Monsoon Asia have been questioned, we quantitatively determined, using new techniques, the emission of these gases from a maize crop fertilised with urea in northern China. The fertiliser was deep-placed by traditional farmers’ practice and emissions of NOx and NH3were determined with a chemiluminescence analyser and a backward Lagrangian stochastic dispersion technique. The emission measurements indicate that 1.2% of the applied N was lost as NOx. This loss is far greater than measured or derived by other researchers, and we suggest that this is because our measurements were made continuously rather than as spot measurements with static chambers. The results for NH3 show that, although the fertiliser was placed below the soil surface, a small amount (7% of the applied N) was still lost to the atmosphere. Soil analyses indicate that the rate of nitrification in this soil was low, and the maximum nitrate (NO3–) concentration found in the soil (31.4 µg N/g) was only 3.9% of the fertiliser N added. Thus, there is little potential for NO3– to be leached down the profile. A study using soil cores and acetylene inhibition to measure denitrifying activity suggested that the rate of denitrification in this soil was also very low. The results suggest that in this soil with slow nitrification and denitrification rates and little potential for leaching, deep placement of the urea to limit NH3 volatilisation is an effective method for increasing fertiliser use efficiency.

Plant testing of wheat crops in south-western Australia, sown using no-till for >7 years, often indicates marginal to deficient levels of the soil immobile elements phosphorus (P), copper (Cu) and zinc (Zn). In this region, P, Cu and Zn fertilisers are usually placed (drilled) with the seed while sowing crops. However, in no-till cropping, because the fertilisers are placed in the same rows as the seed during sowing, in the years after application the 3 elements are no longer mixed through the top 10 cm of soil. It may be more effective to deep band fertiliser below seed while sowing no-till crops. Alternatively, cultivating the top 10 cm of soil every 5–7 years would mix previously applied fertiliser P, Cu and Zn through the topsoil, which should improve the effectiveness of the fertiliser residues for the current and subsequent no-till crops. In field experiments in paddocks in south-western Australia sown using no-till for 7–11 years, we compared these 2 alternative methods to the standard no-till practice of drilling fertiliser with the seed in the same crop rows. No shoot or grain yield responses of wheat were obtained. The exception was that in 1 experiment cultivating the topsoil before drilling P with seed was more effective than drilling or deep banding P. Concentrations of P, Cu and Zn measured in wheat shoots or grain were either unaffected by treatment, or, compared with drilling fertiliser with seed, were larger for the other 2 methods, indicating these 2 methods were more effective at increasing the concentrations of the elements in plant parts. The 3 elements have been shown to have good residual values for crop production in the region. Therefore, we recommend that experiments should not be performed in existing no-till paddocks until the residual value of P, Cu and Zn applied in the old cropping system has become negligible, which could, for Cu and Zn in particular, take many years. In the second year, the experiments were used to compare 4 different ways of collecting soil samples from the top 10 cm of soil (standard soil sampling depth used in south-western Australia) to measure soil test P (Colwell), Cu (ammonium oxalate) and Zn (DTPA). The samples were either collected randomly within the plots (present method), always in the rows used to sow seed and apply fertiliser, always between the rows, or half in and half between the rows. Soil test values for P, Cu and Zn were unaffected by amount of element applied and method of application when samples were collected between rows, at random, or from all banded treatments where fertiliser was placed below the 0–10 cm sampling depth. Soil test values for samples collected in rows increased as the amount of fertiliser applied increased and were about double the values for samples collected half in and half between rows.

Research in Western Australia and South Australia indicated that fertiliser phosphorus (P) banded below the seed of narrow leaf lupin (Lupinus angustifolius L.) at sowing was a more effective method of applying P�fertiliser than the usual placement of P with the seed. This technology has not been investigated in southern New South Wales where lupins have been known to be unresponsive to fertiliser P.We conducted 4 field experiments to examine the effect on lupin yield of applying 6 rates of P (0, 5, 10, 15, 20 and 40 kg/ha) either by placement with or below the seed. To further test responsiveness to P, an additional set of treatments was used; applying P at 40 kg/ha before sowing and then placing additional P below the seed at the 6�rates of application. The grain yield of lupin was increased by P application at all sites, despite the medium to high P�status of 3 of the 4 sites used in these experiments. However, the technique of banding P fertiliser below the seed depth rather than placing it in direct seed contact had only a small advantage in grain yield responsiveness to applied fertiliser P (P = 0.09). Fitted response curves indicated that when P was applied at 15 kg/ha, grain yield increased by 60 kg/ha at one site and 30 kg/ha at the other 3 sites, if P was deep-placed rather than applied in seed contact. This advantage of deep placement of P fertiliser was much smaller than has been reported in Western Australia.Placement of P below the seed of lupin when sown on the red earth and red-brown earth soils of southern New South Wales slightly enhanced the availability of fertiliser P. This applied even when sowing was quite shallow (2–3�cm), provided recommended rates of P fertiliser were used at conventional row spacing (17 cm). Separation of seed and fertiliser to avoid reduced germination may be an advantage when using double row spacing and higher P�application rates.

Foxtail barley (Hordeum jubatum L.) is becoming a more severe weed problem as conservation tillage becomes widely adopted on the southern Canadian prairies. A 5-yr field study was conducted to determine the combined effects of tillage, N rate, N placement and application timing of glyphosate to manage foxtail barley in spring wheat. Wide-blade tillage conducted in fall and spring, compared to zero-till, reduced foxtail barley biomass and seed production in all yr and increased wheat yield in 4 of 5 yr. Foxtail barley was highly competitive with wheat for added N. N fertiliser placed mid-row in 10-cm-deep bands reduced foxtail barley growth in 2 of 5 yr and increased wheat yield in 3 of 5 yr compared with soil surface broadcast N. Wheat yield sometimes was similar when N was banded at 60 kg ha−1 or broadcast at 120 kg ha−1, indicating the large advantage of banding N in some situations. Glyphosate at 800 g ha−1 applied preharvest or postharvest gave similar levels of foxtail barley control in 2 of 3 yr. Results indicate that foxtail barley can be adequately managed in wheat production systems utilizing conservation tillage. Key words: Foxtail barley, Hordeum jubatum, glyphosate, integrated weed management, nitrogen placement, zero tillage

Laboratory and field experiments were conducted to determine the effects of urea fertiliser placed with the seed and flutriafol fungicide seed dressing on germination, coleoptile length and establishment of wheat (cvv. Bass and Hartog) and barley (cv. Grimmett). Interactions with depth of sowing and press wheel pressure were also measured in the field. Placement of urea (1 and 2 g/m) with the seed reduced germination, final coleoptile length and field establishment at 2 seeding depths (40 and 75 mm) and delayed field emergence. Flutriafol (0.025 or 0.1 g/kg seed) had no effect on laboratory germination or field establishment but reduced final coleoptile length in the laboratory and delayed field emergence by up to 4.3 days. Compacting the soil over the seed by applying pressure with a press wheel increased establishment from 28 to 37%. With deep sowing (75 mm), barley gave better establishment than wheat, probably because barley (cv. Grimmett) had longer coleoptiles than wheat (cv. Hartog). The effects of urea, sowing depth, press wheel pressure and crop species on establishment were generally additive. As a result, establishment varied from 3 to 80%, depending on the combination of these factors used. Our results indicate that certain combinations of current farming practices such as placement of urea with the seed, deep sowing and the use of flutriafol could cause establishment problems in winter cereals.

SUMMARYExperiments made under dryland conditions in the post-monsoon period for 3 years showed that deep placement of N and P fertilizers at 12 or 18 cm led to better utilization than their shallow placement at 6 cm. Grain yield was maximal when the fertilizer was placed at 18 cm depth. The yield increase by deep fertilizer placement resulted from higher tiller survival till harvest. In these treatments water use efficiency and mineralizable N content in soil were higher.Of the two varieties tested the taller cultivar (C 306) yielded more in normal years but lodging due to a severe storm in one of the years reduced its yield considerably. While the yield of the tall variety was not much affected by variations in row distances, the dwarf (DL 153–2) responded to these variations and greatest yield was obtained at a row distance of 27·5 cm.

Many rice-growing areas in developing countries are becoming S deficient. A glasshouse experiment was conducted to study the effect of water regimes in successive crops (nonflooded : non-flooded, flooded : flooded and flooded : non-flooded), surface (S) and deep (D) placement of sulfur fertilizer and S sources (elemental S (E) and sulfate S (S)) on the growth of rice. A soil of granitic origin was used and 35S-labelled sulfur fertilizers were used to investigate S uptake by plants and the dynamics of S in soils. Among the sulfur sources, surface-applied gypsum produced the highest total yield, which was 83.6 g pot-1 under flooded conditions. Total yields under flooded conditions were ranked in order SS > SE > DS > DE > control. In the first crop, the highest 35S recovery in the plant was 67.8% from the non-flooded SE, compared with 51.7% in the DE treatment. Deep-placed elemental S (DE) became more effective than SS and SE for the subsequent rice crop, both in terms of plant dry-matter yield and fertilizer 35S content. The highest 35S recovery in the second crop was 29.5% in the previous DE treatment in the flooded: non-flooded system. This compares with 7.5% in the SS treatment in the same cropping system.

One of the adverse effects of no-tillage is the accumulation of nutrients (in particular P and K) in the top soil layer. The subsurface application of mineral fertilizers at a depth of 10–30 cm can reduce this phenomenon and at the same time provide a relatively uniform access to soil nutrients for plant roots. Such a method of mineral fertilizer application can additionally decrease the environmental risk associated with water eutrophication because the water runoff from fields, where the soil P content is high, is reduced. The aim of this research was to evaluate the effect of the subsurface application of different rates of a compound mineral fertilizer on the content of some macronutrients, soil organic carbon content (SOC), and soil pH in a field after the harvest of soybean grown under reduced tillage conditions. The field experiment was conducted during the growing seasons of 2014/2015–2016/2017 in the village of Rogów, Zamość County, Poland. It was set up as a split-plot design in four replicates. The first experimental factor included two methods of mineral fertilization application: fertilizer broadcast over the soil surface (S); fertilizer applied deep (subsurface placed) using a specially designed cultivator (Sub-S). The other factor was the rates of the mineral fertilizer (NPKS): 85 kg∙ha−1 (F85) and 170 kg∙ha−1 (F170). Over the successive years of the study, the SOC content was found to increase. However, neither the fertilization rate nor the method of fertilizer application caused any significant difference in organic carbon. Under subsurface fertilizer application conditions, a higher soil pH was found in treatment F85, however, when the fertilizer was surface-applied, the soil in treatment F170 had a higher pH value. During the three-year study period, the P and K content in the 0–30 cm soil layer was higher than in the 30–60 cm and 60–90 cm layers. In turn, the highest Mg content was determined in the 30–60 cm layer. In the case of both mineral fertilizer application methods, a higher P content was determined in the soil fertilized at a rate of 170 kg NPKS, compared with a rate of 85 kg∙ha−1. The surface application of the higher rate of mineral fertilization resulted in an increase in the soil K content. On the other hand, when the mineral fertilizer was subsurface-applied, a higher soil K was determined in the treatments with lower mineral fertilization.

In Mediterranean-type climates, topsoil frequently dries out during spring. Problems associated with reduced nutrient (P, K) availability in dry topsoil may be overcome by placing fertilisers deeper in the soil, where the soil is more likely to remain moist for longer periods as opposed to conventional fertiliser placement. Deep-P placement has resulted in significant yield improvements for lupin crops in Mediterranean environments because lupin crops generally require soil P supply during spring (throughout the flowering stage); in contrast, wheat yields have seldom improved with deep P placement, presumably because plants have accumulated sufficient P prior to spring (grain filling stage) for maximum grain yields. The P and K accumulation patterns of canola had not been investigated, and therefore any potential yield benefits of deep placed fertilisers were unknown. This study aimed to define the P and K demands of canola throughout the growing season, and assess the viability of deep placement of fertiliser in matching soil P and K supply to crop demand. The study further investigated the impact of deep placement of P fertiliser on root growth and distribution throughout the soil profile. Initial glasshouse studies compared the P and K accumulation patterns of several canola cultivars with wheat, and found that the P and K demand of canola continued until later into the season than wheat, but there was little difference in the P and K accumulation patterns of the various canola cultivars. Further experiments in sand culture determined that regardless of the level of K supply, canola plants had accumulated sufficient K for maximum seed yields by early flowering. Under high P supply, canola plants had accumulated enough P for maximum seed yields by early flowering, but when P supply during vegetative growth was just adequate, plants required a continual P supply until mid silique-filling to attain maximum yields. Because plants had accumulated sufficient K for maximum seed yields by early flowering (therefore topsoil drying in spring was unlikely to affect yields), further field experiments examined only deep placement of P fertiliser to improve P uptake and yields.