Search

Combined manure fertilizer addition with optimal nitrogen (N) input reduces nitrogen demands for wheat while maintaining or increasing its yield and nitrogen productivity. However, the effect of manure addition has not been well explored for dryland wheat production on the Loess Plateau, especially in year with less precipitation. Therefore, a 4-year field experiment was performed: manure fertilizer (with and without) and N fertilization levels (0, 60, 120, 180 and 240 kg ha–1) under two precipitation years (normal and dry year). The target was to quantify the effect of manure addition on: i) wheat yield and nitrogen use efficiency (NUE), ii) crop growth and soil properties, and iii) wheat N status [N accumulation, N nutrition index (NNI)]. Compared with chemical N alone, manure addition increased topsoil organic matter, total nitrogen and the stability of macro-aggregate (R 0.25). Manure addition increased grain yield by 12.5% in normal year and by 38.2% in dry year. The improved topsoil quality, root system, biomass (nitrogen) accumulation all occurred in NM120 or NM180 with manure addition, which brought an improvement of wheat yield and NUE with a suitable nitrogen nutrition status. NM180 (i.e., 150 kg N ha–1 +2000 kg ha–1 manure) and NM120 (i.e., 90 kg N ha–1 +2000 kg ha–1 manure) achieved the highest grain yield in normal and dry years, respectively. In summary, the optimal fertilization decision strategy based on precipitation and nitrogen nutrition index can be applied for dryland wheat production. • Manure addition increased yield and NUE by regulating soil quality, root growth and post-anthesis N accumulation. • NM120 or NM180 with manure addition achieved the highest grain yield in dry and normal years, respectively. • Critical nitrogen dilution curves were established for diagnosing dryland wheat N nutrition status. • Combined manure addition with optimal N input reduced yield loss in years with less precipitation. [ABSTRACT FROM AUTHOR]

Integrated nitrogen (N) management strategies could make significant contributions to improving the efficiency of N use in the northern Corn Belt, particularly for maize, which has high N requirements. Using legume cover crops has been shown to increase both the soil's capacity to supply N and nitrogen use efficiency (NUE), through the reduction in the amount of N fertilizer that must be applied to the following crops. However, the impact of non-legume crops such as winter wheat ( Triticum aestivum L.) on the diminishing return function between crop yield and N supply and its influence on N fertilizer use remains unclear. We hypothesized that maintaining wheat in short maize and soybean- based rotations is instrumental to improve cropping system performance and increase N fertilizer use efficiency while decreasing N requirements for maize. Seven maize and soybean rotations with different frequency of winter wheat with or without underseeded red clover ( Trifolium pratense L. ) were grown in two tillage systems (conventional and zone-tillage) and four long-term N regimes in Ridgetown, ON, Canada (2009–2013). Wheat in the rotation increased maize and soybean yields, negated crop yield lags due to zone-tillage, and decreased maximum economic rates of fertilizer N (MERN). The benefits of wheat in the rotation on maize yield were negated by high N rates; however, similar yields were obtained with lower N levels in rotationally grown maize, resulting in a 17% (conventional till) to 21% (zone-till) increase in partial factor productivity for N fertilizer at MERN (PFP MERN ). While N benefits to crops following wheat alone may be attributed to a higher indigenous plant available soil N, underseeding red clover further increased the agronomic efficiency (AE) of N fertilizer (AE MERN ) up to 32%. Maize yields were also less limited by N supply and less responsive to N fertilization when grown in rotation with wheat, especially in the zone-till system. These results highlight the value of wheat as a system component of dominant maize/soybean short rotations of Ontario and its potential to increase both maize and soybean productivity using less N input. [ABSTRACT FROM AUTHOR]

Highlights: [•] The summer crop of maize was the main contributor to annual N2O emissions. [•] DMPP urea was effective in reducing N2O emissions only in the maize season. [•] Applying DMPP urea did not increase yields. [•] Adjusting N fertiliser rates on estimated residual soil N reduced N2O emissions. [•] Severe yield loss can occur if residual soil N is not estimated correctly. [ABSTRACT FROM AUTHOR]

Highlights: [•] We quantify effects of increasing CO2 on wheat physiology and yield. [•] We test current hypotheses of CO2 acclimation in C3 plants. [•] Yield increases depend on exposure method, rooting system and stress factors. [•] CO2-stimulated growth is not matched by increased N acquisition and N assimilation. [•] Current predictions of CO2-stimulated yield increases may be overstated. [ABSTRACT FROM AUTHOR]

Abstract: Intensively cropped agricultural production systems should be managed to improve soil quality and ecological processes and ultimately strengthen system capacity for sustained biological productivity. We examined the long-term changes (>20 years) in soil quality and productivity with incorporation of ecological management principles in a set of intensively managed row crop systems of the upper Midwest, USA. Replicated experimental treatments include corn (maize)–soybean–wheat cropping systems under four different management regimes: (a) conventional tillage and fertilizer/chemical inputs (Conventional), (b) no tillage with conventional fertilizer/chemical inputs (No-till), (c) conventional tillage with ∼30% of conventional fertilizer/chemical inputs and a leguminous cover crop (Reduced Input), and (d) conventional tillage with no fertilizer/chemical input and a leguminous cover crop (Organic). Effects of these treatments on soils were compared by developing a soil quality index (SQI) from 19 selected soil health indicators. An old field community maintained in early succession provided a benchmark for comparison. Reduction in tillage or fertilizer (No-till, Reduced Input and Organic) resulted in increased SQI and improved crop production. The No-till (SQI=1.02) and Reduced Input (SQI=1.01) systems outperformed Conventional management (SQI=0.92) in nitrogen availability and use efficiency, soil stability and structure improvement, and microbial nitrogen processing. Improvements in soil quality corresponded with increased primary production and crop yield in these systems, illustrating the value of an ecologically defined SQI for assessing the long-term effects of fertility and tillage management regimes in agricultural production systems. [Copyright &y& Elsevier]

Abstract: A nutrient management plan (NMP) field experiment was conducted to investigate the fate of nitrogen (N), phosphorus (P), potassium (K) and salts in a semi-arid environment (San Jacinto, CA). Our mechanistic approach to study NMP performance was based on comprehensive measurements of water and N mass balance in the root zone. A cereal crop rotation (wheat-rye hybrid to sorghum, Triticum aestivum L.–Secale cereale L. to Sorghum bicolor L. Moench) that does not fix atmospheric N was employed during 2007, whereas a legume crop (alfalfa, Medicago sativa L.) that forms nodules to fix N was used in 2008. Blending (2007 and 2008) and cyclic (2007) dairy wastewater (DWW) application strategies (no statistical difference in 2007) were implemented to meet crop water and N uptake. The high content of salts in DWW and accurate application of water to meet evapotranspiration (ET) yielded salt accumulation in the root zone. Leaching these salts after the fallow period resulted in the flushing of nitrate that had accumulated in the root zone due to continuous mineralization of soil organic N. This observation suggested that a conservative NMP should account for mineralization of organic N by (i) leaching salts following harvests rather than prior to planting and (ii) maintaining soils with low values of organic N. For the wheat-rye hybrid–sorghum rotation, losses of nitrate below the root zone were minimal and the soil organic N reservoir and P were depleted over time by applying only a fraction of the plant N uptake with DWW (28–48%) and using DWW that was treated to reduce the fraction of organic N (3–10%), whereas K accumulated similar to other salts. Conversely, with alfalfa approximately 15% of the applied N was leached below the root zone and the soil organic N increased during the growing season. These observations were attributed to fixation of atmospheric N, increased root density, and applying a higher fraction of plant N uptake with DWW (76%). Collectively, our results indicate that NMPs should accurately account for water and nutrient mass balances, and salt accumulation to be protective of the environment. [Copyright &y& Elsevier]

Abstract: The nitrogen (N) balance (N input−N export by the grain) is often used to estimate the risk of N leaching from arable land. In a nine year study during the leaching seasons 1991/1992 to 1999/2000, the relationships between N fertilization, N balance and N leaching in the subsequent percolation period were investigated in a multifactorial field experiment near Kiel in NW Germany at the Hohenschulen Experimental Station. The crop rotation was oilseed rape (OSR) – winter wheat – winter barley, while soil tillage (minimum tillage without ploughing, conventional tillage), application of pig slurry (none, application in autumn, application in spring, application in autumn plus in spring), mineral N fertilization (none, 120 or 240kgNha−1 to cereals), and application of fungicides (none, intensive) were all varied. In each year the rotation and the treatments were located on the same plots. N leaching was calculated by multiplying the drainage volume with the respective N concentration obtained using ceramic suction cups. In all crops, N fertilization significantly increased the N balance in the order mineral N

Both anticipated climate change and dryland salinity pose a strategic threat to the sustainability of about 6 Mha of agricultural land in Western Australia (WA). These phenomena require an integrated analysis to estimate their potential impacts and initiate strategic thinking about adaptation. Water loss below the root zone, i.e. deep drainage, is the primary cause of sub-soil salt mobilisation leading to surface soil salinity in areas cleared of natural vegetation in Australia; hence deep drainage is an important externality of agricultural production. The purpose of this paper is to show how changes in CO2 concentration, temperature and precipitation may affect agricultural production and deep drainage.Results are presented of a simulation experiment with the Agricultural Production Systems Simulator (APSIM)-Nwheat model in which we explored sensitivity of (1) wheat production and quality, and (2) deep drainage, for three sites in WA differing in average precipitation, two soils, various nitrogenous fertiliser rates and present wheat cultivars. Since results of Global Circulation Models (GCM) are still largely inconsistent for this region, we have opted for a factorial approach in adapting 90 years of historical weather data. This set-up enabled separation of effects of CO2, temperature, precipitation and their interactions, and unravelling of the complex interactions between water and nitrogen availability, phenological development and climate change factors, in the extremely variable Mediterranean climate in WA.Elevated CO2 concentration increased yields, particularly if nitrogen fertilisation was sufficient and conditions were relatively dry. Higher temperatures had non-linear effects, with initial (up to 3 °C) benefits on clay soils, but not on sandy soils, and then substantial yield declines. Both elevated CO2 concentrations and temperatures (+3 °C) decreased grain protein, but in financial terms this was more than offset by the increase in yield in most cases. If, in addition, precipitation was decreased, financial returns dropped below present levels, particularly in the low precipitation regions. Deep drainage tended to be slightly higher under elevated CO2 concentrations but when higher temperatures were also simulated this was reversed. Deep drainage was greatly reduced in the low precipitation scenarios. Evidently climate change is not only likely to affect productivity, but also deep drainage and hence dryland salinity. The impact can vary in direction such that both ‘win–win’ and ‘lose–win’ outcomes may occur, particularly depending on the relative change in precipitation. [Copyright &y& Elsevier]