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China and India are the two top consumers of fertilizer nitrogen (N) in the world not only to provide food security to 36% of the global population living in the two countries but also due to fertilizer-related government policies being followed during the last more than 50 years. Excessive fertilizer N use is now a cause of N-related environmental pollution as well as a concern for climate change. Nitrogen use efficiency (NUE) at farmers' fields dictates both production of food crops as well as loss of N to the environment including efforts to curb climate change due to N2O emission. We used a gridded database on N input and N output for wheat, rice, and maize in China and India from 1961 to 2013 to synthesize the dynamics of NUE (percentage of applied N used by the crop) and surplus N (difference between total N input and N output) and in the light of relevant literature interpreted it in terms of past and future fertilizer N management scenarios and fertilizer related policies in the two countries. From 1961 to 2013, the percentage of fertilizer N in total N input in cereal crop production increased from 8-10% to 71-75% in India and from 30-37% to 80-84% in China. In both India and China, NUE has been continuously declining and in 2013 it was in the range of 20-24% (except 32% for wheat in India) due to several-fold increases in fertilizer N use and imbalanced use of fertilizer nutrients (particularly in India)--a consequence of huge subsidies provided by the governments on different fertilizer products. Estimates of maximum N output in the form of crop yield at saturating N input regimes determined from trajectories of N output as a function of total N input for 1961-2013 and 2001-13 revealed that crop and fertilizer N management for rice, wheat, and maize in India and China did not improve significantly since the Green Revolution era. As a large number of studies in India and China show that NUE can be increased by the advancement of technology front in terms of crop and fertilizer management and by reducing the fertilizer N rate without a significant reduction in the yield of crops, recommendations have been given for governments (to frame suitable policies), farmers, extension agencies, and fertilizer dealers. [ABSTRACT FROM AUTHOR]

Increasing amounts of crop residues are being returned to croplands. Understanding nitrogen (N) availability in crop residues under various N fertilization regimes is important in optimizing N management. Pot experiments were conducted to investigate the contribution, fate and residual effects of urea and maize residue-N using a 15N isotope technique. Four N regimes were tested: three basal–topdressing ratios of N applied as urea (100–0, 75–25, 50–50) and one basal application of 75% N as urea and 25% N as manure (75U+25M). An average of 31.4% wheat N uptake was derived from urea, 9.2% from maize residue, and 59.5% from the soil in the first season. During the growing stages of wheat, maize residue contributed 0.3–4.8% and 3.1–13.2% to soil mineral and microbial biomass N, respectively, and those originated from urea was 1.0–4.2% and 4.6–16.8%, respectively. Regarding the fate of urea and residue-N after the first season, 35.9% and 16.9% of urea-15N and residue-15N were recovered by wheat, 28.1% and 46.9% remained in the soil, and 36.0% and 36.2% were lost. The contribution of urea to crop N uptake and N recovery efficiency increased, while that of residue-N decreased with increasing proportion of topdressing N. Substituting 25% mineral N with manure decreased the urea-15N loss without negative effects on crop dry matter and N uptake. Residual urea-15N and maize residue-15N from the previous season contributed 3.9% and 3.0% to summer maize N uptake. Additionally, 29.3% of residue-15N remained in the soil after the second season, while only 18.6% of urea-15N remained. Our study suggests that fertilizer and crop residue are actively involved in soil N transformation and plant N nutrition, emphasizing the capacities of organic residues to sustainably supply nutrients. Considering the utilization of both N fertilizer and maize residue, we may suggest a 75–25 split in N fertilizer application, but more appropriate options need to be further assessed under different cropping systems. [ABSTRACT FROM AUTHOR]

The annual application of fertilizers with nitrogen, phosphorus and potassium to wheat and maize cultures leads to an increase the concentration of heavy metals in their seeds. For this purpose,during the period 2010-2012, was studiedthe effect of application of different doses of chemical fertilizers on the lead concentration of wheat and maize grains. The results showed that with the gradual increase of the chemical fertilizer doses, the lead concentration of the cereal grains also increased. Statistically significant differences from the nonfertilized control were recorded for both grains, 0.046 mg/kg for wheat seeds and 0.059 mg/kg for maize grains respectively, in variant fertilized with N160P80K120. Lead concentrations did not exceed the maximum permitted limit of 0.2 mg Pb/kg, according to ORDER (EC) No. 1881/2006. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the impact of integrated use of biochar and nitrogen (N) fertilizer on soil physicochemical properties at various growth stages of maize and subsequent wheat crop. Biochar was applied before sowing, while N application was carried out in splits to the crops. The study was conducted in district Buner, Pakistan using randomized complete block design with split-plot arrangement. Biochar was applied at the rates of 0, 5, 10, 15 and 20 ton/ha as the main plot factor. The immediate effect of biochar was assessed on maize crop integrated with four levels of N viz. 0, 100,150 and 200 kg/ha applied as sub-plot factor. The residual impact of the previously applied biochar levels coupled with fresh applications of N at the rate of 0, 80, 120 and 200 kg/ha was assessed on subsequent wheat crop grown on the same plots. The soil physicochemical properties were evaluated in the beginning, reproductive stage and at maturity of each crop. The average values of soil pH, electrical conductivity (EC), organic matter (OM), N, P and K of the soil before sowing of maize crop were found to be 8.2, 0.37 dS/m, 0.95%, 1.74 mg/kg, 3.45 mg/kg, 61.5 mg/kg, respectively. Biochar and N application significantly (p≤0.05) increased soil pH whereas soil OM was substantially enhanced only with biochar at the reproductive stage of maize. However, at this stage, the effect of biochar and N application was not significant (p≥0.05) on soil EC. At maturity stage of maize crop, soil pH, OM and EC were not significantly (p≥0.05) varied from that at reproductive stage. Residual biochar significantly (p≤0.05) increased soil pH and OM at reproductive stage of wheat. Similarly, the effect of both residual biochar and different N levels was not significant (p≥0.05) on soil EC. However, at maturity stage of wheat crop soil OM, was significantly (p≤0.05) increased with biochar residues and N applications, whereas soil pH was only influenced by residual biochar. The effect of N was not significant (p≥0.05) on soil pH and EC at maturity stage of wheat crop. As biochar improve the soil physicochemical properties therefore biochar application along with N fertilizer might be helpful in maintaining healthy soil for better crop productivity. [ABSTRACT FROM AUTHOR]

Two field experiments were conducted at El-Serw Agricultural Research Station, Damietta Governorate through summer season 2013 and winter season 2013-2014 at the same location. The aim of this study was to evaluate the effects of N bio-fertilization (Cyanobacteria and Cerealen) and mineral nitrogen applications (70, 140, 210 and 280 kg N ha-1) on growth and nutrients uptake of the maize crop, and to study the residual of N bio fertilization on the subsequent crop (wheat) with mineral nitrogen rates (0, 70, 140 and 210 kg N ha-1). The results showed that Cyanobacteria inoculation + 280 kg N ha-1 gave high maize plant height, maize yield and yield components as well as nutrients content and photosynthetic pigments in maize leaves. Also, the results indicated that the element N at a rate of 280 kg N ha-1 with Cerealen and Cyanobacteria can increase the maize grain yield by 4.14 to 19.25% and the maize stover yield by 6.89 to 16.98%. Moreover, applying N bio-fertilizers could produce high maize grain yield when it combined with two third doses of the recommend mineral nitrogen (210 kg N ha-1). Also, there was a residual effect from N-bio fertilizations applied to maize crop on the subsequent crop (wheat). The residual effect of Cyanobacteria inoculation on yield achieved the highest yield followed by the residual effect of Cerealen inoculations, respectively. Also, the results showed that wheat was fertilized at a rate of 140 kg N ha-1 after maize cultivation inoculated with Cyanobacteria produced more wheat grain and straw yield than that fertilized with 210 kg N ha-1, thus saving 70 kg N ha-1 with a healthy and high production. Concerning to soil properties after maize harvest, Cyanobacteria surpassed Cerealen inoculations in improving soil properties, since available NPK and organic matter content had increased while soil pH in the root zone was decreased by using Cyanobacteria and Cerealen inoculations. [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]

There is a growing concern that greenhouse gas (GHG) emissions during agricultural energy crop production might negate GHG emission savings which was not intended when promoting the use of renewable energy. Nitrous oxide (NO) is a major GHG, and in addition, it is the most powerful ozone-depleting compound that is emitted by human activity. The use of N fertilizers and animal manures is the main anthropogenic source of NO emissions. In spite of their high relevance, we still have limited understanding of the complex underlying microbial processes that consume or produce NO and their interactions with soil types, fertilizers (rate and types), plants, and other environmental variables. In a 2-year field experiment, we compared two important biogas crops in two different agro-ecological regions of northern Germany for their productivity and GHG emissions, using the closed-chamber technique and high time-resolution sampling. Silage maize, which is currently the most widespread crop grown for biogas fermentation purposes in Germany, was compared with an alternative bioenergy crop at each site. The three forms of nitrogen fertilizers/manures were given: calcium ammonium nitrate, cattle/pig slurry, and biogas residue. The greatest NO flux activity occurred in the period of May-July in all crops and at both sites. Flux patterns indicated pronounced effects of soil moisture-soil mineral-N interactions which were also seen as causation of the higher NO fluxes in the bioenergy crop maize compared to the other tested energy crops. However, the NO emission per unit methane production (specific NO emission) was clearly lower in soils planted with maize due to significantly higher methane hectare yield of maize. Our data suggest a linear relationship between increasing N input and increases in NO emission in both years at site with sandy loam texture where highest NO fluxes were measured. At sandy loam site, the percentage of applied N being emitted as NO was 1.9 and 1.1 % in soils cropped with maize and 0.9 and 0.8 % in soils cropped with wheat during the investigation period 2007-2008 and 2008-2009, respectively. In contrast, at site with sandy soil texture, the percentage of applied N emitted as NO was only 0.6 and 0.7 % in maize soils and 0.4 and 0.3 % in grassland during 2007-2008 and 2008-2009 period, respectively. Higher daily and annual NO emissions at the sandy loam site were attributed to the finer soil texture and higher denitrification activity. The present study provides a very good basis for the assessment of direct emissions of greenhouse gases from relevant biogas crops in North-West Europe. [ABSTRACT FROM AUTHOR]

Delphacodes kuscheli, a phloem sap-sucking planthopper and the main vector of the Mal de Río Cuarto virus (MRCV) of maize in Argentina, was used to analyze phenotypic plasticity in behavior and demographic traits in response to different food quality, without masking the effects of density dependence and within-plant heterogeneity. We evaluated selectivity of nymphs and adults for different sites of wheat plants and, on sites suspected to have different food quality because of the presence/absence of meristems and therefore different nitrogen content, we evaluated pre-imaginal survival, nymphal developmental time, proportion of macropterous morphs, adult longevity and feeding rate.Delphacodes kuschelishowed a positive selection for plant zones suspected to have higher food quality and on them insects developed faster, exhibited higher nymphal survival and adult longevity and produced a lower proportion of macropterous morphs. Also on sites suspected to have lower food quality the number of honeydew droplets excreted per day increased and the mean diameter diminished, suggesting that the planthopper could probe more frequently to compensate for different food quality. [ABSTRACT FROM PUBLISHER]

A long-term (six year) field experiment was conducted in Poland to evaluate the effect of meat and bone meal (MBM), applied without or with mineral nitrogen (N) fertilizer, on crop yields, N content and uptake by plants, and soil mineral N balance. Five treatments were compared: MBM applied at 1.0, 1.5, and 2.0 Mg ha−1, inorganic NPK, and zero-fert check. Mineral N accounted for 100% of the total N rate (158 kg ha−1) in the NPK treatment and 50%, 25%, and 0% in MBM treatments. The yield of silage maize supplied with MBM was comparable with that of plants fertilized with NPK at 74 Mg ha−1 herbage (30% DM) over two years on average. The yields of winter wheat and winter oilseed rape were highest in the NPK treatment (8.9 Mg ha−1 grain and 3.14 Mg ha−1 seeds on average). The addition of 25% and 50% of mineral N to MBM had no influence on the yields of the tested crops. The N content of plants fertilized with MBM was satisfactory (higher than in the zero-fert treatment), and considerable differences were found between years of the study within crop species. Soil mineral N content was determined by N uptake by plants rather than the proportion of mineral N in the total N rate. Nitrogen utilization by plants was highest in the NPK treatment (58%) and in the treatment where mineral N accounted for 50% of the total N rate (48%). [ABSTRACT FROM AUTHOR]