Nitrogen yield and nitrogen fixation of winter faba beans

Introducing autumn-sown legumes into Central European farming systems could be beneficial for addressing two challenges for European agriculture, i.e., the substantial deficit of protein sources for livestock and expected changes in agroclimatic conditions. Therefore, a two-year field experiment was conucted under Pannonian climate conditions in eastern Austria to assess nitrogen (N) yield and N fixation of several winter faba bean varieties from different European countries as compared to a spring faba bean. Winter wheat was used as a reference crop for estimating atmospheric N fixation. Winter faba beans were susceptible to frost damage especially in the harder of the two winters. Winter faba bean varieties could not achieve a higher grain yield and a higher grain N yield than the spring faba bean but had a higher grain N concentration (except for one variety). Grain yield and grain N yield of faba beans were severely impaired by drought in one year (with a mean of varieties of 8.3 g N m^?2, winter wheat: 6.4 g N m^?2); in the other year, grain N yield of faba beans considerably surpassed that of winter wheat (with a mean of varieties of 21.5 g N m^?2, winter wheat: 8.8 g N m^?2). After harvest, faba beans left higher nitrate residues in the soil, especially in the subsoil, and higher amounts of N in above-ground residues compared to winter wheat. Faba beans showed high N fixation under optimum conditions (with a mean of varieties of 21.9 g N m^?2) whereas drought considerably impaired N fixation (with a mean of varieties of 6.3 g N m^?2; with no differences between autumn- and spring-sown faba beans). In conclusion, growing winter faba bean varieties in eastern Austria did not result in higher grain yield, grain N yield, and N fixation compared to growing a spring faba bean.     

Cultivation of wheat following pea and triticale/pea mixtures increases yields and nitrogen content

Abstract

An experiment was conducted in 2004–2007 at the University of Podlasie Zawady Experimental Station (52°06′N, 22°50′E), Siedlce, Poland, to examine the effect of either post-harvest residues or residues and straw of spring triticale (Triticale), field pea (Pisum sativum L.) and their mixtures containing the following proportions of both components: 75+25, 50+50, 25+75% on the subsequent crop of winter wheat (Triticum aestivum L.). A field experiment was designed as split-blocks with three replicates. Residue mass, straw mass as well as N, P, K, Ca and Mg amounts were determined in the residues and straw. The residue amount of spring triticale was the greatest. N, Ca and Mg amounts in the residues of spring triticale/field pea mixtures were similar or higher whereas P and K amounts were similar or lower compared with spring triticale residues. Spring triticale straw contained less N, P, Ca and Mg than the straw of either field pea or spring triticale/field pea mixtures. Grain yield, yield components, N content and N uptake in the grain of winter wheat following field pea and spring triticale/field pea mixtures were significantly higher compared with winter wheat following spring triticale. Increasing proportions of field pea in mixtures with spring triticale cultivated as previous crops significantly increased winter wheat grain yields as well as N content and uptake. The residues of the previous crops combined with the straw significantly increased winter wheat grain yield, number of ears per m², number of grains in an ear, thousand-grain weight and N content and uptake. The highest winter wheat grain yield and N uptake were determined following an application of residues and straw of field pea and 25+75% spring triticale/field pea mixture. The grain of winter wheat after field pea had the greatest N content.     

Yields of wheat and soil carbon and nitrogen contents following long-term incorporation of barley straw and ryegrass catch crops

Abstract. Three successive crops of winter wheat were grown on a sandy loam to test the residual effect of long‐term annual incorporation of spring barley straw at rates of 0, 4, 8 and 12 t ha^?1, and ryegrass catch crops with or without additions of pig slurry. Soil receiving 4, 8 and 12 t ha^?1 of straw annually for 18 years contained 12, 21 and 30% more carbon (C), respectively, than soil with straw removal, and soil C and nitrogen (N) contents increased linearly with straw rate. The soil retained 14% of the straw C and 37% of the straw N. Ryegrass catch‐cropping for 10 years also increased soil C and N concentrations, whereas the effect of pig slurry was insignificant. Grain yield in the first wheat crop showed an average dry matter (DM) increase of 0.7 t ha^?1 after treatment with 8 and 12 t straw ha^?1. In the two subsequent wheat crops, grain yield increased by 0.2–0.3 t DM ha^?1 after 8 and 12 t straw ha^?1. No grain yield increases were found after 4 t straw ha^?1 in any of the three years. Previous ryegrass catch crops increased yields of wheat grain, but effects in the third wheat crop were significant only where ryegrass had been combined with pig slurry. Straw incorporation increased the N offtake in the first wheat crop. In the second crop, only 8 and 12 t straw ha^?1 improved wheat N offtake, while the N offtake in the third wheat crop was unaffected. Ryegrass catch crops increased N offtake in the first and second wheat crop. Again, a positive effect in the third crop was seen only when ryegrass was combined with slurry. Long‐term, annual incorporation of straw and ryegrass catch crops provided a clear and relatively persistent increase in soil organic matter levels, whereas the positive effects on the yield of subsequent wheat crops were modest and transient.     

秸秆还田与施氮对冬小麦生长发育及水肥利用率的影响

田间试验研究了小麦-玉米一年两熟耕作区玉米秸秆还田与氮肥配施和化肥单施对冬小麦生长发育、籽粒产量及氮肥表观利用率和水分利用效率的影响。结果表明, 施氮量相同时, 秸秆与氮肥配施越冬前和拔节期冬小麦总茎数和单株分蘖数低于化肥单施, 施氮量在75~225 kg·hm^-2 时, 植株干重高于化肥单施; 孕穗期到成熟期植株干重、成穗率和产量构成因素秸秆与氮肥配施处理高于化肥单施处理, 籽粒产量增加58.9~339.6kg·hm^-2, 水分生产率提高0.026~0.083 kg·m^-3。施氮量在75 kg·hm^-2 时, 秸秆与氮肥配施的氮肥表观利用率低于化肥单施; 在150~300 kg·hm^-2 时高于化肥单施。因此, 针对目前黄淮海麦区小麦-玉米一年两熟种植制度下, 秸秆还田前期生物争氮、后期供肥能力增强的特点, 秸秆连续还田后配施纯氮225 kg·hm^-2, 可有效提高灌水和氮肥利用率, 实现冬小麦高产高效栽培。     

WHEAT RESPONSE TO FARM YARD MANURE AND NITROGEN FERTILIZATION UNDER MOISTURE STRESS CONDITIONS

Information on the combined use of organic and inorganic fertilizers on wheat (Triticum aestivum L.) productivity is lacking under moisture stress conditions of Northwest Pakistan. The present experiment was designed to ascertain the combined effect of organic and inorganic fertilizer management on rainfed wheat. Four levels of farm yard manure, FYM, (0, 10, 20, and 30 Mg FYM ha^?1) and nitrogen (0, 30, 60, 90, and 120 kg N ha^?1) were used. The experiment was conducted at the Agriculture Research Farm of NWFP Agricultural University Peshawar, Pakistan during crop season of 2003–04. The experiment was laid out in randomized complete block design with four replications. Plant height, productive tillers m^?2, grains spike^?1, grain yield, straw yield, and harvest index were significantly higher in plots which received 30 Mg FYM ha^?1. In the case of nitrogen (N) no distinctive differences between the effect of 90 and 120 kg ha^?1 was observed for most of the parameters. Nitrogen application at 90 kg ha^?1 had significantly higher; plant height, grains spike^?1, grain yield, straw yield, and harvest index as compared with the lower levels, i.e., 0, 30, and 60 kg N ha^?1 but were at par with 120 N kg ha^?1. Significantly higher numbers of productive tillers m^?2, grains spike^?1, grain yield, straw yield and harvest index were recorded with application of 30 Mg FYM ha^?1 + 90 kg N ha^?1. The present study suggested that application of 30 Mg FYM ha^?1 + 90 kg N ha^?1 are promising levels for higher production of wheat under moisture stress conditions. Further research work is needed to ascertain the effect of N above 90 kg ha^?1 under different moisture regimes.     

Yield,N Uptake and N Utilization of Early Maturing,Drought and Striga-Tolerant Maize Varieties under Low N Conditions

Performance under sub-optimal nitrogen (N) conditions, of early maturing maize cultivars bred for tolerance to drought and Striga parasitism in the Nigerian savanna is not known. This study evaluated the tolerance of selected early maturing drought and Striga-tolerant maize cultivars to low N conditions in Northern Nigeria. The cultivars were evaluated at 30 and 100 kg N ha^?1. The varieties were compared with an improved maize cultivar that is not tolerant to drought and Striga. Maize grain yield was 26% higher at 100 kg N ha^?1 than at 30 kg N ha^?1 in 2010 and 161% higher100 kg Nha^?1 than at 30 kg Nha^?1 in 2011. The drought and Striga-tolerant varieties produced consistently higher yields than the non-drought-tolerant variety particularly at 30 kg Nha^?1. These cultivars also accumulated higher amount of N, had higher N-uptake efficiency or N-utilization efficiency than the non-drought-tolerant variety ACR 95 TZE-COMP4 C3. Grains yield at low nitrogen rate was associated with high ears m^?2, high dry matter accumulation, high grains m^?2, suggesting that these traits are linked to low-N tolerance. The good performance of the drought-tolerant maize varieties under low N suggests that varieties developed for drought tolerance may be tolerant to low-N conditions.     

Economic and environmental optimization of nitrogen fertilizer recommendations for cereals in Norway

Abstract

Results of 240 annual N fertilizer trials in 1991–2007 in spring and winter cereals are presented. On average, spring barley and oat yields increased little beyond 120 kg N ha^?1 in fertilizer. Somewhat higher figures were found for spring and winter wheat. Regression equations for yield and N uptakes in grain and straw were derived, related to N fertilizer input and the yield level in individual trials (indicator of yield expectancy). These equations accounted for 90% of the variation in yield and 80% of that in N uptake. Quadratic N responses were significant in all cases, as were interactions between N responses and yield level. They were verified with data from 27 separate trials performed in 2008–2010. The yield equations were used to calculate economically optimum N fertilizer levels with varying ratios of product price to fertilizer cost at contrasting levels of yield. The optimum N fertilizer level for barley and oats was found to increase by 8.3 kg N ha^?1 per Mg increase in expected yield. The equivalent figure in wheat was 16.3 kg N ha^?1. Optimum N fertilizer levels decreased by 4.1 and 6.7 kg N ha^?1, for barley/oats and wheat respectively, per unit increase in the cost/price ratio. The equations for N uptake were used to calculate simple N balances between fertilizer input and removal in crop products. Large N surpluses were indicated at low levels of yield expectancy, but the surplus declined markedly with increasing yield level, despite greater N fertilizer inputs at high yield. Calculations made for national average yield levels in recent years showed N surpluses of 50–60 kg N ha^?1 when only grain is removed and 25–40 kg N ha^?1 when straw is removed also. Limiting N input to obtain zero balance reduces yields considerably at average levels of yield expectancy.     

Influence of crop residue management, cropping system and N fertilizer on soil N and C dynamics and sustainable wheat (Triticum aestivum L.) production

Management of N is the key for sustainable and profitable wheat production in a low N soil. We report results of irrigated crop rotation experiment, conducted in the North West Frontier Province (NWFP), Pakistan, during 1999–2002 to evaluate effects of residue retention, fertilizer N application and mung bean (Vigna radiata) on crop and N yields of wheat and soil organic fertility in a mung bean–wheat sequence. Treatments were (a) crop residue retained (+residue) or (b) removed (−residue), (c) 120 kg N ha⁻¹ applied to wheat, (d) 160 kg N ha⁻¹ to maize or (e) no nitrogen applied. The cropping system was rotation of wheat with maize or wheat with mung bean. The experiment was laid out in a spit plot design. Postharvest incorporation of crop residues significantly (p < 0.05) increased the grain and straw yields of wheat during both years. On average, crop residues incorporation increased the wheat grain yield by 1.31 times and straw yield by 1.39 times. The wheat crop also responded strongly to the previous legume (mung bean) in terms of enhanced grain yield by 2.09 times and straw yield by 2.16 times over the previous cereal (maize) treatment. Application of fertilizer N to previous maize exerted strong carry over effect on grain (1.32 times) and straw yield (1.38 times) of the following wheat. Application of N fertilizer to current wheat produced on average 1.59 times more grain and 1.77 times more straw yield over the 0 N kg ha⁻¹ treatment. The N uptake in wheat grain and straw was increased 1.31 and 1.64 times by residues treatment, 2.08 and 2.49 times by mung bean and 1.71 and 1.86 times by fertilizer N applied to wheat, respectively. The soil mineral N was increased 1.23 times by residues, 1.34 times by mung bean and 2.49 times by the application of fertilizer N to wheat. Similarly, the soil organic C was increased 1.04-fold by residues, 1.08 times by mung bean and 1.00 times by the application of fertilizer N. We concluded that retention of residues, application of fertilizer N and involvement of legumes in crop rotation greatly improves the N economy of the cropping system and enhances crop productivity in low N soils.     

Catch Crop and Animal Slurry in Spring Barley Grown with Straw Incorporation

Abstract

Four rates of straw (0, 4, 8 and 12 t ha^?1 yr^?1) were incorporated in a field experiment with continuous spring barley. The experiment was conducted on a sandy soil (5.5% clay) and a sandy loam soil (11.2% clay). After eight years, the straw incorporation was combined with catch-crop growing with and without winter application of animal slurry and also spring fertilization with mineral fertilizer (0, 50, 100 or 125 kg N ha^?1 yr^?1). The combined experiment was conducted for three lyears on the sandy soil and for four years on the sandy loam soil. The effects on barley dry matter yield and N uptake are presented together with the long-term effects of the straw incorporations on crop growth and soil C and N. Grain yield on the sandy loam was unaffected by straw incorporation. On the sandy soil the highest straw application rates reduced grain yield in the unfertilized barley. When the barley received mineral fertilizer at recommended levels (100 kg N ha^?1 yr^?1), grain yield on this soil was also unaffected by the high straw rates. Including a catch crop had a positive effect on the grain yield of barley on both soils. The total N uptake in grain and straw generally increased with straw application up to 8 t ha^?1 yr^?1. With the highest straw application rate (12 t ha^?1 yr^?1), the total N uptake decreased but still exceeded N uptake in barley grown with straw removal. The barley accumulated higher amounts of N when a catch crop was included. The total N uptake in the barley was significantly higher after animal slurry application. The extra N uptake, however, was much lower than the amounts of N applied with the slurry. Incorporation of straw had only a small influence on N uptake after slurry application. The straw, therefore, was not able to store the applied N during winter. In the two four-year periods before the combined experiment, grain yield on the sandy loam was generally negatively affected by straw incorporations. In the second period, N uptake began to show a positive effect of the straw. On the sandy soil, grain yield and N uptake during the whole period were generally positively affected by the straw incorporations except for the highest straw rate (12 t ha^?1 yr^?1). The sandy loam soil showed higher increases in C and N content after the repeated straw incorporations and catch-crop growing than the sandy soil. When application of animal slurry was combined with the catch crop, no further increases in soil C and N were found relative to soil where a catch crop was grown without slurry application. Large amounts of the N applied with the slurry may therefore have been lost by denitrification or nitrate leaching.     

Contribution of Biofertilizers and Fertilizer Nitrogen to Nutrient Uptake and Yield of Egyptian Winter Wheat

ABSTRACT

Nutrient uptake and grain and straw yield of Egyptian winter wheat (Triticum aestivum L. Merr.) were evaluated for two site-years after the seed inoculation with two biofertilizer products, Phosphorien, containing the phosphorus (P)-solubilizing bacteria Bacillus megatherium, and Nitrobien, containing a combination of nitrogen (N)-fixing bacteria Azotobacter chroococcum and Azospirillum liposerum. Ammonium nitrate and polymer-coated urea fertilizers were applied to plots alone and together with the biofertilizers at rates of either 83 kg N ha^?1 or 186 kg N ha^?1 for comparison. The highest grain yield (5.76–6.74 Mg ha^?1) and straw yield (11.49–13.32 Mg ha^?1) occurred at the highest fertilizer rates with N fertilizer. There was a slight additional increase in grain and straw yields when a biofertilizer was applied along with N fertilizer. A slightly higher grain and straw yield was measured with the polymer-coated urea treatment than with the ammonium nitrate treatment. The biofertilizer materials were not as effective as N fertilizers in producing grain (4.02–4.09 Mg ha^?1) or straw (7.71–8.11 Mg ha^?1) for either year, although the Nitrobien + Phosphorien combination increased these parameters over the N-fertilizer control. The effect of the Nitrobien biofertilizer in increasing grain yields was equivalent to a urea application rate of about 13 kg N ha^?1. Biofertilizer inoculations increased iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) concentrations in wheat tissue (at boot stage), but these higher levels did not influence grain or straw yield.     

Modern wheat cultivars have greater root nitrogen uptake efficiency than old cultivars

The availability of nitrogen (N) contained in crop residues for a following crop may vary with cultivar, depending on root traits and the interaction between roots and soil. We used a pot experiment to investigate the effects of six spring wheat (Triticum aestivum L.) cultivars (three old varieties introduced before mid last century and three modern varieties) and N fertilization on the ability of wheat to acquire N from maize (Zea mays L.) straw added to soil. Wheat was grown in a soil where ¹⁵N‐labeled maize straw had been incorporated with or without N fertilization. Higher grain yield in three modern and one old cultivar was ascribed to preferred allocation of photosynthate to aboveground plant parts and from vegetative organs to grains. Root biomass, root length density and root surface area were all smaller in modern than in old cultivars at both anthesis and maturity. Root mean diameter was generally similar between modern and old cultivars at anthesis but was greater in modern than in old cultivars at maturity. There were cultivar differences in N uptake from incorporated maize straw and the other N sources (soil and fertilizer). However, these differences were not related to variation in the measured root parameters among the six cultivars. At anthesis, total N uptake efficiencies by roots (total N uptake per root weight or root length) were greater in modern than in old cultivars within each fertilization level. At maturity, averaged over fertilization levels, the total N uptake efficiencies by roots were 292?336 mg N g^?1 roots or 3.2?4.0 mg N m^?1 roots for three modern cultivars, in contrast to 132?213 mg N g^?1 roots or 0.93?1.6 mg N m^?1 roots for three old cultivars. Fertilization enhanced the utilization of N from maize straw by all cultivars, but root N uptake efficiencies were less affected. We concluded that modern spring wheat cultivars had higher root N uptake efficiency than old cultivars.     

Sodicity Intensifies the Effect of Salinity on Grain Yield and Yield Components of Wheat

ABSTRACT

This study reports the relationship of the leaf ionic composition with the grain yield and yield components of wheat in response to salinity x sodicity and salinity alone. The study was conducted in soil culture in pots with three treatments including control (ECe 2.6 dS m^{? 1} and SAR 4.53), salinity (ECe 15 dS m^{? 1} and SAR 9.56), and salinity x sodicity (ECe 15 dS m^{? 1} and SAR 35). The soil was treated before being put in the pots and the pots were arranged in a completely randomized factorial arrangement with five replications. The seeds of three wheat genotypes were sown directly in the pots and the study was continued till the crop maturity. At booting stage, the leaf second to the flag leaf of each plant was collected and analyzed for sodium (Na⁺), potassium (K⁺), and chloride (Cl^?). At maturity, plants were harvested and data regarding grain yield and yield components were recorded. This study shows that salinity and sodicity in combination decreases the grain yield of wheat more than the salinity alone with a greater difference in the sensitive genotype. This study also shows that as for salinity, the maintenance of lower Na⁺ and higher K⁺ concentrations and higher K⁺: Na⁺ ratio in the leaves relates positively with the better development of different yield components and higher grain yield in saline sodic soil conditions. Although, the leaf Cl^? concentration was increased significantly by salinity as well as salinity x sodicity and would have affected the growth and yield, yet it does not seem to determine the genotypic tolerance or sensitivity to either salinity or salinity x sodicity.     

Bioresource Nutrient Recycling and Its Relationship with Biofertility Indicators of Soil Health and Nutrient Dynamics in Rice–Wheat Cropping System

A field experiment was conducted for 3 years during 2006–2009 in India to study the effects of plant nutrient recycling through crop residue management, green manuring, and fertility levels on yield attributes, crop productivity, nutrient uptake, and biofertility indicators of soil health in a rice–wheat cropping system. The study revealed that soil microbial biomass carbon (SMBC) and carbon dioxide (CO₂) evolution were significantly greatest under crop residue incorporation (CRI) + Sesbania green manuring (SGM) treatment and were found at levels of 364 μg g^?1 soil and 1.75 μg g^?1 soil h^?1, respectively; these were increased significantly by recycling of organic residues. Activities of dehydrogenase and phosphatase enzymes increased significantly after 3 years, with maximum activity under CRI + SGM treatment. The CRI with or without SGM significantly influenced the plant height, number of tillers m^?2, number of grains panicle^?1 or ear^?1, and 1000-grain weight. Mean yield data of rice and wheat revealed that CRI or crop residue burning (CRB) resulted in slightly greater yield over crop residue removal (CRR) treatment. The CRI + SGM treatment again observed significantly greatest grain yields of 7.54 and 5.84 t ha^?1 and straw yields of 8.42 and 6.36 t ha^?1 in rice and wheat, respectively, over other crop residue management treatments. Total nitrogen (N), phosphorus (P) and potassium (K) uptake in rice–wheat system was greatest with amounts of 206.7, 37.2, and 205.6 kg ha^?1, respectively, in CRI + SGM treatment. Fertility levels significantly influenced the rice and wheat yield with greatest grain yields of 6.66 and 5.68 t ha^?1 and straw yields of 7.94 and 5.89 t ha^?1 in rice and wheat, respectively, with the application of 150% of recommended NPK. Total NPK uptake in rice–wheat system also increased significantly with increase in fertility levels with greatest magnitude by supplying 150% of recommended NPK. Overall, nutrient recycling through incorporation of crop residues and Sesbania green manuring along with inorganics greatly improved the crop productivity, nutrient uptake, and biofertility indicators of soil health with substantial influence on SMBC, CO₂ evolution, and dehydrogenase and phosphatase enzyme activities. This indicates that crop residue management along with Sesbania green manuring practice could be a better option for nutrient recycling to sustain the crop productivity and soil health in intensive rice–wheat cropping system in India as well as in similar global agroecological situations, especially in China, Pakistan, and Bangladesh.     

Effects of Irrigation Water Salinity and Leaching Fraction on Yield and Evapotranspiration in Spring Wheat

To determine the effects of irrigation water salinity and leaching fraction on crop evapotranspiration (ETc), grain yield, straw yield, shoot sodium (Na), and chloride (Cl) concentrations of spring wheat (Triticum aestivum L.) cultivar ‘Onfarom 9,’ a pot experiment was conducted using saline soil with electrical conductivity of soil paste extract (ECe) of 13.2 dS m^?1. A factorial experiment with a completely randomized design replicated seven times was used with three levels of saline irrigation water (4, 9, and 12 dS m^?1) and four leaching levels (0, 17, 29, and 37%) included as the factors. The results showed that ETc significantly decreased as a result of an increase in irrigation water salinity (ECi) and decrease in leaching level. Crop evapotranspiration deficit and decreasing irrigation and drainage water effectively resulted in grain and straw yield reduction. Increase in ECi increased accumulation of Cl and Na in crop shoot, but application of leaching decreased this accumulation.     

IMPACT OF WATER AND NUTRIENT MANAGEMENT ON THE NUTRITIONAL QUALITY OF WHEAT

Field experiments were conducted in 2002–03 and 2003–04 growing seasons to determine wheat response to four irrigation regimes applied at different growth stages and four nitrogen levels of 0, 50, 100, and 150 kg nitrogen (N) ha^?1. The experiment was conducted at the research area of the Department of Crop Physiology, University of Agriculture, Faisalabad, Pakistan. Recommended wheat variety “Inqlab-91” was used as the experimental crop. Both irrigation and nitrogen application have positive effects on grain yield increase. The grain crude protein decreased with increasing number of irrigations whereas in contrast, nitrogen application significantly improved grain crude protein at all irrigation levels. Grain phosphorus (P) and potassium (K) percentage increased with the application of irrigation and nitrogen. Grain yield, number of spikes m^?2, grains spike^?1 and grain weight responses were greater at the higher N rates. Mean grain yield in four, three and two irrigation treatments compared with that in one irrigation treatment increased 47, 23, and 9% during 2002–03 and 91, 84, and 23% in 2003–04, respectively. Water deficit reduced spikes m^?2. In both years, the average reduction in spikes m^?2 at maximum irrigation deficit (one irrigation) at all N levels was 24%. Similar reduction occurred in grains spike^?1 where water deficit decreased this component on an average of 36%.     

Yield response of crops amended with sewage sludge in the field is more affected by sludge properties than by final soil metal concentration

Adverse effects on crop yield or quality have been reported in sewage‐sludge treated soils at soil total metal concentrations below those of the current EU directives. A field trial was set up in Belgium (2002–2004) to assess crop response to the application of sewage sludge below these soil thresholds but with sludge metal concentrations either above (high‐metal) or below (low‐metal) sludge metal limits. Two lime‐stabilized and two raw, dewatered sludges were applied annually at rates of 10, 25 and 50 t dry matter (dm) ha^?1 for 3 years with four rates of N‐fertilizer as a reference. Final soil metal concentrations increased to maximums of 1.6 mg Cd kg^?1 and 225 mg Zn kg^?1 through sludge applications. Maize yield was marginally affected by treatments in year 1, whereas wheat and barley grain yields in subsequent years increased up to threefold with increasing sludge or fertilizer rates and were mainly explained by grain‐N. However, the grain yield of winter wheat in year 2 was reduced by about 14% in lime‐stabilized high‐metal sludge treatments compared with wheat receiving N‐fertilizer at equivalent grain‐N. Wheat grain and straw analysis showed no nutrient deficiencies but Zn concentrations in grain and straw were greater than in N‐fertilizer and lime‐stabilized, low‐metal sludge treatments, suggesting Zn toxicity. Sludge properties other than Cd concentration (e.g. electrical conductivity) affected crop Cd in the first year (maize), whereas significant correlations between Cd application and wheat grain Cd were found in the second year. Wheat grain Cd concentrations reached the international trade guideline of 0.1 mg Cd kg^?1 fresh weight in the plots amended with lime‐treated, high‐metal sludge even though soil Cd remained below EU limits. In the third year, barley grain Cd remained largely below EU limits. We discuss the possibility that sludge properties rather than soil total metal concentrations are related to effects on crops in the initial years after sludge applications. In none of the 3 years were any adverse effects on crops found for sludge meeting current EU regulations.     

秸秆还田对冬小麦产量和氮、磷、钾吸收利用的影响

【目的】陕西关中平原是我国典型的冬小麦—夏玉米轮作区,冬小麦播种前将上季收获后的玉米秸秆还田是当地普遍采用的作物秸秆管理方式。本研究以优化秸秆还田条件的小麦养分资源管理,实现作物增产和肥料增效为目标,通过2年的田间定位试验,探索关中地区玉米秸秆还田条件下,冬小麦高产高效的最佳养分管理措施。【方法】试验于2011年10月至2013年5月在陕西省周至县终南镇进行,供试冬小麦品种为周麦23,夏玉米品种为郑单958。采用裂区设计,主处理为玉米秸秆全量还田(S1)和秸秆不还田(S0),副处理为5个不同氮肥施用水平(N 0、84、168、252和336 kg/hm2),种植作物为冬小麦。通过不同氮水平的回归分析,研究了玉米秸秆还田对后茬冬小麦的籽粒产量、生物量和收获期地上部氮、磷、钾养分吸收利用的影响。【结果】与玉米秸秆不还田相比,秸秆还田对冬小麦籽粒产量和收获期地上部氮、磷、钾养分吸收量的影响均表现出低氮降低、高氮增加的趋势。第一年和第二年在施氮量分别低于N 153和187 kg/hm2时,秸秆还田处理小麦减产,相反则增产,并且增产量随着氮肥用量的增加而增大;生物量与产量趋势一致,前后两年玉米秸秆还田与不还田条件下,冬小麦生物量相等时的氮肥用量分别为N 190和202 kg/hm2。在产量构成要素中,同一氮水平时,秸秆还田对小麦穗粒数和千粒重没有明显影响,而每公顷穗数却表现为低氮降低、高氮增加的趋势,所以秸秆还田后穗数增加是小麦增产的主要原因。同时,在玉米秸秆还田条件下,小麦地上部氮、磷、钾吸收量增加时,第一年的氮肥用量分别高于N 275、123和213kg/hm2,第二年分别高于N 200、165和241 kg/hm2,但氮、磷、钾的收获指数不随施氮量的增加而递增。而且过量施氮也会造成小麦籽粒磷含量的降低。【结论】在综合同一施氮水平时,秸秆还田后的冬小麦籽粒产量和地上部氮、磷、钾养分吸收利用的变化,建议在陕西关中平原的冬小麦—夏玉米轮作区域,氮肥用量应控制在N 150~200kg/hm2,以保证在玉米秸秆还田条件下小麦的增产和氮、磷、钾养分资源的高效合理利用。     

Influence of Long-term Tillage,Straw, and N Fertilizer Management on Crop Yield,N Uptake,and N Balance Sheet in Two Contrasting Soil Types

Field experiments (established in autumn 1979, with monoculture barley from 1980 to 1990 and barley/wheat–canola–triticale–pea rotation from 1991 to 2008) were conducted on two contrasting soil types (Gray Luvisol [Typic Haplocryalf] loam soil at Breton; Black Chernozem [Albic Agricryoll] silty clay loam soil at Ellerslie) in north-central Alberta, Canada, to determine the influence of tillage (zero tillage and conventional tillage), straw management (straw removed [S_Rem] and straw retained [S_Ret]), and N fertilizer rate (0, 50 and 100 kg N ha^?1in S_Ret, and only 0 kg N ha^?1in S_Rem plots) on seed yield, straw yield, total N uptake in seed + straw (1991–2008), and N balance sheet (1980–2008). The N fertilizer urea was midrow-banded under both tillage systems in the 1991 to 2008 period. There was a considerable increase in seed yield, straw yield, and total N uptake in seed + straw with increasing N rate up to 100 kg N ha^?1 under both tillage systems. On the average, conventional tillage produced greater seed yield (by 279 kg ha^?1), straw yield (by 252 kg ha^?1), and total N uptake in seed + straw (by 6.0 kg N ha^?1) than zero tillage, but the differences were greater at Breton than Ellerslie. Compared to straw removal treatment, seed yield, straw yield, and total N uptake in seed + straw tended to be greater with straw retained at the zero-N rate used in the study. The amounts of applied N unaccounted for over the 1980 to 2008 period ranged from 1114 to 1846 kg N ha^?1 at Breton and 845 to 1665 kg N ha^?1 at Ellerslie, suggesting a great potential for N loss from the soil-plant system through denitrification, and N immobilization from the soil mineral N pool. In conclusion, crop yield and N uptake were lower under zero tillage than conventional, and long-term retention of straw suggests some gradual improvement in soil productivity.     

Furrow diking and N management for dryland wheat production in permanent raised beds

The permanent bed planting system for wheat (Triticum aestivum L.) production has recently received additional attention. Studies using hard red spring wheat (cultivar Nahuatl F2000) were conducted at two locations in central Mexico. The studies included the installation of three furrow diking treatments, two granular N timing treatments and three foliar N rates applied at the end of anthesis. The objective was to evaluate the effect of these factors on wheat grain yield, yield components and grain N in a wheat–maize (Zea maize L.) rotation with residues of both crops left as stubble. Results indicated that diking in alternate furrows increased both grain yield and the final number of spikes per m². The split application of N fertilizer enhanced the number of spikes per m² and grain N uptake, but the effect on grain yield was inconsistent. Similarly, grain protein increased with the foliar application of 6 kg N ha^?1, depending upon the maximum temperature within the 10 days following anthesis. The normalized difference vegetative index (NDVI) readings collected at four growth stages were generally higher for the split N application than for the basal N application at planting. Grain N uptake was associated to NDVI readings collected after anthesis.     

Effect of Silicon Fertilization on Growth,Yield, and Nutrient Uptake of Rice

A field experiment was conducted to study the effect of silicon (diatomaceous earth, DE) fertilization on growth, yield, and nutrient uptake of rice during the kharif season of 2012 and 2013 in the new alluvial zone of West Bengal, India. Results showed that application of silicon significantly increased grain and straw yield as well as yield-attributing parameters such as plant height (cm), number of tillers m^?2, number of panicle m^?2, and 1000-grain weight (g) of rice. The greatest grain and straw yields were observed in the treatment T₆ (DE at 600 kg ha^?1 in combination with standard fertilizer practice (SFP). The concentration and uptake of silicon, nitrogen (N), phosphorus (P), and potassium (K) in grain and straw were also greater under this treatment compared to others. It was concluded that application of DE at 600 kg ha^?1 along with SFP resulted increased grain, straw, and uptake of NPK.