Identifying the critical phosphorus balance for optimizing phosphorus input and regulating soil phosphorus effectiveness in a typical winter wheat-summer maize rotation system in North China

Phosphorus(P)is a nonrenewable resource and a critical element for plant growth that plays an important role in improving crop yield.Excessive P fertilizer application is widespread in agricultural production,which not only wastes phosphate resources but also causes P accumulation and groundwater pollution.Here,we hypothesized that the apparent P balance of a crop system could be used as an indicator for identifying the critical P input in order to obtain a high yield with high phosphorus use efficiency(PUE).A 12-year field experiment with P fertilization rates of 0,45,90,135,180,and 225 kg P_(2)O_(5)ha^(-1)was conducted to determine the crop yield,PUE,and soil Olsen-P value response to P balance,and to optimize the P input.Annual yield stagnation occurred when the P fertilizer application exceeded a certain level,and high yield and PUE levels were achieved with annual P fertilizer application rates of 90-135 kg P_(2)O_(5)ha^(-1).A critical P balance range of 2.15-4.45 kg P ha^(-1)was recommended to achieve optimum yield with minimal environmental risk.The critical P input range estimated from the P balance was 95.7-101 kg P_(2)O_(5)ha^(-1),which improved relative yield(>90%)and PUE(90.0-94.9%).In addition,the P input-output balance helps in assessing future changes in Olsen-P values,which increased by 4.07 mg kg^(-1)of P for every 100 kg of P surplus.Overall,the P balance can be used as a critical indicator for P management in agriculture,providing a robust reference for limiting P excess and developing a more productive,efficient and environmentally friendly P fertilizer management strategy.

Evaluation of Pathway of Nitrogen Loss in Winter Wheat and Summer Maize Rotation System

The nitrogen loss pathway in winter wheat and summer maize rotation system was studied based on field experimental data. The results showed that nitrogen recovery rate was significantly decreased with nitrogen fertilization rate increased, while residual rate and losses rate had an increasing trend. Accumulated ammonia volatilization loss in winter wheat and summer maize rotation was 12. 8(N0), 22. 0(N120), 33. 0(N240) and 64. 5 kg N ha-1(N360) respectively and rate of ammonia volatilization loss was 3.8, 4.2 and 7. 2 % respectively while urea was mixed with 0 - 10 cm soil or spread before irrigation. Denitrification loss with acetylene-soil core incubation method in winter wheat was lower than 1 kg N ha-1 and rate of denitrification loss was 0. 21 - 0. 26% or trace. Denitrification loss in summer maize was 1 - 14 kg N ha-1 and rate of denitrification loss was 1 - 5 %. The total gaseous loss in winter wheat and summer maize rotation system was less than 10 %, and the main nitrogen fertilizer loss way was leaching below 0 - 100 cm soil profile and accumulated in deeper soil.

Effect of No Tillage and Conventional Tillage on Wheat Grain Yield Variability: A Review

Conservation Agriculture(CA)covers more than 205 million hectares in the world.This made it possible to face and mitigate the challenges of climate change,reducing soil erosion and providing multiple ecosystem services.The first elementary factor influenced is the yield evaluation.It has a direct effect on farmers’choices for sustainable production.The present article records a review focused on wheat yield average positive change compared between conventional tillage(CT)and no tillage(NT)systems.The international database collected showed that NT is adaptable everywhere.The results of wheat yield differentiation showed the influence of crop rotation depending on stations located in different climatic zones.In more than 40 years of research,specialists have succeeded in demonstrating the importance of crop productivity like wheat.The whole integrates also experimentations where the initiation starts more than ten years.

Effects of three types of soil amendments on yield and soil nitrogen balance of maize–wheat rotation system in the Hetao Irrigation Area, China

Excessive fertilization combined with unreasonable irrigation in farmland of the Hetao Irrigation Area(HIR), China, has resulted in a large amount of nitrogen(N) losses and agricultural non-point source pollution.Application of soil amendments has become one of the important strategies for reducing N losses of farmland.However, there is still no systematic study on the effects of various soil amendments on N losses in the HIR.In this study, three types of soil amendments(biochar, bentonite and polyacrylamide) were applied in a maize–wheat rotation system in the HIR during 2015–2017.Yields of maize and wheat, soil NH3 volatilization, N2O emission and NO3– leaching were determined and soil N balance was estimated.The results showed that applications of biochar, bentonite and polyacrylamide significantly increased yields of maize by 9.2%, 14.3% and 13.3%, respectively, and wheat by 9.2%, 16.6% and 12.3%, respectively, compared with the control(fertilization alone).Applications of biochar, bentonite and polyacrylamide significantly reduced soil N leaching by 23.1%, 35.5% and 27.1%, soil NH3-N volatilization by 34.8%, 52.7% and 37.8%, and soil N surplus by 23.9%, 37.4% and 30.6%, respectively.Applications of bentonite and polyacrylamide significantly reduced N2O-N emissions from soil by 37.3% and 35.8%, respectively, compared with the control.Compared with application of biochar, applications of bentonite and polyacrylamide increased yields of maize and wheat by 5.1% and 3.5%, respectively.Our results suggest that soil amendments(bentonite and polyacrylamide) can play important roles in reducing N losses and increasing yield for the maize–wheat rotation system in the HIR, China.

Influence of P-enriched compost application on economics and P use efficiency of a maize–wheat rotation system

Crop phosphorus(P) deficiency and poor utilization of added P is a major agricultural problem due to reduced solubility of soil P and rapid fixation or precipitation of applied P fertilizer in alkaline and calcareous soils. The effects of P-enriched compost and single superphosphate(SSP) fertilization on maize and wheat yields and P use efficiency in a maize–wheat rotation system were studied for three years. On a three-year average, grain yields of maize and wheat after application of P-enriched compost were increased by 18% and 24%, respectively, in comparison with sole addition of a recommended dose of SSP fertilizer. P-enriched compost addition to soil increased maize and wheat yields by 12% and 17%, respectively, compared to P fertilizer plus FYM incorporation. Soil available P concentration and P uptake were affected significantly by the addition of P-enriched compost. On average, increases in P recovery, use efficiency, and agronomic efficiency of 52%, 18%, and 43% were recorded in maize and increases of 50%, 23%, and 49% in wheat. P-enriched compost application yielded 30% and 32%higher economic returns in maize and wheat than SSP fertilization alone.

A Meta-analysis of No-tillage Effects on Greenhouse Gas Emissions from Wheat-based Rotation Cropping Agroecosystem in China

Globally,agricultural soils are considered as one of the most important sources of greenhouse gas(GHG)emissions.No-tillage(NT),one of the most admired ways of climate-smart agriculture,has been deemed to have co-benefit to mitigation of GHG emissions and sustainability for crop yield,however,the effect of NT on GHG emissions is controversial.This study analyzed the overall effects of NT on GHG emissions,as well as the moderators that significantly influenced the overall effects,of the wheat-based rotation cropping systems in China through meta-analysis.The results showed that the overall effect size of NT on methane(CH4)uptake,nitrous oxide(N2O)emission,and global warming potential(GWP)was 0.70(95%Confidence Interval(CI):0.21–1.19),-0.27(95%CI:-0.72–0.18),and-0.39(95%CI:-1.01–0.23),respectively.In temperate climate zones with alkaline soils,the nitrogen application rate of 120–240 kg/ha,NT could significantly reduce GHG emissions and GWP.However,the mitigation effect will be weakened along with NT duration,except for proper straw addition.Overall,NT has the potential to reduce GHG emissions from wheat-based rotation systems in China,but it is necessary to implement NT depending on local conditions,soil characteristics,and field management.

Effect of Different Fertilization Practices on Yield of a Wheat-Maize Rotation and Soil Fertility

A 15-year field experiment was carried out in Henan Province, China, to study the effects of different fertilization practices on yield of a wheat-maize rotation. Fertilizers tested contained N alone (N), N plus P (NP) or plus P and K (NPK), all with or without manure (M). Different long-term fertilization practices affected the yields under the rotation system of wheat and maize differently and the effects on yields was in a general trend of MNPK＞MNP＞MN＞NPK＞NP＞M＞N＞the control. The average contribution rate of soil fertility to the highest yield was 37.9%, and the rest 62.1% came from fertilizer applications. The yield effects of the chemical fertilizers were in the order of N＞P＞K and were increased by application of manure.Balanced fertilization with multielement chemical fertilizers and manure can be effective in maintaining growth in agricultural production. Combined application of chemical fertilizer and organic manure also increased the content of soil organic matter.

Effects of long-term full straw return on yield and potassium response in wheat-maize rotation

The effect of long-term straw return on crop yield, soil potassium(K) content, soil organic matter, and crop response to K from both straw and chemical K fertilizer(K_2SO_4) were investigated in a fixed site field experiment for winter wheat-summer maize rotation in 6 years for 12 seasons. The field experiment was located in northern part of North China Plain with a sandy soil in relatively low yield potential. Two factors, straw return and chemical K fertilizer, were studied with two levels in each factor. Field split design was employed, with two straw treatments, full straw return of previous crop(St) and no straw return, in main plots, and two chemical K fertilizer treatments, 0 and 60 kg K2 O ha^(–1), as sub-plots. The results showed that straw return significantly increased yields of winter wheat and summer maize by 16.5 and 13.2% in average, respectively, and the positive effect of straw return to crop yield showed more effective in lower yield season. Straw return significantly increased K absorption by the crops, with significant increase in straw part. In treatment with straw return, the K content in crop straw increased by 15.9 and 21.8% in wheat and maize, respectively, compared with no straw return treatment. But, straw return had little effect on K content in grain of the crops. Straw return had significant influences on total K uptake by wheat and maize plants, with an increase of 32.7 and 30.9%, respectively. There was a significant correlation between crop yield and K uptake by the plant. To produce 100 kg grain, the wheat and maize plants absorbed 3.26 and 2.24 kg K2 O, respectively. The contents of soil available K and soil organic matter were significantly affected by the straw return with an increase of 6.07 and 23.0%, respectively, compared to no straw return treatment. K_2SO_4 application in rate of 60 kg K2 O ha^(–1) showed no significant effect on wheat and maize yield, K content in crop straw, total K uptake by the crops, soil available K content, and soil organic matter. The apparent K utilization rate(percentage of applied K absorbed by the crop in the season) showed difference for wheat and maize with different K sources. In wheat season, the K utilization rate from K_2SO_4 was higher than that from straw, while in maize season, the K utilization rate from straw was higher than that from chemical fertilizer. In the whole wheat-maize rotation system, the K absorption efficiency by the two crops from straw was higher than that from K_2SO_4.

Trends of Yield and Soil Fertility in a Long-Term Wheat-Maize System

The sustainability of the wheat-maize rotation is important to China’s food security.Intensive cropping without recycling crop residues or other organic inputs results in the loss of soil organic matter(SOM)and nutrients,and is assumed to be nonsustainable.We evaluated the effects of nine different treatments on yields,nitrogen use efficiency,P and K balances,and soil fertility in a wheat-maize rotation system(1991-2010)on silt clay loam in Shaanxi,China.The treatments involved the application of recommended dose of nitrogen(N),nitrogen and phosphorus(NP),nitrogen and potassium(NK),phosphorus and potassium(PK),combined NPK,wheat or maize straw(S)with NPK(SNPK),or dairy manure(M)with NPK(M1NPK and M2NPK),along with an un-treated control treatment(CK).The mean yields of wheat and maize ranged from 992 and 2235 kg ha-1 under CK to 5 962 and 6 894 kg ha-1 under M2NPK treatment,respectively.Treatments in which either N or P was omitted(N,NK and PK)gave significantly lower crop yields than those in which both were applied.The crop yields obtained under NP,NPK and SNPK treatments were statistically identical,as were those obtained under SNPK and MNPK.However,M2NPK gave a significant higher wheat yield than NP,and MNPK gave significant higher maize yield than both NP and NPK.Wheat yields increased significantly(by 86 to 155 kg ha-1 yr-1)in treatments where NP was applied,but maize yields did not.In general,the nitrogen use efficiency of wheat was the highest under the NP and NPK treatments;for maize,it was the highest under MNPK treatment.The P balance was highly positive under MNPK treatment,increasing by 136 to 213 kg ha-1 annually.While the K balance was negative in most treatments,ranging from 31 to 217 kg ha-1 yr-1,levels of soil available K remained unchanged or increased over the 20 yr.SOM levels increased significantly in all treatments.Overall,the results indicated that combinations of organic manure and inorganic nitrogen,or returning straw with NP is likely to improve soil fertility,increasing the yields achievable with wheat-maize system in a way which is environmentally and agronomically beneficial on the tested soil.

Effects of mulches on water use in a winter wheat/summer maize rotation system in Loess Plateau, China

Limited water resources often result in reduced crop yield and low water productivity(WP). In northwestern China, crop production is generally dependent on precipitation. Therefore, a variety of agricultural rainwater harvesting(ARH) techniques have been used for conserving soil moisture, ameliorating soil environment, increasing crop yield, and improving water use efficiency. A two-year(2013–2015) field experiment was conducted under a typical sub-humid drought-prone climate in Yangling(108°24′E, 34°20′N; 521 m a.s.l.), Shaanxi Province, China, to explore the effects of mulching(same for summer maize and winter wheat) on soil moisture, soil temperature, crop water consumption, and crop yield with a winter wheat/summer maize rotation. Crops were planted in a ridge-furrow pattern and the treatments consisted of a transparent film mulch over the ridges(M1), a crop straw mulch in the furrows(M2), a transparent film mulch over the ridges and a crop straw mulch in the furrows(M3), a black film mulch over the ridges and a crop straw mulch in the furrows(M4), and a control with no mulch(CK). Results showed that M4 was the best treatment for improving soil water storage and content, and decreasing crop water consumption during the summer maize and winter wheat rotation. In both maize and wheat seasons, M1 had a higher soil temperature than M2 and CK, and M3 had a higher soil temperature than M4. In the maize seasons, M4 had the highest yield, WP, and precipitation productivity(PP), with the average values for these parameters increasing by 30.9%, 39.0%, and 31.0%, respectively, compared to those in CK. In the wheat seasons, however, M3 had the highest yield, WP, and PP, with the average values for these parameters being 23.7%, 26.7%, and 23.8% higher, respectively, than those in CK. Annual yield(maize and wheat yields combined) and WP did not differ significantly between M3 and M4. These results suggested that M3 and M4 may thus be the optimal ARH practices for the production of winter wheat and summer maize, respectively, in arid and semi-arid areas.

Effects of saline irrigation on soil salt accumulation and grain yield in the winter wheat-summer maize double cropping system in the low plain of North China

In the dominant winter wheat(WW)-summer maize(SM) double cropping system in the low plain located in the North China, limited access to fresh water, especially during dry season, constitutes a major obstacle to realize high crop productivity. Using the vast water resources of the saline upper aquifer for irrigation during WW jointing stage, may help to bridge the peak of dry season and relieve the tight water situation in the region. A field experiment was conducted during 2009–2012 to investigate the effects of saline irrigation during WW jointing stage on soil salt accumulation and productivity of WW and SM. The experiment treatments comprised no irrigation(T1), fresh water irrigation(T2), slightly saline water irrigation(T3:2.8 dS m^(–1)), and strongly saline water irrigation(T4: 8.2 dS m^(–1)) at WW jointing stage. With regard to WW yields and aggregated annual WW-SM yields, clear benefits of saline water irrigation(T3 & T4) compared to no irrigation(T1), as well as insignificant yield losses compared to fresh water irrigation(T2) occurred in all three experiment years. However, the increased soil salinity in early SM season in consequence of saline irrigation exerted a negative effect on SM photosynthesis and final yield in two of three experiment years. To avoid the negative aftereffects of saline irrigation, sufficient fresh water irrigation during SM sowing phase(i.e., increase from 60 to 90 mm) is recommended to guarantee good growth conditions during the sensitive early growing period of SM. The risk of long-term accumulation of salts as a result of saline irrigation during the peak of dry season is considered low, due to deep leaching of salts during regularly occurring wet years, as demonstrated in the 2012 experiment year. Thus, applying saline water irrigation at jointing stage of WW and fresh water at sowing of SM is most promising to realize high yield and fresh irrigation water saving.

Seasonal and Interannual Variations of Carbon Exchange over a Rice–Wheat Rotation System on the North China Plain

Rice–wheat(R–W) rotation systems are ubiquitous in South and East Asia,and play an important role in modulating the carbon cycle and climate. Long-term,continuous flux measurements help in better understanding the seasonal and interannual variation of the carbon budget over R–W rotation systems. In this study,measurements of CO2 fluxes and meteorological variables over an R–W rotation system on the North China Plain from 2007 to 2010 were analyzed. To analyze the abiotic factors regulating Net Ecosystem Exchange(NEE),NEE was partitioned into gross primary production(GPP) and ecosystem respiration. Nighttime NEE or ecosystem respiration was controlled primarily by soil temperature,while daytime NEE was mainly determined by photosythetically active radiation(PAR). The responses of nighttime NEE to soil temperature and daytime NEE to light were closely associated with crop development and photosynthetic activity,respectively. Moreover,the interannual variation in GPP and NEE mainly depended on precipitation and PAR. Overall,NEE was negative on the annual scale and the rotation system behaved as a carbon sink of 982 g C m-2per year over the three years. The winter wheat field took up more CO2 than the rice paddy during the longer growing season,while the daily NEE for wheat and rice were-2.35and-3.96 g C m-2,respectively. After the grain harvest was subtracted from the NEE,the winter wheat field became a moderately strong carbon sink of 251–334 g C m-2per season,whereas the rice paddy switched to a weak carbon sink of107–132 per season.

Estimating daily actual evapotranspiration of a rice–wheat rotation system in typical farmland in the Huai River Basin using a two-step model and two one-step models

The objective of this study is to evaluate the performance of three models for estimating daily evapotranspiration(ET) by employing flux observation data from three years(2007, 2008 and 2009) during the growing seasons of winter wheat and rice crops cultivated in a farmland ecosystem(Shouxian County) located in the Huai River Basin(HRB), China. The first model is a two-step model(PM-Kc);the other two are one-step models(e.g., Rana-Katerji(R-K) and advection-aridity(AA)). The results showed that the energy closure degrees of eddy covariance(EC) data during winter wheat and rice-growing seasons were reasonable in the HRB, with values ranging from 0.84 to 0.91 and R2 of approximately 0.80. Daily ET of winter wheat showed a slow decreasing trend followed by a rapid increase, while that of rice presented a decreasing trend after an increase. After calibrating the crop coefficient(Kc), the PM–Kc model performed better than the model using the Kc recommended by the Food and Agricultural Organization(FAO). The calibrated key parameters of the R-K model and AA model showed better universality. After calibration, the simulation performance of the PM-Kc model was satisfactory. Both the R-K model and AA model underestimated the daily ET of winter wheat and rice. Compared with that of the R-K model, the simulation result of the AA model was better, especially in the simulation of daily ET of rice. Overall, this research highlighted the consistency of the PM-Kc model to estimate the water demand for rice and wheat crops in the HRB and in similar climatic regions in the world.

A Field Study on Effects of Nitrogen Fertilization Modes on Nutrient Uptake,Crop Yield and Soil Biological Properties in Rice-Wheat Rotation System

Rational application of nitrogen (N) fertilizers is an important measure to raise N fertilizer recovery rate and reduce N loss.A two-year field experiment of rice-wheat rotation was employed to study the effects of N fertilization modes including a N fertilizer reduction and an organic manure replacement on crop yield,nutrient uptake,soil enzyme activity,and number of microbes as well as diversity of microbes.The result showed that 20% reduction of traditional N fertilizer dose of local farmers did not significantly change crop yield,N uptake,soil enzyme activity,and the number of microbes (bacteria,actinomycetes,and fungi).On the basis of 20% reduction of N fertilizer,50% replacement of N fertilizer by organic manure increased the activity of sucrose,protease,urease,and phosphatase by 46-62,27-89,33-46,and 35-74%,respectively,and the number of microbes,i.e.,bacteria,actinomycetes,and fungi by 36-150,11-153,and 43-56%,respectively.Further,organic fertilizer replacement had a Shannon's diversity index (H) of 2.18,which was higher than that of other modes of single N fertilizer application.The results suggested that reducing N fertilizer by 20% and applying organic manure in the experimental areas could effectively lower the production costs and significantly improve soil fertility and biological properties.

A Process-based Model of N_2O Emission from a Rice-Winter Wheat Rotation Agro-Ecosystem:Structure,Validation and Sensitivity

In order to numerically simulate daily nitrous oxide(N2O) emission from a rice-winter wheat rotation cropping system,a process-based site model was developed(referred to as IAP-N-GAS) to track the movement and transformation of several forms of nitrogen in the agro-ecosystem,which is affected by climate,soil,crop growth and management practices.The simulation of daily N2O fluxes,along with key daily environmental variables,was validated with three-year observations conducted in East China.The validation demonstrated that the model simulated well daily solar radiation,soil temperature and moisture,and also captured the dynamics and magnitude of accumulated rice aboveground biomass and mineral nitrogen in the soil.The simulated daily N2O emissions over all three years investigated were generally in good agreement with field observations.Particularly well simulated were the peak N2O emissions induced by fertilizations,rainfall events or mid-season drainages.The model simulation also represented closely the inter-annual variation in N2O emission.These validations imply that the model has the capability to capture the general characteristics of N2O emission from a typical rice-wheat rotation agro-ecosystem.Sensitivity analyses revealed that the simulated N2O emission is most sensitive to the fertilizer application rate and the soil organic matter content,but it is much less sensitive to variations in soil pH and texture,temperature,precipitation and crop residue incorporation rate under local conditions.

Response of dryland crops to climate change and drought-resistant and water-suitable planting technology:A case of spring maize

Climate change has a significant impact on agriculture.However,the impact investigation is currently limited to the analysis of meteorological data,and there is a dearth of long-term monitoring of crop phenology and soil moisture associated with climate change.In this study,temperature and precipitation(1957-2020)were recorded,crop growth(1981-2019)data were collected,and field experiments were conducted at central and eastern Gansu and southern Ningxia,China.The mean temperature increased by 0.36°C,and precipitation decreased by 11.17 mm per decade.The average evapotranspiration(ET)of winter wheat in 39 years from 1981 to 2019 was 362.1 mm,demonstrating a 22.1-mm decrease every 10 years.However,the ET of spring maize was 405.5 mm over 35 years(1985-2019),which did not show a downward trend.Every 10 years,growth periods were shortened by 5.19 and 6.47 d,sowing dates were delayed by 3.56 and 1.68 d,and maturity dates advanced by 1.76 and 5.51 d,respectively,for wheat and maize.A film fully-mulched ridge-furrow(FMRF)system with a rain-harvesting efficiency of 65.7‒92.7%promotes deep rainwater infiltration into the soil.This leads to double the soil moisture in-furrow,increasing the water satisfaction rate by 110‒160%.A 15-year grain yield of maize increased by 19.87%with the FMRF compared with that of half-mulched flat planting.Grain yield and water use efficiency of maize increased by 20.6 and 17.4%when the density grew from 4.5×10^(4)to 6.75×10^(4)plants ha-1 and improved by 12.0 and 12.7%when the density increased from 6.75×10^(4)to 9.0×10^(4)plants ha-1,respectively.Moreover,responses of maize yield to density and the corresponding density of the maximum yield varied highly in different rainfall areas.The density parameter suitable for water planting was 174 maize plants ha-1 with 10 mm rainfall.Therefore,management strategies should focus on adjusting crop planting structure,FMRF water harvesting system,and water-suitable planting to mitigate the adverse effects of climate change and enhance sustainable production of maize in the drylands.

Fate of ^(15)N-Labeled Urea Under a Winter Wheat-Summer Maize Rotation on the North China Plain

一个地实验被进行在冬小麦(Triticum aestivum L.) 和夏天玉米(Zea mays L.) 下面调查 15N 标签脲和它的剩余效果的命运诺思中国平原上的旋转系统。比作 360 kg N 的常规申请率哈 ? 1 (N360 ) ， 120 kg N 的减少的率哈 ?(N120 ) 1 导致了重要增加(P 【 0.05 ) 在小麦，产量和没有重要差别被作出对有利的裁决玉米。在在收获的 0 100 厘米土剖面，与 N360 相比， N120 不管多么导致了重要减少(P 【 0.05 ) 百分比剩余 N 和百分比未予说明的 N，它可能从管理系统反映了损失。在土剖面的剩余化肥 N 25.6%44.7%和20.7%分别地，，38.2%为 N120 和 N360 在器官的 N 水池0.3%3.0%和11.2%相应地，24.4%在硝酸盐水池，显示一个更高的潜力因为沥滤的损失以常规率与申请联系了。在由接替庄稼的土剖面的剩余 N 的恢复是不到 7.5% 应用 N。为 N120，全部的土壤 N 平衡是否定的；然而，仍然有可观的矿物质 N (NH+4-N 并且没有 ? 3-N ) 在在收获以后的土剖面。因此， N120 能在短期内被认为农学的联盟者可接受，要不是长期的可持续性， N 率应该基于土壤矿物 N 测试和植物组织硝酸盐测试被推荐维持土壤肥力。

The Effect of Organo-Mineral Fertilizer Applications on the Yield of Winter Wheat, Spring Barley, Forage Maize and Grass Cut for Silage

Biosolids were applied with urea to produce a granulated organo-mineral fertiliser (OMF) for application by farm fertiliser equipment to a range of agricultural crops. The recommended rates of nitrogen, phosphate and potash were calculated for the test crops using “The Fertiliser Manual”, which assesses the nutrient requirement based on previous cropping, rainfall and soil index. The OMF produced similar crop yields compared to ammonium nitrate fertiliser when applied as a top-dressing to winter wheat, forage maize and grass cut for silage in the cropping years 2010 to 2014. In 2012 the grain yield of spring barley top-dressed with OMF was significantly lower than the conventional fertiliser treatment, due to dry conditions following application. For this reason it is recommended that OMF is incorporated into the seedbed for spring sown crops and The Safe Sludge Matrix guidelines followed. The experimental work presented shows that OMF can be used in sustainable crop production systems as a source of nitrogen and phosphorus for a range of agricultural crops.

Effect of steam-flaking on chemical compositions,starch gelatinization,in vitro fermentability,and energetic values of maize,wheat and rice

Intact and steam-flaked grains of maize,wheat and rice(with whole hulls) were analyzed for chemical composition,starch gelatinization degree(SGD) and in vitro fermentation characteristics to investigate the influence of cereal type and steam-flaking(SF) processing on their nutritive values.The treatments were arranged in a 3×2 factorial design.Obvious differences(P<0.001) in chemical composition and energetic values were observed among the different cereal types.SGD and gas production(GP) rate was significantly increased(P<0.001) by SF processing.SF processing also increased(P<0.01) the proportion of propionic acid and decreased the acetic:propionic acid ratio in vitro.Steam-flaking also increased organic matter digestibility and the energetic value of the cereal grains,especially rice.Based on these results,rice probably is more amendable to SF processing than maize and wheat.In conclusion,it is feasible to partially substitute maize grain with wheat or rice in ruminant diets,and steam-flaking can significantly improve the nutritional value of wheat and rice grains.

Effect of Nitrogen Management on Yield and Water Use Efficiency of Rainfed Wheat and Maize in Northwest China

A field experiment with four treatments and four replicates in a randomized complete block design was conducted at the Changwu Experimental Station in Changwu County, Shaanxi Province, of Northwest China from 1998 to 2002. The local cropping sequence of wheat, wheat-beans, maize, and wheat over the 4-year period was adopted. A micro-plot study using 15N-labelled fertilizer was carried out to determine the fate of applied N fertilizer in the first year. When N fertilizer was applied wheat (years 1, 2 and 4) and maize (year 3) grain yield increased significantly (P<0.05) (>30%), with no significant yield differences in normal rainfall years (Years 1, 2 and 3) for N application at the commonly application rate and at 2/3 of this rate. Grain yield of wheat varied greatly between years, mainly due to variation in annual rainfall. Results of 15N studies on wheat showed that plants recovered 36.6%-38.4% of the N applied, the N remained in soil (0-40 cm) ranged from 29.2% to 33.6%, and unaccounted-for N was 29.5%-34.2%. The following crop (wheat) recovered 2.1%-2.8% of the residual N from N applied to the previous wheat crop with recovery generally decreasing in the subsequent three crops (beans, maize and wheat).