秸秆还田配施稳定性氮肥对麦玉轮作水氮利用的影响

为探究秸秆还田配施稳定性氮肥对关中地区麦玉轮作体系作物生长及水氮利用的综合影响,并确定合理的高产高效施肥管理措施,设置两种秸秆还田模式(秸秆不还田、秸秆全量还田)和两种施氮措施(常规尿素和减量施用稳定性氮肥),以无秸秆还田且不施肥作为对照,共5个处理,研究分析作物产量、地上部生物量、土壤氨挥发累积量、土壤含水率、土壤硝态氮残留量及水氮利用效率。结果表明：秸秆还田配施氮肥会分别显著提高夏玉米和冬小麦产量28.03%～39.63%和90.10%～112.52%、地上部生物量27.88%～34.00%和78.96%～107.64%;施用稳定性氮肥较施用常规尿素分别降低夏玉米季和冬小麦季全生育期土壤氨挥发累积量50.18%～59.32%和68.21%～73.43%;秸秆还田会显著提高夏玉米季0～10 cm土壤含水率6.29%～21.38%,显著提高冬小麦季0～10 cm土壤含水率6.80%～25.06%;相同施肥措施下,秸秆还田会显著降低夏玉米与冬小麦收获期0～100 cm土壤NO^-₃-N残留量7.34%～10.78%和6.57%～11.24%,在相...     

Application of epic model to nitrogen cycling in irrigated processing tomatoes under different management systems

Vegetable crops such as processing tomatoes (Lycopersicon esculentum Mill.) are usually complex in terms of nitrogen (N) dynamics because of the large amounts absorbed by the crop, the short growing season and the use of irrigation. Complexity increases when N is supplied from an organic source. A crop simulation model could be very useful to improve N management in this crop. Processing tomatoes were grown on raised beds and furrow irrigated in 1994 and 1995 in the Sacramento Valley of California. Fertilizer N and/or purple vetch (Vicia sativa L.) as green manure and composted turkey manure were used as sources of N. The Erosion Productivity Impact Calculator (EPIC) model was calibrated with 1994 data and validated with 1995 data. Plant growth was accurately simulated in the conventional systems that used fertilizer N and in the low input system that used fertilizer N plus vetch. The model accurately simulated above-ground biomass in a system that used vetch and no synthetic fertilizer N, but it over-predicted Leaf Area Index (LAI). Nitrogen deficiency was observed in the plants in this system. The model simulated nitrogen deficiency mainly as a reduction in biomass production but in the real world the reduction of leaf area was the first effect of nitrogen deficiency in the vegetative phase. Yields were accurately predicted except when diseases affected plant growth. A simple reduction factor of nitrate movement in the bed adequately addressed the movement of nitrate. In general, the model accurately predicted the evolution of inorganic nitrogen in different soil layers during the crop season. However, simulated inorganic N in the upper 15 cm was underestimated in the last part of the crop season and consequently N uptake at harvest was slightly over-predicted in some cases. Nitrogen distribution and access of the roots to inorganic nitrogen are discussed as causes of this discrepancy between model simulated and observed values.     

滴灌精准施肥装置棉田施氮配肥能力研究

在SPAD营养诊断氮素施肥模型基础上,确定滴灌棉花不同生育期的最佳施氮量;结合单次灌溉时间、轮灌区面积的相关研究,确定不同规格配肥盘的配肥时间。通过对比配肥盘单位时间配肥量与施肥量之间的关系,确定滴灌精准施肥装置的施氮配肥能力。结果表明:滴灌棉田单位时间施肥量只与单井出水量Q和特定棉花生育时期的施氮量Nd有关。该装置100、200、300 g 3个规格配肥盘无论在任何单井出水量情况下,都无法满足棉花全生育期追施氮肥的需要,400 g与500 g规格的配肥盘也只能满足特定单井出水量条件下的棉花追氮任务,并在此基础上对装置的优化与改进进行了阐述。     

氮肥和磷肥用量对小麦产量的影响

合理控制化肥用量已成为农业发展的必经之路,为了有效减少化肥用量、提高地力水平、增加作物产量,采用田间裂区试验,分析了不同绿肥品种下氮肥与磷肥用量对小麦产量等指标的影响。结果显示,绿肥混播条件下,氮磷肥料分别减施至120 kg N/hm2与80 kg P2O5/hm2时,小麦可达到其产量的最高值,这表明该种施肥处理方式具有较好的应用效果与应用价值,可在农业生产中进行大力推广。      

Agricultural practices,soil fertility management modes and resultant nitrogen leaching rates under semi-arid conditions

Under semi-arid or arid conditions, growing needs for agricultural commodities dictate the intensification of agricultural activities through the application of irrigation and fertilization practices aimed at increasing crop yields. A certain amount of the added irrigation water is designed to seep below the root zone and leach excessive salts accumulated in the irrigated soil. This entails, in part, recharging the ground water-table aquifers. Hence, intensification of agricultural activities introduces a long-term risk of groundwater pollution by unused fertilizers, e.g., nitrogen, salts and pesticides, herbicides, leached from the irrigated fields. To avert or minimize this risk, the amounts of applied water and fertilizer should be determined and minimized by optimizing them to match crop requirements. The objectives of the present work were to determine the amounts of water and salts leached below several agricultural areas subjected to differing soil fertility practices, and to try to relate them to the yields obtained. Published data and experimental data sets of water, chloride and nitrate concentration – depth distributions were used and analyzed. The results show that intensification of agricultural activities leads to increased hazards to surface and groundwater pollution and this can be diminished provided balanced irrigation – fertilization programs are developed for different crops, by using the results of leachate loads seeping from long-term fertility and irrigation studies (permanent plot experiments).     

Evaluation of the RZWQM for the Simulation of Water and Nitrate Movement in Level-Basin,Fertigated Maize

This study concerns the evaluation of the root zone water quality model (RZWQM) to simulate the seasonal water and nitrate movement in a level basin irrigated corn field under three different nitrogen (N) fertilizer treatments. The three N treatments, superimposed over a split basal dose applied before and at planting, were: a single broadcast application of 150 kg N/ha as urea (100% amidic form), a single fertigation application of the same N as UAN (50% amidic, 25% ammonium and 25% nitrate) with the first irrigation, and multiple UAN fertigations with three irrigations. Certain variety-specific maize crop parameters in the model were obtained by fitting these parameters to field data from the single fertigation treatment. The model was then evaluated on water and N results for the treatments. The model adequately simulated the water and nitrate transport for the season, with the seasonal averages of measured and predicted values differing by less than 5%. The most significant differences between measured and simulated water and nitrate occurred near the soil surface (15 cm depth), mostly during the days when the soil was extremely wet following irrigations. With the soil hydraulic properties estimated by simple means, the model tends to overestimate downward water fluxes and related nitrate transport through a compacted layer; however, it is found to be a useful tool to study the relative impacts of alter- nate nitrogen fertilizer and irrigation practices on root zone water quality.     

Management model for decision support when applying low quality water in irrigation

Use of low quality water for irrigation of food crops is an important option to secure crop productivity in dry regions, alleviate water scarcity and recycle nutrients, but it requires assessment of adverse effects on health and environment. In the EU-project “SAFIR¹” a model system was developed that combines irrigation management with risk evaluation, building on research findings from the different research groups in the SAFIR project. The system applies to field scale irrigation management and aims at assisting users in identifying safe modes of irrigation when applying low quality water. The cornerstone in the model system is the deterministic “Plant-Soil-Atmosphere” model DAISY, which simulates crop growth, water and nitrogen dynamics and if required heavy metals and pathogen fate in the soil. The irrigation and fertigation module calculates irrigation and fertigation requirements based on DAISY's water and nitrogen demands. A Water Source Administration module keeps track of water sources available and their water quality, as well as water treatments, storage, and criteria for selection between different sources. At harvest, the soil concentrations of heavy metals and pathogens are evaluated and the risk to consumers and farmers assessed. Crop profits are calculated, considering fixed and variable costs of input and output. The user can run multiple “what-if” scenarios that include access to different water sources (including wastewater), water treatments, irrigation methods and irrigation and fertilization strategies and evaluate model results in terms of crop yield, water use, fertilizer use, heavy metal accumulation, pathogen exposure and expected profit. The management model system can be used for analysis prior to investments or when preparing a strategy for the season.     

不同氮肥和磷肥用量对小麦产量的影响分析

当前合理控制化肥用量已然成为农业发展的必经之路,为了有效减少化肥用量、提高地力水平、增加作物产量,此次研究针对不同氮肥和磷肥用量对小麦产量的影响,进行了深入的探究。研究中采用田间裂区试验,分析了不同绿肥品种下氮肥与磷肥用量对小麦产量等指标造成的影响。结果显示,绿肥混播条件下对氮磷肥料分别减施至120kg N/hm2与80kg P2O5/hm2时,小麦可达到其产量的最高值,这表明该种施肥处理方式具有较好的应用效果与应用价值,可在农业生产中进行大力推广。     

拔节期淹水条件下施氮量对玉米干物质积累和氮素吸收利用的影响

[目的]揭示拔节期淹水胁迫下施氮量对玉米干物质积累分配及氮素吸收利用的影响.[方法]以春玉米"宜单629"为供试作物,采用2因素裂区田间试验,主处理为土壤水分状况,包括全生育期适宜水分(CS处理)和拔节期淹水6d(YS处理);副处理为施氮量,包括0、90、180、270 kg/hm2和360 kg/hm2,分别记为N0...     

Farmer participatory testing of standard and modified site-specific nitrogen management for irrigated rice in China

Rice in China receives high amounts of fertilizer nitrogen (N) that are often not used efficiently by the crop. A recently developed site-specific N management (SSNM) approach enables the application of fertilizer N to dynamically match the field- and season-specific needs of the rice crop for N. We used farmer participatory research for on-farm testing of N fertilization by standard and farmer-modified SSNM for irrigated rice. Our study was done in 14 villages in four provinces of China in 2003 and 2004. Twelve to 15 farmers were randomly selected in each study village in each year for a dialogue with the research team and for a rapid rural technology assessment (RRTA). Based on the information obtained from the RRTA, modified SSNM (MSSNM) schemes were developed through dialogue between a research team and farmers at a workshop in each village. Modification mainly involved decreasing the number of fertilizer-N topdressings and increasing the rate of basal N application. Among the 514 farmers surveyed during the workshops, 95% were willing to adopt SSNM and MSSNM technologies and 76% were willing to conduct SSNM or MSSNM experiments. More than two-thirds of the farmers preferred adopting MSSNM rather than the standard SSNM. Based on the farmers’ willingness, 144 farmers were selected to conduct an experiment to compare SSNM or MSSNM with the farmers’ fertilizer practices (FFP). The rate and distribution of fertilizer N during the growing season of MSSNM were in between those of SSNM and FFP. SSNM and MSSNM, compared with FFP, maintained rice yields with significantly less fertilizer N and no significant increase in total labour input. The reduction in fertilizer-N input averaged 48 kg N/ha for SSNM and 23 kg N/ha for MSSNM. The study suggests that there is potential for large-scale dissemination of SSNM technology in China.     

辣椒水肥一体化效应研究进展

在作物的生长过程中,水和肥是必不可少的两大要素,合理的灌溉和施肥对作物减投增效十分有利。传统的“大水大肥”方式不仅会降低水肥利用率,而且还加剧了农田土壤环境的污染问题。水肥一体化技术作为一项将水分和养分耦合运筹的新技术,可达到精准施肥、改善土壤环境、节水增产等目的,从而有效缓解资源与环境的矛盾问题,推动绿色农业的可持续发展。本文先综述了辣椒的生长发育、干物质积累、水肥利用、产量及品质指标对水肥一体化的响应,并针对该技术在农业生产中的实践应用,提出合理利用智能系统、多要素一体化技术和耦合模型规划建议,以期为水肥一体化在辣椒高产栽培中的应用提供参考。     

基于多时相多参数融合的麦玉轮作小麦产量估算方法

为了进一步提高冬小麦产量预测的准确性,针对麦玉轮作体系缺乏直接把前茬作物信息纳入到当季作物的产量估算及管理中的研究状况,利用前茬玉米季中长势遥感信息及产量信息,融合小麦拔节期、灌浆期及成熟期长势遥感信息、播前施肥信息及土壤特性信息等多时相多模态数据,基于GPR算法,建立多时相多模态参数融合的麦玉轮作体系小麦产量估算模型,结果显示：基于多生育期的产量估算模型较单生育期最优产量估算模型性能有所提升,R²提高0.01～0.03。其中基于拔节期产量估算模型精度略低于多生育期产量估算模型,但精度相近。基于多模态参数融合的产量估算模型中,除玉米作物信息与土壤特性信息融合构建的产量估算模型,多模态参数融合的产量估算模型精度较相应低模态参数融合的产量估算模型精度高。四模态参数融合的GPR模型决定系数R²为0.92,RMSE为213.75 kg/hm²,较其他模型,R²提高0.02～0.41。对于小麦产量估算模型,各模态参数影响由大到小依次为施肥信息、小麦遥感信息、土壤特性信息、玉米作物信息。玉米作物信息对于多模态参...     

Measurements and simulations of heat and water balance components in a clay soil cropped with winter wheat under drought stress or daily irrigation and fertilization

Soil water and temperature dynamics were measured in a field experiment with winter wheat on a clay soil. There were four treatments: Control (C), receiving natural precipitation, drought (D), protected from rain by plastic screens during the growing season, daily irrigation (I) and daily irrigation and fertilization (IF). Treatments C, D and I received the nitrogen fertilizer as a single application of solid fertilizer in spring. In IF daily dressings of nutrients were supplied in the irrigation water. All treatments received 20 g Nm^–2. An associated experiment with a newly sown grass ley (L) that was irrigated and fertilized daily (total 5.6 g Nm ^–2) was also performed. Standard meteorological variables (air temperature and humidity, wind speed, precipitation, global radiation, and relative cloudiness) and crop development data (green area index, crop height, relative root distribution in depth) above and below ground were used as driving variables within a physically based dynamic model (SOIL) for simulating water and heat fluxes. Measured soil temperature and water content from one treatment (I) were used to tune the model parameters, tentatively set from literature data. Thereafter, water and heat fluxes in the other treatments were simulated using the same parameter values but with different crop-related measurements as driving variables for each treatment. Measured soil temperature and water content in C, D, IF and L could thus be used for validation of the simulations. The theory formulated in the model could accurately explain measured treatment differences in soil water and temperature dynamics. Since the soil-related parameters were identical in all treatments, the model was shown to be applicable over a wide range of moisture conditions.     

精准施肥自动控制系统的设计

以华邦公司的W77E58型单片机为控制核心,选用美国生产的SPAD-502 叶绿素仪,测定作物当前生长期的氮含量,通过GPS测定当前地块的位置,结合GIS的当前地块当前生长期氮含量数据,实时计算出差值,给出当前地块所需施的氮肥量,通过PC机将数据传送到单片机,利用步进电机的细分技术均匀施肥.该控制系统能够实现以lm2的尺度进行变量控制施肥.首次使用叶绿素测定仪检测作物中氮元素的含量,在很大程度上解决了过去土壤检测实效性差的问题.     

水氮耦合技术在经济作物栽培中的研究进展

灌水量与施肥量是影响作物生长的两大重要因素,传统的灌溉与施肥方式下,农田水肥利用效率低,不利于农业可持续发展,而适宜的灌水与施肥能够显著优化作物生长。水氮耦合技术通过合理调控作物在不同生育期的水肥需求,达到节水优质高产的目的。本文首先介绍了水氮耦合技术发展概况,阐述了水氮耦合技术的研究意义,同时也明确了该技术在经济作物栽培中的应用效果与发展前景。最后对水氮耦合技术存在的问题进行了深入思考。     

施肥对采煤塌陷复垦土壤团聚体组成及其碳、氮分布的影响

【目的】研究施肥对采煤塌陷复垦土壤团聚体组成及其碳、氮分布的影响,为改善采煤塌陷复垦土壤的物理团粒结构与化学性质,促进复垦土壤碳氮循环与利用提供一定理论基础。【方法】以山西省晋城市采煤塌陷复垦区土壤为研究对象,在常规灌溉条件下,以不施肥处理为对照(CK),研究了有机肥、无机肥、有机无机肥配施3种施肥处理对0～20、20～40 cm土层团聚体组成及碳、氮分布的影响。【结果】与CK相比,有机肥处理显著增加了土壤>2mm和1～2 mm粒级团聚体量,降低了0.053～0.25 mm和<0.053 mm粒级微团聚体量,单施化肥较有机肥处理提高了微团聚体量。单施有机肥、有机无机肥配施处理土壤的平均质量直径(MWD)、几何平均直径(GMD)显著高于单施化肥处理,分形维数(D)低于化肥处理。有机肥处理土壤有机碳、全氮量最高,有机无机肥处理配施次之,单施化肥处理显著低于有机肥处理;土壤有机碳、全氮主要分布在>2 mm、1～2 mm、0.25～1 mm粒级大团聚体,显著高于0.053～0.25 mm、<0.053 mm粒级小团聚体;有机肥处理、有机无机肥配施处理土壤>2 mm、1～2 mm、0.25～1 mm粒级团聚体中的有机碳、全氮量要显著高于单施无机肥处理的。各施肥处理土壤1～2 mm、0.25～1 mm粒级团聚体有机碳、全氮贡献率较高,显著高于其余粒级。有机肥、有机无机配施处理各级团聚体(除0.053～0.25 mm外)的C/N值显著高于CK,而单施化肥处理与CK差异不显著。【结论】不同施肥处理(尤其是有机肥)提高了复垦土壤大团聚体量,增强了团聚体稳定性,提高了团聚体有机碳、全氮量。     

Increasing water productivity with improved N fertilizer management

There is continuing debate about the role of water productivity and the potential to increase it in response to significantly increased water demand to meet the future needs for food—estimated to be roughly double that of today by 2050. The debate centers round the relative potential benefits of enhancing rainfed agriculture, improving irrigation and expanding areas of both. All expansion and intensification options will require significantly more water to be used, often in places where the ecosystem impacts of agriculture are already severe. Improvement in water productivity can result from improving the provision and management of the other factor inputs of crop production. There is considerable debate on the ability of other inputs—typically nitrogen—to substitute for water. This paper describes a set of simulations undertaken with well calibrated maize (Zea mays L.) crop model in Decision Support System for Agro-technology Transfer (DSSAT). The simulations investigate the response to nitrogen under rainfed conditions in Florida, and show that neither the transpiration ratio nor the harvest index are constant in practice, and that fertilizer use can enhance water productivity, even in quite high yield conditions and that the transpiration ratio can be increased by N fertilizer application at low levels of crop water use.     

Do farmers waste fertilizer? A comparison of ex post optimal nitrogen rates and ex ante recommendations by model, site and year

While there appear to be costs to farmers of over-applying nitrogen, there is evidence in many regions that farmers are applying nitrogen at levels that exceed those suggested by government extension services. A major reason why farmers would apparently waste money by applying more fertilizer than a crop can use is a perception that the general recommendations are not appropriate for their individual situations. In this paper we estimate the economically optimal rates for 7 Ontario sites over multiple years using four yield response functional forms to examine whether the profit-maximizing rates as determined at the end of the growing season (ex post optimal rates) are generally higher than recommended rates due to site, year, or yield response functional form differences. There was no statistical or economic basis for selecting one response model over another suggesting functional form choice or perception is not a reason for over-application. However, there was a great deal of variability found between the actual optimal rate for the season and the ex ante recommended rate, which is constant across seasons for a given site. While the recommended rate is higher than the maximum economic rate of nitrogen (MERN) on the majority of sites examined, the distribution is skewed due to a few large differences. When the recommended rate is lower than the ex post MERN in a given year, it tends to occur on less productive sites and is much lower. The pay-off function to alternative nitrogen rates is generally flat as the difference between the MERN and recommended was less than $10/ha on approximately one-third of the trials but there are large differences in the good years on less productive sites. Thus, the decision to apply more than average to take advantage of the good years is appropriate since the cost of over-application is low compared to the cost of under-application. While the pay off to soil testing for nitrogen and consequently variable rate application technology is brought into question, there appears to be significant value to information on the growing conditions for the upcoming season particularly on less productive sites. Another implication of the study is the need to have a sufficient range of application rates in nitrogen field trials for accurate estimation of the underlying response function.     

Analysis of nitrate pollution control policies in the irrigated agriculture of Apulia Region (Southern Italy): A bio-economic modelling approach

Nitrate leaching is one of the many forms of environmental pollution resulting from irrigation and intensive agriculture. In this work, a method of combining an agronomic simulation model (EPIC) and a mathematical multi-objective programming model is used to analyse the effects of three agricultural policies on farmer’s revenue and nitrate leaching. An evaluation of the net social costs associated with the different policy measures is also given. The farmer’s behaviour in different policy scenarios was studied in terms of selected crops, irrigation technique and method, and adopted management practices with focus on farm management practices and water application efficiency. Irrigation water pricing, subsidies to adopt improved management levels, and taxation on the use of nitrogen fertilizer were examined. A trade-off emerges between the levels of nitrate leaching and net farmer’s revenue more pronounced for nitrogen tax policies than for water pricing. The results obtained indicate that nitrate leaching can be reduced by about 40% with an associated net social cost of 269 €/ha for the water pricing policy, 183 €/ha for the tax on fertilizer and 95 €/ha for subsidies to high efficiency management.