Nitrogen Management Practices Research Articles

氮肥农学效应与环境效应国际研究发展态势

PDF HTML阅读 XML下载 导出引用 引用提醒 氮肥农学效应与环境效应国际研究发展态势 DOI: 10.5846/stxb201412312621 作者: 作者单位: 农业部面源污染控制重点实验室/中国农业科学院农业资源与农业区划研究所,农业部面源污染控制重点实验室/中国农业科学院农业资源与农业区划研究所,农业部面源污染控制重点实验室/中国农业科学院农业资源与农业区划研究所,农业部面源污染控制重点实验室/中国农业科学院农业资源与农业区划研究所,农业部面源污染控制重点实验室/中国农业科学院农业资源与农业区划研究所,农业部面源污染控制重点实验室/中国农业科学院农业资源与农业区划研究所,农业部环境保护科研监测所 作者简介: 通讯作者: 中图分类号: 基金项目: 公益性行业（农业）科研专项（201003014） A bibliometrical analysis of status and trends of international researches on the agronomic and environmental effects of nitrogen application to farmland Author: Affiliation: Ministry of Agriculture Key Laboratory of Nonpoint Source Pollution Control/ Institute of Agricultural Resources and Regional Planning,Ministry of Agriculture Key Laboratory of Nonpoint Source Pollution Control/ Institute of Agricultural Resources and Regional Planning,Ministry of Agriculture Key Laboratory of Nonpoint Source Pollution Control/ Institute of Agricultural Resources and Regional Planning,Ministry of Agriculture Key Laboratory of Nonpoint Source Pollution Control/ Institute of Agricultural Resources and Regional Planning,Ministry of Agriculture Key Laboratory of Nonpoint Source Pollution Control/ Institute of Agricultural Resources and Regional Planning,Ministry of Agriculture Key Laboratory of Nonpoint Source Pollution Control/ Institute of Agricultural Resources and Regional Planning,Agro-Environmental Protection Institute, Ministry of Agriculture Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:分析国内外农田氮素农学效应和环境效应研究的发展动态、研究热点，为以后研究农田氮素效应提供参考。基于ISI Web of Science数据库，检索出以"农田氮肥施用"为主题的所有SCI论文（1957-2014年8月），并分别提取出与"农学效应"、"环境效应"、"适宜施氮量"相关的文献，采用计量学方法，分析各研究方向的主要热点、研究机构、发文期刊和高被引论文等。共检索出关于农田施氮研究的SCI文献7460篇，其中与"农学效应"研究相关的文献2773篇，主要涉及到施氮肥对小麦、玉米、水稻、大豆等作物产量、氮素利用率和土壤有机碳的影响；与"环境效应"研究相关的文献1609篇，主要涉及到氮肥施用对氨挥发、硝化反硝化、温室气体排放、硝酸盐淋失、地下水水质等环境因素的影响；与"适宜施氮量"研究相关的文献408篇，主要涉及氮肥施用量、氮肥管理等。刊发各类研究成果最多的机构主要来自欧美发达国家，影响力大的期刊与高被引论文也主要来自欧美国家，中国在该领域的研究发展迅速，以中国科学院、中国农业大学、南京农业大学和中国农业科学院等为代表的中国研究机构的研究水平逐渐进入世界前列。文献计量学可用于分析农田氮素效应主题的研究热点和发展态势，目前氮素农学效应仍是研究的重点，随着当前环境污染问题日益突出，农田氮素环境效应研究越来越多，特别是氮流失对水体水质的影响备受关注，而基于氮素综合效应确定农田适宜施氮量是同时保障粮食安全和环境安全的有效措施。中国在相关研究领域的研究起步较晚，高影响力论文偏少，优秀国际期刊不足，但研究实力不断增加，研究成果也逐渐被国际社会所认可。 Abstract:The primary topics and trends in the development of research on the agronomic and environmental effects of nitrogen application, both in China and abroad, were analyzed to provide references and highlight opportunities for future research in the field of farmland nitrogen application. The Institute for Scientific Information (ISI) Web of Science database was used to retrieve Scientific Citation Indexed (SCI) papers published (1957-2014) on the topic of "nitrogen fertilizer application", and literature relevant to "agronomic effects", "environmental effects", and "appropriate nitrogen application" was extracted. The bibliometric method was used to analyze the main focus, research institutions, publishing journals, and citation indices of the publications in each research branch. A total of 7460 SCI articles on farmland nitrogen research were published during this period. Of these, 2,773 were related to "agronomic effects", which mainly included the effects of nitrogen application on nitrogen use efficiency, soil organic carbon, and yields of wheat, corn, rice, and soybeans, as well as other crops. There were 1609 articles related to "environmental effects", which mainly included the effects of nitrogen application on ammonia volatilization, nitrification and denitrification, greenhouse gas emissions, nitrate leaching, groundwater quality, and other environmental topics. There were 408 articles were related to "appropriate nitrogen application", which mainly covered the aspects of quantity of nitrogen fertilizer application and field nitrogen management. Most of the publications were by researchers affiliated to institutions in developed countries in Europe and North America; most of the publications in mainstream journals and the most highly cited publications were also by researchers based in developed European and American countries. However, research on farmland nitrogen application has developed rapidly in China, and some institutions, including the Chinese Academy of Sciences, China Agricultural University, Nanjing Agricultural University, and the Chinese Academy of Agricultural Sciences, have gradually become global leaders in this area. The bibliometric method can be used to analyze the primary topics and developmental trends in research on nitrogen application. Currently, investigation of the agronomic effects of nitrogen application is the main focus of research on nitrogen. Research on the environmental effects of nitrogen, especially the impacts of nitrogen loss on water quality, is receiving increasing attention, because of serious water quality problems around the world. Tremendous research opportunities lie in development of appropriate nitrogen management practices that could simultaneously guarantee food security and environmental quality. China has only recently entered this field of research, with few highly cited articles in well-recognized international journals by Chinese researchers, but the research capacity of Chinese institutions has been growing and their research achievements have increasingly been recognized by the international community. 参考文献 相似文献 引证文献

Influence of irrigation, crop residue mulch and nitrogen management practices on soil physical quality

Improvement in soil structure is a prerequisite for maintaining soil physical health/quality and for sustaining agricultural productivity at higher level. Field experiments were conducted during the kharif season of 2012 and 2013 on maize crop in a sandy loam soil to study the impact of different management practices viz., irrigation, crop residue mulch and nitrogen (N) fertilization on soil physical quality indices like least limiting water range (LLWR), S index, mean weight diameter (MWD), water stable aggregates (%WSA) and whole soil stability index (WSSI), and their impact on crop growth and yield. Maize (cv HQPM 1) was grown in a split-split plot design with two levels of irrigation (irrigated and rainfed), two levels of mulch (no mulch and wheat residue mulch @ 10 t ha−1) and three levels of N (0, 75 and 150 kg N ha−1). Soil physical quality parameters such as S index, LLWR, MWD, %WSA and WSSI increased due to irrigation, crop residue mulching and N application. Application of irrigation, mulch and N @ 150 kg ha−1 significantly increased the S index by 3.5, 9.9 and 4.3 per cent, respectively compared to the respective control treatments (rainfed, no mulch and no N treatments). Crop residue mulching significantly increased LLWR by 48.3, 11.4 and 31.6 per cent over no-mulch treatment at 0–15 cm soil depth at 67 days after sowing (DAS), 95 DAS and harvest, respectively. Application of irrigation registered significantly higher MWD by 21.4 per cent after maize harvest over the rainfed treatment, whereas, mulching increased MWD by 6.7 per cent after maize harvest than no-mulch treatment. After maize harvest, mulching registered significantly higher WSA by 7.8 per cent over the no-mulch treatment. The root growth, grain and biomass yield of maize was significantly correlated with the saturated hydraulic conductivity of soil at 0–15 cm soil depth. Therefore, growing maize crop with need based irrigation at critical growth stages, N application @ 150 kg ha−1 and crop residue mulching @ 10 t ha−1 resulted in better soil physical quality and maize yield in sandy loam soil of Delhi region.

Productivity and profitability of aerobic rice (Oryza sativa) as influenced by varieties and integrated nitrogen management

A field experiment was conducted during the kharif seasons of 2009 and 2010 at Indian Agricultural Research Institute, New Delhi to study productivity and profitability of aerobic rice as influenced by varieties and integrated nitrogen management. The experimental treatments included 2 rice varieties, viz. Pusa Basmati 1 and Pusa Basmati 1121 and 8 integrated nitrogen management practices, viz. N control (N0); 100% RDN (120 kg N/ha through urea); 75% RDN + 25% N through farmyard manure; 75% RDN + 25% N through green manuring; 75% RDN + 25% N through biofertilizers; 75% RDN + 25% N through vermicompost; 100% N through FYM+GM+BF+VC and 100% N through FYM+GM+BF+VC+ZnSO4. The results showed that rice variety Pusa Basmati 1 out performed Pusa Basmati 1121 in yield attributes, grain yield and harvest indices. Application of recommended dose of nitrogen (RDN) through integrated nitrogen management (INM) approach significantly increased the crop growth parameters, yield attributes, grain as well straw yields and net returns over other INM approaches. Treatment with 100% N by FYM+GM+BF+VC+Zn showed highest crop growth and yield attributes, grain and straw yield and net returns as compared to other integrated nitrogen management treatments, but this treatment was closely followed by 100% N by FYM+GM+BF+VC and 75% RDN + 25% VC during both the years.

Field-level comparison of nitrogen rates and application methods on maize yield, grain quality and nitrogen use efficiency in a humid environment

ABSTRACTAppropriate nitrogen (N) management practices are of critical importance in improving N use efficiency (NUE), maize (Zea mays) yield and environmental quality. A six-year (2005–2010) on-farm trial was conducted in Ottawa, Canada to assess the effects of N rates and application methods on grain yield and NUE. In four out of the six-year study, grain yield increased by 60–77 kg ha−1 by sidedress, compared to 49–66 kg ha−1 for each kg N ha−1 applied at preplant. Grain yield response to N between the two strategies was similar in the other growing seasons. Sidedress strategy required 15 kg N ha−1 less of the maximum economic rate of N (MERN) than preplant application. Our results indicate that sidedress application of 90–120 kg N ha−1 with a starter of 30 kg N ha−1 resulted in greater yield, grain quality and NUE than preplant N application in this cool, humid and short growing-season region.

Identification of nitrate leaching loss indicators through regression methods based on a meta-analysis of lysimeter studies.

This study presents a meta-analysis of 12 experiments that quantify nitrate-N leaching losses from grazed pasture systems in alluvial sedimentary soils in Canterbury (New Zealand). Mean measured nitrate-N leached (kg N/ha × 100 mm drainage) losses were 2.7 when no urine was applied, 8.4 at the urine rate of 300 kg N/ha, 9.8 at 500 kg N/ha, 24.5 at 700 kg N/ha and 51.4 at 1000 kg N/ha. Lismore soils presented significantly higher nitrate-N losses compared to Templeton soils. Moreover, a multiple linear regression (MLR) model was developed to determine the key factors that influence nitrate-N leaching and to predict nitrate-N leaching losses. The MLR analyses was calibrated and validated using 82 average values of nitrate-N leached and 48 explanatory variables representative of nitrogen inputs and outputs, transport, attenuation of nitrogen and farm management practices. The MLR model (R (2) = 0.81) showed that nitrate-N leaching losses were greater at higher urine application rates and when there was more drainage from rainfall and irrigation. On the other hand, nitrate leaching decreased when nitrification inhibitors (e.g. dicyandiamide (DCD)) were applied. Predicted nitrate-N leaching losses at the paddock scale were calculated using the MLR equation, and they varied largely depending on the urine application rate and urine patch coverage.

Fertilization impacts on green leafy vegetables supplied with slow release nitrogen fertilizers

ABSTRACTConventional over-fertilization in green leafy vegetables has promoted the need for alternative nitrogen management practices. A novel slow-release fertilizer, coated with inorganic minerals, was developed in our lab. The membrane structural characteristics and nitrogen release profile of the product were systematically studied. Furthermore, different fertilization treatments were prepared to study the potential nitrogen use efficiency in Brassica chinensis L., cultivated under open field and greenhouse cultivation patterns. With a relatively smooth surface, coating layer of the newly developed fertilizer stacked by bonded multi-layer of polyaryl polymethylene isocyanate was formed by tightly arraying solid phosphate rock powder granules. After immersing the fertilizer in water, there was about 13% nitrogen released after 24 h and 30% of nitrogen released in 7 days. Moreover, the fertilizer significantly enhanced the yield of Brassica chinensis L. by 28.2%. Nitrogen use efficiency of vegetables treated with the fertilizer was much higher than that of conventional fertilization.

Influence of varieties and integrated nitrogen management on productivity and nutrient uptake in aerobic rice (Oryza sativa)

A field experiment was conducted during the wet (kharif) seasons of 2009 and 2010 at New Delhi to study the influence of Basmati varieties and integrated nitrogen management on productivity and nutrient uptake in aerobic rice (Oryza sativa L.). The treatments included two Basmati rice varieties, viz. Pusa Basmati 1 and Pusa Basmati 1121 and eight integrated nitrogen management (INM) practices such as N control (N0); 100% recommended dose of nitrogen (RDN, i.e. 120 kg N/ha through urea); 75% RDN+25% N through farmyard manure (FYM); 75% RDN+ 25%N through green manuring (GM); 75% RDN+ 25% N through Azotobacter biofertilizers (BF); 75% RDN+25% N through vermicompost(VC); 100% N through FYM+GM+BF+VC and 100% N through FYM+GM+BF+VC+ ZnSO4. The results showed that Basmati rice variety Pusa Basmati 1 produced significantly higher grain yield as compared to Pusa Basmati 1121. Among the N management treatments, highest grain and straw yield was obtained through 100% N through FYM+GM+BF+VC+Zn followed by 100 % N through FYM+GM+BF+VC and 75% RDN+25% VC. Nutrient uptake in grain was higher in Pusa Basmati 1 over Pusa Basmati 1121. However, straw of Pusa Basmati 1121 showed higher N, Zn, Fe, Mn and Cu uptake than Pusa Basmati 1. Total N, Zn and Fe uptake in grain and straw was higher in Pusa Basmati 1 as compared to Pusa Basmati 1121. Total uptake of Mn and Cu was inclined in rice variety Pusa Basmati 1121 than Pusa Basmati 1. Application of RDN and INM showed significantly increased N, Zn, Fe, Mn and Cu uptake in grain as well as straw as compared to control.

Effect of integrated nitrogen management on growth and yield of sesame (Sesamum indicum L.)

A field experiment was conducted during kharif season of 2011 in vertisols at Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani to study the effect of integrated nitrogen management on growth and yield of sesame varieties. The results indicated that variety AKT-101 was superior over Phule Til-1 in producing higher growth, yield attributes and yield. Among different integrated nitrogen management practices, application of recommended dose of fertilizer (60:40 N: P2O5 kg/ha) had the highest growth, yield attributes and yield of sesame which was at par with the application of 25% N through vermicompost + 75% N through urea. Gross monetary returns and net monetary returns were higher in recommended dose of fertilizer than integrated nitrogen levels. Among different varieties, AKT-101 recorded highest gross and net monetary returns.

Characterization of water stress and prediction of yield of wheat using spectral indices under varied water and nitrogen management practices

There is a need to characterize the water stress in wheat using suitable indices, which will help us to find out the water stress sensitive period for efficient use of irrigation water. Recently indices based on canopy spectral reflectance, which are non destructive, fast and reliable, are being used effectively to characterize the water stress. A field experiment was carried out during the year 2010–2012 in split plot design with four levels of irrigation (irrigation at 0.4 IW/CPE, 0.6 IW/CPE, 0.8 IW/CPE and 1.0 IW/CPE, IW=6cm) as main plot factors and three sources of nitrogen (100%N from urea, 50% N from urea and 50% N from farmyard manure (FYM) and 100% N from FYM) as subplot factors. The objective of the study was to find out the water stress indices best correlated with wheat grain and biomass yield, to determine the optimum growth stage for measurement of water stress indices and to predict the grain and biomass yield of wheat based on water stress indices. The canopy reflectance was measured in the spectral range of 350–2500nm with 1nm bandwidth with the help of hand held ASD FieldSpec Spectroradiometer at seven phenostages, viz., crown root initiation (CRI), tillering, booting, flowering, milk, soft dough and harvesting stage. Then different water stress indices were computed as: water index (WI)=R970/R900, normalized water index-1 (NWI-1)=(R970−R900)/(R970+R900), normalized water index-2 (NWI-2)=(R970−R850)/(R970+R850), normalized water index-3 (NWI-3)=(R970−R920)/(R970+R920), normalized water index-4 (NWI-4)=(R970−R880)/(R970+R880), where R and the subscript numbers indicate the light reflectance at the specific wavelength (in nm). It was observed that spectral reflectance based water indices recorded at the milk stage, WI and NWI-1 were significantly negatively correlated with the grain yield and NWI-1 and NWI-3 were significantly negatively correlated with the biomass yield of wheat, having maximum correlation coefficients. Validation of regression model based on NWI-1 could account for the maximum 87.5% variation in the observed grain yield and the regression model based on WI could account for maximum 89.2% variation in the observed biomass yield of wheat with minimum root mean square errors. So the regression models based on NWI-1 and WI recorded at milk stage can be successfully used to predict the grain and biomass yield of wheat in advance.

A reappraisal of the critical nitrogen concentration of wheat and its implications on crop modeling

The concept of critical nitrogen (N) concentration (Ncc) has been used for both diagnostic purposes and modelling of wheat-N relations. Ncc has been derived with two contrasting approaches: one against above ground biomass (Ncc-biomass), and one against developmental stages (Ncc-stage). While the former has been claimed in diagnostic use, both approaches are adopted in wheat simulation models. This paper provides data from North China Plain (NCP) to re-exam the Ncc-stage relationships used in two widely used wheat models (APSIM and CERES) and to compare the Ncc-biomass vs. Ncc-stage relationships. The results revealed significant higher maximum and critical N concentrations in leaves of wheat in NCP than the values used in the APSIM-wheat model. Recalibration of the APSIM model with the new N concentrations led to improved simulations for wheat biomass and N uptake, particularly under low N input. Our results also show that the Ncc-stage relationship appeared to be more robust than the Ncc-biomass relationship, and it helped explain the variations in wheat Ncc-biomass curves from different regions. This likely reflects the fact that Ncc-stage curve captures the stage-driven formation of structural biomass and carbohydrate reserves of wheat, which is the main cause for N dilution. The implications of the findings on modelling of wheat–nitrogen relationships and on nitrogen management practices are also discussed.

Nitrogen timing and rate effects on growth and grain yield of delayed permanent-water rice in south-eastern Australia

The need for continual improvement in water productivity of rice farming has led to the development of delayed permanent (continuous) water (DPW) irrigation practice for drill-sown rice in south-eastern Australia. Current rice-growing practices have the crop flooded for most, or all, of its growing period, whereas DPW has reduced the period of flooding during the vegetative phase, resulting in significant water savings. The changed water-management practice required nitrogen (N) management practices to be investigated, because traditional N application timings and rates may no longer be suitable. Six experiments were conducted over three rice-growing seasons, 2010–11, 2011–12 and 2012–13, on two soil types in south-eastern Australia. Nitrogen applications at sowing, early tillering, mid-tillering and pre-PW were investigated at different rates and split-timing combinations. In the third season, three current commercial semi-dwarf rice varieties, Reiziq, Sherpa and Langi, were investigated for their growth and grain yield using different N treatments under DPW management. Nitrogen applied with the seed at sowing increased vegetative plant growth but did not increase grain yield, whereas N applied at early tillering had no significant impact on plant growth or grain yield. Nitrogen applied at mid-tillering often increased plant growth but did not lead to increased grain yield over treatments that received all N before PW application at 18–22 days before panicle initiation. When rice is managed under DPW, all N should be applied in one application, before the application of PW. The results from this research show that applying 100 kg N ha–1 before PW for rice grown under DPW was the best N-management option for the experimental fields. All three varieties grew and yielded well under the practice of DPW and responded similarly to N application rates and timings.

Conducting a Blue Dye Demonstration to Teach Irrigation and Nutrient Management Principles in a Residential Landscape

This publication discusses the “blue dye” test, which is one way that Extension professionals can show homeowners how water and nutrients move through the soil following irrigation. The information should be useful for county agents to demonstrate basic irrigation and nitrogen management practices and their effects on nitrate-nitrogen (N) leaching. This 4-page fact sheet was written by George Hochmuth, Laurie Trenholm, Esen Momol, Don Rainey, Claire Lewis, and Brian Niemann, and published by the UF Department of Soil and Water Science, November 2013. http://edis.ifas.ufl.edu/ss594

Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management

Abstract. The effects of nitrogen and straw management on global warming potential (GWP) and greenhouse gas intensity (GHGI) in a winter wheat–summer maize double-cropping system on the North China Plain were investigated. We measured nitrous oxide (N2O) emissions and studied net GWP (NGWP) and GHGI by calculating the net exchange of CO2 equivalent (CO2-eq) from greenhouse gas emissions, agricultural inputs and management practices, as well as changes in soil organic carbon (SOC), based on a long-term field experiment established in 2006. The field experiment includes six treatments with three fertilizer N levels (zero N (control), optimum and conventional N) and straw removal (i.e. N0, Nopt and Ncon) or return (i.e. SN0, SNopt and SNcon). Optimum N management (Nopt, SNopt) saved roughly half of the fertilizer N compared to conventional agricultural practice (Ncon, SNcon), with no significant effect on grain yields. Annual mean N2O emissions reached 3.90 kg N2O-N ha−1 in Ncon and SNcon, and N2O emissions were reduced by 46.9% by optimizing N management of Nopt and SNopt. Straw return increased annual mean N2O emissions by 27.9%. Annual SOC sequestration was 0.40–1.44 Mg C ha−1 yr−1 in plots with N application and/or straw return. Compared to the conventional N treatments the optimum N treatments reduced NGWP by 51%, comprising 25% from decreasing N2O emissions and 75% from reducing N fertilizer application rates. Straw return treatments reduced NGWP by 30% compared to no straw return because the GWP from increments of SOC offset the GWP from higher emissions of N2O, N fertilizer and fuel after straw return. The GHGI trends from the different nitrogen and straw management practices were similar to the NGWP. In conclusion, optimum N and straw return significantly reduced NGWP and GHGI and concomitantly achieved relatively high grain yields in this important winter wheat–summer maize double-cropping system.

On-Farm Participatory Technology Development Effects on Resource Conservation Technologies in Rainfed Upland Paddy in Himachal Pradesh, India

Rice is a major cereal crop in Himachal Pradesh, a Himalayan state of India, where paddy acreage is about 78,000 ha with a low average yield of 19.62 q ha−1 due to rainfed upland farming. High seeding rates and poor resource-use efficiency of conventional fertilizer nitrogen (N) management practices in rainfed upland paddy have also been major production constraints in rainfed upland ecosystems. To validate and refine the production technology on seed rate and fertilizer N management, the Farm Science Centre, Sundernagar, India, conducted numerous on-farm trials (OFTs) during 2006–2010 under an on-farm participatory technology development approach to enhance resource use efficiency through these resource conservation technologies and boost the paddy productivity in the region. Results of two OFTs conducted during Kharif 2006 in the Mandi District of Himachal Pradesh on different seed rates under different sowing methods on VL Dhan-221 and Sukaradhan-1 (HPR-1156) cultivars suitable for rainfed upland conditions revealed that the seed rate at 80 kg ha−1 sown in rows 20 cm apart resulted in the greatest average paddy productivity to the tune of 25.6 q ha−1 besides greater profitability, followed by a seed rate at 60 kg ha−1 sown in rows 20 cm apart (25.2 q ha−1), over the earlier State Agricultural University (SAU)–recommended practice, that is, seed rate at 100 kg ha−1 in rows 20 cm apart. This refinement in the seed rate was accepted by the participating farmers of the region. The greatest average benefit/cost (B/C) ratio was observed in plots with seed rate at 60 kg ha−1 sown in rows 20 cm apart. Based on these results and data compilation from other locations of the state, now the SAU has refined the seed rate from earlier recommendation of 100 kg ha−1 to 60 kg ha−1 in rows 20 cm apart as well as 80 kg ha−1 through broadcast method under rainfed upland paddy in Himachal Pradesh. Results of two OFTs conducted during Kharif 2009 on integrated nutrient management in rainfed upland paddy revealed that farmyard manure (FYM) at 10 t ha−1 + nitrogen, phosphorus, and potassium (N, P, K) at 15:30:30 kg ha−1 at sowing followed by 15 kg N ha−1 15 days after sowing (DAS) and remaining the N [i.e., 30 kg N ha−1] at tillering (45–50 DAS) resulted in the greatest grain yield of 29.85 and 31.67 q ha−1 in VL Dhan-221 and HPR-1156, respectively, with respective greater yields of 35.99 and 36.51% over farmers’ practice, besides better profitability. To further standardize fertilizer N split doses and assess their effect on paddy productivity, another OFT was conducted during Kharif 2010 under rainfed upland paddy conditions in HPR-1156. The results revealed that NPK at 60:30:30 kg ha−1 (whole of P and K as basal, 50% N at 15 DAS, 25% N each at 45–50 DAS and 70–75 DAS splits) resulted in better grain yield (34.3 q ha−1) and net profitability (₹29,786 ha−1) over other treatments. Overall, it is concluded that these resource conservation technologies developed under the OFT participatory approach can enhance the rainfed upland paddy productivity and strongly show that there is dire need to split the N requirement of rainfed upland paddy in 2–3 splits to reduce the fertilizer N losses, enhance resource-use efficiency, and increase productivity and profitability in Himachal Pradesh, India.

Adoption potential of nitrate mitigation practices: an ecosystem services approach

Nitrate pollution from agricultural drainage has caused water quality concerns worldwide, but there are several promising technologies to help mitigate this environmental degradation. While these practices primarily aim to improve water quality, they may also provide other ‘additive’ benefits or ecosystem services and the awareness of such benefits may influence their potential to be adopted by farmers. To investigate the impact that perceived ecosystem services has on a practice's adoption potential, we used a mixed methods approach consisting of a literature review, producer surveys, and a group discussion to explore farmer interest in and perceived benefits (on-farm and regional) of seven subsurface drainage nitrate reduction practices (controlled drainage, bioreactors, wetlands, nitrogen management rate, nitrogen management timing, cover crops, and diversified crop rotations). The nitrogen management practices were shown to be accessible and realistic options for water quality improvement as they elicited high interest and had the highest level of compatibility. However, these practices did not provide many other complementary ecosystem services. Conversely, wetlands had a high literature review-derived ecosystem service count, but were considered to have low compatibility, and survey respondents indicated less interest in this practice. The practice of cover cropping showed more moderate, yet consistently positive results for all factors.

Simulating the fate of nitrogen and optimizing water and nitrogen management of greenhouse tomato in North China using the EU-Rotate_N model

The objectives of this study were to compare nitrate leaching and gaseous N loss from greenhouse tomato grown under different water and fertilizer management, and to optimize water and nitrogen management practices. A greenhouse experiment with different water and nitrogen management practices was conducted in Shouguang county, northern China, from August 2010 to June 2011. Four treatments were imposed: furrow irrigation+conventional fertilizer (farmer's practice, FP), FP+crop residues (FPR), drip irrigation+optimal fertilizer (DO), and DO+crop residues (DOR). The EU-Rotate_N model was used to simulate tomato growth, water movement and N fate. The simulation results indicated that nitrate leaching and gaseous N loss were the main pathways of N loss in greenhouse tomato production in the study area. The amounts of nitrate leaching under furrow treatments accounted for 43–67% of total N input. Gaseous N loss under all treatments accounted for about 3–14% of total N input. Drip irrigation and optimal N fertilizer application can significantly reduce nitrate leaching and improve water and nitrogen use efficiencies (WUE, NUE). Compared with farmer's practices (FP, FPR), nitrate leaching under drip irrigation (DO and DOR treatments) decreased by about 90%, while the NUEs was increased 2- to 3-fold. In addition, adding crop residues (DOR, FPR) reduced nitrate leaching by 15% compared to the treatments with no crop residues (DO, FP), while it increased the gaseous N loss by about 35%. Furrow irrigation is the most commonly practiced method for most vegetable production in northern China, and this farmer's practice was selected to obtain the best management practices (BMPs) for irrigation schedules and N fertilization rates. More than 288 scenarios combining various types of irrigation and fertilizer practices were simulated per season. Agronomic indices (tomato yield, WUE and NUE), environmental indices (nitrate leaching and gaseous N loss), and economic index (value to cost ratio) were selected as the evaluation indices to identify the BMPs. An osculating value method was used to evaluate combinations of irrigation and fertilizer practices. The results indicated that the BMPs under furrow irrigation conditions are to irrigate tomato with 300mm and apply fertilizer N at a rate of 150kg Nha−1 in the autumn–winter season, and to irrigate with 300mm and apply fertilizer N at a rate of 250kg Nha−1 in the spring–summer season.

Conservation tillage and optimal water supply enhance microbial enzyme (glucosidase, urease and phosphatase) activities in fields under wheat cultivation during various nitrogen management practices

Field experiments were conducted on sandy clay loam soil at New Delhi, during the winter season of 2007 and 2008 to investigate the effect of tillage, irrigation regimes, i.e. sub-optimal, optimal and supra-optimal water supply, and integrated nutrient management practices (INM) on soil enzymatic activities after cultivation of wheat (Triticum aestivum). Soil glucosidase (54.5%), urease (88.8%), acid phosphatase (97.4%) and alkaline phosphatase (85.3%) activities increased significantly under conservation tillage compared with conventional tillage fields. An optimal water supply (i.e. three irrigations) led to a significant increase in soil enzymatic activity over sub-optimal (i.e. two) and supra-optimal (five) irrigation. Urease activity was slightly lower in the sub-optimal irrigations, but higher in supra-optimal irrigations by 15.5% than in optimal irrigation in conventional tillage. This study suggests that inorganic and organic nutrient combinations with conservation tillage and optimal water supply significantly improved soil enzymatic activities.

Winter sorghum (Sorghum bicolor) productivity as influenced by tillage practices and nitrogen management in Vertisols of SAT, India

Sustainable food production in semi-arid tropical countries can be achieved through efficient conservation and utilization of rainwater and nutrient management. A field experiment was conducted to assess the effect of tillage practices and integrated nitrogen management on soil water conservation, water use efficiency and sorghum production during winter seasons of 2000–2001, 2001–2002 and 2002–2003 at the Research Farm of Central Soil and Water Conservation Research and Training Institute, Research Centre, Bellary (15°09′N latitude, and 76°51′E longitude), India. Experiment was laid out in a split plot design with tillage practices as main treatments and nitrogen management through organic materials alone (OMA), inorganic material, urea alone (UA) and blending of 50% each of organic and inorganic materials (INMs) as sub treatments. Winter sorghum grain yield of 2020kgha–1, during study period was higher by 6% with reduced tillage (RT1), when tillage operations were reduced to 2 harrowing+1 hoeing+1 hand weeding, and grain yield increased further to 2151kgha–1 and was higher by 13% with conventional tillage, CT (1 ploughing+2 harrowing+2 hoeing+1 hand weeding) compared to lower grain yield of 1905kgha–1 produced under reduced tillage RT2 (1 harrowing+1 hoeing+weedicide application). Mean water use efficiency (WUE) was 8.98kgha–1mm–1 with CT compared to 8.48kgha–1mm–1 produced with RT2. Among the integrated nitrogen management (INM) practices, sorghum grain yield of 2063kgha–1 was higher by 9% with application of 50% N through organic materials and 50% N through urea and when N was supplied through urea alone, sorghum grain yield increased further to 2120kgha–1 and was higher by 12% compared to 1892kgha–1 produced with supplying N through organic materials alone. Mean WUE of 8.84kgha–1mm–1 and 9.40kgha–1mm–1 were 11% and 18% higher with INM and UA, respectively compared to 7.97kgha–1mm–1 with OMA. In pooled data, higher grain yield of 2244kgha–1, straw yield of 3.81tha–1 and WUE of 9.44kgha–1mm–1 were recorded under CT and UA and were attributed to higher availability and uptake of soil water and nutrients, as a result of higher dry matter production in leaves and stem and its translocation to head at physiological maturity.

Agroeconomic Analysis of Nitrate Crop Source Reductions

AbstractThis paper presents an agroeconomic approach to assess the economic impact of improving nitrogen and irrigation management practices in California’s Tulare Lake Basin and the Salinas Valley. The approach employs a self-calibrated mathematical programming model with a constant elasticity of substitution production function and two nests: one for irrigation and one for nitrogen. Agricultural crop yields are maintained as a worst-case for improving nitrogen use efficiency. Small reductions (<25%) in nitrate load to groundwater can be achieved at relatively low costs. Load reductions of 50% may require more costly nitrogen management practices and a broader education strategy with higher reductions in farm net revenues and irrigated area. Other policy instruments such as a tax and levees on applied nitrogen may help reduce groundwater load and raise revenues for alternate drinking water supplies in affected areas. The model also provides further evidence that it is possible to integrate agronomic and ...

Grain yield and apparent N recovery efficiency of dry direct-seeded rice under different N treatments aimed to reduce soil ammonia volatilization

Soil ammonia volatilization induced by urea application at sowing negatively affects seed germination and early seedling growth of dry direct-seeded rice. Previous research suggests that ammonia volatilization can be reduced through nitrogen (N) management practices such as split application of urea, delaying the first urea application, and using N fertilizers which are less prone to volatilization. The objective of this study was to examine the impact of these N management practices on grain yield and nitrogen use efficiency of dry direct-seeded rice. Pot and field experiments were conducted under different N treatments. In the pot experiment, N treatments were 1.0 and 0.5gNpot−1 as urea at sowing, 1.0gNpot−1 as urea at 10 days after sowing (DAS), and 1.0gNpot−1 as ammonium sulfate at sowing. In the field experiment five N treatments were used while keeping the total N rate as 150kgNha−1. These treatments included reducing the rates of urea applied at sowing from 90 to 60 and 30kgNha−1, delaying the first urea application to 10 DAS at 90kgNha−1, and application of ammonium sulfate as 90kgNha−1 at sowing. Reducing rate of urea applied at sowing, delaying the first urea application, or application of ammonium sulfate significantly increased plant growth, grain yield, above-ground N uptake and apparent N recovery (ANR) efficiency of dry direct-seeded rice, compared with higher rate of urea application at sowing. Here we demonstrate that by adoption of proper N management practices, a grain yield of above 6tha−1 can be achieved in dry direct-seeded rice production system. Such findings may greatly help in the wide spread of dry direct-seeded rice technology, particularly in central China.