Site-specific nutrient management for intensive rice cropping systems in Asia

Irrigated rice (Oryza sativa L.) yield increases in Asia have slowed down in recent years. Further, yield increases are likely to occur in smaller increments through fine-tuning of crop management. On-farm experiments at 179 sites in eight key irrigated rice domains of Asia were conducted from 1997 to 1999 to evaluate a new approach for site-specific nutrient management (SSNM). Large variation in initial soil fertility characteristics and indigenous supply of N, P, and K was observed among the eight intensive rice domains as well as among farms within each domain. Field- and season-specific NPK applications were calculated by accounting for the indigenous nutrient supply, yield targets, and nutrient demand as a function of the interactions between N, P, and K. Nitrogen applications were fine-tuned based on season-specific rules and field-specific monitoring of crop N status. The performance of SSNM was tested for four successive rice crops. Average grain yield in the SSNM increased by 0.36 Mg ha⁻¹ (7%) compared to the current farmers’ fertilizer practice (FFP) measured in the same cropping seasons or 0.54 Mg ha⁻¹ (11%) compared to the baseline FFP yield before intervention. Average nutrient uptake under SSNM increased by about 10% in the same seasons or by 13% (N) and 21% (P, K) compared to the baseline data. Yield increases were associated with a 4% decrease in the average N rate, but larger amounts of fertilizer-K at sites where the previous K use was low. Average N use efficiencies increased by 30–40%, mainly through the use of improved in-season N management schemes. Across all sites and four successive rice crops, profitability increased by US$ 46 ha⁻¹ per crop or 12% of the total average net return. The performance of SSNM did not differ significantly between high-yielding and low-yielding climatic seasons, but improved over time with larger benefits observed in the second year. Average profitability increased from US$ 32 ha⁻¹ pre crop in the first year to US$ 61 ha⁻¹ pre crop in the second year due to improvements in the SSNM approach and re-capitalization of P and K applied in the first year. SSNM required little extra credit for financing, and remained profitable even if rice prices are somewhat lower than current levels. Further, scope for improvement exists at many sites by alleviating other crop management constraints to nutrient use efficiency. Profit increases ranged from US$ 4 to 82 ha⁻¹ per crop among eight rice domains. However, profit decreases occurred in about 25% of all cases, indicating that a certain minimum level of crop care is required for SSNM to be profitable. Yields at sites with labor-saving direct-seeding of larger fields were about 1 Mg ha⁻¹ lower than those achieved at sites with labor-intensive transplanting and good management, raising concern about future trends in rice production. SSNM has potential for improving yields and nutrient efficiency in irrigated rice to close existing yield gaps. The major challenge for SSNM will be to retain the success of the approach while reducing the complexity of the technology as it is disseminated to farmers. The nature of the approach will need to be tailored to specific circumstances in different countries. In some areas, SSNM may be field or farm specific, but in many areas it is likely to be just region and season-specific.     

Faba bean in cropping systems

The grain legume (pulse) faba bean (Vicia faba L.) is grown world-wide as a protein source for food and feed. At the same time faba bean offers ecosystem services such as renewable inputs of nitrogen (N) into crops and soil via biological N₂ fixation, and a diversification of cropping systems. Even though the global average grain yield has almost doubled during the past 50 years the total area sown to faba beans has declined by 56% over the same period. The season-to-season fluctuations in grain yield of faba bean and the progressive replacement of traditional farming systems, which utilized legumes to provide N to maintain soil N fertility, with industrialized, largely cereal-based systems that are heavily reliant upon fossil fuels (=N fertilizers, heavy mechanization) are some of the explanations for this decline in importance. Past studies of faba bean in cropping systems have tended to focus on the effect of faba bean as a pre-crop in mainly cereal intensive rotations, whereas similar information on the effect of preceding crops on faba bean is lacking. Faba bean has the highest average reliance on N₂ fixation for growth of the major cool season grain legumes. As a consequence the N benefit for following crops is often high, and several studies have demonstrated substantial savings (up to 100–200 kg N ha⁻¹) in the amount of N fertilizer required to maximize the yield of crops grown after faba bean. There is, however, a requirement to evaluate the potential risks of losses of N from the plant–soil system associated with faba bean cropping via nitrate leaching or emissions of N₂O to the atmosphere as a consequence of the rapid mineralization of N from its N-rich residues. It is important to develop improved preventive measures, such as catch crops, intercropping, or no-till technologies, in order to provide farmers with strategies to minimize any possible undesirable effects on the environment that might result from their inclusion of faba bean in cropping system. This needs to be combined with research that can lead to a reduction in the current extent of yield variability, so that faba bean may prove to be a key component of future arable cropping systems where declining supplies and high prices of fossil energy are likely to constrain the affordability and use of fertilizers. This will help address the increasing demand by consumers and governments for agriculture to reduce its impact on the environment and climate through new, more sustainable approaches to food production. The aims of this paper are to review the role of faba bean in global plant production systems, the requirements for optimal faba bean production and to highlight the beneficial effects of faba bean in cropping systems.     

Wheat cropping systems and technologies in China

Chinese wheat (Triticum aestivum) production has developed rapidly during the last 57 years, largely due to improved crop management technologies and new varieties. The history of wheat planting technologies in China was reviewed, and the physiological mechanisms that allow wheat to attain high yield under these planting systems were analyzed. The use of leaf number and stage of development to indicate the optimum timing for applications of fertilizers and irrigation water, and uniform seeding at reduced seeding rates to control lodging contributed significantly to the substantial progress in wheat productivity. However, flood irrigation and tillage-based practices also resulted in serious problems, including a decline in soil fertility and quality, environmental pollution, and inefficient use of water resources. The major future challenges facing wheat production are to improve water and nutrient use efficiency. Conservation agriculture-based resource conservation technologies such as zero or reduced tillage, flat or raised bed-planting systems, and rational management of crop residues to eliminate burning in the field are among the strategies we strongly recommend for improving agricultural environments and stabilizing/increasing wheat production in China.     

Nitrogen flows and balances as affected by water and nutrient management in a sorghum cropping system of semiarid Burkina Faso

Efficient use of external inputs and water conservation are a prerequisite of sustainable agricultural productivity in semiarid West Africa. A field experiment was carried out during 3 years (2000–2002) at Saria in semiarid Burkina Faso (800 mm of annual rainfall, PET of 2000 mm per year) to assess the effects of stone rows or grass strips of Andropogon gayanus Kunth cv. Bisquamulatus (Hochst. Hack.) as soil and water conservation (SWC) measures, the sole application of an organic (compost-N) or mineral (urea-N) nitrogen and the combined use of SWC and compost-N or urea-N on N flows and balances. The trial was conducted on a Ferric Lixisol with 1.5% slope and comprised nine treatments in two replications. The SWC measures were put along contours lines. During the three consecutive years, all treatments induced negative annual N balances (−75 to −24 kg N ha⁻¹). The main factors explaining these negative balances were N exports by sorghum biomass and soil erosion-induced N losses. Large amounts of N (7 kg N ha⁻¹ per year in 2000 and 44 kg N ha⁻¹ per year in 2002) were lost in the control treatment through runoff and eroded sediments, which corresponds respectively to about 10 and 43% of the total outflow of N. Sole stone rows and grass strips reduced erosion N losses to 8 and 12%, respectively, of the total annual loss. The combined application of SWC measures and nutrients inputs reduced erosion N losses to only 2–7% of the annual N loss. The application of urea-N or compost-N led to the lowest soil N mining over the 3 years, whereas the highest N mining was observed in plots without added N. We conclude that N mining in poor fertile soils of West Africa can be mitigated through an integration of local water and nutrient management practices.     

Alternative cropping systems can have contrasting effects on various soil-borne diseases: Relevance of a systemic analysis in vegetable cropping systems

Vegetable production makes an intensive use of pesticides, and a major challenge is to build alternative cropping systems that can control pests and diseases with fewer uses of chemical products. An on-farm analysis was conducted in Southeast France to assess the efficacy of several cropping systems in simultaneously controlling two major pests: root-knot nematodes (Meloidogyne spp.) and lettuce drop due to Sclerotinia sclerotiorum. Ten cropping systems resulting from the combinations of three crop sequences and two alternative techniques, solarization and green manure, were assessed during two years. The use of solarization once a year or once every two years limited the occurrence of S. sclerotiorum. Sorghum green manure tended to increase S. sclerotiorum incidence; the effect was positively correlated with green manure duration. Especially when no vegetable was cropped in summer, the green manure crop duration was lengthened and this probably created soil conditions favorable to the development of the fungus. The incidence of root-knot nematodes was largely dependent on crop rotation: a melon crop in summer increased its incidence on the subsequent lettuce crops whereas a summer sorghum cover crop had no effect. The cropping systems that limited Sclerotinia development in soil tended to support the root-knot nematode populations. These results should motivate farmers and advisers to adopt a systemic analysis and take into account the various interactions among inoculum level, soil characteristics, crop rotations, and technical management options for designing sustainable vegetable production systems.     

Integrated assessment of cropping systems in the Eastern Indo-Gangetic plain

Both intensification and diversification of cropping systems may allow improving the productivity and sustainability of agricultural production in the Indo-Gangetic Plain (IGP), but the choices to be made require integrated assessment of various cropping systems. A field experiment was conducted from 1999 to 2002 on a sandy clay loam (Inceptisol) to evaluate nine predominant cropping systems in West Bengal, India. Productivity, energy use efficiency, and nutrient uptake generally increased with increasing cropping intensity. Positive residual effects of potato and jute on yield and energy output of subsequently grown crops were observed as well as maintenance or improvement of soil properties such as soil organic matter, available P, and available K. The P balance was positive for most systems, except for jute-containing systems. However, negative K balances occurred due to almost complete removal of crop biomass in all systems, suggesting that recommended rates of applied K fertilizer were to low for sustaining soil K supply over the longer term. Cropping systems containing potato had the highest levels of yield, net return, benefit to cost ratio and energy productivity, but energy use efficiency was reduced due to higher energy consumption in these systems. Jute–wheat and jute–rapeseed–rice systems showed high energy use efficiency along with moderate cost and return. Based on economic considerations alone, jute–potato–rice, rice–potato–rice and rice–potato–sesame can be recommended as cropping systems for resource-rich growers in the eastern part of the IGP. Systems such as jute–wheat, rice–wheat and jute–rapeseed–rice appear to be most suitable for small and marginal farmers that cannot afford the large production costs associated with crops such as potato.     

常德稻田耕制改革的成效及经验

耕作制度改革是农业结构调整的重要内容 ,也是解决目前农民卖粮难、种粮效益低的主要途径。介绍了常德市在稻田耕制改革上取得的成就、特点和经验 ,对耕制改革中出现的问题进行了思考。     

三种稻田改制模式发展前景初探

根据道县的生产特点，提出了大豆－晚稻，中稻－再生稻，花生－晚稻三种适合该县近期推广的稻田种植模式，分析了三种模式的经济效益和发展前景。     

Management of Meloidogyne incognita in yam-based cropping systems with cover crops

The effect of intercropping cover crops was with yam was assessed for nematode management both in pot and field conditions in Nigeria. The cover crops were sown with yams in pots containing sterile soil and inoculated with 5000 eggs of Meloidogyne incognita. In the field, each cover crop was separately intercropped with yams inoculated with 10,000 nematodes. From both pot and field experiments, no nematode damage was observed on yam tubers that were intercropped with Aeschynomene histrix, Crotolaria juncea, and Tagetes erecta. Damage in intercropped tubers was reduced by 72.7% with Mucuna pruriens, Centrosema pubescens, and Pueraria phaseoloides and by 58.3% with Stylosanthes guianensis compared to yams planted without cover crops; they also had lower (p ≤ 0.05) nematode populations. Cajanus cajan, Lablab purpureus and Vigna unguiculata however, supported high nematode populations and led to nematode damage in intercropped yams. Tubers from M. incognita-inoculated plants were more damaged and lost 42% more weight (p ≤ 0.05) following three months of storage than tubers from uninoculated plants. Intercropping yams with selected cover crops can be useful in managing M. incognita without reducing yam yields.     

Potato growth and yield using nutrient film technique (NFT)

Potato plants, cvs Denali and Norland, were grown in polyvinyl chloride (PVC) trays using a continuous flowing nutrient film technique (NFT) to study tuber yield for NASs Controlled Ecological Life Support Systems (CELSS) program. Nutrient solution pH was controlled automatically using 0.39M (2.5% (v/v) nitric acid (HNO₃), while water and nutrients were replenished manually each day and twice each week, respectively. Plants were spaced either one or two per tray, allotting 0.2 or 0.4 m² per plant. ALl plants were harvested after 112 days. Denali plants yielded 2850 and 2800 g tuber fresh weight from the one- and two-plant trays, respectively, while Norland plants yielded 1800 and 2400 g tuber fresh weight from the one- and two-plant trays. Many tubers of both cultivars showed injury to the periderrn tissue, possibly caused by salt accumulation from the nutrient solution on the surface. Total system water usage throughout the study for all the plants equaled 709 liters (L), or approximately 2 L m^-2 d^-1 (7.2 mmol m^-2d^-l). Total system acid usage throughout the study (for nutrient solution pH control) equaled 6.60 L, or 18.4 ml m^-2 d^-1 (7.2 mmol m^-2d^-l). The results demonstrate that continuous flowing nutrient film technique can be used for tuber production with acceptable yields for the CELSS program.     

Environmental impacts of potato nutrient management

Use of soluble chemical fertilizers for crop production, particularly to supply nitrogen, phosphorus, and potassium, has increased potato yields and quality for several decades. Over the past 10 years, however, there has been an increased concern over the environmental impact of agricultural fertilizers, particularly as nonpoint sources of water pollution. Currently, nitrogen is a target for improved use efficiencies in potato to reduce potential nitrate contamination of groundwater. Phosphorus management is increasingly being examined as a potential non-point source contaminant of surface waters. Potato researchers throughout North America are conducting studies that focus on maintaining or enhancing crop production while reducing the potential of negative environmental impacts. Precision agriculture, cover crops, slow-release fertilizers, and genetic manipulation are key strategies being studied. Concurrently, new challenges are arising, such as concerns over phosphorus leaching and heavy metal contamination in fertilizers. These have the potential to restrict nutrient use in agricultural systems, requiring both potato producers and scientists to seek additional alternatives to improve nutrient-use efficiency.     

低洼稻田改制模式初探

分析了南县低洼稻田的现状及存在的问题 ,提出了一系列种植结构调整综合配套措施。     

湖南稻田耕作制度改革的形势与对策

总结了湖南从1999年以来实施稻田耕作制度改革所取得的主要成效，阐明了这一轮稻田耕作制度改革的新特点，分析了存在的主要问题．并有针对性地提出了稳步推进我省稻田耕作制度改革的对策措施。     

Yield and yield components of saffron under different cropping systems

This study was conducted to evaluate yield and yield components of saffron (Crocus sativus L.) in response to (i) production system (PS) (irrigated vs. non-irrigated); (ii) corm size (CS) (medium −2.25 to 3 cm diameter vs. small corms <2.25 cm diameter); (iii) planting depth (PD) (10 cm vs. 20 cm); and iv) planting density (PDEN) (51 corms m⁻² vs. 69 corms m⁻²).This fully replicated multifactorial design was started in August 2000, and carried through November 2003, when the fourth saffron harvest took place. The total and average fresh weight of stigmas, and the number of flowers were measured at each harvest.Results indicate that three of the four factors tested (PS, CS and PD) had a significant effect on the quantitative yield during the two most productive flowering years (2001 and 2002) and on the total flowering. Irrigated cultivation, medium size corms and 10 cm planting depth had the greatest effect in increasing the quantitative production of saffron.Yield was also affected by planting density in contrasting ways. Whereas at high PDEN yield increased per unit of surface, at low PDEN, yield increased with respect to the initial number of corms planted.The fresh weight of stigmas per flower yield component, an important aspect that determines the quality of the spice, was enhanced when corms were planted at 20 cm depth and when irrigation was applied to the crop.     

永州市稻田种植制度新特点及优化模式分析

分析了永州市稻田种植制度新特点，讨论了稻田改制的主要模式及经济效益，提出了值得推广的几种主要稻田高效种植模式。     

Lowering carbon footprint of durum wheat by diversifying cropping systems

Improving cropping systems may help mitigate greenhouse gas emissions. This study determined the carbon footprint of durum wheat (Triticum turgidum L.) produced in diverse cropping systems. Durum was grown in rotation systems which had different combinations of oilseed, pulse, and cereal crops at five site-years in Saskatchewan, Canada. Total greenhouse gas emissions from the decomposition of crop residues along with various production inputs were used for the estimation of carbon footprint. On average, emissions from the decomposition of crop straw and roots accounted for 25% of the total emissions, those from the production, transportation, storage, and delivery of fertilizers and pesticides to farm gates and their applications 43%, and emissions from farming operations 32%. Durum wheat preceded by an oilseed crop (Brassica napus or Brassica juncea) the previous year had carbon footprint of 0.33 kg CO₂e kg⁻¹ of grain, or 7% lower than durum in cereal-cereal-durum system. Durum preceded by a biological N-fixing crop (Cicer arietinum chickpea, Lens culinaris lentil, or Pisum sativum pea) the previous year lowered its carbon footprint by 17% compared with durum preceded by a cereal crop. Durum produced in a pulse-pulse-durum system had carbon footprint 0.27 kg CO₂e kg⁻¹ of grain, 34% lower than durum grown in cereal-cereal-durum systems. Diversifying cropping systems with oilseeds and biological N-fixers significantly lowered carbon footprint of durum wheat.     

超级稻协优9308单季生产集成技术示范

新昌地处浙江东部 ,曹娥江上游 ,为山区县。在２０世纪８０年代 ,水田以连作稻占绝对优势 ,年播种面积近２万ｈｍ２。近年来随着市场开放 ,社会经济的发展 ,稻田种植结构调整 ,连作稻播种面积已下降到３００ｈｍ２左右 ,单季中晚稻占主导地位。水稻种植制度的更替 ,为种植业结构调整优化提供了机遇 ,但也对提高土地生产率提出了挑战。它迫切需要少种高产多收高效安全的水稻生产新技术。当前超级稻协优９３０８的育成及其配套技术的形成为实现单季稻高产提供了生产技术。开展超级稻高产集成技术示范 ,对于推动超级稻的生产应用 ,提高稻田生产…