An Economic Evaluation of Crop Rotations in Southwestern Saskatchewan

This study reports on an economic analysis of twelve crop rotations considered feasible for southwestern Saskatchewan. The results suggest that producers in this region should consider selecting a more intensive cropping system than has been the tradition. The three-year fallow-wheat-wheat rotation with recommended rates of nitrogen and phosphorus (N and P) fertilizers provided the highest expected net returns under most reasonable input cost and product price assumptions. Expected net returns for the traditional two-year wheat rotation and for the continuous wheat rotation averaged about 24 percent lower. The application of recommended rates of N fertilizer increased expected net farm income for the three-year and continuous wheat rotations by 6.6 and 10.5 percent, respectively. Use of P fertilizer in the three-year wheat rotation increased expected net farm income by an average of 20.6 percent. Average production costs increased as the proportion of summerfallow in the rotation decreased. Break-even stubble /fallow yield ratios that provided equivalent net returns from stubble and fallow cropping averaged 64 percent for the three-year wheat rotation and 76 percent for the continuous wheat rotation. Annual income variability was greatest for the continuous crop rotations and lowest for the two-year wheat rotation. Cette étude résume l'analyse économique de douze rotations de cultures jugées viables dans le Sud-Ouest de la Saskatchewan. Les résultats suggérent que les producteurs de cette région ont avanlage à considérer un systéme de production plus intensif que de par le passé. Les meilleurs revenus nets anticipés pour la plupart des suppositions raisonables des coúts de production et des prix des den rées furent accomptis avec la rotation de trois ans jachére-blé-bléfertilisée selon les recommendations en S et P. Les revenues nets anticipés avec la rotation traditionnelle de blé de deux ans (jachére-blé) et la rotation de blé continu furent en moyenne approximativement 24 pour-cent plus bas que la meilleure rotation. L'emploi d'engrais azotés aux taux recommendés augmenta le revenu net anticipé de 6,6 pour-cent pour la rotation de blé de trois ans et de 10.5 pour-cent pour la rotation de blé continu. L'amendement du sol en phosphate augmenta le revenu net anticipé de 20.6 pour-cent dans la rotation de blè de trois ans. Les coúrts deproduction augmentirènt à mesure que la proportion de Ierre en jachire duns la rotation diminuait. Les taux d'èquilibre des rendemenis chaume/jachire produisant des revenus nets equivalentr pour la culture sur le chaume el la jachire furenl en moyenne 64 pour-cent pour la rotation de blè de trois ans et 76 pour-cent pour la rotation de blè continu. La variabilite du revenu annuel fut la plus grande pour les rotations de culiures continues el la plus foible pour la rotation de blè de deux ans.     

Farmer-to-farmer technology diffusion and yield variation among adopters: the case of improved cowpea in northern Nigeria

This article examines the magnitude and sources of yield variation among adopters of improved cowpea varieties in northern Nigeria promoted through farmer‐to‐farmer diffusion. The results reveal important efficiency differences between the lead farmers who have contacts with breeders and the follower farmers who get technology and information from the lead farmers. Differential adoption of the package of seed, insecticide, fertilizer, and recommended cereal‐cowpea cropping pattern provides much of the explanation for yield variation among adopters. The component often missing, and hence accounting for much of the yield variation, is the crop management technology relating to the cereal‐cowpea cropping pattern. No efficiency variation is attributed to the source of technology and information, such as whether improved cowpea was obtained from breeders or lead farmers. Technology source has a rather indirect influence on efficiency through its effect on package adoption where breeders promote greater package adoption among the lead farmers than the lead farmers do among the follower farmers. Possible ways of disseminating crop management technological information through the farmer‐to‐farmer technology diffusion are recommended to better exploit the yield and profitability potentials of improved cowpea varieties in northern Nigeria.     

Farm-level adaptation to climate change in Western Bangladesh: An analysis of adaptation dynamics,profitability and risks

Using long-term district-level climate data and a case study from a drought-prone village in western Bangladesh, this research explored trends in climate change, and analysed farmers’ adaptation dynamics, profitability and risks. This is the first study of its kind for drought-prone areas in Bangladesh.Farmers perceived climate changes included increases in temperature and decreases in rainfall which were as consistent with the trends of Chuadanga climate records. Farmers’ adaptation measures included changes in cropping systems, cropping calendars, crop varieties, agronomic practices, crop diversification and improved animal husbandry. Reducing environmental stress, ensuring self-sufficiency in staple crops (mainly rice) and other crop production practices, and enhancing economic viability of farm enterprises have underpinned these adaptations. Off-farm and non-farm wage employment, temporary migration, self-employment and educating children, constituted the core non-farm adaptation strategies.Emerging cropping systems like maize/cucumber and maize/stem amaranth/rice were economically more viable than the traditional rice/rice and rice/maize systems. Despite some uncertainties, farming was preferred to off-farm work, generating higher returns to labour for all cropping systems. Limited access to stress-tolerant varieties, extension services and affordable agricultural credit, combined with high production costs, variability in crop yields and output prices, are the main barriers to adaptation. Stronger agricultural research and support services, affordable credit, community-focussed farming education and training are critically important for effective adaptation to climate change.     

河南省不同典型农业生产区玉米施肥现状及增产潜力评价

[目的]通过调研2017年河南省不同典型农业生产区玉米的施肥现状,发现河南省玉米种植效益普遍较低主要与化肥不合理施用相关,提出相应的施肥建议以获得最大增产。[方法]采用实地问卷调查的方法,选择河南省禹州、长葛(两个粮食作物种植区)、杞县(一个经济作物种植区)3个典型农业经济区域作为调查地点,共调查了828家农户玉米的产量、施肥种类、施肥量、施肥时间、施肥方式等。[结果]河南省粮作区玉米产量为4 500.00～10 500.00kg/hm~2,养分投入量为90.00～1 249.00kg/hm~2,且仅有单质肥料和复合肥的投入,禹州、长葛两地粮作区平均PFP分别为19.18%和22.46%,、增产潜力分别为23%和26%;杞县经作区玉米产量在4 731.00～11 320.00kg/hm~2,养分投入量为0.00～1 206.00kg/hm~2。经作区有机肥的投入,使其肥料种类相对较多,该区域平均PFP为31.19%,平均增产潜力为34%。[结论]根据当地土壤肥力,粮作区玉米种植可适当减少氮肥投入量,降低基追比,增施磷钾肥,改进后玉米有20%～30%的增产潜力;经作区玉米种植严格把控氮磷钾的配施,增施有机肥,增加基肥种类,改进后玉米有30%～40%的增产潜力。     

Factors influencing adoption of conservation tillage in Australian cropping regions*

The purpose of this research is to improve understanding of conservation tillage adoption decisions by identifying key biophysical and socio‐economic factors influencing no‐till adoption by grain growers across four Australian cropping regions. The study is based on interviews with 384 grain growers using a questionnaire aimed at eliciting perceptions relating to a range of possible long‐ and short‐term agronomic interactions associated with the relative economic advantage of shifting to a no‐tillage cropping system. Together with other farm and farmer‐specific variables, a dichotomous logistic regression analysis was used to identify opportunities for research and extension to facilitate more rapid adoption decisions. The broader systems approach to considering conservation tillage adoption identified important determinants of adoption not associated with soil conservation and erosion prevention benefits. Most growers recognised the erosion‐reducing benefits of no‐till but it was not an important factor in explaining whether a grower was an adopter or non‐adopter. Perceptions associated with shorter‐term crop production benefits under no‐till, such as the relative effectiveness of pre‐emergent herbicides and the ability to sow crops earlier on less rainfall were influential. Employment of a consultant and increased attendance of cropping extension activities were strongly associated with no‐till adoption, confirming the information and learning‐intensive nature of adopting no‐till cropping systems.     

Assessment and improvement of the efficiency of nitrogen use on commercial dairy farms

Nine dairy farmers participated in a project which ran over a four year period from 1997 to 2001, with the aim of improving nitrogen use efficiency (NE) and reducing nitrogen surpluses. Results from systems research and the disadvantages of large nitrogen losses and low NE to the economics of the farm business and the environment were outlined and possible mitigation strategies were discussed with the farmers during visits by a dairy consultant. Initial nitrogen use efficiency (nitrogen output/nitrogen input) ranged from 10% to 23% and nitrogen surplus from 259 to 785 kg N ha¹. During the project nitrogen efficiency improved by an average of 5.4% and nitrogen surpluses reduced by an average of 186 kg N ha¹. The largest changes in nitrogen output per hectare were due to changes in stocking rate rather than changes in milk yield per cow or milk protein content. Nitrogen input was dominated by nitrogen fertilizer input, which for farms applying more than 150 kg N ha¹accounted for between 41% and 85% of total nitrogen input. Reduction in mineral nitrogen fertilizer use was the main way that farmers improved nitrogen efficiency and reduced nitrogen surpluses.     

Improving the productivity of vertisols in the Accra plains of Ghana using leguminous cover crops

The productivity of the Vertisols of the Accra plains is low, in spite of its high potential fertility. This could be attributed to physical constraints and low organic matter content. A study was conducted at the Agricultural Research Centre, Kpong, to assess the suitability of Mucuna pruriens, Mimosa invisa and Stylosanthes guianensis, in short fallows, for improving the fertility, physical properties, moisture conservation and weed control in the case of these soils. Mucuna had the highest biomass of 5.3tha^?1, as opposed to 4.1tha^?1 under natural fallow. The mucuna and stylosanthes biomass had comparatively higher total N values (240.75 and 203.51kgha^?1, respectively) than mimosa and natural fallow (152.46 and 162.74kgha^?1, respectively). Soil organic carbon, one year after the incorporation of cover crops, was found to be relatively higher under the cover crops (mucuna, stylosanthes and mimosa) than it was under natural fallow. Bulk densities were thus lower under the cover crops than they were under natural fallow. Also, soils under the cover crops had higher total porosity, water infiltration rates and moisture storage than they did under natural fallow. Weed cover, 115 days after planting maize, was significantly lower in plots previously under Mucuna pruriens than it was under natural fallow, Stylosanthes guianensis and Mimosa invisa. There was a negative linear correlation between cover crop biomass and weed density (R ² = 0.593–0.805). Grain and stover yields of maize were higher under Mucuna pruriens than they were under natural fallow (138 and 70 per cent higher, respectively). Burning of the natural fallow resulted in greater weed growth than when the material was worked into the soil (41 and 8 per cent, respectively). Grain yield was significantly greater under mucuna than it was under natural fallow (3.1 and 1.3tha^?1, respectively).     

Soil and cropping system research in semi-arid West Africa as related to the potential for conservation agriculture

Semi-arid West Africa faces challenges to increase sorghum and pearl millet production to meet food needs for a growing human population while increasing soil carbon (C), nutrient levels, and water holding capacity that are documented benefits of conservation agriculture. This review focuses on the wealth of research on cropping systems, tillage, crop residue, nutrient, and weed management as related to conservation agriculture. It also identifies needs for multidisciplinary, integrative research to assist the transition from current production systems to conservation agriculture. Crop residue use as livestock feed, or fuel are major constraints to adoption of conservation agriculture, which could be reduced by wood production in agroforestry systems, alternate energy sources, and increased forage supply. Crop residue and grain yields are related, thus improved crop, soil, water, nutrient, and weed management to increase grain yield would also increase the supply of crop residue with potential for ‘left over’ crop residue being available for soil mulching. Incorporating indigenous shrubs and/or cover crops could also increase crop residue supply. Species diversity can be increased through crop rotation, agroforestry, cover crops, and intercrops. Higher grain and stover yields and increased profit potential for resource-poor farmers in West Africa will be required before wide-scale adoption of conservation agriculture will be possible.     

基于农业供给侧结构性改革背景的秸秆资源与利用研究

[目的]分析农业供给侧结构性改革背景下我国秸秆资源产出与利用的变动趋势,就如何以农业供给侧结构性改革为契机促进我国秸秆资源利用提出对策与建议。[方法]利用试验数据检索和定量计算的方法,重点从种植业结构调整、现代种业创新、轮作休耕等任务着手,分析农业供给侧结构性改革对我国秸秆资源与利用产生的影响。[结果]以"镰刀弯"地区玉米结构调整为主要内容的种植业结构调整达到2020年规划期目标时,较2015年可减少玉米秸秆产出1 501万t,同时可为地区畜牧业发展提供青贮玉米等优质饲料、且玉米全株青贮通过养殖粪污得以过腹还田;若通过作物育种技术将水稻的经济系数提高0.03,可减少水稻秸秆产出1 360万t;实行耕地轮作休耕能够减少区域秸秆供应量,且随着轮作休耕试点面积的不断扩大,其减少秸秆产出的作用将持续增强。[结论]推进农业供给侧结构性改革,有望减少"无效秸秆"产出,减轻秸秆处置压力,促进秸秆综合利用,推动解决"小秸秆"带来的"大问题"。未来应在保证粮食安全的前提下,积极推进农业结构调整,转变发展方式,因地制宜调减"高产秸秆"作物改种"低产秸秆"或"零秸秆"作物;在充分发挥作物经济产量潜力的同时,通过积极培育和推广"低产秸秆"型作物品种、优化"低产秸秆"型高产栽培模式等途径控制作物秸秆产量。     

The grain potential of cultivated lands in Mainland China in 2004

The regional test yields of certificated cultivars of grain crops represent the potential yields for the given region under the current natural and technical conditions. Therefore, it is appropriate to use the regional test yields to estimate the gross grain potential of Mainland China.In this paper, we calculated the grain potential of cultivated lands for each of the 105 agro-ecological regions in China. First, cropping system in each agro-ecological region was assumed to be the best use of the agro-climatic resources. Second, the potential per hectare for each of the crops was calculated for a given agro-ecological region, based on the regional test yields of certificated cultivars of grain crops in a given cropping system. For rain-fed and dry lands, their grain potentials were further modified by water-restricting coefficients. The water-restricting coefficients were calculated by dividing the hydro-thermal potential with the corresponding photosynthesis-thermal potential for different grain crops, which were obtained from Regulations of Farmland Grading. Thereafter, the grain potential per hectare of each agro-ecological region was calculated considering the cropping system and the potentials per hectare of all the crops in the cropping system. The gross grain potential of each county in a given region was then obtained by multiplying the grain potential per hectare and the total area of cultivated lands in the county. Finally, the gross grain potential of each agro-ecological region and the whole Mainland China were obtained by summarizing the grain potentials for all of the counties. The results showed that the gross grain potential of Mainland China was 0.92 billion t in 2004. It should be pointed out that this calculation on the grain potential did not sufficiently consider the crop growth restricting factors of cultivated lands, such as soil fertility, fertilizer input, and so on. Since the grain potential is far above the actual grain yield, it suggests that the cultivated land assurance for grain security in Mainland China is relatively high. The results of each agro-ecological region showed that the highest grain potentials were distributed in Huang-Huai-Hai Plain, Northeast China, Middle and Lower Reaches of Yangtze River and Sichuan Basin, where excellent hydro-thermal condition and flat terrain are ideally suitable for crop growth.     

A meta-analysis of intercropping in Africa: impacts on crop yield,farmer income,and integrated pest management effects

Poverty and hunger in Africa are prevalent and will increase in absolute terms with population growth and continued land degradation. Therefore, there is a need for sustainable agricultural strategies, such as conservation agriculture (CA) and integrated pest management (IPM). Among CA practices, intercropping holds the promise of providing benefits to smallholders through increased crop yields and income as well as improved resource use. We review intercropping’s effects on crop yield, income, and output of IPM practices in Africa. On average, intercropping increases crop yields by 23% and gross income by 172 USD/ha, but effects vary significantly depending on management practices and agro-ecological factors. There was no evidence that yields and gross income for intercropping treatments increase when leguminous intercropping combinations, minimum/reduced tillage, pesticides, or fertilizers were utilized. Dual use of herbicides and intercropping practices garnered 1442 USD/ha more in gross income and yielded 1422 kg/ha more compared to those in conventionally managed fields, signifying the positive influence supplemental inputs can have on intercropping’s effects. Although IPM practices increased yields by 20%, on average, IPM systems integrated with intercropping yielded 24% less than IPM systems that did not. This meta-analysis indicates that intercropping is an advantageous sustainable agricultural practice, but that its effective implementation would depend on considering other factors such as adequate control of competing vegetation. There is a clear need for more scientific studies which examine intercropping’s role in complex sustainable agricultural systems, in order to understand its effects in differential environmental and socioeconomic situations and to optimize the practice’s transfer and benefits.     

典型家庭农场组织化程度对生产效率的影响分析

现阶段中国农业生产仍属于高投入、低效率的粗放模式,粮食安全缺乏可持续性.研究不同规模下不同组织形式的家庭农场生产效率,有助于揭示在中国农业高质量发展阶段中通过转变农业经营组织形式提高粮食生产效率,保障国家粮食安全的新路径.本文利用湖北武汉、安徽郎溪等地家庭农场的问卷调查数据,采用三阶段DEA方法比较纯种植与种养结合两类...     

Sustainable crop intensification through surface water irrigation in Bangladesh? A geospatial assessment of landscape-scale production potential

Changing dietary preferences and population growth in South Asia have resulted in increasing demand for wheat and maize, along side high and sustained demand for rice. In the highly productive northwestern Indo-Gangetic Plains of South Asia, farmers utilize groundwater irrigation to assure that at least two of these crops are sequenced on the same field within the same year. Such double cropping has had a significant and positive influence on regional agricultural productivity. But in the risk-prone and food insecure lower Eastern Indo-Gangetic Plains (EIGP), cropping is less intensive. During the dryer winter months, arable land is frequently fallowed or devoted to lower yielding rainfed legumes. Seeing opportunity to boost cereals production, particularly for rice, donors and land use policy makers have consequently reprioritized agricultural development investments in this impoverished region. Tapping groundwater for irrigation and intensified double cropping, however, is unlikely to be economically viable or environmentally sound in the EIGP. Constraints include saline shallow water tables and the prohibitively high installation and energetic extraction costs from deeper freshwater aquifers. The network of largely underutilized rivers and natural canals in the EIGP could conversely be tapped to provide less energetically and economically costly surface water irrigation (SWI). This approach is now championed by the Government of Bangladesh, which has requested USD 500 million from donors to implement land and water use policies to facilitate SWI and double cropping. Precise geospatial assessment of where freshwater flows are most prominent, or where viable fallow or low production intensity cropland is most common, however remains lacking. In response, we used remotely sensed data to identify agricultural land, detect the temporal availability of freshwater in rivers and canals, and assess crop production intensity over a three-year study period in a 33,750 km² case study area in southwestern Bangladesh. We combined these data with georeferenced and temporally explicitly soil and water salinity information, in addition to relative elevation classifications, in order to examine the extent of winter fallows and low productivity rainfed cropland that could be irrigated by small-scale surface water pumps. Applying observations of irrigated crop sowing dates and yields from 510 wheat, 550 maize, and 553 rice farmers, we also modeled crop intensification production scenarios within the case study area. We conservatively estimate that at least 20,800 and 103,000 ha of fallow and rainfed cropland, respectively, could be brought into intensified double cropping using SWI. Scenario analysis indicates that if 25%–75% of the fallow or low-intensity land were converted to irrigated maize, national aggregate production could increase by 10–14% or 29–42%, respectively. Conversion to wheat would conversely boost national production by 9–10% or 26–31%. Irrigated rice is however unlikely to contribute >3%. In aggregate, these actions could generate between USD 36–108 million of revenue annually among farmers. Intensification therefore has important land use policy and food and income security implications, helping to rationalizei SWI investments. Crop choice, water resource allocation, and water governance will however remain crucial considerations for irrigation planners.     

Changes in grain handling catchments in Australia: an historical perspective

This paper explores some of the important issues that influence the magnitude of receival site grain catchments in Australia. Changes in grain harvests, transport and grain handling technologies and costs; changes in farming systems, crop yields and harvesting capacity; investments in roads and on‐farm storage and economies of size in grain receival infrastructure are shown in combination to affect the size of grain catchments in major grain‐growing regions of Australia over the last 30 years. The size of grain catchments that minimise growers’ costs of road transport of their harvested grain and their receival point charges in various time periods are determined. Differently shaped grain catchments are considered. The main finding is that the size of grain catchments that minimise farmers’ grain transport, off‐farm storage and handling costs since the mid‐1980s has consistently increased, principally due to lessening real costs of road transport, more on‐farm storage and economies of size in grain receival, despite higher grain yields and a greater intensity of cropping. These findings are consistent with the observed reduction in the number of receival sites in many grain‐growing regions of Australia. Site rationalisation is less evident in states where the receival network is owned and operated by a grower cooperative.     

Managing phosphorous soil dynamics over space and time

Understanding the relationship between soil fertility dynamics and crop response is conceptually appealing. Even more appealing is comprehension of the spatial and temporal heterogeneity of these connections over a production surface and across seasons. But gaining knowledge about these interactions is difficult because nutrient carryover dynamics and crop response to inputs are determined simultaneously on the one hand, and sequentially on the other. A second problem enters when crops are rotated, for example, the corn [Zea mays (L.) Merr.]–soybean [Glycine max (L.) Merr.] system commonly practiced in the U.S. Corn Belt. This article examines nutrient carryover–crop response dynamics using data from a corn‐soybean, variable rate nitrogen (N), and phosphorous (P) experiment conducted over five years in Minnesota, USA. Site‐specific corn response to N and P and soybean response to P is estimated with a P carryover equation. Estimates are used in a dynamic programming model to determine site‐specific optimal N and P fertilizer policies, soil P evolution, and profitability. The net present value of managing N and P site‐specifically is compared to a strategy in which these inputs are managed uniformly following Extension guidelines. The results suggest that when P carryover is accounted for in determining optimal P fertilizer rates, returns to the variable rate strategies are higher than returns to a uniform or whole‐field management strategy.     

Challenging Small‐Scale Farming: A Non‐Parametric Analysis of the (Inverse) Relationship Between Farm Productivity and Farm Size in Burundi

We use a non‐parametric approach to investigate the (inverse) relationship between farm productivity and farm size. A kernel regression is used on data of mixed cropping systems to study the determinants of production including different factors that have been identified in literature as missing variables in the testing of the inverse relationship such as soil quality, location and household heterogeneity. Household data on farm activities and crop production were gathered from 640 households in 2007 in two Northern provinces of Burundi. Our results do not reject the findings of an inverse relationship between farm size and productivity. However, we find that size returns vary substantially with farm size, that is, between 0.2 for the smallest farms and 0.8 for the largest farms. Other factors that significantly affect production include soil quality. Finally, we find a significant positive association between food security and farm size.     

Nitrogen fixation during decomposition of sugarcane (Saccharum officinarum) is an important contribution to nutrient supply in traditional dryland agricultural systems of Hawai'i

Nitrogen (N) is unique among essential elements required for life, in that it must be fixed from the vast atmospheric reservoir before most organisms can use it. Prior to industrial nitrogen fixation, many agricultural systems were limited in their productivity by N. What sustained N in the ancient Hawaiian dryland (rain-fed) agricultural systems that lacked legumes or other known significant N inputs? N-fixation during sugarcane (Saccharum officinarum) growth and litter decomposition was examined in settings representing pre-European Hawaiian agriculture. We did not detect associative N-fixation during the growth of five Hawaiian sugarcane cultivars. In contrast, N-fixation during the decomposition of leaf and stalk material was important. We found that the depth of the mulch layer significantly affected N-fixation levels during decomposition; values of N-fixation in different depths of senesced leaf litter ranged from 0.69 to 1.36?gN/kg of litter integrated over the lifetime of decomposition. Compared to senesced leaf litter, N-fixation during decomposition of non-senesced leaf litter was ～77% and stalk material ～140% per unit mass. Peak rates of N fixation occurred between 200 and 400 days of decomposition, and ranged from 1.37 to 3.27?gN/kg/yr. Our empirical results were extrapolated to represent the traditional Hawaiian cropping system; we calculated N-fixation inputs of 4.8–39.0 kgN/ha/yr, with fixed N adding 17–40% of the amount of N added through litter. Findings indicate that significant N may be introduced into natural cropping systems through mulching practices and that small changes in practices greatly alter the total inputs. The use of mulch was likely an important source of N in pre-industrial settings and may be used in contemporary systems to reduce nitrogen fertilizer requirements.     

中国收获面积差及其产量潜力情景分析

[目的]文章以提升耕地复种为切入点,从区域自然资源禀赋与利用的角度研究我国粮食产量潜力,能为国家科学优化水土资源配置,推进农业供给侧结构性改革提供有益参考。[方法]引入收获面积差的概念,在作物单产与耕地面积保持不变的前提下,从提升复种的角度估算我国收获面积差及其产量潜力。[结果]2005年左右网格尺度研究结果表明:第一,不同水资源分配情景下,中国可收获面积差在0.135亿~0.363亿hm~2(约合2亿~5.4亿亩)之间波动;第二,与不同农业土地利用水平下可能获得的作物产量相结合,该收获面积差最高可转化成7.4亿t的产量潜力;第三,最实际情况下,通过水资源、作物类型、灌溉措施3方面配置,我国拥有0.135亿hm~2(2亿亩)收获面积差,其可转化为1.17亿t的产量潜力,相对于现实产量5.97亿t,约增产19.6%。第四,长江中下游地区同时拥有好的水热条件与相对优良的灌溉设施,而该地区较大的收获面积差与产量潜力说明其水土资源利用还有较高的调整优化空间。[结论]粮食总产受作物单产、耕地面积、复种指数等3个方面综合影响,但前两大因素对我国粮食产量潜力的贡献已经非常有限。     

Does carbon farming provide a cost‐effective option to mitigate GHG emissions? Evidence from China

In this study, we apply a whole farm bioeconomic analysis to explore the changes in land use, farm practices and on‐farm greenhouse gas (GHG) emission under varying levels of agricultural greenhouse gas abatement incentives in the form of a carbon tax for a semi‐arid crop‐livestock farming system in China's Loess Plateau. Our results show that the optimised agricultural enterprises move towards being cropping‐dominated reducing on‐farm emission since livestock perform is the major source of emission. Farmers employ less oats‐based and rapeseed‐based rotations but more dry pea‐based rotations in the optimal enterprise mix. A substantial reduction in on‐farm greenhouse gas emission can be achieved at low cost with a small increase in carbon incentives. Our estimates indicate that crop‐livestock farmers in China's Loess Plateau may reduce their on‐farm GHG emission between 16.6 and 33 per cent with marginal abatement costs <￥100/t CO₂e and ￥150/t CO₂e in 2015 Chinese Yuan. The analysis implies that reducing greenhouse gas emission in China's semi‐arid crop‐livestock agriculture is potentially a low‐cost option.     

基于EOS/MODIS数据的南方水稻面积提取技术

该文以我国南方15省、市和自治区为研究区域,采用高时频的EOS/MODIS卫星数据,构建了水稻播种面积识别算法,实现了南方各类水稻(早稻、晚稻和单季稻)种植面积的快速提取。该研究在很大程度上解决了困扰农情遥感监测业务运行中水稻种植面积及其空间分布的难题,可为作物估产、农作物长势以及墒情遥感监测提供基础。