Risk aversion and land allocation between annual and perennial crops in semisubsistence farming: a stochastic optimization approach

This article analyzes the effect of production uncertainty on farmland allocation decisions between perennial and annual crops, focusing on a representative farmer's attitude toward risk. A dynamic stochastic optimization model that considers net planting—the difference between new plantings and removals of perennial crops that achieve full production cycle—is used. The effect of uncertainty on the representative farmer's decisions to increase or decrease perennial crops’ acreage, on the optimal path, is examined. Our results reveal that the response of optimal path of net planting to uncertainty related to perennial crop production is highly affected by the farmer's attitude toward risk. A risk‐averse or a low‐risk loving farmer tends to reduce land allocation to perennial crops under uncertainty, while a high‐risk loving farmer will do exactly the opposite. Also, due to disutility of farming, the farmer tends to reduce land allocation to perennial crops when prices are high enough for him to attain a desired income level expectation. One implication of this research is the need for mechanization—in sub‐Saharan countries in particular—that increases per‐acreage yield and output in semisubsistence agriculture.     

A STOCHASTIC MODEL FOR THE OPTIMAL REPLACEMENT OF RUBBER TREES

Recognizing the lack of realism in optimal replacement analyses that assume constant prices and yield patterns over time, a stochastic model appropriate to rubber production is developed. Data drawn from Peninsular Malaysia are used to implement the model. The results suggest that efforts should be directed towards establishing bench mark maximum annuities as guides to more economic replanting decisions rather than emphasizing earlier replanting per se. The significance of price stabilization policies also becomes evident.     

粮食主产区耕地质量影响因素与粮食产能关系分析

[目的]分析耕地质量构成要素对粮食产量影响,探讨提高粮食生产能力途径和方法。[方法]文章选取河南省粮食主产区内近10年来的土地资源调查、农用地分等、耕地地力评价、粮食产能核算等多项成果数据,以4.645 0万个行政村为评价单元,采用GIS空间分析法,建立了耕地质量单因素变化及因素指标组合与粮食产能关系曲线,测算了多模型影响下耕地质量因素改变量对粮食产能的影响大小。[结果](1)耕地质量影响因素各指标分级变化会引起粮食产能改变,总体上,当耕地所处的环境因素改善后,粮食产能将不断增加,因素指标分级对粮食增产能力的影响大小各不相同,11个因素的理论最大增产量和平均增产能力排序大致相当,但最大与最小间相差约8倍;(2)自然质量分充分体现了因素指标组合状态,四次多项式是表示耕地质量因素组合与粮食产能最佳关系模型,即随着自然质量总分提高,标准粮产量提升值呈现"倒S"型变化,即自然质量总分每变化0.01个单位,标准粮提升或降低78.15kg/hm~2。[结论]该文成果为粮食核心区内高标准农田建设提供数据支撑。     

接好断链,实现循环,促进粮食单位产量提高

有效提高粮食单产是保证粮食总产量最积极有效的途径。促进有机质更多地还田,不断保护和提升土壤质量,是最经济、有效、可持续的办法。同时还能达到环境效益、生态效益及社会效益等多重目标。该文提出增加土壤有机质,实现农业生产良性循环的举措。     

Food Manufacturers’ Sustainable Product Launch Strategy: Game Theory Approach

This article constructs a manufacturers’ sustainable food product launch game theory based model to understand the decision-making. The results based on derivations and simulations of the egg industry show that the lead manufacturer and the follower manufacturer have different launch criteria for sustainable products. The lead manufacturer decides to launch a sustainable product when the relative maximum willingness to pay for the sustainable product is higher than the relative cost and/or the absolute value of the maximum willingness to pay for the sustainable product is sufficiently higher than the absolute value of the cost of the sustainable product. The follower launches primarily based on the degree of substitution. When consumers perceive that the sustainable product is differentiated and distinguishable enough from the conventional product, the follower is more likely to launch a sustainable product. The simulation results show that egg manufacturers, both the leader and the follower, under both the worst and best case scenarios will launch sustainable egg products to increase their profit. Our results are supported by industry data, which shows that both national and store brand manufacturers have increasingly marketed sustainable eggs over the past few years.     

论我国生物多样性保护和可持续利用法律体系的重构

我国生物多样性占世界第八位，但近年生物多样性受胁状况日趋显著。我国尚未建立完善、科学的生物多样性保护法律体系，仅有针对某一特定生物资源的强制性保护立法，缺乏与其他生物资源要素之间必要的立法协调；由于自然资源法成为生物多样性法律规范的构成主体和表现形式，造成我国生物多样性保护机制独立运行的极大障碍，因此应当从生态资源的内在互动关系出发，以生物多样性保护法律体系从传统自然资源法律体系中分离出来为途径，以建立物种复合保护机制为手段，以生物多样性资源产权制度及相应的侵权救济法律制度构建为保障，重构我国生物多样性资源的立法保护体系，从而有效地维护生物圈的正常代谢，最终实现社会生态系统的稳定与发展。     

南方丘陵山区农业可持续发展综合评价及实证分析

[目的]基于农业可持续发展的内涵(农业经济、资源环境、文化科技和农村社会等四个方面),结合南方丘陵山区山多、森林覆盖率高的特点,通过实地调研并咨询农业相关方面的专家,构建了南方丘陵山区农业可持续发展评价指标体系;全面诊断南方丘陵山区农业可持续发展状况和存在的问题。[方法]文章以江西省莲花县为实证,运用加权综合评价模型、协调度模型和发展障碍度模型对研究区农业可持续发展现状、可持续发展潜能和障碍因素进行分析研究。[结果]研究区农业可持续发展综合能力处于良性增长的态势,2000—2016年农业可持续发展综合评价指数年均增长10.25%;可持续发展协调度综合指数0.78。[结论]研究区农业可持续发展具有较好的前景;影响研究区农业可持续发展的主要障碍因素为农村社会,它对总体目标贡献了66.48%的障碍度。加快农村城镇化进程,减少农村贫困率有助于促进农村社会的和谐发展。     

THE ECONOMIC OPTIMISATION OF SOW REPLACEMENT DECISIONS BY STOCHASTIC DYNAMIC PROGRAMMING

A stochastic dynamic programming model is designed to determine the economic optimal replacement policy in swine breeding herds. This optimal policy maximises the present value of net revenues from sows present in the herd and from subsequent replacement gilts over a given planning horizon. The model also calculates the total extra profit to be expected from trying to retain an individual sow until her optimal lifespan and not replacing her immediately. This total extra profit is an economic index which makes it possible to rank sows within the herd on future profitability and, therefore, can be used as a management guide in culling decisions. For typical Dutch values the optimal replacement decisions result in an average herd life of 3.43 parities. The maximum economic life of sows of average productivity turns out to be 10 parities. All data can easily be adjusted to represent a specific herd or a different region of the world.     

A MODEL OF NEW ZEALAND APPLE SUPPLY RESPONSE TO TECHNOLOGICAL CHANGE*

A supply response model for New Zealand apples is specified and equations for new plantings, removals, yields and adoption of an innovation are estimated. The model expands on perennial crop models previously estimated by incorporating the time pattern of adoption of a planting innovation and formulation of a measure of yield expectations given technological change.     

气候资源管理与可持续发展

该文讨论了气候资源概念的内涵与外延及其属性问题,旨在为气候资源管理研究提供基本理论支撑;简要探讨了气候资源管理与可持续发展的关系,分析了当前中国气候资源管理与可持续发展面临的形势与挑战;运用可持续发展的理论和战略的思维,研究认为,加强气候资源管理,合理开发利用和保护气候资源,提高气候资源的有效利用,是实现人与自然和谐、可持续发展的重要途径;提出应树立新的管理理念,采取法律制约、政策引领、技术推动和道德规范等多种手段综合治理。     

松嫩盆地水资源可持续开发利用的问题与对策

水资源是影响21世纪中国社会经济持续发展的重要因素。对于松嫩盆地来说,水资源能否可持续开发与利用,直接关系到松嫩盆地的根本经济建设和国土自然环境的稳定。依据可持续发展的思想,分析了影响松嫩盆地水资源可持续开发利用的突出问题,并提出了相应的对策和措施。     

四川省水稻产投特征变迁及技术进步对单产的影响

[目的]了解四川水稻产投特征和技术进步对单产的影响,促进水稻可持续生产。[方法]分析了改革开放以来四川省水稻产投特征和技术特征变动,并基于索洛余值法测算了1980~2015年四川省科技进步对水稻单产的贡献情况。[结果](1)全省水稻单产水平及物质与服务费用投入均呈现波动增长趋势,人工投入逐年递减,但人工成本在生产成本中的比重较大;(2)四川省水稻品种选育、栽培管理技术、推广技术、稻作经营方式和农业政策不断变迁,更适应当前以普通家庭生产和新型经营主体共同发展的局面对技术的需求;(3)整体来看,近36年技术进步对四川省水稻单产水平提高的贡献率较低,生产经营较为粗放;(4)分时期看,2005年前,技术进步对全省水稻单产水平提高的贡献率较高,但之后尤其是近5年,技术进步并未对水稻单产水平提高产生影响,要素投入是水稻单产水平提升的主要因素。[结论]提出了加强科技研发及投入水平、"一主多元"联合推广、生产管理技术培训和丘区节本增效生产的政策建议。     

景观异质性视角下生物多样性对农田生产力的影响研究进展与启示

目的 通过总结景观异质性的相关文献,明确现阶段景观异质性研究中生物多样性对农田生产力影响的趋势和方向,为后续研究与相关政策制定提供理论支持和参考依据。方法 文章对国内外不同景观异质性下对生物多样性和农田生产力的影响情况进行分析,梳理生物多样性对农田生产力的影响方式,了解影响农田景观异质性大小的因素和原理,系统总结了三者之间存在的级联关系,提出了农田可持续发展的实践建议。结果 （1）景观空间异质性对生物多样性—农田生产力关系具有显著的积极影响,但存在一定的阈值,超过该值则会产生负面影响;（2）在空间异质性视角下,农田中生物多样性与生产力之间存在广泛的正相关关系,农田面积作为一项操作简便且影响较大的农田景观指标,具有巨大的潜力;（3）景观的时间异质性和功能异质性与农田生物多样性—生产力关系同样具有积极的协同作用,在未来的研究中应当占有一席之地。结论 从景观异质性的视角出发,农田生物多样性对生产力有着广泛的积极影响,同时存在一个阈值使得二者关系达到最大值,通过采取保护小斑块农田等方法实现生态和生产的“双赢”,实现高质量的农业可持续健康发展。     

基于层次分析和模糊评判的湖北省休闲农业区域发展潜力分析

［目的］生态功能区划是区域自然资源开发管理、生态环境保护及产业布局的重要依据,在此基础上,对休闲农业发展潜力进行评价,以期为区域休闲农业的持续发展提供参考意见。［方法］鉴于影响区域休闲农业发展潜力的因素较多,且某些因子存在一定程度的模糊性,文章通过构建湖北省休闲农业区域发展潜力评价指标体系,采用模糊评价法对其进行定量研究分析。［结果］基于生态功能区划的湖北省休闲农业区域发展潜力评价体系综合得分6882,处于中等发展水平,仍有很大的发展潜力。模糊评价向量中隶属度最大值为0298,发展潜力较大,其中农业资源、生态环境、空间布局的模糊评价向量隶属度最大值分别为0384、0286和0442,发展潜力较大,而生态服务功能重要性和生态环境敏感性的模糊评价向量隶属度最大值分别为0259和0315,发展潜力一般。［结论］湖北省基于生态功能区划发展休闲农业应加强生态环境、休闲农业等方面的工作。研究结果对湖北省休闲农业的持续发展具有一定指导意义,也为区域休闲农业的发展提供一定参考。     

Household-level effects of China's Sloping Land Conversion Program under price and policy shifts

This study examined how agricultural households involved in China's Sloping Land Conversion Program (SLCP) could respond to expected changes in environmental and livestock policies and changing commodity prices. We calibrated a farm household model using 2009 survey data collected in northeast Gansu Province, China, and examined the responses of four different household groups. Household groups were distinguished based on the resources they possessed for either cropping, livestock husbandry or off-farm employment. We also calculated the opportunity cost of converting sloping land from grain crop production to perennial grass production and included the net value of the replacement crop in these calculations. Our model simulations indicated that subsistence-oriented households were most likely to participate in the SLCP, and that SLCP payment reductions could have large negative income effects for this group. Reductions in SLCP payments increased income inequality among households in the study area. Migration- and cropping-oriented households have fewer incentives to participate in the SLCP. With rising commodity prices, SLCP payments need to rise to avoid that subsistence-oriented households reconvert their land from perennial grasses to annual grain crops. Local government policies related to livestock production are being devised in Gansu as a method to lift incomes, and these policies could also have positive environmental benefits by increasing grass production on sloping land. The introduction of these livestock promotion policies had modest income effects but did not alter the area grown with grasses under the SLCP.     

Spatial pattern of arable land-use intensity in China

In recent years, the sustainable utilization of China’s arable land has been confronted with several challenges. The China government has been very strict in arable land protection, and a package of policies and measures have been promulgated. All these endeavors are of great significance for proposing an innovative policy system for sustainable land use in China. However, above stated policies are all designed from the perspective of space control with the purpose of reducing arable land loss or increasing arable land area, few policies have been designed from the perspective of utilization control, namely guide the actual arable land farming in sustainable ways and constraint unreasonable land use behavior such as overuse, rough use, land abandonment. In this paper, we analyze spatial distribution of average land-use intensity (ALUI) at the county-level in Mainland China, which can be used as a significant index for evaluating the rationality of arable land use and providing effective decision-making supporting information for design of regional arable land protection policy. Based on the experimental results, there is still considerable room for yield improvement as the ALUI of ∼73.1 % counties are lower than 0.7 while the 53.60 % counties are lower than 0.6. Furthermore, the ALUI dataset shows significant global spatial autocorrelation characteristic. Boundaries of regions that aggregated by counties with high ALUI are more consistent with that of provincial administrative districts, comparing with that of sub-standard farming system regions. On the other hand, counties with low ALUI are mostly cluster in mountains, hills, or plateaus, where grain yield is mainly limited by regional hydrothermal conditions. In addition, counties with different ALUI status have been divided into six classes, using k-means clustering algorithm. This will facilitate the understanding of appropriate arable land protection and utilization paths for different regions and the rethinking of current support policies on farmland protection.     

2013年罗非鱼产业生产现状及发展趋势分析

论文从罗非鱼苗种生产、成鱼养殖,产品加工和市场贸易四个产业主要环节概述了2013年罗非鱼产业生产现状,总结了罗非鱼产业发展的特点,分析了罗非鱼产业的发展趋势,提出了加强罗非鱼常年繁育技术研究与示范、积极推广生态健康高效的经营方式、提高罗非鱼产品质量,加强质量安全监管和建立自主的销售渠道、大力开拓国内外新市场等建议,以保障罗非鱼产业的可持续发展。     

我国大豆种植时空分布与风险费率研究

[目的]在我国大豆种植锐减、进口攀升和自然灾害加重的背景下,摸清我国大豆种植时空分布特征、风险费率对制定大豆种植和保险政策,保障大豆粮食安全有重要意义。[方法]文章依据1978—2016年全国省级大豆播种面积、产量、单产及进口等数据,基于风险损失和产量分布模型,运用数理统计、直线滑动平均模拟法和单产分布模型模拟推导法,分析全国大豆种植的时空分布变化,评估相应的生产风险并厘定各地大豆农业保险费率。[结果] 1978—2016年我国大部分省份都有大豆种植,1998年后,仅青海未种植大豆,东北和黄淮海地区一直是我国大豆主产区。2005年全国大豆达到最大播种面积959万hm~2,随后锐减,2015年仅为2005年的67.8%;产量变化趋势和面积变化趋势一致;平均单产为1 153 kg/hm~2,呈现出上升趋势。大豆进口逐年增加,2016年大豆进口总量8 391万t,创历史新高。全国大豆发生灾害风险的平均频率为27.24%,西藏、宁夏、陕西发生灾害风险的频率较高,各地呈现出轻灾(18.24%)中灾(5.74%)重灾(1.95%)巨灾(1.30%)的特征。全国大豆种植的平均费率为4.40%,陕西、河南、安徽、辽宁、吉林和内蒙古大豆种植大省的费率较高,而黑龙江大豆种植的费率则较低,为3.72%。[结论]我国大豆种植结构需要调整,在大豆种植大省,如陕西、河南、安徽等,降低种植面积;在保持黑龙江大豆种植优势的同时,发展河北、山东等低风险地区的大豆种植;在开展大豆农业保险时,实行地区差异化费率。     

做好地块调整是发挥土地整理项目最大效益的重要环节

研究目的：发现土地整理项目存在的问题,改进工作,提高土地整理项目效益。研究方法：实地调查法,文献资料法,总结归纳法。研究结果：中国农户土地承包经营规模小,耕作地块零散,耕作效率低。国土资源部主导的土地整理工作偏重工程,鲜有进行地块调整和扩大耕作地块的。研究结论：应学习日本土地整理过程中注重产权调整和地块置换的经验,在未来的土地整理中,将承包地产权调整和地块置换作为重要环节,以扩大耕作单元面积和经营规模,提高劳动生产率,促进农业产业化发展和田间工程设施的可持续利用。     

DYNAMIC FARM—LEVEL PLANNING MODEL FOR BEEF FEEDLOT PRODUCTION AND MARKETING

The study is aimed at formulating and empirically applying a dynamic farm-level model for the planning of optimal beef feedlot production and marketing strategies. A dynamic programming (DP) model is used to calculate the optimal feeding schedule (i.e. liveweight gain sequence), market liveweight and stock replacement for a single bull calf over a one-year planning period, taking into account seasonal fluctuations of planning parameters such as beef prices, feeding costs, nutritional requirements, and stock replacement costs and obtainability. The DP model includes a linear programming (LP) subroutine for calculating least-cost feed rations. The planning model is empirically applied using data and assumptions representative offeedlots in the Coastal Plain region of Israel where most feedlot production and marketing decisions are made by ‘rule-of-thumb’ using set liveweight gain sequences, market standards and stock replacement decisions. The empirical findings indicate that the profitability of feedlot production and marketing could be increased by an average of 10% over that obtained from ‘rule-of-thumb’ decision rules.