现代化农区耕地利用形态转型研究

[目的]耕地利用转型是农业发展转型和土地利用转型的重要组成部分。探讨现代化农区耕地利用形态转型的一般特征,可以为区域耕地资源优化配置提供科学依据。[方法]基于GIS平台,结合耕地利用动态度、区域差异指数、耕地景观格局变化表征模型,分析黑龙江省垦区建三江管理局1976~2014年耕地利用形态变化规律。[结果](1)建三江垦区耕地利用可以划分为4种典型形态:耕地散布态、耕地密布态、耕地连布态和耕地满布态,耕地形态转型经历了旱地拓张期(1976~1986年)、水田萌发期(1986~1996年)、水田拓张期(1996~2006年)和旱—水转换期(2006~2014年);(2)旱地拓张期,垦殖率由18.55%猛增至45.96%,旱地占土地总面积比重由18.55%升至44.34%,旱地景观格局集聚度不断提升,水田"零星"镶嵌于研究区内;(3)水田萌发期耕地总量稳中有升,水田面积小幅增加,占耕地面积比重由3.53%提升至6.63%,水田景观破碎度较高;(4)水田拓张期垦殖率基本稳定,新增耕地以水田为主,主要来源于未利用地(沼泽地)、草地、林地的垦殖以及旱地转化,水田种植优势明显增强,景观集聚度升高;(5)旱—水转换期,水田比重由29.48%上升至80.90%,主要表现为耕地内部旱地—水田的转变。水田最大斑块所占景观面积比例骤然上升,水田逐渐占据绝对优势地位,逐渐由"破碎化"转向"聚集化"。(6)气候变暖、地貌适宜、经济效益是该区域耕地利用转型的重要原因,但地形地貌、土壤等自然条件以及发展水平、交通区位等社会经济条件的差异,使得耕地利用转型具有区域差异性。[结论]黑龙江省垦区建三江分局在全球气候变暖和国家粮食安全战略背景下,其耕地利用经历了面积逐渐扩展、结构不断调整的形态转型,其本质是农业生产投入规模和强度的提升。耕地利用形态转型规律可以为区域耕地利用调控提供依据。     

Technical efficiency in paddy farms of Tamil Nadu: an analysis based on farm size and ecological zone

Despite the wider application of efficiency analysis in Indian agriculture, little has been done on the investigation of intra and interecological variations, size differences and their interactions. However, ecological issues have paramount implications for the low-input sustainable agricultural production. Furthermore, due to the various causes of efficiency, the age-old size-based debate on efficiency differences is not yet resolved. The present study examines the level of technical efficiency across ecological zones and farm size groups in paddy farms of the southern Indian state of Tamil Nadu. The study showed that 90% of the variation in output among paddy (IR-20) farms in the state is due to differences in technical efficiency. Land, animal power and fertilisers have significant influence on the level of paddy production. Varying from 0.59 to 0.97, the mean technical efficiency was found to be 0.83. The use of F-test in two-way analysis of variance (ANOVA) and censored regression (Tobit model), with dummies for ecological zones, farm size groups and their interactions, has shown that, at mean level, the level of technical efficiency among paddy farms of the state differs significantly across agro-ecological zones and size groups as well, The study further indicated that small-sized paddy farms in zone II and medium-sized paddy farms in zone III are represented by ecologically size-biased production techniques; thus achieving higher technical efficiency.     

吉林省农产品进出口对农业经济增长的效应———基于出口扩展型生产函数的实证研究

吉林省是一个农业大省,农产品进出口在整个对外贸易中占有举足轻重的地位,进出口贸易与经济增长之间的相互关系历来也是学术研究的重点。文章首先分析吉林省农产品贸易的发展状况与特点,研究了吉林省农产品贸易对农业经济的贡献率与拉动率;然后以柯布道格拉斯生产函数为基础,构建出口扩展型生产函数模型,对吉林省农产品进出口与农业经济增长,农业劳动投入、资本投入与农业经济增长的关系进行了实证分析,结果表明吉林省农产品进出口、农业固定资本投入对农业经济增长均具有正向的促进作用,农业就业人数的变化对农业经济增长的作用不显著。其中吉林省农产品出口额每增加1%,会促进农业地区生产总值增加0.198%,进口每增加1%,促进农业经济增长0.205%,农产品进出口总额每增加1%,农业地区生产总值增加0.227%。因此,吉林省要努力发展外向型农业,提高优势农产品在国际市场上的份额;同时增加农业资本投入,优化投资结构。     

刺参池塘养殖经济效益分析

论文对刺参池塘养殖的投入、产量、产值和效益进行了分析.结果显示：在投入方面,参苗投入占总投入的比例最大;塘租和人工方面的投入相近,并列排在第二位.通过对投入与产出的效益分析发现,投苗密度是影响产量和经济效益的重要因素.通过对不同调查池塘整体投入分析发现,养殖投入的增加可以在一定程度上提高刺参的产量,但是过高的投入会造成投入与产出不成正比,最终可能会导致经济效益较大幅度的下降.     

Better Technology, Better Plots, or Better Farmers? Identifying Changes in Productivity and Risk among Malagasy Rice Farmers

We introduce a method for properly attributing observed productivity and risk changes among new production methods, farmers, and plots by controlling for farmer and plot heterogeneity. Results from Madagascar show that the new system of rice intensification (SRI) is indeed a superior technology. Although about half of the observed productivity gains appear due to farmer characteristics rather than SRI itself, the technology generates the estimated average output gains of more than 84%. The increased estimated yield risk associated with SRI would nonetheless make it unattractive to many farmers within the standard range of relative risk aversion.     

稻鳅共生种养模式试验研究

[目的]稻鳅共生是典型的稻田综合利用模式,符合生态农业发展方向。通过对稻鳅共生生态系统的生理生态学机制开展试验研究,为进一步推广稻鳅共生种养模式提供科学依据。[方法]采用田间试验方法,以水稻单作为对照,研究了不同泥鳅养殖密度下的稻鳅共生对水稻农艺性状、土壤理化性质、水稻产量构成的影响,并对稻鳅共生种养模式进行了经济效益分析。[结果]与对照处理相比,水稻长势在株高、有效分蘖率、根长等方面有一定提高。养殖田水稻株高增高了3%,有效分蘖率提高了8%~11%,根长提高了8.8%~31.3%。在土壤理化性质方面,与对照相比,土壤容重降低了7.1%~21.2%,孔隙度增加了4.1%~14.7%。实验前后养殖田内土壤有机质增加了3.5%~26.5%,对照田降低了2.5%~5.8%。土壤肥力(氮、磷、钾)减少,但减少幅度小于对照处理。稻鳅共生种养模式下水稻产量提高了5%~25%,同时稻田增收泥鳅1 725~3 375kg/hm2,净收入为1.836 0万~2.307 0万元/hm2,经济效益提高了3.65~4.84倍。稻鳅共生种养模式中泥鳅的养殖密度为30万尾/hm2时稻田的生态效益和经济效益最佳。[结论]稻鳅共生有效改善了土壤理化性质,促进了水稻的生长,提高了稻田产量和产值。     

1990－2015年三峡库区重庆段水田时空分布及演变特征

目的 水田作为三峡库区重要的耕地类型与湿地景观,对保障该区的粮食和生态安全起到了不可替代的作用。分析水田的时空分布及演变特征,为农业结构调整、水田经营政策的制定以及保障库区生态系统的安全提供一定的理论基础。方法 文章基于三峡库区重庆段1990年、2005年、2015年土地利用图像,利用ArcGIS和FRAGSTATS软件,运用土地利用转移矩阵、核密度估计以及景观指数模型等方法,分析三峡库区重庆段在不同时段水田的时空分布与演变特征。结果 2015年三峡库区重庆段水田面积为5 267.94 km²,占耕地总面积的26.70 %,平均坡度为11.87°,其中丘陵地区水田面积分最大,不同区县间水田面积差异显著。（2）近25 年草地、建设用地和水田间发生显著转移,1990—2005年水田主要转向旱地,2005—2015年水田主要转向建设用地,且转出面积大于转入面积,水田的总面积持续减少。（3）近25年来三峡库区重庆段水田面积的核密度分布呈现“西密东疏”“南密北疏”的分布格局。1990年水田分布的聚集区表现为江津和长寿2个核心分布带;2005—2015年江津的核密度值由高密度区转变为低密度区,水田分布的聚集区仅剩长寿核心分布带。（4）在7种土地利用类型中,水田的景观优势度居于中间位置,随着水田面积不断减少,水田景观的破碎化进一步扩大。结论 从粮食安全和生态保护的角度出发,未来产业结构调整和高标准农田建设中,必须稳定一定数量和质量的水田面积,充分发挥水田的生产和生态功能。     

The Evolving Structure of Chinese R&D Funding and its Implications for the Productivity of Agricultural Biotechnology Research

China’s research and development (R&D) policy has changed considerably over recent decades, and great changes occurred in 2006 when the main programme objective of China’s R&D changed from the 863 Programme and 973 Programme to the National Science and Technology Major Project. One topic that has drawn extensive attention is whether the investment reform improved R&D productivity in China. Using a unique panel dataset from 160 universities, this paper examines the effect of the investment reform on productivity improvement in China’s agricultural biotechnology sector. We use a panel count data model with a dynamic feedback mechanism to model the knowledge production process. Strong evidence indicates that the investment reform greatly contributes to knowledge output production in China’s agricultural biotechnology sector. We also find that the input quality is more important than the absolute quantity; human research capacity exhibits the greatest contribution to the output of patents; past knowledge accumulation helps produce more patents; and entry barriers to patent production exist in China’s agricultural biotechnology sector. Moreover, the patent explosion in China may have been largely caused by improvements in the human capital input quality.     

林业上市公司科技创新的投入产出分析

基于分位数回归法和最小二乘法,对24家林业上市公司2012—2015年的科技创新投入产出数据构建的多元回归模型进行分析。结果表明:最小二乘法的分析结果显示在林业上市公司中,专利授权所占比例、无形资产所占比例与研发人员数量、研发投入金额、研发人员所占比例、研发投入所占比例之间均不存在显著的相关关系;而分位数回归法的分析结果显示在不同分位点下,自变量对专利授权所占比例、无形资产所占比例存在一定的显著影响。此外,针对部分林业上市公司存在科技创新意识薄弱投入稍显不足、专利授权所占比例和产出成果质量较低、科技创新投入产出效率不足以及研发人员和研发资金投入并不能确保科技创新产出增加的现象,提出增强科技创新意识、强化投入产出监管等建议。     

基于PLS模型的中国林业产值影响因素分析

利用1994～2007年关于中国林业投入与产出的相关数据,采用偏最小二乘回归法,对影响中国林业产出的诸种投入因素进行研究。实证研究发现:中国林业产出主要受林业固定资产投资、林业基本建设投资和林业从业人员人数以及从业人员年均工资等投入因素的影响;且各种投入影响因素对林业第一、二、三产业的影响程度存在差异。为此,建议:保持林业投入适度增长,加大对林业劳动力的教育和培训力度,增强其再就业能力;加强林业固定资产投资和林业基本建设投资,尤其是营林固定资产投资和森工基本建设投资;借助林权制度改革,多渠道拓宽就业途径,以促进林业劳动力向第三产业转移。     

Contract farming and smallholder incentives to produce high quality: experimental evidence from the Vietnamese dairy sector

In emerging markets for high‐value food products in developing countries, processing companies search for efficient ways to source raw material of high quality. One widely embraced approach is contract farming. But relatively little is known about the appropriate design of financial incentives in a small farm context. We use the example of the Vietnamese dairy sector to analyze the effectiveness of existing contracts between a processor and smallholder farmers in terms of incentivizing the production of high quality milk. A framed field experiment is conducted to evaluate the impact of two incentive instruments, a price penalty for low quality and a bonus for consistent high quality milk, on farmers’ investment in quality‐improving inputs. Statistical analysis suggests that the penalty drives farmers into higher input use, resulting in better output quality. The bonus payment generates even higher quality milk. We also find that input choice levels depend on farmers’ socio‐economic characteristics such as wealth, while individual risk preferences seem to be less important. Implications for the design of contracts with smallholders are discussed.     

An Input-Output Analysis of the Impacts of Increased Export Demand for Saskatchewan Products

Five export scenarios were analyzed in this study. These included increases in the level of exports of: live cattle, slaughtered meat and meat products, grains, including wheat and other grains, crude oil, and potash. Each of these exports has a unique impact in terms of both absolute and relative values of several economic and resource demand criteria. A summary of rankings of the various scenarios' impacts is presented in Table 8. These rankings are based on the value of the economic and resource multipliers generated by each export scenario.
The above table indicates that there may exist trade-offs, in terms of the promotion of one type of commodity export versus another. For example, in terms of employment impacts, scenario B (meat and meat products) generates the largest impacts per dollar of final demand. Alternatively, this scenario is least preferred in terms of the contribution to provincial GDP and imports while at the same time requiring large amounts of energy.
The results presented in this paper can be applied for an analysis of regional economic development policies. That is, this type of analysis can be incorporated into a more general policy analysis of alternative regional development strategies. In this paper, only the benefits of expanded exports are estimated. The other side of the equation, of course, represents the costs of achieving these increased export levels. Examination of the excess capacity, investment needed to expand output and the opportunity cost of investment capital are important ingredients of the costs of achieving increased levels of export. However, in spite of these limitations, this study has shown that regional policy makers must be cognizant of the macro-level economic as well as resource use impacts of continued development of export markets.     

How Different is Mining from Mineral Processing? A General Equilibrium Analysis of New Resources Projects in Western Australia

Western Australia has experienced an investment surge in the minerals sector of the economy in recent years. Unlike previous surges, this one involves a large proportion of mineral-processing projects. In this study, the differential effects on the WA economy of 25 mining and 10 mineral-processing projects are analysed using an economy-wide model of WA. The results indicate that: (i) both the mining and mineral-processing projects will have substantial flow-on benefits to the WA economy as a whole; (ii) on an A$1-million-invested basis, mineral processing has larger flow-on effects on employment and generates more export revenue than does mining once the projects are operational.     

马尾松脂材两用人工林经济效益分析与评价——以广西国有派阳山林场为例

采用项目投资的财务效益评估手段,以脂材两用经营模式16a生马尾松采脂林为对象,对其经济效益进行了分析评价。结果表明:在该经营模式下,采脂林分总产值、净收益、净现值(NPV)、内部收益率(IRR)分别为147 173.1元.hm-2、85556.9元.hm-2、15 587.7元.hm-2、37%,比未采脂林分提高194.5%、214.1%、342%、76.2%;采脂林分动态投资回收期为10.6a,比未采脂林分缩短4.8a。运用该模式经营马尾松人工林能获得极高的经济收益和在较短时间内收回投资成本,提高资金的利用效率。     

明代皖南平原的圩田与农业生产

洪武时期，旧有圩田得到迅速恢复；建文至正德期间，圩田有较明显的发展，扩大了耕地面积，富豪围垦在其中占有重要地位，同时，圩田发展与蓄水防洪的矛盾已经凸显；嘉靖以后，水灾呈现加剧的趋势，除固有的自然因素的原因外，过度围垦、民人渔利、修防低效等社会因素起着重要作用，同时，对圩田的治理有新的进展。圩田在皖南平原农业生产上具有重要作用。     

2种稻谷中铅前处理方法的比较研究

用干法灰化法和微波消解法分别对稻谷样品进行前处理检测铅的含量.结果显示,用微波消解法测得的铅含量略高于干法灰化法,且测定稳定、简便、快速,更适合于稻谷样品的前处理.     

基于SD模型的诸城市农业结构仿真优化研究

［目的］预测2017—2035年诸城市农业结构的变化趋势,对农业结构进行多情景优化仿真,提出优化调整建议。［方法］文章以山东省诸城市作为研究对象,将农业结构划分为种植、种养结合和加工休闲3个子系统,选取56个指标,运用多元统计回归分析等方法构建41个方程,建立农业结构系统动力学（System Dynamics,简称SD）模型,运用Vensim—PLE软件进行仿真优化分析。［结果］SD模型预测结果表明,到2035年,粮食作物播种面积1105万hm2,总产量8037万t,经济作物播种面积652万hm2,总产量15203万t; 生猪出栏量达到29615万头,家禽出栏量1105 231亿只,畜禽粪污利用率8792%; 农业总产值达到25132亿元,休闲农业产值6134亿元,食品加工业产值1 25263亿元。假设种植业生产中的农业科技投入增加2个百分点, 2035年粮食作物产量较优化前增加576万t; 经济作物产量较优化前增加2814万t; 假设有机肥施用补贴增加3个百分点, 2035年畜禽粪污利用率较优化前提高762个百分点; 假设农产品加工业的研发力度和科技投入增加1个百分点, 2035年食品加工产值较优化前增加73521亿元; 农产品加工业产值占农业总产值比值由优化前的325：1达到41：1。［结论］为进一步推进诸城市农业结构调整,迫切需要加大农业科技投入,完善有机肥扶持政策,培育种养结合新型经营主体,重点扶持培育加工龙头企业,发展现代化休闲农场,促进农业产业融合发展。     

1990—2020年中国耕地利用的“水旱分异” 格局及机制分析

：研究目的：基于水田、旱地分异视角观察耕地利用结构性问题,揭示耕地利用隐性转型特征。研究方法：基于1 km栅格及地理探测器分析1990—2020年我国水田、旱地资源时空变化及其影响因素。研究结果：（1）1990—2020年水田总数下降、旱地增加,且水田及旱地的损失多位于自然禀赋较优的地区,而新增多位于开发利用适宜性较差的地区,水田、旱地的空间变化具有省际差异,其中黑龙江水田、新疆旱地的增加和广西水田、旱地的减少较为突出;（2）在水田、旱地、其他用地的变化中,前二者的相互转换规模显著,以黑龙江和四川最为活跃,且以2000年、2015年为节点经历了快速转化—平缓—快速转化的阶段性变化;（3）粮经比、水资源总量和有效灌溉面积共同影响水田—旱地的双向转换。此外,旱地向水田的转换受复种指数和人均耕地面积影响,而水田向旱地的转换对年日照时数、土壤侵蚀较为敏感。可见与旱地转为水田相比,水田转为旱地的变化受自然资源禀赋的影响更强。研究结论：水田及旱地在时空分布、地类转换及驱动机制上形成了分异格局,应基于水旱分异展开耕地资源利用的优化重构。     

PRICISM v. STRUCTURALISM IN SUB-SAHARAN AFRICAN AGRICULTURE

A re-examination of data frequently used to support the notion of price discrimination against agriculture in Sub-Saharan Africa suggests that the extent of agricultural taxation has been overstated. In addition, a review of the evidence on the aggregate agricultural supply response to price indicates that elasticities are low, with the most plausible estimates lying in the range 0.2–0.4. Eight structural constraints explaining the poor supply response, to which Sub-Saharan Africa is particularly prone, are identified. Further evidence is presented to show that output responds more significantly to structural factors than to price, and that investment in rural infrastructure will bring about an improved response to price. Capital constraints limit price-induced private investment, so that public sector led investment in new technology and rural infrastructure would appear to be the single most important strategy for reversing the decline in African agriculture.     

江苏省新收获稻谷质量情况调查

为了解江苏省2020年新收获稻谷的质量现状,抽取了覆盖全省产粮大县(市)的1252份样品作为试验样品,依据《GB 1350—2009稻谷》和《GB/T 17891—2017优质稻谷》规定的指标进行检测和分析.结果显示:江苏省新收获稻谷三等及以上占比99.4％,粳稻出糙率平均值为82.0％,整精米率平均值为67.8％,水...