Soil CO2 emission and carbon budget of a wheat/maize annual double-cropped system in response to tillage and residue management in the North China Plain

To investigate the impacts of tillage and crop residue managements on soil CO₂ emission and C budget in a wheat (Triticum aestivum L.)/maize (Zea mays L.) double-cropped system in the North China Plain (NCP), a field experiment was conducted consisting of four treatments: tillage with crop residues retention (CT+), tillage with crop residues removal (CT?), no-till with crop residues retention (NT+), and no-till with crop residues removal (NT?). Daily soil CO₂ fluxes changed with crop growing stage and peaked during the most vigorous growth of period, fluxes in maize season were higher than those in wheat season. Compared to the tilled soils, cumulative CO₂ emissions were significantly lower under no-till treatments. The largest cumulative CO₂ emission occurred under CT+ (65?g CO₂-C m^?2 y^?1) and the smallest was under NT+ (39?g CO₂-C m^?2 y^?1). After 5 years of the experiment, soil organic carbon (SOC) sequestration were greater with crop residues retention (CT+ and NT+) than with crop residues removal (CT? and NT?), the maximum SOC stock was in NT+ (5940?g C m^?2) while the minimum was in CT? (3635?g C m^?2). NT+ could help to mitigate CO₂ emission in the annual wheat/maize double-cropping system of the area.     

Does sustainable intensification of maize production enhance child nutrition? Evidence from rural Tanzania

Food insecurity, child malnutrition, and land degradation remain persistent problems in sub‐Saharan Africa. Agricultural sustainable intensification (SI) has been proposed as a possible solution to simultaneously address these challenges. Yet there is little empirical evidence on if agricultural management practices and inputs that contribute to SI from an environmental standpoint do indeed improve food security or child nutrition. We use three waves of data from the nationally‐representative Tanzania National Panel Survey to analyze the child nutrition effects of rural households’ adoption of farming practices that can contribute to the SI of maize production. We group households into four categories based on their use of three soil fertility management practices on their maize plots: “Nonadoption”; “Intensification” (use of inorganic fertilizer only); “Sustainable” (use of organic fertilizer, maize–legume intercropping, or both); and “SI” (joint use of inorganic fertilizer with organic fertilizer and/or maize–legume intercropping). The results from multinomial endogenous treatment effects models with the Mundlak–Chamberlain device suggest that use of practices in the “SI” category is associated with improvements in children's height‐for‐age and weight‐for‐age z‐scores relative to “Nonadoption,” particularly for children aged 25–59 months. These effects appear to come through improvements in both crop income and productivity.     

Agricultural technology adoption and child nutrition enhancement: improved maize varieties in rural Ethiopia

Adoption of improved crop varieties can lead to multiple benefits to farm households, including increased productivity, incomes, and food consumption. However, possible impacts of adoption on child nutrition outcomes are rarely explored in the literature. This article helps bridge this gap through an impact assessment of the adoption of improved maize varieties (IMVs) on child nutrition outcomes using a recent household survey from rural Ethiopia. The conceptual linkage between IMV adoption and child nutrition is first established using an agricultural household model. Instrumental variable estimation suggests the overall impacts of adoption on child height‐for‐age and weight‐for‐age z‐scores to be positive and significant. Quantile instrumental variable regressions further reveal that such impacts are largest among children with poorest nutrition outcomes. Finally, by combining a decomposition procedure with system of equations estimation, it is found that the increase in own‐produced maize consumption is the major channel through which IMV adoption affects child nutrition.     

国内外玉米价格传导关系影响研究基于收购政策市场化改革背景

[目的]玉米在国家粮食安全中占有重要地位,是国内外市场联系最为紧密的大宗农产品之一。文章旨在探讨收购政策市场化改革前后,国内外玉米价格传导关系是否发生变化,为政府推进玉米供给侧改革提供理论依据。[方法]该文选取2009—2018年国内外玉米价格周度数据,利用向量误差修正模型和门限向量误差修正模型分别对收购政策市场化改革前后国内外玉米市场间价格传导关系进行实证分析。[结果]长期内,国内外玉米价格存在长期稳定的均衡关系,国际玉米价格对国内玉米价格具有持续稳定的正向传导关系;短期内,收购政策市场化改革前,国内外玉米价格间存在线性调整关系,具体表现为国际玉米价格向国内玉米价格单向传导关系;而收购政策市场化改革后,国内外玉米价格短期非均衡误差调整动态存在门限非对称调整关系,且改革后未来国内玉米价格受到当期国内玉米价格影响较大。[结论]这些结论对推进玉米供给侧改革,维护国内玉米市场的健康有序发展有一定的参考作用。     

冻融稳定型羟丙基糯玉米淀粉的制备及特性研究

以糯玉米淀粉为原料,制备冻融稳定型羟丙基淀粉。并对淀粉乳浓度、环氧丙烷浓度、反应温度、反应时间、氢氧化钠浓度、硫酸钠浓度对羟丙基淀粉的冻融稳定性和分子取代度的影响进行了研究。确定制备冻融稳定型羟丙基淀粉的最佳工艺参数为：淀粉乳浓度40％,环氧丙烷浓度12％,反应温度50℃,反应时间25h,氢氧化钠浓度1.3％,硫酸钠浓度14％。同时对羟丙基糯玉米淀粉的透明度和抗老化特性进行了研究。随淀粉冻融稳定效果的增加,其淀粉的透明度和抗老化性均增加。     

The Boys from Bothaville, or the Rise and Fall of King Maize: A South African Story

This paper tells the story, for the first time, of a maverick maize farmers' association in South Africa during the period of apartheid. NAMPO (National Maize Producers' Organization), that grew out of SAMPI (South African Maize Producers' Institute), ultimately achieved a unique, if short-lived, breach in the normal operations of 'organized agriculture': a set of relations and practices that bound together white farmers, the National Party and the state. The paper provides an account of SAMPI/NAMPO's project of 'King Maize' and an explanation of its fall after a brief period of victory from 1981 to 1985. This explanation draws on broader patterns of agrarian change in contemporary capitalism combined with the fracturing of the original agrarian bloc of apartheid in the 1980s, marking the end of a 'second moment' of South Africa's version of a Prussian path of capitalist development.     

标准助力,推动山西鲜食玉米产业发展——DB14/T867-2014《鲜食糯玉米果穗等级划分》解读

本文简述了山西鲜食糯玉米果穗等级划分标准的编制原则、主要内容、技术指标确定依据、验证方法等,旨在规范市场,保护农民、农村、加工企业和消费者的经济利益,体现优质优价,进一步做大做强糯玉米产业。     

我国玉米加工业技术效率的实证分析——以4个玉米主产省为例

文章运用数据包络分析法（DEA）对1998—2005年我国4个玉米主产省（吉林、辽宁、山东、河北）玉米加工业的技术效率及其分解进行了实证分析。结果表明,玉米加工业的综合技术效率是由纯技术效率和规模效率共同作用的结果;4个玉米主产省玉米加工业的平均技术效率水平较低,而且各子行业（淀粉及其制品业、饲料加工业、酒精制造业、白酒制造业）的技术效率值差距较大;但从1998—2005年技术效率的变化来看,玉米加工业的技术效率呈上升的趋势。     

A paradigm shift in African agricultural research for development: the role of innovation platforms

To demonstrate the development impact of their outputs, agricultural research and development (R&D) organizations used to focus on the efficiency and effectiveness of technologies. In recent years, innovation systems thinking has started to address institutional and organizational barriers to technological change in African agriculture. The main approach used has been the multi-stakeholder innovation platform (IP). This paper analyses the requirements for improving the competence and skills of IPs actors in agricultural value chains, food systems, and natural resource management. As case studies, it uses IPs in the maize and cassava value chains that were initiated in the dissemination of new agricultural technologies in Africa (DONATA), in both West and Central Africa, and made reference to the rice IPs facilitated by AfricaRice. Yields and incomes in maize and cassava IPs significantly increased and inter-actor relationships and behavioural change among the diverse social and economic operators were enhanced. This achievement built on three capacity development interventions: (i) learning workshops that sensitized and informed technocrats and policy-makers and nurtured their involvement and ownership, (ii) competence and skill training of IP facilitators and practitioners, and (iii) coaching and mentoring of these facilitators and practitioners. To better facilitate IPs, facilitators and practitioners need to learn to observe, recreate, test, and perfect the IP process and value chain approach. Practicable tools that can be visualized and put into practice by the IP actors are essential. The DONATA on which the paper is based has been invaluable in terms of experiential learning.     

A Case of Mistaken Identity? Measuring Rates of Improved Seed Adoption in Tanzania Using DNA Fingerprinting

Studies of improved seed adoption in developing countries are almost always based on household surveys and are premised on the assumption that farmers can accurately self-report their use of improved seed varieties. However, recent studies suggest that farmers’ reports of seed varieties planted, or even whether the seed is local or improved, are sometimes inconsistent with the DNA fingerprinting results of those crops. We use household survey data from Tanzania to test the alignment between farmer-reported and DNA-identified maize seed types planted. In the sample, 70% of maize seed observations are correctly reported as local or improved, while 16% are type I errors (falsely reported as improved) and 14% are type II errors (falsely reported as local). Type I errors are more likely to have been sourced from other farmers, rather than formal channels. An analysis of input use, including seed, fertiliser, and labour allocations, reveals that farmers tend to treat improved maize differently, depending on whether they correctly perceive it as improved. This suggests that errors in farmers’ seed type awareness may translate into suboptimal management practices. The average yield of seed that is correctly identified as improved is almost 700 kg per hectare greater than that of type I errors. This indicates that investments in farmers’ access to information, seed labelling, and seed system oversight are needed to complement investments in seed variety development.