Managing the soils of sub-saharan Africa

Many constraints to intensive food-crop production in tropical Africa are related to tropical soils. Improved technologies are available for different ecological regions. Important technological innovations include manual land clearing, mulch farming, conservation tillage and tiedridges, agroforestry, cover crops, mixed- and relay-cropping, and early sowing for improved and sustained productivity. Irrigation, animal traction or draft animals, and the use of chemical fertilizers are also important. Much of the agrarian stagnation in Africa is caused by neglect and misuse of the most basic of all resources, the soil. In fact, the root cause of the perpetual famine can be traced to the misuse of soil and water resources and issues related to their misuse. Substantial increases in food production are possible if the proven technologies can be effectively transferred and implemented. Priorities lie in both short-term development projects and in initiating long-term research to understand soil and water resources and how to manage them. The agrarian research must address the issue of improving the welfare of resource-poor farmers.     

Rangeland productivity and exploitation in the sahel

Results of a Malian-Dutch research project on the Sahelian pastures and their utilization suggest reasons why some efforts to develop traditional livestock farming in this area have been unsuccessful. Failure to appreciate the effects of low soil fertility as well as low rainfall on pasture production has resulted in underestimation of the productivity of the nomadic and seminomadic livestock farming system and overestimation of the possibilities for increasing production by better management and by modernization.     

建立新的食物系统观

食物的生产和消费是农业生态系统的精髓,它决定性地作用于农业生态系统的结构和功能,也作用于生存环境,农业活动主要是建造和利用食物系统.健康的食物系统,使生态系统可能持续发展,生产力成倍增长,可兼顾生态和生产双重效益,是食物安全的保证.增加动物性食物,减少对植物性食物,尤其是谷物的依赖,是我国与全球食物系统调整的方向.其中,合理利用天然草地,大力发展栽培草地或实行草田轮作,发展草食家畜,减缓对耕地资源的掠夺性利用,是完善食物系统的必然途径.     

天祝夏季草原放牧条件下牦牛产奶性能的研究

在天祝藏族自治县下南泥沟、岱乾上南台和乌鞘岭3个暖季牧场,对不同胎次牦牛的产奶量、乳脂肪、乳蛋白质含量及牧场草产量进行了研究.结果表明:3个牧场,1~5胎次母牦牛产奶量随胎次的增加而增高,5胎以后,母牦牛产奶量开始下降;下南泥沟牧场3~5胎母牦牛日均产奶量显著高于岱乾上南台和乌鞘岭牧场(P<0.05);下南泥沟7~8月份牦牛月产奶量(33.96 kg)比岱乾上南台(28.07 kg)和乌鞘岭(27.30 kg)牧场分别高出21.8%和14.7%.3个牧场牦牛乳脂肪及蛋白质含量差异不显著.3牧场中,下南泥沟牧场可食牧草产量高于岱乾上南台牧场和乌鞘岭牧场,而其放牧强度却低于该两牧场.     

SUSTAINABLE DEVELOPMENT OF CROP-LIVESTOCK FARMS IN AFRICA

Crop-livestock farms across Africa are highly variable due to in agroecological and socioeconomic factors, the latter shaping the demand and supply of livestock products. Crop-livestock farms in Africa in the 20-first century are very different from most mixed farms elsewhere in the world. African crop-livestock farms are smaller in size, have fewer livestock, lower productivity and less dependency on imported feed than farms in most countries of Europe, the Americas and the intensive agricultural systems of Asia. This paper discusses the role African crop-livestock farms have in the broader socio-agricultural economy, and how these are likely to change adapting to pressures brought on by the intensification of food systems. This intensification implies increasing land productivity (more food per hectare), often leading to more livestock heads per farm, producing fertilized feeds in croplands and importing feed supplements from the market. This discussion includes (1) the links between crop yields, soil fertility and crop-livestock integration, (2) the increasing demand for livestock products and the land resources required to meet to this demand, and (3) the opportunities to integrate broader societal goals into the development of crop-livestock farms. There is ample room for development of crop-livestock farms in Africa, and keeping integration as part of the development will help prevent many of the mistakes and environmental problems related to the intensification of livestock production observed elsewhere in the world. This development can integrate biodiversity, climate change adaptation and mitigation to the current goals of increasing productivity and food security. The inclusion of broader goals could help farmers access the level of finance required to implement changes.     

The potential for grass-fed livestock: resource constraints

Using pasture and grazed forest-range for a system of producing live-stock by feeding grass alone reduces the inputs of energy about 60 percent and land resources about 8 percent, but also reduces by about half the production of animal protein in the United States. Under a system in which only grass was fed, livestock would be restricted to beef, milk, and lamb production. The amount of grain fed to U.S. livestock is about 135 million tons (metric) or about ten times the amount consumed by the U.S. population.     

NEW ZEALAND DAIRY FARM SYSTEMS AND KEY ENVIRONMENTAL EFFECTS

• NZ dairy farming systems are based on year-round grazing of perennial pasture (ryegrass/white clover). • Milk production per hectare has increased by about 29% with increased use of externally-sourced feeds over the last two decades. • Externally-sourced feeds with a low protein concentration can potentially reduce N₂O emissions and N leaching per unit of production. • Systems analysis is important for evaluating mitigations to minimize trade-offs between environmental impacts. This paper provides an overview of the range of dairy pasture grazing systems used in New Zealand (NZ), the changes with increased inputs over time and associated key environmental effects including nitrogen (N) leaching and greenhouse gas (GHG) emissions. NZ dairy farming systems are based on year-round grazing and seasonal milk production on perennial ryegrass/clover pasture where cows are rotationally grazed in paddocks. There was an increase in stocking rate on NZ dairy farms from 2.62 cows ha⁻¹ in 2000/2001 to 2.84 cows ha⁻¹ in 2015/2016. During the same period annual milk solids production increased from 315 to 378 kg·yr⁻¹ per cow. This performance has coincided with an increase in N fertilizer use (by ~ 30%) and a twofold increase in externally-sourced feeds. Externally-sourced feeds with a low protein concentration (e.g., maize silage) can increase the efficiency of N utilization and potentially reduce N losses per unit of production. Off-paddock facilities (such as standoff or feed pads) are often used to restrict grazing during very wet winter conditions. A systems analysis of contrasting dairy farms in Waikato (largest NZ dairying region) indicates that the increased input would result in an increase in per-cow milk production but little change in efficiency of milk production from a total land use perspective. This analysis also shows that the increased inputs caused an 11% decrease in N footprint (i.e., N emissions per unit of milk production) and a 2% increase in C footprint (i.e., greenhouse gas (GHG) emissions per unit of milk production).     

Science and Technology Backyard model: implications for sustainable agriculture in Africa

Sustainable food production to feed the growing population in Africa remains a major challenge. Africa has 64% of the global arable land but produces less than 10% of its food locally due to its inherently low soil nutrient concentrations. Poor soil fertility and a lack of fertilizer use are the major constraints to increasing crop yields in Africa. On average only about 8.8 kg NPK fertilizer is applied per hectare by African smallholder farmers. There is therefore considerable potential for increasing food production through sustainable intensification of the cropping systems. The low crop yields in Africa are also partly due to limited farmer access to modern agronomic techniques, including improved crop varieties, a lack of financial resources, and the absence of mechanisms for dissemination of information to smallholders. This study analyzed the Science and Technology Backyards (STBs) model and investigated its use for the transformation of agriculture in Africa. Some key lessons for sustainable crop intensification in Africa can be found from analysis of the STB model which is well established in China. These include (1) scientist-farmer engagement to develop adaptive and innovative technology for sustainable crop production, (2) dissemination of technology by empowering smallholders, especially leading farmers, and (3) the development of an open platform for multiple resource involvement rather than relying on a single mechanism. This review evaluates the benefits of the STB model used in China for adoption to increase agricultural productivity in Africa, with a perspective on sustainable crop intensification on the continent.     

采用参与式方法评估中国玉米研究的优先序

 采用参与式方法,对全国5个玉米生态区进行了参与式农村评估(PRA),并邀请专家以参与式学术研讨的方式对PRA所获得的玉米生产发展限制因素进行分析,以及对不同生态区的限制因素的重要性进行排序,在此基础上得出了我国玉米研究的优先序。结果表明,干旱是未来我国玉米生产发展的第一限制因素,也是玉米科研最优先的研究领域。栽培管理技术和农业技术推广等是近期我国政府在制定相关产业发展政策时必须考虑的重要领域。     

中国畜牧业生产波动的特征及路径识别

基于1978—2016年畜禽产品年度产量数据,采用HP滤波技术和非线性MS-AR模型,分析中国畜牧业生产波动的特征,从畜牧业生产区制转换的视角剖析畜牧业生产波动的具体路径,探讨影响畜牧业生产波动和路径转换的原因。结果表明:从生产波动变化趋势上看,猪肉生产增长高峰期出现最早,其次是牛肉、羊肉、禽肉和禽蛋生产,牛奶生产增长高峰期出现时间最晚;从生产波动比较上看,猪肉生产波动幅度最小,其他畜牧产业生产波动幅度相对较大,各畜牧产业生产波动趋势存在差异,但近年来总体趋于收敛。通过模型识别将畜牧业生产划分为低速、中速和快速增长3个区制,低速和中速增长区制下各畜禽业产品产量平均增长率在3%和5%左右,而快速增长区制下平均增长率在10%以上;猪肉生产倾向于保持中速增长,牛肉、羊肉和牛奶生产容易出现低中速增长往复徘徊的现象,禽肉和禽蛋生产在各区制下均较为稳定且区制变迁较为平稳;改革开放以来,除牛奶产业以外,其他畜牧产业生产基本在低速或中速增长区制时间最长。基于此,提出针对不同畜禽产业在不同发展阶段相机制定不同调控政策,推动畜禽产业规模化养殖和产业化经营水平,提高畜禽产业抗冲击能力等建议。     

AGRONOMIC AND ENVIRONMENTAL BENEFITS OF REINTRODUCING HERB- AND LEGUME-RICH MULTISPECIES LEYS INTO ARABLE ROTATIONS: A REVIEW

● Arable-ley rotations can alleviate soil degradation and erosion. ● Multispecies leys can improve livestock health and reduce greenhouse gas emissions. ● Ley botanical composition is crucial for determining benefits. ● Lack of livestock infrastructure in arable areas may prevent arable-ley uptake. ● Long-term (10–25 years) research is needed to facilitate evidence-based decisions. Agricultural intensification and the subsequent decline of mixed farming systems has led to an increase in continuous cropping with only a few fallow or break years, undermining global soil health. Arable-ley rotations incorporating temporary pastures (leys) lasting 1–4 years may alleviate soil degradation by building soil fertility and improving soil structure. However, the majority of previous research on arable-ley rotations has utilized either grass or grass-clover leys within ungrazed systems. Multispecies leys, containing a mix of grasses, legumes, and herbs, are rapidly gaining popularity due to their promotion in agri-environment schemes and potential to deliver greater ecosystem services than conventional grass or grass-clover leys. Livestock grazing in arable-ley rotations may increase the economic resilience of these systems, despite limited research of the effects of multispecies leys on ruminant health and greenhouse gas emissions. This review aims to evaluate previous research on multispecies leys, highlighting areas for future research and the potential benefits and disbenefits on soil quality and livestock productivity. The botanical composition of multispecies leys is crucial, as legumes, deep rooted perennial plants (e.g., Onobrychis viciifolia and Cichorium intybus) and herbs (e.g., Plantago lanceolata) can increase soil carbon, improve soil structure, reduce nitrogen fertilizer requirements, and promote the recovery of soil fauna (e.g., earthworms) in degraded arable soils while delivering additional environmental benefits (e.g., biological nitrification inhibition and enteric methane reduction). Multispecies leys have the potential to deliver biologically driven regenerative agriculture, but more long-term research is needed to underpin evidence-based policy and farmer guidance.     

可持续挖掘草原生产潜力的途径、技术及政策建议

草原是中国第一大陆地生态系统,面积近4亿hm~2,占国土面积的41.7%,是中国发展现代农业和现代畜牧业的重要资源,是保障国家生态安全的重要屏障带。然而,由于长期不合理开发利用,中国草原面临严峻的生态退化、植被生产力衰减、草畜矛盾突出、畜产品生产效率低下等问题,生态和生产功能均严重下降,成为国家实施可持续发展战略的制约性区域之一。系统地、可持续地挖掘草原生产潜力,有效提升草原生态和生产功能,是加强生态安全和生态文明建设,加速现代畜牧业转型发展的重要保障。挖掘草原生产潜力主要有三方面途径,一是进行退化草原恢复,提高草原生产力;二是进行旱作栽培草地建设;三是发展高效草业。针对不同类型退化草原,采取自然恢复、优化利用、人为改良等改良与恢复措施,可加速退化草原恢复进程,并提高退化草原生产力20%—30%甚至40%—50%。在半干旱区由于水土资源的限制,应重点发展以粮改饲为主的旱作栽培草地,以挖掘本土牧草优异资源为主,选育和扩繁抗旱、抗寒、耐牧型牧草品种,研发和应用旱作草地栽培技术、收获加工技术、土壤保育及耐旱材料等,提高水土资源利用率和旱作栽培生产效率,可提高生产力2—3倍。在区域水资源条件较好且综合平衡的基础上,适度发展高效节水灌溉人工草地,如按提高生产力10—20倍计,每年可增加饲草1.5×10~7—3×10~7 t,可解决2×10~6—4×10~6 hm~2草地的优质饲草的生产问题。为保障可持续挖掘草原生产潜力,提出相关政策建议。一是发挥草原生态补奖机制的长效驱动作用,紧紧把握推进方式转变,在草畜平衡的范畴中鼓励草地优化利用,以不断挖掘政策效益和可持续挖掘草地的第一性生产潜力和第二性生产力;二是建议和实施可持续挖掘草原生产潜力研发计划行动。重点开展天然草原饲草生产力提质增效关键技术研究与集成示范,半农半牧区高效草牧业技术模式和示范,突破生产饲草生产土地资源的高效开发利用技术、水土生物等资源的综合高效利用技术,提高资源利用效率;制约草畜结合的饲草质量差、调制利用差、转化效率差的技术难题,综合提高饲草转化利用效率。三是建立不同类型区现代草业大示范区。针对不同草地类型的特点和面积进行战略布局,建立区域性的大示范区,形成较为完善的产业链条,实现区域内各种资源的整合和优化配置。四是培育新型生产经营主体,建立完善市场体系,鼓励建立多元主体综合体形式运作市场,助推草业经济的发展。     

建立草地农业系统工程发展南方精准养殖业

草地农业系统工程是以草地生产业为主要内容，结合农田，林土，水域，加工，信息系统等多种资源和产业共同完成，并以畜禽为生产手段或纽带的现代系统性，精准化的产业，南方有很丰富的饲草资源和良好的社会经济条件，在此基础上利用现代高科技知识，建立草地农业系统工程，发展南方精准养殖业，提高资源的的利用率和生产效益，最终达到开发闲置资源，增加畜产品产量，减轻北方草原压力之目的。     

Reality vs. rhetoric – a survey and evaluation of tsetse control in East Africa

Odor baited methods of controlling tsetse have received considerable attention as ecologically friendly ways for African farmers to reduce their levels of livestock trypanosomosis. Over the last decade, a number of tsetse control projects have been set up in East Africa using these methods. Although much has been written, few hard data are available regarding their ongoing success, problems, and sustainability. To evaluate the situation on the ground, the authors conducted a series of site visits to a number of such tsetse control projects in Kenya. A comparison of these projects with others across the region identified the possible constraints to a wider uptake of these methods. Poor information, coupled with inappropriate research and development policies, were found to be the key constraints. These could be overcome with a farmer-based approach to control, with a better application of existing techniques, and with a greater role for veterinarians. Tsetse control needs to become demand rather than supply driven, if it is to bean important component of livestock disease control in Africa. This revised version was published online in June 2006 with corrections to the Cover Date.     

Frontiers in crop production: chemical research objectives

The science of chemistry and chemicals will continue to be an integral part of future crop production technologies. In assessing and defining the future role of chemistry three imperatives must be considered: (i) the necessity to preserve natural resources, (ii) the complementary solutions offered by the rapidly advancing biological sciences, and (iii) the specific requirements of developing regions where increasing crop productivity is most important. Chemical research objectives for improving crop protection and crop growth must take into account the perceivable and potential changes in crop production techniques, which, in turn, are dictated by a number of accentuating constraints.     

西北牧区退牧还草工程生态补偿依据与标准

针对西北牧区退牧还草补偿标准的不合理性,依据草地承载力理论和草畜动态平衡原理,采用西北牧区草地资源数据,结合草地生态经济系统中单位草地的净初级生产量和载畜量,确定退牧区不同草地类型禁（休）牧饲料粮、围栏、补播的补偿标准．     

Molecular detection of virulence genes in Campylobacter species isolated from livestock production systems in South Africa

Campylobacter species are a major cause of foodborne bacterial infections in both developed and developing countries worldwide. Campylobacter jejuni is responsible for the majority of infections. This study was conducted to identify virulenceassociated genes in Campylobacter species isolated from livestock production systems in South Africa. A total of 250 fecal samples consisting of cattle(n=50), chickens(n=50), goats(n=50), sheep(n=50) and pigs(n=50) were randomly collected from livestock in Eastern Cape and KwaZulu-Natal provinces of South Africa between April and October 2018. The samples were analyzed for the presence of virulence genes in Campylobacter species using molecular PCR-based methods. It was found that 77 and 23% of Campylobacter jejuni and Campylobacter coli respectively were isolated from all the livestock samples. There were positive significant(P0.05) correlations amongst all the virulence genes that were investigated. Chisquare and Fisher's exact tests were implemented to test for the effect of livestock species on the presence or absence of virulence genes. The study demonstrated that most of livestock species can potentially cause zoonotic infections and food poisoning due to the high prevalence of Campylobacter. The high prevalence of virulence genes highlights the significance of Campylobacter in livestock production systems in South Africa. This requires the implementation of one-health approaches to reduce the impact of foodborne and zoonotic diseases for the welfare of human and animal health.     

Using timed automata and model-checking to simulate material flow in agricultural production systems—Application to animal waste management

Due to intensification and specialisation of animal production and the increasing pressure of environmental regulations, the careful management of animal wastes becomes a key point for the sustainability of livestock farming. This paper addresses the dynamic representation of a network composed by a set of production units (i.e., livestock farms) that need to transfer their wastes to a set of consumption units (i.e., crops onto which wastes may be spread over). The dynamics of stocks (taken as continuous fluxes with imprecise parameters) is combined with management decisions or actions (taken as discrete events). Various temporal constraints determine the possibilities of waste transfers. For each production or consumption unit, these constraints are modelled as a timed automaton. Possible allocation of wastes is then analysed using model-checking techniques applied to the global timed automaton resulting from the product of all the elementary timed automata. To this end, the Kronos software based on the Timed Computational Tree Logic (TCTL) is used. Our approach is illustrated through the analysis of a typical farming system made of livestock and crop enterprises in the context of the Reunion Island. Using the computer tool implementing this approach, we show how an initial waste management policy can be improved by simulation to find a better waste allocation to crops.     

影响青贮玉米产量因素研究进展

青贮玉米是畜牧业重要的饲料资源,具有生产周期短,生产成本低,经济效益好,易于被家畜吸收消化的特点。青贮玉米的研究是推动草食家畜生产力及畜产品发展的重要环节。青贮玉米的产量不稳定,受到多重因素限制,文章就青贮玉米品种的选择、栽培管理技术、环境条件等方面进行论述,旨在为进一步提高青贮玉米的产量提供借鉴,为反刍动物生产优质畜产品提供参考。     

中国农牧系统养分管理研究的意义与重点

中国由于农牧分离和不合理的养分管理方式导致了农田硝酸盐淋失、水体富营养化、氨挥发和温室气体排放等环境问题日益严重。研究中国“土壤-作物-畜牧业”生产系统（即农牧系统）养分流动特征,通过优化农牧系统养分管理,保持养分合理流动与循环,减少各个环节的养分环境排放,提高系统利用率是农牧业可持续发展的关键,也可为“化肥减施”、“有机肥替代化肥”、“畜禽养殖废弃物资源化利用”和“面源污染阻控”等国家行动提供科学依据。本文对中国农牧系统养分投入、利用率和环境排放等特征、国内外农牧系统养分管理研究进展进行了分析,提出中国农牧系统养分管理研究重点。目前中国农牧系统养分流动特征是过渡依赖化肥养分投入提高粮食和饲料产量,进而支持集约化畜牧业发展;而农牧分离的生产方式导致了农牧系统养分流动效率低,环境排放高;都市圈及其周边是排放的热点区域。国际研究经验表明,农牧结合是可持续集约化农业的必然出路,农牧结合的核心是通过改善畜禽粪尿管理,减少养分的损失和提高养分在农田循环的比例和数量。兼顾提高农牧业生产力和保护环境的“土壤-作物-畜牧业”系统养分管理已经成为全球关注的焦点。未来,中国农牧系统养分管理研究应包括：（1）典型农作系统“土壤-作物-畜牧”系统养分流动规律和环境效应的定量研究;（2）有机肥替代化肥机理与调控途径研究;（3）畜禽粪尿养分循环利用机理和减排技术研究;（4）高产高效“土壤-作物-畜牧”系统设计研究。