Variable-timing,fixed-rate application of cattle biogas effluent to rice using a leaf color chart: microcosm experiments in Vietnam

ABSTRACT

Livestock production plays a leading role in agricultural land-use change. Producing biogas from livestock waste and subsequently using the biogas effluent as fertilizer for crops is a promising option to solve environmental problems resulting from expanding livestock production. However, it is difficult to promptly and accurately measure the nitrogen (N) concentration of effluent for farmers in developing countries, making precise N management difficult. The objectives of the current study were (1) to evaluate the feasibility of variable-timing, fixed-rate application of cattle biogas effluent using a leaf color chart (LCC) for rice (Oryza sativa L.) and (2) to determine the optimum LCC threshold for grain yield. We conducted two microcosm experiments in the Mekong Delta of Vietnam in 2018 using eight treatments of N-fertilizer application. In the Zero treatment, we applied no N. In the Estd treatment, we split-applied N as effluent (E) at fixed rate and timing as the standard method. In E2.75, E3.00, E3.25, E3.50, and E3.75, we applied effluent whenever the LCC value went below 2.75, 3.00, 3.25, 3.50, and 3.75, respectively. In U3.25, we applied N as urea (U) whenever the LCC value fell below 3.25. The total effluent-N application rate ranged from 90 to 210 kg N ha^?1 season^?1. Rice growth was normal but there was a substantial yield gap between the two microcosm experiments due to the seasonal difference in solar radiation. Rice yield tended to increase with increasing LCC threshold. There was a positive linear relationship between LCC and chlorophyll content (SPAD) values (R ² = 0.73–0.79). Grain yield was well explained (R ² = 0.70–0.89) by the seasonal mean LCC or SPAD value. Plant total N uptake increased with increasing LCC threshold, but the three calculated indices of N use efficiency (NUE) – apparent N recovery, agronomic NUE, and internal NUE – were not always improved with a higher LCC threshold. Our results showed that the tested variable-timing, fixed-rate strategy for the application of cattle biogas effluent was feasible and the optimum LCC threshold for grain production was 3.75 under the current microcosm conditions.     

重庆市畜禽粪便年排放量的估算研究

畜禽养殖产生的粪便已成为我国农村面源污染的主要来源，因而畜禽粪便的排放量也越来越引起人们的重视。通过对重庆市畜禽养殖业进行调查，结合国内外有关研究，确定重庆市畜禽粪便年排放量估算方法和各种估算参数。以2001年为基准，估算出重庆市主要畜禽(猪、牛、羊、马、兔、家禽等)年粪尿排放量和粪尿中对环境产生污染的主要物质量(有机质、氮、磷、钾)，以便对重庆市畜禽粪便污染作一个定量的认识。估算结果为重庆市2001年畜禽粪尿排放7421万t，其中有机质为806万t，氮42.5万t、磷21.48万t、钾44.98万t。该研究结果可为重庆市工农业生产布局和环境污染治理提供决策依据。     

家畜营养缓释弹丸的研制及其在家畜瘤胃中的降解曲线

利用几缓释试剂加上几种赋形剂和微量矿物元素，按不同的处方进行合理配方，在弹丸模具中通过磨碎、混合、霁压等工艺成型为家畜营养缓释弹丸。将此弹丸每2枚分为一组，共分8组，分别称重后，经瘤胃瘘管投服给8只供试羊只，并且左右其降解的2.8，15,30,45,60,75和90d分别收集被降解后弹丸，置于65℃干烘箱内烘2h，室温放置12h后逐个称重；用直接投服的方法，将弹丸投服给另外6只供试羊只，分别在投饲后第60d和第90d时各屠宰3只供试羊收集弹丸。结果表明：家畜营养缓释弹丸在羊瘤胃中的降解率分别为0.97%，5.29%，16.17%，31.63%，34.26%，41.47%，43.76%和49.73%；采用直接投服的方法，在第60d、第90d屠宰时弹丸重量分别为 15.98克和13.80克。     

山东省东营市种草养畜产业化经营调查

通过对山东省东营市种草养畜产业化经营情况的调查,与湟中县的种草养畜情况进行对比分析,提出了加快湟中县种草养畜产业化发展的对策和措施。     

吉林省畜牧机械化发展状况刍议

吉林省是农业大省．有大力发展畜牧业的基础。本文介绍了国内外畜牧业的发展现状，指出了吉林省发展畜牧业存在的问题，给出了相应的对策。认为在未来的发展中应该采取以机械化促进畜牧业的发展．以畜牧业的发展来带动机械化的方法，来进一步提高和完善吉林省的畜牧业机械化，使其能够更好的为吉林省的畜牧和经济建设服务。     

Livestock Services and the Poor

This paper reviews the economic framework for the delivery of livestock services to the poor. It is argued that the demand for livestock products is likely to increase rapidly and the ability of the poor to participate in the opportunities presented by this growth is linked critically to the availability of good service support, both on the input and output side. Governments therefore have a responsibility to supply the necessary public goods (including the institutions and legal frameworks), and the market infrastructure for facilitating the emergence of efficient markets for livestock services. The paper further argues that the dynamics of public policy in developing countries are much more complex than the simple application of economic logic. It is the larger political economy that often dictates policy choices. It is therefore important to integrate political economy and governance issues into the economic debate on livestock service delivery. The paper also reviews the context in which the markets for livestock services will need to function. Different countries are facing very different sets of issues, and the identification of possible interventions in livestock service markets would require careful field research and analysis. In this context, the paper suggests the elements of a research agenda for the next few years.     

加速发展社会主义现代化草原畜牧业

目前我国进入“WTO后过渡期”,加快向市场经济和自由贸易制度靠拢。这就要求我国草原畜牧业要改变传统经营方式,从宏观层面合理配置畜牧业资源。通过实施“北繁南育”战略,将北方地区草食家畜的繁殖优势与南方区域的草食家畜育肥优势有机结合起来,生产符合国内外市场需要的绿色畜产品,同时有效解决我国生态环境恶化、畜产品竞争力低下、农牧民增收困难的矛盾,实现我国传统草原畜牧业向现代化草原畜牧业的转变。     

高效液相色谱-荧光检测畜禽粪污中四种氟喹诺酮类抗生素残留

为了建立高效液相色谱-荧光测定畜禽粪污中氧氟沙星、诺氟沙星、环丙沙星、恩诺沙星残留的分析方法,将畜禽粪便样品经乙腈超声提取,再经正己烷液-液萃取,并经氮吹浓缩,乙腈与水混合溶解残渣,过微孔滤膜,采用高效液相色谱-荧光检测,以0.01 mol/L四丁基溴化胺(pH 3.0)/乙腈(94/6,V/V)为流动相,于激发波长280 nm、发射波长480 nm处进行检测。结果表明,畜禽粪污样品中4种喹诺酮类抗生素的平均回收率为77.8%～98.2%,相对标准偏差为3.5%～7.2%,检测限为0.005～0.010μg/kg。该方法简便、快速,可满足畜禽粪污中4种喹诺酮类兽药残留量的同时检测。     

农村散养家畜防疫的现状及建议

在农村散养家畜春秋集中防疫中,一些地方不够重视、实施者仅为应付检查、监督检查不到位,致使防疫密度和免疫水平低下,通过参与近几年的春秋防工作,看到了如今制约农村散养家畜防疫的现状,提出几点建议,希望能够对农村散养家畜防疫工作的提高有所帮助,使农村养殖事业健康、严密、科学的发展。