Toposequential Variation in Soil Fertility and Rice Productivity of Rainfed Lowland Paddy Fields in Mini-Watershed (Nong)in Northeast Thailand

Abstract

Mini-watersheds called Nongin Thai are geographical components of rainfed lowland rice culture in Northeast Thailand, and constitute distinct units in understanding environmental constraints for low and unstable rainfed rice production there. The toposequential variation of soil fertility and its relation to rice productivity within mini-watersheds, was examined by phytometry of sampled soils and field measurements of rice growth and yield. The phytometry experiment with irrigated potted rice using soils sampled from various rice fields within each mini-watershed, revealed that soil fertility as evaluated by rice dry matter production showed a 5 times difference among the fields at most. The difference in the soil fertility was ascribed primarily to that in nitrogen (N) supply capacity, which itself had a strong correlation with soil organic carbon (SOC) content. Accordingly, the biomass production of pot-grown rice was proportional to SOC. content, which suggested the usefulness of SOC as an index for soil fertility evaluation. The effect of clay on the soil fertility was much less than that of SOC. The actual rice yield in each field also showed quite large field-to-field variation, most of which was explained by the SOC content, rice growth duration and fertilizer application rate even though water availability also affected the yield. The yield positively correlated with growth duration and hence with earlier transplanting. Both SOC and clay contents of fields showed steep gradients with ascending field elevation within mini-watersheds, resulting in a marked toposequential distribution of rice yield. The toposequential distributions of SOC and clay contents imply that rice culture after deforestation accelerated soil erosion from upper to lower fields. The large toposequential gradient in soil fertility requires different resource and crop management for each toposequential position, in order to improve rice productivity of the mini-watershed as a whole.     

广东省果蔗施肥状况典型调查与分析

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Analysis on development situation of farmer professional cooperatives in Jian＇ou city

根据多年的工作实践,经过充分的调研,探讨了建瓯市农民专业合作社发展的现状特点、存在的困难及问题,提出了进一步推动建瓯市农民专业合作社发展的相关对策。     

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对植物新品种保护背景下的农民特权问题进行了研究,指出农民特权制度是为了平衡植物育种者和相关公众利益而产生的。在此基础上,分析了我国农民特权规定中存在的不足,并提出应在借鉴国外先进立法经验的基础上,从权利主体、权利客体和权利内容3个方面完善农民特权制定,合理构建育种者与农民利益分析机制。     

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珠三角有一种特殊的农业流动人口—"代耕农"群体。作为临时劳动力的"代耕农",其分散耕作小块土地的经营模式,已经难以适应当前珠三角农村经济发展的新形势,调整土地经营方式势在必行。珠三角乡镇企业的发展,劳动力的大量转移,农业机械化程度的提高,农民对农业收入依赖性的减弱等,都为集中土地,实行农业集约化准备了可靠的客观条件。应结合珠三角农村实际,通过土地流转,集中土地,发展农业集约化。     

蕉城区农民专业合作社发展问题及对策

总结了蕉城区农民专业合作社发展的现状,并对存在的问题提出相关对策。     

建瓯市农民专业合作社发展情况分析

根据多年的工作实践,经过充分的调研,探讨了建瓯市农民专业合作社发展的现状特点、存在的困难及问题,提出了进一步推动建瓯市农民专业合作社发展的相关对策。     

基于农产品质量安全的农户生产行为分析

农户生产行为是影响农产品质量安全的重要源头因素,根据计划行为理论对农户安全生产行为的主、客观影响因素进行分析,以理论分析模型设置问卷在无锡市进行实地调研,在对调研结果进行因子分析提取主成分影响因子后,建立二项Logistic模型进行回归分析得到农残了解、政府政策等影响农户安全生产行为的主要因素,根据调研分析结果提出政策建议。     

三明市农民专业合作社发展现状与思路

本文阐述了三明市农民专业合作社发展概况,当地政府高度重视进一步发展组织经营农民专业合作社工作,深入调查、研究,分析三明市农民专业合作社存在的主要问题,并出台了政策文件,使农民专业合作社在发展现代农业中发挥更大作用,促进农民增收。     

西安市职业农民发展存在问题及对策

针对当前由于农业收益低、农民兼业化日益严重、专职从事农业生产的高素质农民日益减少的问题,为了弄清西安城市化、工业化进程对从事农业生产的农民状况可能发生的影响及解决对策,通过统计调查、抽样调查、专家评估的方法,对西安职业农民的发展现状和制约农民职业化的相关因素进行了调查分析。结果表明,西安市职业农民人数相对较少,职业农民整体文化程度不高,平均年龄偏大。制约职业农民发展的主要因素为：职业农民队伍素质较低,职业农民培育难度大,资金需求多融资难度大,土地流转不规范,合作社规模小等。要发展高素质的职业农民,就要加大对职业农民培养的力度,采取开展职业农民资格认证、加强农业技术培训力度、扶持农民专业合作社、放宽政策支持、给予资金扶持、建立规范有序的土地使用权流转机制等有效措施,从而缓解由于农业从业人员数量和质量的下降对农业生产发展的影响。