农村经济发展中生态农业建设与乡镇企业发展之间的关系

阐述了生态农业原理和基本内涵,论述了生态农业和乡镇企业之间的相互关系,提出了分析建议和对策.     

Nutrient input-output budget of shifting agriculture in Eastern Amazonia

A case study on the nutrient input-output budget of slash and burn agriculture was carried out in Northeast-Pará, Brazil, where such a land-use system has been practised for about 100 years. A common cropping period lasts for two years and the fields lie fallow for 4 to 8 years. We quantified rates of deposition, fertilization, and losses due to the burn, harvest and leaching. Six fields of different phases in the rotational cycle were under study during a 19 month period. During the fallow period, the input of Na, K, Mg, N, P and S via deposition exceeded the estimated losses with the seepage water. The Ca budget was almost balanced. The balance of fields in the transition from the fallow to the cropping phase was negative for Na, K, Ca, Mg, N, and S. The P balance was positive when NPK fertilizer was applied, and negative without fertilizer application. The nutrient balance for K, Mg, Ca, N, and P was also negative on the field in transition from the cropping to the fallow period. The nutrient budget for an entire land-use cycle of 9 years was estimated by the false time series approach. In the case of an NPK fertilization during the cropping period there were net losses of 75 kg K ha^–1, 125 kg Ca ha^–1, 16 kg Mg ha^–1, 285 kg N ha^–1 and 13 kg S ha^–1. Na (86 kg ha^–1) and P (11 kg ha^–1) were accumulated. The harvest was the most important flux for the K (61%) and P (62%) output. The element transfer into the atmosphere during the burn caused the main losses of N (60%), S (65%), Ca (58%) and Mg (41%). The most important path of Na loss was leaching (92%). The net K losses were severe as they represented 45% of the K store found extractable in the soil down to 1m depth and in the above ground biomass. The presented results may be useful in planning a sustainable and environmentally protective method of land-use within a shifting cultivation system. It is strongly recommended that slash burning be abandoned in order to keep the nutrients in the ecosystem.     

广东省农业用水定额编制概述

将广东省分为6个灌溉用水定额分区,并选定20个典型县,通过对各分区主要粮食作物、蔬菜、果树等灌溉用水定额进行调查,统计分析得出了各分区以水稻、薯类等为主的粮食作物,以叶菜、瓜果、椒类等为主的蔬菜和以香蕉、荔枝、龙眼等为主的果树等的农业灌溉用水定额。     

高吸水性树脂在农业中的应用

介绍了高吸水性树脂的吸水机理及农用高吸水性树脂的性能、种类和使用方法，分析了高吸水性树脂抗旱节水、改良土壤和促进作物生长的作用机理和影响因素，指出了当前研究中所存在的问题及改进的方向.     

江西省农业旱情预测模型的建立与应用

根据农业用地的不同性质分别建立旱地缺墒模型,灌溉水田、水浇地、菜地与望天田缺水度模型,并据此建立江西省农业旱情预测模型,对江西省农业旱情进行预测.为科学抗旱和减少旱灾损失提供依据和指导.     

基于公众通信网络平台的精确农业网络构成

为提高信息化程度,构建精确农业网络,利用现代公众通信网络平台,结合无线传感器网络,配置网络拓扑,设计Sink节点802.15.4协议与GSM网络协议转换的适配器和协议集,可低成本便捷地实现多个农业生产场景综合监测和调控,使信息技术与农业生产有效融合。     

永城煤工业经济负效应问题解析

永城煤工业的经济负效应日益凸显,面对污染、沉陷、就业,经济和文化的消退等问题,政府和企业应采取科学转型、合理处置责权关系、实施土地综合开发、强化环境治理、活跃文化产业、加强社会保障等措施,以解决煤工业经济负效应问题的当务之急。     

政府参与循环农业发展的行为与作用机理分析  ———基于湖北省的实证调研

摘 要 该文从经济学角度对政府参与循环农业发展的作用机理进行了探讨,并结合对湖北省两个国家级 和4个省级生态农业试点县（市）的实地调研,对政府参与循环农业发展的实践行为进行了分析。研究结 论表明:“市场失灵”和循环农业的经济特性是政府参与循环农业的根源所在。当前中央和地方各级政府 围绕循环农业的发展,分别从规划、立法和政策引导、项目推进、环境监管等方面着力推进循环农业的发 展,并取得了较好的实效。与此同时,政府在循环农业发展中仍然存在一些缺陷和不足之处,如政策和法 制体系仍然有待完善、公共基础设施投入不足,技术支撑体系尚未建立等。鉴于此,提出政府应进一步完 善法律法规和政策体系,加强循环农业公共物品的供给、建立地方党政领导主抓循环农业发展责任制等几 个方面。     

Inhibitions of cotton seedling growth by volatile ketones emitted by cover crop residues

Low-input, sustainable agriculture (LISA) systems can include soil incorporation of residues of weeds and legume cover crop species. However, both seed germination and seedling growth of crops, including cotton (Gossypium hirsutum L.), are inhibited by volatile organic compounds emitted by these residues during decomposition. A cotton seedling-growth assay was used to demonstrate that C₄ through C₉ ketones released by decomposing legume residues significantly inhibited root and shoot elongation, root and shoot fresh and dry weight gain, and cotyledon expansion. Seedling root and shoot water relationships were relatively insensitive to those components of plant residue volatile emissions. Concentration (0.0, 0.5, 1.0, 1.5, or 2.0M/cm³ sterile greenhouse soil mix) and root-zone temperature (20 or 30°C) altered the activity of the more inhibitory ketones. Molecular weight (carbon chain length), carbon chain branching, and position of the carbonyl group also influenced ketone inhibitory activity.Mention of a commercial or proprietary product does not constitute an endorsement by the U.S. Department of Agriculture.