Monitoring nutrient flows and economic performance in African farming systems (NUTMON); III. monitoring nutrient flows and balances in three districts in Kenya
Monitoring nutrient flows and economic performance in African farming systems (NUTMON); III. monitoring nutrient flows and balances in three districts in Kenya
复制标题
监测非洲农业系统的养分流动和经济表现（NUTMON）；
DOI：
10.1016/s0167-8809(98)00132-7
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
J. Vlaming
中科院分区：
文献类型：
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作者：
H. Van den Bosch;J. N. Gitari;V.N Ogaro;S. Maobe;J. Vlaming
对肯尼亚三个不同地区的26个农场进行了营养平衡研究。使用Farm-NUTMON这一结合了养分流动和平衡计算与经济农场分析的研究工具，计算了农场内部个人活动和整个农场的主要营养素氮、磷和钾的平衡。考虑了流入农场的四个流量(化肥、有机肥和饲料、大气沉积、固氮)、流出农场的六个流量(农产品、其他有机产出、淋溶、气体损失、侵蚀和人类排泄物)和六个内部流量(外部饲料、家庭废物、作物残渣、放牧、动物粪便和农产品的家庭消费)。通过采访农民，收集了有关化肥使用、有机材料使用、产量、家庭消费以及残留物、粪便和生活垃圾管理的数据。通过使用基于文献数据(传递函数)的经验关系，对沉积、淋溶和气态损失进行了假设。根据农场的总坡度与土壤流失数字进行了侵蚀估计。所有农场的平均平衡为−71kgN+3kgP和−9kgKha−1yr−1，农场间差异较大，地区间差异较小。据估计，排放(淋溶、气体损失和侵蚀)远远高于输入(大气沉积和固氮)。经济作物的田间流入和流出远高于粮食作物。狼尾草(Pennisetum Purpereum)下的土壤养分开采是严重的，因为在狼尾草-牲畜-粪便循环中估计损失很高。根据对这一案例研究结果的评价，提出了改进该方法的建议。制定土壤肥力的可持续性指标需要将养分平衡与实际土壤养分储量和其他土壤质量指标联系起来。
A nutrient balance study was carried out for 26 farms in three different districts in Kenya. Balances for the major nutrients nitrogen, phosphorus and potassium were calculated for individual activities within the farms and for the entire farms, using Farm-NUTMON, a research tool that combines calculation of nutrient flows and balances with economic farm analysis. Four flows into the farm (chemical fertilizer, organic fertilizer and feeds, atmospheric deposition, nitrogen fixation), six flows out of the farm (farm products, other organic outputs, leaching, gaseous losses, erosion and human excreta) and six internal flows (consumption of external feeds, household waste, crop residues, grazing, animal manure, and home consumption of farm products) were considered. Data on fertilizer use, use of organic materials, yields, home consumption and the management of residues, manure and household waste were gathered by interviewing the farmer. Assumptions for deposition, leaching and gaseous losses were made by using empirical relationships based on literature data (transfer functions). Erosion was estimated relating the overall slopes of the farms to soil loss figures. The mean balance of all farms was −71kg N, +3kg P and −9kgKha−1yr−1, with large variations between farms and little variation between districts. Emissions (leaching, gaseous losses and erosion) were estimated to be much higher than immissions (atmospheric deposition and N-fixation). Inflows and outflows at field level were much higher for cash crops than for food crops. Soil nutrient mining under napier grass (Pennisetum purpereum) was severe from high estimated losses in the napier-livestock-manure cycle. Based on an evaluation of the results of this case study, recommendations were made for improvement to the approach. Developing a sustainability indicator for soil fertility requires the nutrient balance to be linked to the actual soil nutrient stocks and other soil quality indicators.