On-farm experiments were conducted in farmers' fields at 6 different sites in Western Usambara Mountains (WUM) in northern Tanzania during the 2000-2001 cropping season. The objectives were to study the effects of Tughutu ( Vernonia subligera O. Hoffn) pruning in combination with Minjingu phosphate rock (MPR) or triple super phosphate (TSP) supply on the concentration of P in the tissues and seed yields of common bean, and to assess the economic returns of these different technologies to farmers. The experimental design was a randomized complete block with each of the 6 farmers'fields used as a replicate. The treatments included: control, MPR or TSP each at 26 kg P ha-1, Tughutu at 2.5 t ha-1,and Tughutu at 2.5 t ha-1 combined with MPR or TSP at 26 kg P ha-1.Addition of MPR or TSP alone significantly raised P concentration in bean shoots from 1.27 mg g-1 to 1.70 and 1.95mg g-1 respectively. Combining MPR or TSP with Tughutu increased P concentration above the proposed deficiency level of 2 mg g-1. The relative agronomic effectiveness (RAE) of MPR ranged from 12.5% to 45.0%. Seed yields of common bean was markedly increased by 28%-104% from MPR or TSP supply alone, and 148%-219% from Tughutu application combined with 26 kg P ha-1 of MPR or TSP relative to the control. With Tughutu alone, seed yield increased by 53%.From economic analysis, the increase in seed yield with the supply of MPR or TSP combined with Tughutu translated into a significantly (P ≤0.001) higher marginal rate of return and dollar profit for common bean farmers in WUM in northern Tanzania. It is concluded that Tughutu and its combined application with MPR or TSP is an appropriate integrated nutrient management strategy that may increase bean yields and dollar profit to the rural poor communities in Tanzania.
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机译：在2000-2001种植季节，在坦桑尼亚北部西部乌桑巴拉山（WUM）的6个不同地点的农民田间进行了农场试验。目的是研究将Tughutu（Vernonia subligera O.Hoffn）修剪与Minjingu磷酸盐岩（MPR）或三重超磷酸盐（TSP）供应组合对普通豆组织中P的浓度和种子产量的影响，以及评估这些不同技术对农民的经济回报。实验设计是一个随机的完整块，将6个农民田地中的每一个用作复制品。处理包括：对照，MPR或TSP分别为26 kg P ha-1，Tughutu为2.5 t ha-1和2.5 t ha-1的Tughutu与MPR或TSP分别为26 kg P ha-1。单独使用TSP或TSP可使豆芽中的P浓度分别从1.27 mg g-1升高至1.70 mg和1.95mg g-1。将MPR或TSP与Tughutu结合使用可将P浓度提高到建议的2 mg g-1缺乏水平以上。 MPR的相对农学有效性（RAE）为12.5％至45.0％。相对于对照，单独施用MPR或TSP，普通豆的种子产量显着提高了28％-104％，而施用Tughutu和26 kg Pha-1的MPR或TSP则显着提高了148％-219％。单单使用Tughutu，种子产量就增加了53％。从经济分析来看，MPR或TSP与Tughutu结合使用，种子产量的增加使普通豆的边际收益率和美元利润显着提高（P≤0.001）坦桑尼亚北部WUM的农民。结论是，Tughutu及其与MPR或TSP的联合应用是一种适当的综合养分管理策略，可以提高坦桑尼亚农村贫困社区的豆类产量和美元利润。
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Research and Technology Promotion, Cape Peninsula University of Technology, Cape Town Campus, Keizersgracht, P.O. Box 652, Cape Town 8000 South Africa;
