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Evaluation of forage legumes for soil fertility improvement in maize/cassava production systems.

机译：玉米/木薯生产系统中用于改善土壤肥力的饲用豆科植物的评价。

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摘要

Soil fertility decline is a major factor limiting crop production in smallholder farms in sub-Saharan Africa. This research examined intercropping of Clitoria ternatea and Lablab purpureus forage legumes as potential nutrient sources in maize and cassava production systems. The legumes accumulated nutrients (2-yr avg.) of 50 to 101 kg N ha -1, 4 to 8 kg P ha-1, 33 to 83 kg K ha -1, 7 to 32 kg Ca ha-1, and 5 to 7 kg Mg ha-1 during the long rain season, with dolichos producing the greater values. Nutrient contents of clitoria were greater than dolichos during the short rain season, with values 20 to 40% lower than the long rain season. Intercropping reduced nutrient contents of the legumes to 80% of monoculture, and was most pronounced for clitoria intercropped with cassava. Delayed harvest of dolichos from two to four mo after planting increased dolichos nutrient accumulation between two and fourfold. Fertilizer inputs increased maize and stover yields by 70% over maize grown without fertilizer inputs. Intercropping maize with clitoria increased grain and stover nutrient accumulation by values ranging from 50 to 80%, compared to maize monoculture without fertilizer inputs, while intercropping maize with dolichos yielded less grain and stover. Cassava monoculture resulted in the greatest tuber yields (9 Mg ha -1), while intercropping of cassava with a legume reduced tuber yield by 21%. Clitoria intercropping with maize and/or cassava resulted in area by time equivalent ratios ranging from 1.2 to 1.6, while those of dolichos ranged from 1.1 to 2.0, indicating that intercropping of legumes with maize or cassava improved biological efficiency of the systems.;An asymptotic model best described clitoria and dolichos dry matter disappearance and nutrient release across different harvest management strategies, resulting in rates of 0.2 and 0.5 k wk-1 for clitoria and dolichos residues, respectively. Nitrogen release was generally slowest in clitoria and in dolichos 4-mo cut foliage. The k-values for nutrient release of dolichos ranged from 0.2 to 2.5 wk-1, and those for clitoria 0.3 to 1.0 wk-1. Across harvest management strategies, the general order of nutrient release was K > P > Mg > N, while that of dolichos cut at 2 mo was K > Mg > N > P and K > N > P > Mg for dolichos cut at 4 mo. These results demonstrated the legumes potential to supply nutrients for maize grain and cassava tuber production, and indicated that biological efficiency may be improved by intercropping maize with legumes. The need to develop N and K replenishment recommendation for cropping systems with cassava is suggested. Further research aimed at reducing nutrient losses by synchronizing nutrient release with principal crop demand is recommended.
机译：土壤肥力下降是限制撒哈拉以南非洲小农农场作物产量的主要因素。这项研究检查了玉米和木薯生产系统中的Clitoria ternatea和Lablab purpureus豆科作物间作作物作为潜在的营养来源。豆类积累的营养素（平均2年）为50至101 kg N ha -1、4至8 kg P ha-1、33至83 kg K ha -1、7至32 kg Ca ha-1和5在长时间的雨季中可达到7千克Mg ha-1，而长毛虫的产值更高。在短雨季节，河谷的营养成分要比土拨鼠多，其值比长雨季节要低20％至40％。间作使豆类的营养成分减少至单作的80％以下，而间作与木薯间作的气候最明显。播种后，家畜的收获延迟从2到4个月增加，家畜的养分积累增加了2到4倍。与没有肥料输入的玉米相比，肥料输入的玉米和秸秆单产提高了70％。与没有肥料输入的玉米单作相比，间种于玉米间作的玉米可增加50％至80％的谷物和秸秆养分积累值，而间种有小菜蛾的玉米可减少谷物和秸秆的产量。木薯单一栽培导致最大的块茎产量（9 Mg ha -1），而套种木薯和豆科植物使块茎产量降低21％。玉米和/或木薯的Clitoria间作导致的时间当量比范围为1.2至1.6，而玉米饼的间等当数比为1.1至2.0，这表明豆类与玉米或木薯的间作提高了系统的生物效率。该模型最恰当地描述了不同收获管理策略中的clitoria和dolichos干物质消失和养分释放，导致clitoria和dolichos残留率分别为0.2和0.5 k wk-1。氮素的释放通常在clitoria和4个月切的短毛虫中最慢。毛线虫营养释放的k值介于0.2到2.5 wk-1之间，而锦蛇属的k值介于0.3到1.0 wk-1之间。在整个收获管理策略中，养分释放的一般顺序为：K> P> Mg> N，而在2 mo切开的家禽的养分释放顺序为K> Mg> N> P，而在4 mo切开的家畜的K> N> P> Mg 。这些结果表明豆科植物具有为玉米籽粒和木薯块茎生产提供营养的潜力，并表明通过将豆类与玉米间作可以提高生物效率。建议为木薯种植系统制定氮和钾补充建议。建议进一步研究，以通过使养分释放与主要农作物需求同步来减少养分流失。

著录项

  • 作者

    Njunie, Michael Ngunjiri.;

  • 作者单位

    North Carolina State University.;

  • 授予单位 North Carolina State University.;
  • 学科 Agriculture Agronomy.;Agriculture Soil Science.
  • 学位 Ph.D.
  • 年度 2002
  • 页码 132 p.
  • 总页数 132
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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