In temperate systems, it is well known that forage legumes can improve both nitrogen (N) supply and yields of subsequent cereal crops. While this is assumed to be true in tropical systems, it is less well tested, particularly in smallholder settings where forage is often cut and removed from the field. This paper confirms the potential of short phases of tropical forage legumes to provide N to subsequent crops in seasonally dry tropical farming systems. Across five experiments, maize and rice grain yields increased by up to 80 % after 4−8 month rotations of forage legumes, but the benefits were smaller when legume growth was reduced, biomass was removed for forage, or the yield potential of cereal crops was lower. We found that the additional N cycling from legumes can last for at least 2 years, although the benefit diminishes with time. When all legume material was retained as mulch, the estimated additional N provided to subsequent no-till maize crops was the equivalent of 9−15 kg urea-N per tonne of above-ground legume biomass produced but fell to 1.5−3 kg urea-N/t if forage was removed. After shoot removal, more legume N cycled to a subsequent rice crop (equivalent of 11–13 kg urea-N/t of legume biomass) than to a no-till maize crop, presumably because more below-ground material mineralised. Of the legumes tested, Clitoria ternatea grew best across a variety of environments and use patterns and provided the largest yield benefits to subsequent crops. This research demonstrates the potential to integrate short phases of tropical herbaceous forage legumes into smallholder crop-livestock systems in the seasonally dry tropics, and, in doing so, improve or maintain staple grain crop production and household food self-sufficiency.

在温带系统中，众所周知，豆科牧草可以改善后续谷类作物的氮 (N) 供应和产量。虽然这在热带系统中被认为是正确的，但它没有得到很好的测试，特别是在经常从田间切割和移除草料的小农环境中。本文证实了热带牧草豆科植物短时期为季节性干旱热带农业系统中的后续作物提供氮的潜力。在五个实验中，豆科植物轮作 4-8 个月后，玉米和稻谷的产量提高了 80%，但当豆科植物生长减少、去除草料生物量或谷类作物的产量潜力降低时，收益较小。降低。我们发现豆类中额外的氮循环可以持续至少 2 年，尽管收益会随着时间的推移而减少。当所有豆类材料都保留为覆盖物时，估计为后续免耕玉米作物提供的额外氮相当于每吨生产的地上豆类生物量 9-15 kg 尿素氮，但下降到 1.5-3 kg 尿素氮如果草料被移除，则为 N/t。去除芽后，更多的豆科植物 N 循环到随后的水稻作物（相当于 11-13 kg 尿素-N/吨豆科植物生物量）而不是免耕玉米作物，可能是因为更多的地下物质被矿化。在测试的豆类中，与免耕玉米作物相比，更多的豆科植物 N 循环到随后的水稻作物（相当于 11-13 kg 尿素-N/吨豆科植物生物量），大概是因为更多的地下物质被矿化。在测试的豆类中，与免耕玉米作物相比，更多的豆科植物 N 循环到随后的水稻作物（相当于 11-13 kg 尿素-N/吨豆科植物生物量），大概是因为更多的地下物质被矿化。在测试的豆类中，Clitoria ternatea在各种环境和使用模式中生长最好，并为后续作物提供最大的产量收益。这项研究证明了将热带草本牧草豆科植物的短阶段整合到季节性干旱热带地区的小农作物-牲畜系统中的潜力，并在此过程中改善或维持主粮作物生产和家庭粮食自给自足。