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• Tropical forage legumes were grown in rotation or relays with maize and rice. • Subsequent maize yields increased by up to 80 % if legumes were retained as mulch. • Maize yield increased less (15−35% higher) after legume forage was harvested. • Forage legumes grown in rotation with rice increased subsequent yields by 40–70 %. • Clitoria ternatea proved the most beneficial forage legume for diverse systems. 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. [ABSTRACT FROM AUTHOR]

Context: Increasing demand for livestock products in developing countries provides opportunities for smallholder farmers to increase and diversify their income through increased livestock production. However, livestock production in these systems is often limited by inadequate animal nutrition, and farmers need ways to increase the availability and quality of livestock feed without compromising yields of food crops or increasing the area of land planted to forages. Aim: Using eastern Indonesia as a case study, we explore the potential for herbaceous legumes, integrated into existing mixed crop–livestock systems, to address specific production issues in smallholder beef systems. Methods: Through a series of in-village feeding demonstrations, we tested three opportunities to increase livestock production through the use of herbaceous legumes: (i) increasing reproduction rates of cows by maintaining their liveweight (LW) and body condition score during the dry season; (ii) increasing the survival and LW gain of unweaned calves; and (iii) increasing LW gain of growing bulls. Key results: Small amounts of legume (~10 g DM/kg LW) were enough to maintain LW of cows grazing poor-quality grasses and crop residues during the dry season. At higher levels of inclusion in the diet (~20 g DM/kg LW), feeding legumes increased the LW gain of growing cattle and survival of unweaned calves, providing benefits similar to a purchased concentrate, but at lower cost. Conclusions: Our results demonstrate how strategic use of herbaceous legumes can increase beef production from low-input systems by maintaining LW of cows, and increasing survival of unweaned calves and LW gain of growing bulls. Implications: Integration of herbaceous legumes into existing cropping systems removes many of the barriers to supplementary feeding. Improved livestock nutrition does not need to be based on purchased concentrates or increases in land used for forage production. The results are applicable to many other mixed crop–livestock systems throughout Southeast Asia. Smallholder livestock production in Indonesia and other countries in Southeast Asia is often limited by inadequate nutrition, and farmers require options to increase feed available for livestock without compromising yields of food crops. Across multiple on-farm feeding experiments, we show that integration of herbaceous legumes into mixed crop–livestock systems can be used to increase reproduction, survival and liveweight gain of cattle. In this way, strategic use of herbaceous legumes can increase beef production from low-input systems. [ABSTRACT FROM AUTHOR]