Rurangwa Edouard, Vanlauwe Bernard, Giller Ken E
Rwanda Agriculture Board, P.O. Box 5016, Kigali, Rwanda.
Plant Production Systems, Wageningen University, P.O. Box 430, 6700 AK Wageningen, The Netherlands.
Agric Ecosyst Environ. 2018 Jul 1;261:219-229. doi: 10.1016/j.agee.2017.08.015.
Common bean and soybean yield poorly on smallholder farms in Rwanda. We evaluated the benefits of inoculation combined with P fertilizer and manure on yields of common bean and soybean in three agro-ecological zones (AEZs), and their residual effects on a subsequent maize crop. In the first season, the treatments included inoculum, three rates of manure, and two rates of P fertilizer, with nine replications (three per AEZ). Both legumes responded well to inoculation if applied together with manure and P fertilizer. Grain yields varied from 1.0 t ha to 1.7 t ha in unamended control plots to 4.8 t ha for common bean and 3.8 t ha for soybean in inoculated plots with both P and manure addition. The response of common bean and soybean to inputs varied greatly between AEZs. In the AEZ with low and erratic rainfall (Bugesera), yields of both legumes and maize were low and maize after soybean failed to yield any grain due to drought. In this regard, early maturing legume varieties are advised in regions of low rainfall. Responses of maize to an input applied to the legumes strongly increased when other inputs were applied together to the legume. This allowed greater maize yields which ranged from 0.8 t ha in control plots to 6.5 t ha in treatments previously inoculated with P and manure added for maize grown after common bean and from 1.9 t ha in control plots to 5.3 t ha for maize grown after soybean. The amount of N-fixed measured using the N-natural abundance method differed between the two legumes and varied between 15 and 198 kg N ha for common bean and between 15 and 186 kg N ha for soybean and differed enormously among treatments and AEZs. Application of inputs to the legumes also resulted in enhanced N and P uptake of the subsequent maize. The use of inoculum combined with manure and P fertilizer is a good option for smallholder farmers growing common bean and soybean in rotation with maize. We observed strong effects of environment and call for care when targeting crops and technologies for sustainable crop production.
在卢旺达的小农户农场中，普通豆和大豆产量很低。我们评估了接种根瘤菌结合磷肥和粪肥对普通豆和大豆在三个农业生态区（AEZs）产量的影响，以及它们对后续玉米作物的残留效应。在第一季，处理措施包括接种物、三种粪肥施用量和两种磷肥施用量，共九个重复（每个农业生态区三个）。如果将接种物与粪肥和磷肥一起施用，两种豆类作物都对接种反应良好。未改良对照地块的谷物产量从1.0吨/公顷到1.7吨/公顷不等，而在添加了磷肥和粪肥的接种地块中，普通豆的产量为4.8吨/公顷，大豆为3.8吨/公顷。普通豆和大豆对投入物的反应在不同农业生态区之间差异很大。在降雨少且不稳定的农业生态区（布热塞拉），两种豆类作物和玉米的产量都很低，大豆之后种植的玉米因干旱未能收获任何谷物。在这方面，建议在降雨少的地区种植早熟豆类品种。当其他投入物一起施用于豆类作物时，玉米对施用于豆类作物的投入物的反应会大幅增加。这使得玉米产量更高，普通豆之后种植的玉米，对照地块产量为0.8吨/公顷，之前接种并添加了磷肥和粪肥的处理地块产量为6.5吨/公顷；大豆之后种植的玉米，对照地块产量为1.9吨/公顷，处理地块产量为5.3吨/公顷。使用氮自然丰度法测量的固氮量在两种豆类作物之间有所不同，普通豆在15至198千克氮/公顷之间，大豆在15至186千克氮/公顷之间，且在不同处理和农业生态区之间差异巨大。对豆类作物施用投入物还导致后续玉米对氮和磷的吸收增加。对于与玉米轮作种植普通豆和大豆的小农户来说，接种物与粪肥和磷肥结合使用是一个不错的选择。我们观察到环境影响很大，并呼吁在针对可持续作物生产的作物和技术时要谨慎行事。
