Low levels of nitrogen (N) and phosphorus (P) in soils in sub-Saharan Africa (SSA) limit maize (Zea mays) production in smallholder farms. We tested the hypothesis that desmodium (Desmodium intortum (Mill.) Urb.), a fodder legume, and food legumes commonly grown with maize in Western Kenya avail N and P and improve the performance of maize in intercrops. We measured available N and P in 15 cm topsoil at 4, 8 and 12 weeks after planting (WAP), and corresponding maize shoot weight in three seasons: 2017 long rains (LR), 2017 short rains (SR), and 2018 LR at Thomas Odhiambo Campus of icipe at Mbita Point in western Kenya. Treatments were additive 1:1 maize-legume intercrops; maize-bean (Phaseolus vulgaris L.), maize-cowpea (Vigna unguiculata (L.) Walp.), maize-crotalaria (Crotalaria ochroleuca G. Don), maize-desmodium, maize-green gram [Vigna radiata (L.) Wilczek] and maize-groundnut (Arachis hypogaea L.), and maize monocrop as a control, replicated four times in a complete randomized design. This experiment was established in 2003 and treatments were repeated every season on the same plot (for 31 seasons up to 2018 LR). At the beginning (year 2003), experimental plots were infested with 100 g of striga seeds per 250 g soil. Across the three last seasons corresponding to this study, we observed an increase in available N in maize-desmodium plots compared to maize monocrop plots. Available P measured at 4, 8 and 12 WAP in 2017 SR and at 4 WAP in 2018 LR was higher in maize-desmodium than in maize monocrop at the same sampling times (P < 0.05). The shoot weight for maize grown with desmodium was consistently higher than that for maize grown in monocrop. Maize grain yield for maize-desmodium was 5.0, 3.1 and 4.3 Mg ha⁻¹ in 2017 LR, 2017 SR and 2018 LR, respectively, compared to 0.5, 0.4 and 1.8 Mg ha⁻¹ for maize monocrop in the three respective seasons. Other intercrops were comparable with maize monocrop. Historic maize yields were constantly higher in maize-desmodium than maize monocrop and other maize-legume intercrops. We show that desmodium improves N and P availability, growth and yield of maize. We recommend studies on biological N fixation and changes in rhizosphere to understand mechanisms behind observed improvement in N and P availability.

撒哈拉以南非洲（SSA）土壤中的氮（N）和磷（P）含量低，限制了小农户玉米的生产。我们检验了以下假设：在肯尼亚西部的玉米中通常使用的饲用豆科植物豆蔻（Desmodium intortum（Mill。）Urb。）和豆类食物利用氮和磷，可以改善玉米在间作中的性能。我们在种植后4、8和12周测量了15厘米表层土壤中的有效氮和磷（WAP），以及三个季节对应的玉米苗重：2017年长雨（LR），2017年短雨（SR）和2018年LR肯尼亚西部姆比塔角icipe的Thomas Odhiambo校园。玉米豆科作物间作1：1的增产处理。玉米豆（菜豆），玉米-pea豆（Vigna unguiculata（L.）Walp。），玉米-猪屎豆（Crotalaria ochroleuca G.Don），玉米-脱粉，玉米绿克[ Vigna radiata（L.）Wilczek]和玉米-花生（Arachis hypogaeaL.）和玉米单作作对照，在完全随机设计中重复了四次。该实验建立于2003年，每个季节都在同一块地上重复进行处理（直到2018年LR为止的31个季节）。在开始的时候（2003年），每250 g土壤中有100 g的striga种子被侵染。在与本研究相对应的最后三个季节中，我们观察到与玉米单作田相比，玉米-地皮田中的有效氮增加。在相同的采样时间下，2017年SR的4、8和12 WAP和2018 LR的4 WAP测得的可用P高于单季玉米（P <0.05）。用除沫器培育的玉米的苗芽重量始终高于单季作物种植的玉米。玉米脱皮的玉米籽粒产量为5.0、3.1和4.3 Mg ha ^-1分别在2017年LR，2017 SR和2018 LR中，相比之下，三个季节的玉米单季作物分别为0.5、0.4和1.8 Mg ha ^-1。其他间作与玉米单作相当。玉米-历史上玉米的历史单产一直高于玉米单作和其他玉米-豆类间作。我们显示，除草剂改善了玉米的氮和磷利用率，生长和产量。我们建议对生物固氮和根际变化进行研究，以了解所观察到的氮和磷有效性改善的机制。