Poor soil fertility and erratic rainfall constrain crop production in rain-fed smallholder farming systems in sub-Saharan Africa. Integration of drought tolerant and N₂-fixing crops into maize-based cropping systems is a risk-averse strategy that also improves nitrogen cycling. A field experiment was carried out during the 2017/18 and 2018/19 cropping seasons in Goromonzi district in Zimbabwe. The trials were established on 14 farms, and on two field types (homefields and outfields), with eight treatments from a combination of cropping systems (maize and cowpea monocrops or maize/cowpea intercrops) and with or without nitrogen fertilizer (+N; -N). The trials were implemented on the same field plots for the two consecutive seasons. An improved cowpea variety and a landrace were used. The objectives were to determine 1) the productivity of the different cropping systems under variable soil fertility conditions, 2) N₂-fixation of the two cowpea types when planted as monocrops or intercrops, and 3) mineral composition of maize and cowpea grains from intercrops and sole crops. Contrary to expected results, soil properties were not significantly different (P > 0.05) between field types. The land equivalent ratios (LER) were >1 for both seasons, implying improved land productivity under intercropping. Intercropping significantly reduced cowpea nodulation and active nodules, but not the total nodule weight, resulting in similar proportion of nitrogen derived from the atmosphere (%Ndfa) for cowpea grown as monocrop or in intercropping with maize. However, the total amount of fixed nitrogen was reduced in intercropping systems due to the smaller cowpea biomass compared to monocropping. Maize and cowpea grain mineral contents (Fe, Zn, Mn, Cu, Ca, Mg, P, K) were significantly affected by the cropping season only. We showed that intercropping maize with cowpea generally increases system productivity, in addition to substantial amounts of nitrogen being added to the system through N₂-fixation. However, intercropping was not an agronomic biofortification option in these nutrient-depleted soils. Finally, annual variation in grain mineral quality can be larger than the annual variation in grain yield, potentially posing serious challenges to human nutrition.

撒哈拉以南非洲地区土壤肥力差和降雨不稳定限制了雨养小农耕作系统的农作物产量。耐旱和N _2的整合将作物固定在玉米种植系统中是一种规避风险的策略，也可以改善氮循环。在津巴布韦Goromonzi地区的2017/18和2018/19种植季节进行了田间试验。该试验在14个农场和两个田地类型（家田和野外）上进行，采用了多种耕作系统（玉米和cow豆单季作物或玉米/ co豆间作）的八种处理方法，有无氮肥（+ N;- N）。连续两个赛季在相同的田间试验中进行了试验。使用改良的cow豆品种和地方品种。目的是确定1）在可变土壤肥力条件下不同种植系统的生产力，2）N ₂当种植为单作作物或间作作物时，固定两种cow豆类型； 3）间作和单一作物的玉米和cow豆谷物的矿物质组成。与预期结果相反，田间类型之间的土壤特性没有显着差异（P> 0.05）。两个季节的土地当量比（LER）均大于1，这意味着间作套种提高了土地生产率。间作显着减少了pea豆的结瘤和活动结节，但未减少总结节重量，因此，作为单作或与玉米间作的cow豆，来自大气的氮比例（％Ndfa）相似。然而，由于与单作相比cow豆生物量较小，因此在间作系统中固定氮的总量减少了。玉米和cow豆的矿物质含量（铁，锌，锰，铜，钙，镁，磷，K）仅受种植季节的影响。我们表明，玉米与through豆间作通常可以提高系统生产力，此外还可以通过N向系统中添加大量的氮。_2-固定。然而，在这些营养贫乏的土壤中，间作并不是农业生物强化的选择。最后，谷物矿物质质量的年变化可能大于谷物产量的年变化，可能对人类营养构成严重挑战。