Intercropping is a common practice among farmers in sub-Saharan Africa, regarded as a sustainable way of improving land productivity to meet food and nutritional requirements for a growing population, especially in marginal areas. Cowpea (Vigna unguiculata L. Walp) is often intercropped with major cereal crops, maize (Zea mays L.), sorghum (Sorghum bicolor L. Moench) and pearl millet (Pennisetum glaucum L.R.Br). Here we conducted a systematic literature review on cowpea intercropped with maize, sorghum or pearl millet reported in sub-Saharan Africa with the objectives (i) to determine yield and productivity of component crops and (ii) to quantify biological N₂-fixation in sole or intercrops. We retrieved 60 unique publications combining 1196, 998 and 25 observations of yields, land productivity and N₂-fixation, respectively, for crops grown as intercrops and monocrops. The major results are as follows: (1) land productivity of cowpea intercropped with maize, sorghum and pearl millet is favourable, with average land equivalent ratios of 1.42 ± 0.47, 1.26 ± 0.35 and 1.30 ± 0.32, respectively; (2) no significant differences between the proportion of nitrogen derived from the atmosphere (%Ndfa) for sole or intercropped cowpea were found, with average values of 56.00 ± 4.89 and 46.62 ± 7.05, respectively; (3) however, the total amount of fixed nitrogen was higher in cowpea monocropping systems due to higher biomass production; nitrogen fixation was 57 kg N ha⁻¹ and 36 kg N ha⁻¹ in monocrops and intercrops respectively. We conclude that cereal-cowpea intercropping is a pathway for intensification for the low nutrient input systems of smallholder farmers in sub-Saharan Africa. Our review also suggests potential for improvement of these systems, based on the choice of the associated varieties, planting patterns and sowing time, cowpea leaf harvesting as a vegetable, and fertilization.

中文翻译：

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撒哈拉以南非洲谷物-w豆间作系统的生产力和生物固氮作用。回顾

间作是撒哈拉以南非洲农民的普遍作法，被认为是提高土地生产力以满足不断增长的人口（尤其是边缘地区）粮食和营养需求的可持续方式。豇豆（豇豆大号。 Walp）常常与间作主要谷类作物，玉米（玉蜀黍L.），高粱（高粱属荞）和珍珠粟（狼尾草灰绿LRBr）。在这里，我们对撒哈拉以南非洲报道的玉米，高粱或珍珠粟与玉米套种的cow豆进行了系统的文献综述，目的是（i）确定组成作物的产量和生产力，以及（ii）量化生物学上的N ₂固定在鞋底或间作中。我们检索了60种独特的出版物，分别将间作作物和单作作物种植的作物的产量，土地生产力和N ₂固着性结合了1196、998和25个观察结果。主要结果如下：（1）套种玉米，高粱和珍珠粟的cow豆的土地生产率较高，平均土地当量比分别为1.42±0.47、1.26±0.35和1.30±0.32；（2）单独或间作的pea豆的大气氮含量（％Ndfa）之间没有显着差异，平均值分别为56.00±4.89和46.62±7.05；（3）但是，cow豆单作系统中固定氮的总量较高，这是因为生物量较高。固氮量为57 kg N ha单作和间作分别为^-1和36 kg N ha ^-1。我们得出结论，谷物-cereal豆间作是强化撒哈拉以南非洲小农户低营养输入系统的一种途径。我们的综述还根据相关品种的选择，种植方式和播种时间，cow豆作为蔬菜的收成以及施肥情况，提出了改善这些系统的潜力。