Effects of irrigated cover crop cultivation period on common bean and soybean yield

Abstract Cover crop inclusion is essential for improving soil management in tropical no till systems; however, the optimal duration of irrigated off‐season cultivation remains uncertain. This 3‐year field study evaluated nine cover crop species or mixtures and four cultivation periods (60, 75, 90, and 105 days) on biomass production, soil chemical properties, and subsequent common bean ( Phaseolus vulgaris L.) and soybean ( Glycine max L. Merr.) yields in the Brazilian Cerrado. Cover crops were grown under center pivot irrigation in a recurring sequence of cover crops–bean–soybean. Biomass increased linearly with longer cultivation, reaching 6,309 kg ha − 1 at 105 days. Millet ( Pennisetum glaucum L.; 5,563 kg ha − 1 ) and the forage mixture containing grasses (5,259 kg ha − 1 ) produced the highest biomass. Soil analyses in the third year showed that the diversified Salud mixture containing grasses, legumes, and brassicas enhanced Ca, Mg, P, K, S, and soil organic matter compared with most single species covers and spontaneous vegetation. Soybean yield was significantly affected by cover crop species, with the highest yield following the Salud mixture (4,973 kg ha − 1 ), whereas bean yield was not species dependent. Extending cover crop duration from 60 to 105 days increased bean yield from 2,064 to 2,306 kg ha − 1 and soybean yield from 4,955 to 5,303 kg ha − 1 . These results demonstrate that extending irrigated cover crop growth up to 105 days enhances biomass production, improves soil fertility, and increases soybean and bean productivity in tropical cropping systems.