Phosphate and nitrogen fertilization interactions with different cover crops on the yield of main crops in a Brazilian Cerrado Ferralsol

ABSTRACT Growing off-season cover crops effectively enhances ecological diversity and improves nutrient cycling in agricultural systems, particularly when nutrient losses and low use efficiency are prominent. This study aimed to assess the interaction between different off-season cover crops and varying nitrogen (N) and phosphorus (P) application rates on common beans, soybeans, and corn yields, as well as on soil organic matter (SOM) and available P content (Mehlich-1) in a Cerrado loamy soil. The experiment was conducted as a strip-plot factorial design with three replications in Planaltina, Distrito Federal, Brazil, from 2017 to 2020 under a no-tillage system. A fallow control and different cover crops were assigned to the rows of the three blocks and cultivated during the off-season from February to May, including Urochloa ruziziensis, Crotalaria spectabilis, millet (Pennisetum glaucum L.), white oat (Avena sativa) and a mix of cover crops (white oat, millet, buckwheat [Fagopyrum esculentum Moench], and radish [Raphanus sativus L.]). Combinations of N and P rates were assigned to the columns of the blocks, and the effects of the interactions of the factorial were assessed on subsequently cultivated commercial summer crops, including soybeans (Glycine max L.) in the 2017/18, 2018/19, and 2020/21 seasons and corn (Zea mays L.) in the 2019/20 season. Furthermore, common beans (Phaseolus vulgaris L.) were grown during all winter cropping seasons from 2017 to 2020. Cover crops reduced the dependence of commercial crops on mineral N and P fertilizers, although response to increasing rates was still present. Moreover, the magnitude of this effect varied with the specific crop species and commercial crops. Among the cultivated species, U. ruziziensis and white oat; U. ruziziensis, white oat, millet, and the mix; and U. ruziziensis and C. spectabilis exhibited the greatest potential for increasing yield in beans; soybeans; and corn, respectively.