Short-term impacts of different intercropping times of maize and ruzigrass on soil physical properties in subtropical Brazil

Intercropping maize (Zea mays L.) with ruzigrass (Urochloa ruziziensis) is a strategy for improving soil physical quality. However, effects of ruzigrass sowing time on soil physical properties with maize intercropping are unknown. Therefore, this study aimed to evaluate the short-term effects of intercropping times of maize and ruzigrass over three years (2019/2020-2021/2022) on the soil physical properties and grain yield of maize and soybean (Glycine max L.). The study was conducted in southern Brazil, in an Oxisol (602 g kg-1 of clay) under notillage. Under rainfed conditions, different intercropping times were evaluated during fall-winter, (i) ruzigrass sown before maize, (ii) sown at the time of maize sowing, (iii) sown 15 days after maize, and (iv) no intercropping (sole maize). Soybeans were grown every year during summer. The physical properties of the soil were evaluated during the six growing seasons. In the short-term, the bulk density in the 10-20 cm layer was 10% lower in the intercropping of ruzigrass sown before maize than that of sole maize. Macroporosity was 17% greater when ruzigrass was sown before maize compared with sowing performed 15 days after maize and it was 33% greater compared with no ruzigrass (sole maize) between the rows of maize. Although intercropping improved soil physical conditions, the soybean grain yield was not affected in two of the three years and was not correlated with the physical soil properties. In contrast, the maize yield was 17% higher when ruzigrass was intercropped 15 days after sowing maize than in the intercropping before maize sowing. The results suggest that the benefits of intercropping maize with ruzigrass on soil physical quality were greater when ruzigrass was sown before or at the time of maize sowing. The intercropping of maize with ruzigrass can be recommended as a management practice that improves the physical quality and other ecosystem services of the soil.