Impact of sowing time of maize and ruzigrass intercropping systems on soil chemical, physical and microbiological properties in an Oxisol from southern Brazil

Abstract

The sowing time of ruzigrass (Urochloa ruziziensis) intercropped with maize (Zea mays L.) influences the above- and belowground biomass, affecting soil properties. This study evaluated the effects of sowing times of maize and ruzigrass on the physical, chemical, and microbiological properties in an Oxisol in southern Brazil. The sowing time included intercropping maize with ruzigrass (i) sown before maize, (ii) sown at the time of maize sowing, (iii) sown after maize, and was compared to the (iv) sole maize (control treatment). The soil physical (bulk density, total porosity, macroporosity, and saturated hydraulic conductivity), chemical (soil pH, soil organic matter, phosphorus, potassium, calcium, and magnesium), and microbiological properties (microbial biomass carbon, microbial biomass nitrogen, arylsulfatase, β-glucosidase, and acid and alkaline phosphatase activities) were analyzed after three years. Sowing time of maize with ruzigrass affected the competition between ruzigrass and maize and impacted soil properties. In the intercropping of ruzigrass sown before maize, the bulk density at the 10–20 cm depth was 10 % lower than in the sole maize. The benefits of intercropping maize with ruzigrass for bulk density, total porosity, macroporosity, microbial biomass, and enzyme activity were higher when ruzigrass was sown before and at the time of maize sowing than that of ruzigrass sown after maize and sole maize. Sowing of ruzigrass after maize sowing was less effective in improving the physical and microbiological properties of the soil. The changes in soil chemical properties under intercropping maize with ruzigrass took longer to be observed than the soil physical and microbiological properties, indicating that physical and microbiological properties are more sensitive indicators of soil quality. The results of this study can be used to guide integrated intercropping strategies in no-tillage cropping systems to maximize positive effects on soil quality.