Cover Crops and Tillage: Effects on Soil Chemical Properties and Rice Yield

Mechanical soil intervention with a chisel in cover crops (CCs) is a promising strategy for minimizing the superficial compaction of soil in a no-tillage system (NTS). The objective of this study was to evaluate the effect of mechanical chiseling associated with successive crops and preceding cover crops to assess grain yield and changes in soil chemical properties after rice cultivation for two consecutive years. The experimental design comprised randomized blocks in a 5 × 2 factorial scheme with four replications. The treatments consisted of five cover crops (Cajanus cajan, Crotalaria juncea, Urochloa ruziziensis, Pennisetum glaucum, and fallow), with or without soil mechanical chiseling. Soil samples from the 0–5, 5–10, 10–20, and 20–40 cm layers were collected, and the chemical properties were analyzed after rice cultivation. Under U. ruziziensis, the chemical properties were improved by mechanical scarification; however, the initial acidity increased in the 5–40 cm layer. The cultivation of P. glaucum and C. juncea prior to rice, regardless of scarification, improved the soil chemical properties in the 0–40 cm layer. Mechanical soil scarification and the use of C. cajan as a cover crop increased the grain yield of upland rice by approximately 552 and 1454 and 1330 kg ha−1 compared to the P. glaucum and U. ruziziensis, respectively.