Direct Drilling of Soybean in a Pensacola Bahiagrass Pasture in the Northwest Region of Rio Grande Do Sul, Brazil

The response of methods of soil preparation (M1=conventional tillage, and with notillage using the following herbicides M2=50% Paraquat plus 50% Orizalin; M3=50% Paraquat plus 50% Diquat and M4=Paracol (20% Paraquat plus 20 Diuron)) and row spacing (E1=17 cm, E2=24 cm, E3=51 cm and E4=68 cm) on soybean grain yield direct drilled in an eight-year-old grazed sward of Bahiagrass cv. Pensacola (Paspalum notatum var. saurae Parodi) were studied in southern of Brazil. The results showed that direct drilling of soybean on Pensacola accompanied by desiccant herbicides is a viable agronomic practice. The narrow row spacing is beneficial to this agronomic practice resulting in higher grain yields. The relationship between soybean grain yield and Pensacola dry matter yield was expressed by a negative linear regression. In spite of the damage to the Pensacola caused by herbicides and by soybean competition the sward recovered immediately after the soybean maturation and harvest.