Deep banding increases phosphorus removal by soybean grown under no-tillage production systems

Abstract

Phosphorus fertilizer placement can have significant agronomic and environmental implications in long-term no-till (NT) systems. The objective of this study was to evaluate soybean [Gly-cine max (L.) Merr.] response to P fertilizer placement strategies under long-term NT management. A field study was performed near Nao-Me-Toque-RS (Location 1) and Sao Sepe-RS (Loca-tion 2), southern Brazil, during the 2014/2015 growing season. The experimental design was a randomized complete block with three replications. Triple superphosphate was applied using five strategies: (i) strip tillage with deep band (ST-DB); (ii) strip tillage with band-applied 5 by 5 cm (ST-B); (iii) no-till with broadcast (NT-BR); (iv) no-till with band-applied 5 by 5 cm (NT-B); (v) and no-till with surface band (NT-SB). Plant height, dry weight, and P uptake were evaluated at 20, 40, 60, and 80 d after emergence (DAE) as well as P removed and grain yield at harvest. The ST-B application promoted greater plant height, dry weight, and P uptake at 80 DAE. However, ST-DB showed the greatest P removal compared to other treatments. Also, greater yields were obtained for ST-DB and NT-BR. Soil sampling after harvest showed that ST-DB increased soil test P levels by 19 and 11% at the 15- to 25-cm layer for Locations 1 and 2, respectively. While NT-BR increased soil test P by 43 and 36% at the 0- to 5-cm layer for Locations 1 and 2, respectively. Deep band P fertilizer placement maintained or increased soybean yield and P use under long-term NT in tropical soils.