Abstract

Quantifying soil and plant response to surface applied limestone and phosphogypsum (PG) will help promote no-tillage soybean production. Our objective was to determine effects of annual surface application of phosphogypsum and limestone on soil profile chemistry, fertilizer use efficiency, soybean leaf nutrient concentrations, seed yield, and yield components under a no-tillage system (NTS). The study was conducted in the Brazilian Cerrado under field conditions during three growing seasons on an acidic clay loam soil. Four soil remediation treatments [(limestone, lime + phosphogypsum, phosphogypsum and control (no soil correction)] with four fertilizer levels (0, 50, 100 and 150% of recommended P and K fertilizer for soybean) were arranged in a randomized design using a 4 × 4 factorial design. Treatments involving lime application improved soil chemical characteristics of the soil, resulted in significant increases in plant nutrient concentrations, and increased soybean grain yield. In contrast, application of phosphogypsum did not improve plant development conditions and resulted in no significant changes in soil properties or soybean grain yield. Using increased fertilizer application rates for 3 years also produced significant increases in soybean grain yield. Our results imply that, for acidic soils liming NTS is the best practice to increase fertilizer use efficiency.

Key words: Calcium carbonate, Glycine max, no-tillage system (NTS), mineral nutrition, soil acidity.