Effect of management systems in soil chemical attributes

Abstract

Soil chemical attibutes were assessed after nine years on a typical Dystrophic Red Latosol located in Passo Fundo, State of Rio Grande do Sul, Brazil. Four soil management systems – 1) no-tillage, 2) minimum tillage, 3) conventional tillage using a disk plow followed by use of a disk harrow, and 4) conventional tillage using a moldboard plow followed by use of a disk harrow – and three crop rotation systems [I (wheat/soybean), II (wheat/soybean and common vetch/corn), and III (wheat/soybean, common vetch/corn, and white oat/soybean)] were evaluated. In November 2001 after winter crops were harvested compound soil samples were collected at the following depths (cm): 0-5, 5-10, 10-15, and 15-20. A randomized complete block design, with split- plots and three replicates, was used. The main field plots (4 x 90 m) were formed by soil management systems, while the subplots (4 x 10 m) consisted of crop rotation systems. The values of pH and concentration of extractable P, and exchangeable K was affected by soil management. Higher contents of soil organic matter, extractable P, and exchangeable K were observed in the 0-5 cm layer for the conservation tillage systems (minimum tillage and no-tillage), as compared to the conventional tillage systems (disk plow and mold- board plow). The values of soil organic matter, P, and K were higher in the 0-5 cm layer, when compared to the ones observed in the 15-20 cm layer, in all soil management and cropping systems, while the opposite occurred with pH. Soil acidification was detected under both conservation tillage systems. The yield of white oat, wheat and soybean grown under no-tillage and minimum tillage was were than the yield obtained for white oat, wheat and soybean after conventional tillage systems (disk plow and moldboard plow). The lowest soybean and wheat yield obtained in monoculture.