CHEMICAL AND PHYSICAL CHARACTERISTICS OF 4 SOIL TYPES UNDER CONVENTIONAL AND NO-TILLAGE SYSTEMS

This study was conducted to determine how soils of different origin respond to no-till practices, with emphasis on organic C accumulation and its subsequent effect on soil properties. Tillage experiments which had been running for between 5 and 15 years on four southeastern USA soils with textures of sandy loam, loam, silt, and sandy clay loam were utilized. Soil samples were collected from conventional and no-tillage treatments at depths of 0-2.5, 2.5-7.6, and 7.6-15.2 cm. No-tillage plots had higher bulk density, aggregate stability, organic C, exchangeable cations and acidity, cation exchange capacity, and extractable P, K, and Mn, but most of these properties were not significantly different (P<0.05) from those of conventional plots. Modulus of rupture and extractable Fe decreased in the no-till plots. Most of these changes, other than bulk density, occurred as a result of increases in organic C content, and the lack of more significant differences is attributed to inadequate residue production and/or its rapid decomposition in this relatively hot, moist climate.