Long and Short-Term Effect of Conventional Tillage on Some Soil Properties of Sugar Cane Grown Vertisol

Abstract

Soil tillage imposed different effects on soil properties. The aim of this study was to determine the effect of a long (LT)(> 40 years) and short - term (ST) (< 10 years) effects of conventional tillage in a sugar can grown in a vertisol on some soil properties as compared to native vegetation (NV). The tillage sequence was sub-soiling, smoothing by disc harrowing, leveling and ridging (every 4 - 5 years) and re-ridging annually. The results showed that, weight of particulate of organic matter associated with sand particles (POM) in the LT (9.6 g kg-1) and ST (6.7 g kg-1) were significantly (P = 0.007) higher than that reported in NV (2.1 g kg-1). In the 0 - 10 cm soil depth tillage had no effect on total nitrogen (TN), organic carbon (OC) and bulk density (Bd). However, in the 10 - 20 cm soil depth, significantly (P > 0.03) more N was incorporated in the LT tillage (0.46g kg-1) compared to NV and ST tillage (0.26-0.33g kg-1). In this depth (10 - 20 cm), LT tillage significantly (P < 0.01) decreased Bd from 1.8 (in ST) and 1.7 (in NV) to 1.5 g cm-3. In the third depth (20 - 30 cm), TN and Bd were not affected while OC was significantly (P = 0.009) decreased from 4.9 (in NV) to 2.2 (in LT) and 1.7 g kg-1 (in ST). In the lower soil depth (30 - 40 cm), there seemed to be more incorporation of OC (though not significant) in the LT compared to ST and NV. Therefore, more C and N were brought into the lower soil depth (particularly in the 10 - 20 cm depth) in LT. This might subject the soil under sugar cane production to degradation. It could be concluded that, in heavy textured soils under cane production in the dry tropics, soil degradation by tillage might not be a constraint if non-inverted tillage implements were used. This could possibly be attributed to physical protection of organic matter by the high clay content (> 52%).