Long- and short-term effects of cultivation on properties of a Vertisol under sugarcane plantation

The effect of long- (>40 years) and short-term (<10 years) cultivation on some soil properties in sugarcane (Saccharum officinarum L.) grown on a Vertisol were compared to native vegetation in the semi-arid tropical region of Sudan. Tillage practices were sub-soiling, smoothing by disc harrowing, leveling and ridging (done every 4-5 years) and re-ridging annually. Particulate organic matter (POM) with long-term (8.2 g kg(-1)) and short-term cultivation (6.6 g kg(-1)) were significantly (P <= 0.007) higher than for native vegetation (2.1 g kg(-1)). In the 0-10 cm soil depth, cultivation 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) greater N was present under the long-term cultivation (0.46 g kg(-1)) than under native vegetation and short-term cultivation (0.26-0.33 g kg(-1)). At 10-20 cm, soil bulk density under long-term cultivation (1.5 mg m(-3)) was lower (P <= 0.01) than under short-term cultivation (1.8 mg m(-3)) and native vegetation (1.7 mg m(-3)). At 20-30 cm, TN and bulk density were not affected, but OC was significantly (P <= 0.009) higher under native vegetation (4.9 g kg(-1)) than under short-term cultivation (1.7 g kg(-1)). It could be concluded that, long-term production of sugarcane in fine textured soils (>52% clay) improved soil properties relative to native vegetation in the semi-arid tropics. (C) 2004 Elsevier B.V. All rights reserved.