Short-term contribution of mineral N from soil organic matter during the rainy season in a vertisol of the semi-arid tropics of Sudan.

This study was conducted to monitor the effect of tillage on potentially mineralizable nitrogen during the growing season of rain-fed sorghum (Sorghum bicolor). Two sites (with conventional tillage & traditional tillage) located southern central clay plain were selected. Auger soil samples were taken from the 0-30 and 30-60 cm soil depths every two weeks during the rainy season. Results showed that content of total mineral nitrogen (NH + 4-N+NO - 3-N) in traditional tillage was significantly higher than that obtained under conventional tillage. Accordingly, mineral nitrogen under traditional tillage determined after 2, 4, 6, 8 and 10 weeks were 366.2, 217.78, 206.12, 202.86, 189.8 kg ha -1 , respectively. Respective values for conventional tillage were