Effect of tillage and field condition on soil physical properties, cane and sugar yields in Vertisols of Kenana Sugar Estate, Sudan

Abstract An experiment was conducted to study the effect of heavy disc harrowing in combination with chisel ploughing to depths of 10, 20, and 30 cm, on soil physical properties, cane yield, and sugar yield. The experiment was executed in two non-fallow, two semi-fallow and one fallow field conditions, in Kenana Sugar Estate, Sudan. Results showed that the final surfaces for all tillage treatments were clean and smooth. Percent residue cover ranged from 4.2 to 5.4. After seedbed preparation percent clods greater than 1 cm in diameter ranged from 31.1 to 35.8, while gravimetric moisture content in the tillage zone ranged from 29.9 to 30.5. No significant differences were observed between treatments in residue cover, clod size and moisture content. Soil penetration resistance in the five sites measured after the last irrigation showed no significant differences. Cone index ranged from 802 to 934 kPa. Bulk density measurements also showed no significant differences between tillage treatments. Yield data showed that chisel ploughing to depths of 20 and 30 cm before disc harrowing, significantly increased cane and sugar yields than conventional tillage at Kenana. The highest field productivity (105.27 Mg ha −1 ) was obtained with the combined disc harrowing and 20 cm chisel ploughing. Yield of cane per hectare under this method was 8.38 Mg ha −1 higher than that under the conventional method. Sugar yield per hectare increased by 1 metric ton, which was 8.6% higher than that of the conventional method. The relation between tillage depth ( x ) and cane yield ( Y ), in tons of cane per hectare, for average Kenana field condition could be expressed by the third-order polynomial: Y=158.141−7.725x+0.293x 2 −0.003x 3 The fallow, semi-fallow and non-fallow sites were not significantly different in cane yield. All tillage methods studied were more intensive than adequate levels for soil conservation practices found in the reviewed literature; it is suggested to omit the re-harrowing operation of Kenana conventional tillage.