Effectiveness of sugarcane residue incorporation at different water contents and the Proctor compaction loads in reducing soil compactibility

Incorporation of crop residues into the soil can reduce its susceptibility to compaction. However, the significance of incorporated crop residue at di fferent soil water contents at the time of compaction and the compaction lo ads is not well documented. The compactibility of three soils which contain ed different amounts of sugarcane residue was investigated at different wat er contents and compaction loads. The compaction loads were chosen to simul ate the energy exerted by harvesters, trucks, vanguards, transporters and t he standard Proctor test, respectively A clay loam soil (Typic Ustochrepts) , a clay soil (Typic Calcioahis), and a silty clay soil (Typic Torrifluvens ) were thoroughly mixed with sugarcane residues of 0, 6.9 and 15.3 g per kg of soils, corresponding to 0, 27 and 60 Mg ha(-1), respectively. The sugar cane residue-soil mixtures were compacted using the standard Proctor proced ure with different rammer drops, and dry bulk density was measured. The com paction was carried out at different soil water contents related to the con sistency limits of the soils. Sugarcane residue was effective in reducing b ulk density obtained with different compaction loads at different water con tents. The optimum water content for maximum bulk density under compaction load of 551J was obtained at 0.8 plastic limit (PL). For other compaction l oads, however, the optimum moisture content was at FL. Results suggested th at soil compatibility caused by heavy machinery of sugarcane production at water content lower than FL, can be reduced by incorporating 60 Mg ha(-1) o f sugarcane residue. Filed tests are required in order to verify the labora tory experimental data. (C) 2000 Elsevier Science B.V. All rights reserved.