Effects of tillage, stubble and rainfall energy on infiltration

Simulated rain, of high and low drop kinetic energy, was applied to a range of tillage and stubble treatments, to determine whether any soil physical changes that had occurred affected infiltration of rainfall into soil. Soils from two tillage trials were examined. One is a hardsetting alfisol where wheat had been grown for 4 years, and the other is a stable oxisol where maize had been grown for 7 years. Stubble was removed from the surface of both soils so that the effects of soil physical properties on infiltration could be measured. Existing crusts were removed on the oxisol to measure infiltration as a response to soil physical properties. Existing crusts were left intact on the alfisol to examine effects on infiltration of seal formation over a fallow period. Constant conductivity and transient conductivity Green and Ampt equations were filted to the infiltration data to allow comparison between treatments. Results indicate there was no surface sealing under low energy rain, but under high energy rain, surface sealing reduced infiltration. For both soils, where there was no pre-existing seal, infiltration did not vary across tillage treatments (averaged over stubble treatments) indicating that tillage management had not caused changes in soil physical properties that affect infiltration. On the alfisol, seals formed rapidly and infiltration was greatly reduced when there was no stubble present. Tillage throughout a fallow period improved infiltration by destroying seals.