Effects of rice husk application on mechanical properties and cultivation of a clay soil with and without planting

Abstract

In this study, effects of rice husk (RH) application on mechanical properties and cultivation of a clay textured soil were investigated with and without barley planting. A rate of 5% (w/w) rice husk as a dry weight basis was added to a clay textured soil by alone (RH) and with 5 kg N/da of ammonium sulphate (RHN) in order to increase the biological activity and the decomposition rate of rice husk in soil. Rice husk applied soils including control treatment were incubated at field capacity under greenhouse conditions for 2 months. After this period, barley was sown in a half number of the pots. All pots having barley planted and without planted were incubated together for 6 more months. Study was carried out in a factorial experimental design on barley planting and without planting pots in 3 treatments (control, RH and RHN) with 3 replications. At the end of the study, liquid limit (LL), plastic limit (PL), plasticity index (PI), consistency index (Ic), field capacity (FC), permanently wilting point (PWP) and organic matter (OM) contents of soils were determined. The highest values were determined for LL in RH+nitrogen+barley planting (RHNP), for PL in RH application without planting and for PI in control application with barley planting (CP). Barley planting increased LL and PI values of soil significantly. LL values of soils significantly correlated with PL (0.664**), PI (0.880**) and PWP (0.948**). PL values of soils significantly correlated with OM (0.699**) and PWP (0.821**). PI values of soils significantly correlated with FC (0.654**) and PWP (0.713**). Ic values gave the significant correlations with PL (0.908**), OM (0.787**), FC (-0.611**) and PWP (0.615**). Ic values in all RH treatments were higher than that in control treatments. It was concluded that clay textured soil in control treatment can have deformation when it is cultivated at the field capacity without RH application; however clay soils can be cultivated without deformation after application of RH.