Effect of root refuse of liquorice on different characteristics of soils from southern regions of Iran. II. Chemical characteristics and fertility indices

Population increase and increasing demand for food have extended agriculture to troublesome lands with low organic matter. Incorporation of organic residues and build up of soil organic matter is a practical way to improve the undesirable properties of such lands. Root refuse of liquorice is added to soils as a soil amendment in some parts of Iran, but its effects on soil chemistry and fertility has not been studied yet. The present study was conducted to evaluate the effect of root refuse of liquorice on some of the soil chemical properties (e.g., pH and EC), and fertility indices such as nitrogen (N), phosphorus (P), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) concentrations. To 6 samples of surface soils (0- 15) em of southern Iran, equivalent rates of 0, 10, 20, and 30 tons ha(-1) of root refuse of liquorice were added, and the samples were incubated under room temperature and moisture content of field capacity for 50 days. At the end of incubation time, pH and EC as well as the total-N, extractable-P, Zn, Mn, Fe, and Cu were determined. Application of root refuse of liquorice, especially at higher rates, resulted in ( I) increases in the pH and decreases in the EC, (2) no significant changes in the total-N but decreases in the extractable-P, and (3) increases in the extractable Cu, Mn, and Fe, and decrease in Zn of the tested soils.