Effects of biosolid application on soil properties and kiwi fruit nutrient composition on high-pH soil

Macro- and micronutrient availability in high-pH soil is a major constraint in crop production especially for the sensitive plants, such as kiwi fruit. A field study was conducted to investigate the multiyear effects of biosolid application on nutrient availability of agricultural soil and elemental sufficiency in kiwi fruit. Solar-dried biosolid applied at 0, 25, 50, 100 and 200 t ha(-1) annually for successive 2 years. The considered soil properties included pH, EC, organic matter, N, P, K, macro-microelements, heavy metals and DTPA-extractable elements were determined. Results showed that biosolid addition significantly reduced to initial soil pH from 8.2 to 7.8 at higher application doses. Optimization of pH resulted in increased levels of soluble elements in all treatments studied. Biosolid application particularly increased Fe, Cu, Zn, Mn and B concentrations to sufficient levels. Among the other elements analyzed, were not significantly affected by biosolid application. Biosolid addition also increased soil DTPA-extractable elements, especially Cd, Cu, Mn, Pb and Zn. Significant increases in DTPA-extractable elements occurred for increasing application rates at 50, 100 and 200 t ha(-1) compared to control. We conclude that municipal biosolid applied at an annual rate at or less than 200 t ha(-1) can be safely used for kiwi fruit production on high-pH soils.