Evaluation of the potential of Zeolite as a soil conditioner for two Zambian Soils

Abstract

Poor nutrient and water holding capacities characterise highly weathered soils, thereby limiting soil productivity. This study was conducted to investigate the potential of improving soil productivity through amending soils with zeolite to effect improvements on moisture and cation retention capacities. Two experiments were carried out: i) In the first experiment, an ALISOL and ACRISOL were each amended with zeolite to effect increases in CEC by 0, 25, 50, 75, 100 and 125%. The mixtures were placed in pots and allowed to equilibrate for a period of six weeks, and thereafter soil moisture retention and CEC were determined. ii) In the second experiment, the agronomic performance of zeolite was evaluated on the same soils used in the first experiment. A factorial experiment was carried out in the greenhouse with five levels of urea (0, 1, 2, 3, 4 g / plant) as the main plot, and zeolite to effect an increase of 0, 25, 50, 75 and 100% on CEC as the sub-plot. Maize was used as the test crop and this was harvested at the end of eight weeks when dry matter yield was determined. Significant (p<0.05) increases in moisture retention and CEC were obtained. For every gram of zeolite added to a kilogram of soil, plant available water increased by 0.12% for ACRISOL and a non-significant increase of 0.02% on ALISOL. Soil CEC increased by 0.10 cmol/kg and 0.11 cmol/kg for ALISOL and ACRISOL respectively. A combination of urea at 2 g/pot and zeolite at 100% CEC increase increased maize dry matter yield by 75% in the ALISOL and 57% in the ACRISOL. When the zeolite application rate exceeded 16.21 g / kg soil (36.58% in ALISOL and 60.27% in ACRISOL), maize dry matter yield declined. This was found to correlate with declining tolerance of maize to increasing sodium (Na) concentrations. This study has shown that within a limited range, addition of zeolite iv to soils can help increase soil productivity by increasing soil moisture retention and cation exchange capacities.