Effects of cow dung manure on some physical And chemical properties on saline - sodic soils in Kiboko Makueni district (Kenya)

Abstract

The effect of cow dung manure on some physical and chemical properties of salinesodic soils in Kiboko, Makueni district were examined. Two soil types, namely, chromo- haplic Lixisols for site 1 and mollic and sodic Solonchaks for site 2 were selected in two different farms. Within each farm, 15 plots each measuring 5 x 5 m were treated with different levels of cow dung manure (0, 10, 20, 30 and 40 tonnes/ha) in three replicates. After 18 weeks of application of cow dung manure, soil samples were taken from the top two horizons for physical and chemical analysis. In addition, water samples used for irrigation were analyzed to determine their chemical characteristics and their suitability for irrigation. At site 1, there was little evidence of improving the physical and chemical properties of the soil ,notably, bulk density, antecedent moisture content, organic carbon, soil pH, EC, CEC, % total N, ESP and SAR when compared with the control. However, after the application of 40 tonnes /ha there was significant difference in aggregate stability (P::; 0.05) among the treatments and the two top horizons when compared with the control. Similarly Ksat significantly improved (P::;0.05) after the application of 20 and 40 tonnes ha-l. The highest final infiltration rate was obtained from the plots which received 20 tonnes /ha of cow dung manure. This was significantlydifferent (P::; 0.01) from the control. At site 2, there were significant improvements in aggregate stability, infiltration rate and available water. In the two top horizons, aggregates stability improved with increasing rate of cow dung manure. There were significant differences in aggregate stability among the treatments (p::;0.01) when compared with the control. After the application of30 tonnes/ha the final infiltration rate were significantly different (psO.05) from the control, while other physical and chemical parameters improved slightly. The irrigation water from the boreholes in the two sites fall under very high saline class (EC= 4.08 and 5.10 dSm-1 at 2Stpc for site 1 and 2 respectively) and low to medium sodium hazard (SARadj=lS.27 and 11.92 for site 1 and 2 respectively). The Kiboko river, which was also used in site 2, falls under medium saline class (EC= 2.04dSm-1 at 2S0c) and low sodium hazard (SARadj=3.92).