Changes in chemical properties of soil in an organic agriculture system

Organic agriculture has been associated with the change in soil characteristic and capability of supporting crop growth. The objective of this study was to determine the fluctuation of selected soil chemical properties as managed under organic agriculture system with different kinds of crop for eight years. Observations were carried out during 2013 to 2016 on soil samples collected for total organic carbon, total nitrogen, available phosphate, exchangeable K, exchangeable Al and pH, and crops yield. Total soil organic carbon ranged from 1.97 to 3.46%. Similar patterns were also exhibited by total N and exchangeable K in the range from 0.19 to 0.33 % and 0.22 to 0.44 cmol.kg(-1), respectively. Available P tended to increase linearly from 5.54 to 10.72 mg.kg(-1) as observed on exchangeable K. Soil pH increased in 2014 but tended to steady in the following years. In contrast, the exchangeable Al declined from 1.47 to 0.10 mg.kg(-1). In all cases, the yield of crops in organic agriculture system was lower than that of conventional cropping system. Increasing rate of cow manure application was suggested.