Soil Nutrient Balance in Farming Systems of the Agricultural Resource System Research Station, Chiang Mai, Using Plot Database for Rapid Assessment

The objective of this study was to assess the soil nutrient and organic carbon balances in a farming system of Agricultural Resource System Research Station, Chiang Mai, Thailand. According to FAO framework, quantification of key soil nutrient inputs and outflows by plant nutrient components and regression models were applied to evaluate soil nutrient and soil organic carbon balances by using the extracted data of 39 rice-based cultivated plots from the tailored plot database during July, 2014 and June, 2015. The assessment results indicated that 63.13 kg N and 40.52 kg K/ha/yr from crop residue and green manure sources (IN2) were needed for maintaining the balances. In order to maintain phosphorus balance, only phosphorus from IN2 was not possible, but needed to apply 65.03 kg P/ha/yr from mineral fertilizer and manure sources (IN1). At least 5,219 kg/ha/yr of organic carbon was required to recover the soil organic carbon balance, which in the cultivation implementation, incorporating one crop of green manure before rice cultivation should be considered.