Introduction of On-site Soil Analysis and Diagnosis System

Abstract

Crops must absorb all essential elements sufficiently, because a yield of crop is determined by the Minimum which is the growth limiting factor of Liebig's law of minimum. The minimum is determined by soil testing and recommended as a fertilizer corresponding to the amount of crop production for the crop period before cultivation but the amount of the fertilizer is supplied by farmers’ experiences on the growing condition of crop during cultivation. Owing to the diversity of soil chemical properties, soil must be categorized to be recommended the adequate amount of fertilizer. Therefore we categorized soil as 8 soil testing types with soil pH and soil organic matter (SOM) of Korean soil information system. We also set up the on-site soil analysis and diagnosis system in order to recommend the nutrients by soil testing during cultivation. The process of system was composed of three steps: 1) analyzing chemical properties of pH and Eh and nutritional properties of N and P and osmotic properties of EC or sum of nitrate and sulfate and chloride, 2) diagnosing soil condition as one of 64 kinds of soil conditions with categorizing with 4 chemical properties and 8 nutritional status and 2 osmotic aspects, 3) recommending the amount of minimum according to the soil condition and soil testing type and how to supply fertilizers by a series of pH buffer and fertilizer and water. Soil diagnosis chart Nutrient situation Chemical situation 5.6 ≤ pH ≤ 7.4 pH ≤ 5.5 pH ≥ 7.5 Eh7 < 0.48V NP sufficiency NP sufficient Worrying NO2 Worrying NH3 Worrying denitrification NP deficiency NP shortage Volatilizing NO2 Volatilizing NH3 Denitrification P deficiency P shortage N/P imbalance (P precipitated by Al, Fe) N/P imbalance (P precipitated by Ca, Mg) Immature compost N deficiency (good growth) Crop uptake N Volatilizing NO2 Volatilizing NH3 Denitrification N deficiency (bad growth) N shortage Highly volatilizing NO2 Highly volatilizing NH3 Excessive denitrification N excess Excessive N fertilizer Excessive N fertilizer and Immature compost Excessive compost and manure High N immature compost P excess Excessive P fertilizer - - Soluble P fertilizer or excess manure K excess Reverse osmotic pressure - Excessive compost tea Excess immature compost