Korean Journal of Soil Science and Fertilizer ISSN:0367-6315(Print) 2288-2162(Online) 한국토양비료학회 학회지

Soil organic matter (SOM) is one of the most representative indicators of soil fertility. In order to quickly estimate the SOM content through soil color in the field, a soil color chart (AG-1941-Color Chart, University of Illinois Extension, USA) and soil color meter (SPAD 503) were used. The results are summarized as follows. A total of 173 soil samples were analyzed, of which 78 were paddy soil and 95 upland soil (including plastic film house soil). The soil color mater was more useful than the soil color chart in estimating the SOM content. The coefficient of determination of the regression equation for estimating soil organic matter content using the soil color chart was 0.5857*** for upland soil, 0.5460*** for all soil, and 0.3499*** for paddy soil. In the case of upland soils, estimating the SOM content using regression model of upland soil had higher estimating power than using regression equation of all soils. The coefficient of determination of the regression equation for estimating soil organic matter content using a soil color meter was higher in the model divided (R² = 0.9537***) in to paddy and upland soil than in all soil model (R² = 0.7738***). When the highest value of SOM content used for model validation was excluded, the coefficient of determination of the existing model was reduced, but the trend was the same. When using the soil color meter, the all soil model decreased from 0.9029 to 0.5723, and from 0.9095 to 0.6879 when dividing the paddy and upland soils. Also, when using the soil color chart, the all soil model was reduced from 0.5246 to 0.2111, and when dividing the paddy and upland soil from 0.5987 to 0.1863.

Soil organic matter content estimation model using SPAD 503.