Impact of Soil Fertility in 93 Paddy Fields of Hokuriku Region

To contend with decreasing gross amounts and soaring costs, viable rice production in Japan requires high yield levels. This chapter assessed the effects of nitrogen fertilizer and soil chemical properties on rice yield. Data were collected from 93 paddy fields at a farm larger than 30 hectares in Hokuriku Region, Japan. Koshihikari, the most widely planted rice variety in Japan, was cultivated in the sampled fields. Soil chemical properties were quantified using 12 variables, namely pH, cation exchange capacity, phosphoric acid content, silicic acid content, content, and saturation of the three exchangeable bases, and the equivalent ratios of calcium to magnesium and magnesium to potassium.