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

Growth and yield components of sweet potato (Ipomoea batatas L.) were investigated under 0, 25, 50, 75, and 100% application rates of soil test based fertilizer recommendation with 5.5 kg 10a^-1 N, 10.1 kg 10a^-1 P₂O₅, and 19.8 kg 10a^-1 K₂O under polyethylene mulch. Soil chemical properties showed no significantly increased by increasing application rates of fertilizer recommendation. The 75% and 100% treatments increased total fatty acid methyl ester (FAME), bacterial FAME, Gram-negative and –positive bacterial FAME, and fungal FAME. The soil of 75% treatment had a significantly lower community of Gram-positive bacteria compared with 0%, 25%, and 50% treatments. The marketable root number was significantly higher in fertilizer 25% and 75% treatments, whereas marketable root weight was significantly higher in fertilizer 50% treatment. The highest increase in productivity of sweet potato is reached with 75% fertilization (3,305 kg 10a^-1) of fertilizer recommendation and optimum fertilizer rates based on regression yield curve was 80% fertilization of fertilizer recommendation. These results indicate that new soil test based fertilizer recommendation was more effect on the productivity of sweet potato as well as soil nutrient conservation under polyethylene mulch system.

Regression yield curve of sweet potato different according to application rates of fertilizer recommendation.