Estimation of Optimum Organic Fertilizer Application under Fertilizer Recommendation System

Organic fertilizer has been one of soil management to improve crop productivity and soil fertility.Unfortunately, there is little information on optimum level of organic fertilizer for crop cultivation.In this study, we were tried to use the fertilizer recommendation system for determining organic fertilizer application under upland soil condition.This work was carried out; 1) to compare the effects of organic fertilizer and compost application on yields of Chinese cabbage, and 2) to estimate optimum levels on three types of organic fertilizer of 0, 50, 100, 200, and 400% with 320 kg N ha -1 .The yield of Chinese cabbage in organic fertilizer plots was ranged from 71.3 to 74.1% compared to yield index of NPK. which was 2-7 times higher than in compost treatments due to improvement of N uptake efficiency.However, organic fertilizer was required addition of about 1.5-2.0times amount to the 4 Mg ha -1 to gain the same yield of NPK treatment, these was similar soil properties of NPK treatments.This result indicated that fertilizer recommendation system could be alternative to calculate optimum levels of organic fertilizer for crop cultivation in upland soil.