Effects of long-term application use of compost on the physico-chemical properties of andosols and yields of cabbage [Brassica oleracea capitata] and Japanese radish [Raphanus sativus]

Studies were done on the effects of long-term use of compost made of cow manure and barks on the physico-chemical properties of andosol and yields of horticultural crops. The aim of the studies was to set standards for soil diagnosis and minimum fertilizer application schedules. The yields of cabbages and Japanese radishes were greatly affected by the weather conditions, and they varied considerably, almost two folds between the lowest and highest yields in cabbage heads and more than three folds in the weight of Japanese radish roots. The effect of the application of the compost was not apparent in the first year on the yields of cabbages and Japanese radishes. But the yields increased more than 10% to more than 30% in the following years. However, their yields were not much greater than those in the plots that had only chemical fertilizers, though the compost was given to them for many years. This trend was seen in the yield of Japanese radish roots. If the soil contained a certain amount of phosphorus, the effect of phosphorus in the compost on the yields was not obvious. With regard to the physical property of soil, the difference between the sold phases of the plots with and without compost applications tended to widen. Even when bases were applied equally, the amount of bases in the soil decreased rapidly in the plots with good absorption property while they accumulated in the plots where crop yields were low with not nitrogen fertilizer. Cation exchange capacity (CEC) increased even in the increased with application of the compost and fused magnesium phosphate. CEC increased even in the no-nitrogen plots when phosphorus was applied. Total carbon and total nitrogen increased every year when 3 t/1Oa of compost was applied yearly, though the amounts had some fluctuations.