Vol. 5, Issue 2, Part A (2023)

Compost is the organic matter derived from plants, animals, and waste organic decomposition or fermentation subjected to the process. The addition of organic matter to the soil is very important so that plants get enough nutrients for growth. One of the materials in making compost is water hyacinth. Inorganic fertilizers are deliberately created by human beings in factories and contain high levels of certain. As for some commonly used inorganic fertilizers such as urea, SP-36, KCl, and ZA (Ammonium Sulphate). The research aimed to determine the effect of water hyacinth compost and N, P, K, and S fertilizer application on K-available, K-uptake, and yield of shallot plants. The experiment was carried out from June to September 2020 at the Experimental Garden of the Laboratory of Soil Chemistry and Plant Nutrition, Faculty of Agriculture, Universitas Padjadjaran, Jatinangor, Sumedang. The experimental design used was a randomized completely block design (RCBD) consisting of seven treatments with four repetitions, namely: control; 1 N, P, K, S recommendations; ¾ N, P, K, S recommendations; ½ compost + ¾ dose of N, P, K, S; 1 compost + ¾ dose of N, P, K, S; 1½ compost + ¾ dose of N, P, K, S; and 1 compost + 1 N, P, K, S. The compost used 25 Mg ha-1 water hyacinth compost and the recommended fertilizer was 200 kg urea, 300 kg SP-36, 200 kg KCl, and 500 kg ZA. The results showed that (1) a combination of water hyacinth compost with N, P, K, and S fertilizers was affected significantly K-available, K-uptake, and shallot bulb yield consisting of wet weight, dry weight, and number of bulbs; and (2) The ½ Compost + ¾ N, P, K, and S fertilizer treatment produces eight tubers per polybag with an average fresh tuber weight and dry stored tuber weight respectively weighing 113.24 g and 83.83 g polybag-1, this treatment is the most efficient in increasing the quantity of shallots because it did not show significantly different results from the 1 compost + ¾ N, P, K, S fertilizers treatment which produced the highest quantity among the other treatments.