Total N in Soil, N Absorption, and Growth of Corn (Zea mays L.) Due to the Amendment of Sago Palm Waste Compost and NPK Compound Fertilizer to Ultisols

Ultisols is one of Indonesia’s largest soil orders (41.9 million ha) of the total acid dry land (102.8 million ha). Considering its wide distribution, Ultisol can be used as agricultural land. However, Ultisols are acidic to very acidic reactions, with pH around 3.10-5, high nutrient leaching, low organic matter content, and macronutrients. Applying organic matter to reduce the leaching of bases and improve soil chemical activity is important in overcoming the Ultisol soil problem. Corn is an agricultural commodity that has a strategic role in providing food and increasing the national economy. Corn is a source of carbohydrates and protein that can substitute for or complement rice. The research objective was to determine the effects of organic fertilizers when applied together with NPK compound fertilizers on soil N-total, N-uptake by plants, growth, and yield of maize. The study was carried out in a plastic house using a completely randomized design with a factorial pattern: factor 1. Sago palm waste compost (K) consisted of K0 0 tons ha −1 , K1 15 tons ha −1 , K2 30 tons ha −1 and K3 45 tons ha −1 , while factor 2: NPK fertilizer (M): M0 0 kg ha −1 , M1 150 kg ha −1 , and M2 300 kg ha −1 . The results showed that the treatment of compost sago palm waste independently could increase plant growth. Plant height and the number of leaves were 161.29 cm, and 12.56, respectively. Applying 30 tons ha −1 of sago palm waste compost and 150 kg ha −1 of NPK fertilizer could increase soil total-N and plant N uptake by 0.30% and 2.33%, respectively.