Analysis of NPK nutrient content and the nutrient balance of cassava for sustainable high productivity in Ultisols soil

The decline in soil fertility and productivity has been a problem in cassava cultivation. The plant biomass transported from cassava fields at harvest losses several nutrients. This study aimed to determine the nitrogen (N), phosphorous (P), and potassium (K) nutrient content of plant parts of cassava and the nutrient balance. The cassava varieties of UK1 Agritan, Malang 4, Barokah, UJ-5, and Mangu were grown in 3 replications using a completely randomized design. Two harvesting methods, the farmer’s harvest method (FHM) and the harvest method introduced (HMI) were applied. The FHM transported all tuber and other plant parts biomass, and the HMI transported all tuber and 60% of the stem from the cassava field. Each replication was one row of plants 20 m long and a spacing of 1 m. The cassava fertilized at 169 kg N, 84 kg P, and 170 kg K per hectare in grooves around the plant. The leaves of the five varieties contain higher N, P, and K than the petiole, stem, and tuber. At harvest, the N and P nutrients were mainly transported from the leaves, and K nutrients from the tubers. For a yield of 40 tons ha-1 fresh tubers, the FMI resulted in an average nutrient balance for N (-222 kg ha-1) and K (-103 kg ha-1) and P (48 kg ha-1), the HMI resulted in an average nutrient balance of 305 kg N, 56 kg P, and 82 kg K per hectare. The HMI is recommended for sustainable soil fertility and high productivity of the cassava field