BIOFERTILIZER-COATED UREA FOR PROMOTING YIELD OF LETTUCE AND REDUCING NITROGEN FERTILIZER DOSE IN FIELD EXPERIMENT

Abstract

Urea intensive application is considered to reduce soil quality, and food quality. The constraints of urea application in tropics are low effectivity due to intensive leaching and volatilization. In order to decrease the urea dose, cheap and renewable biofertilizer application is suggested. Coating urea with biofertilizer become an easy way to apply both biofertilizer. In the previous research, biofertilizer-coated urea (BCU) had been formulated by using Bacillus subtilis, B. megaterium, Azotobacter chroococcum and A. vinelandii. The objective of this research was to verify the effect of BCU on the growth and yield of lettuce (Lactuca sativa L.) cv. Romaine; and decrease of urea dose in a planting season. The field experiment was arranged in randomized block design with five treatments and five replications. Lettuces were treated with a dose and half dose of two BCU formulations. The results showed that BCU didn’t affect growth, P uptake and plant yield but half dose of BCU produced the same lettuce productivity with one dose of urea. Half dose of BCU resulted in the same shoot N uptake as one dose of urea but a dose of particular BCU formulation possibly decreased N uptake. The population of total Bacillus and Azotobacter in the rhizosphere was determined by dose and BCU formulation but they didn’t change abruptly after BCU application. The experiment suggested that application of urea coated by carrier-based biofertilizer was reliable to support lettuce cultivation and reduce the urea dose.