THE POTENTIAL OF THE CONSORTIUM (Azotobacter spp. and Phosphate Solubilizing Bacteria) IN INCREASING PLANT N UPTAKE, PLANT NITROGEN CONTENT, Azotobacter spp. POPULATION AND LETTUCE (Lactuca sativa L) CROP YEALD

Abstract

Indonesia is a tropical agricultural country that has an Andisol soil order which is potential to be used for the cultivation of lettuce (Lactuca sativa L.). To increase lettuce yields, farmers generally use excessive synthetic NPK fertilizers. This has resulted in serious pollution and land degradation. As an effort to restore soil fertility conditions that are environmentally friendly is through the application of biological fertilizers. Biofertilizer inoculation that potentially used is a form of consortium, which consists of the N-fixing group, namely Azotobacter spp and phosphate solubilizing bacteria (Pseudomonas sp.). The characteristics of the consortium inoculant that need to be investigated are its viability and effectiveness when applied in the field to lettuce cultivation. The experimental data analysis was carried out based on the linear model of the Randomized Block Design (RBD), consisting of seven treatments, namely: control; NPK 100% recommended dosage; consortium 10 l / h + 100% NPK; consortium 10 l / h + 75% NPK; ; consortium 10 l / h + 50% NPK; consortium 10 l / h + 25% NPK. The results showed that consortium inoculation of 10 l / h + 50% NPK could increase the population of Azotobacter spp. and the yield of fresh lettuce increased by 49.24%. Meanwhile, in the application of the consortium inoculation of 10 l / h + 25% NPK, tend increasing N absorption value. The consortium inoculant can reduce the NPK requirement by 50% followed by a higher fresh weight yield of lettuce compared to use 100% NPK, by using conventional method.