Influences of Combined Application of Organic and Inorganic Fertilization Rates with Biofertilizer on Potato under Integrated Weed Managements

The complementary effects between different rates of inorganic and organic fertilization in the presence of multi-biofertilizer and integrated weed managements on tuber yield of potato and associated weeds were studied in two successive seasons in sandy soil. The initial biofertilization, raised the counts of phosphate dissolving bacteria, Azotobacter spp., Azospirillum spp. and Pseudomonas spp. in potato rhizosphere receiving organic manure, compared to chemical fertilizer application under different weed control treatments. Associating biofertilizer with 75 or 50% farmyard manure (FYM) and 25 or 50% NPK fertilization under hand hoeing application respectively, acquired always higher counts of tested microorganisms. The results indicate that the highest number and dry weight of weeds were exerted by using 75% FYM and 25% NPK compared to other fertilization treatments. Application of half rate of metribuzin herbicide and supplementary by one hand hoeing was the master weed control treatment and produced the highest tuber yield. Addition of fertilizing necessity to potato plants as 50% from organic source (FYM) and 50% from inorganic fertilizer (NPK) along with biofertilizer produced the greatest number of tubers per plant, tuber weight and tuber yield with 6.3, 26.3 and 41.7% increases over the standard treatment (100% NPK). Application of 50% FYM + 50% NPK along with biofertilizer recorded the highest values of N, P and K in potato tubers under different weed control treatments. Generally, under the conditions of the complementary fertilization (50% FYM+ 50% NPK) in the presence of biofertilizer and integrated weed control method (half rate of metribuzin + one hand hoeing) led to greater tuber yield of potato