APPLICATION OF VERMICOMPOST TO BORO RICE (BRRI dhan 28) CAN SAVE PHOSPHATE FERTILIZER WITH SUSTAINING PRODUCTIVITY AND SOIL FERTILITY

The study was conducted to investigate the application outcome of vermicompost (VC) and phosphorus (P) on the growth, yield contributing traits, yield, and post-harvest soil fertility status. Six treatment combinations were used and which were T1: VC0% P0% (Control treatment); T2: VC100% P0% (VC @ 6 t ha-1 + P @ 0 kg ha-1); T3: VC75%P25% (VC@ 4.5 t ha-1 + P @ 22.5 kg ha-1); T4: VC50% P50% (VC @ 3 t ha-1 + P @ 45 kg ha-1); T5: VC25% P75% (VC @ 1.5 t ha-1 + P @ 67.5 kg ha-1) and T6: VC0%P100% (VC @ 0 t ha-1 + P @ 90 kg ha-1). Recommended doses of VC and P were 6 t ha-1 and 90 kg TSP ha-1, correspondingly. Recommended amount of urea, muriate of potash, gypsum and zinc sulphate was implemented to each study unit, and TSP and VC were applied as per treatments specification. Different growth and yield influencing traits namely the plant height, number of leaf hill-1, number of effective tillers hill-1, number of spikelet panicle-1, number of grains panicle-1, number of filled grains panicle-1, as well as grain yield and biological yield were obtained with the highest values in T3 (VC75% P25%), and almost all the values were statistically analogous to T4 (VC50% P50%) treatment, in some cases with T5 (VC275% P75%) treatment. Contrastingly, the lowest values were found in T1 treatment (control). Addition of VC with P improved soil properties by increasing significantly the soil pH, soil organic matter, total N and available P content as well as by increasing numerically in the content of post-harvest soil regarding exchangeable K and available S. The studied soil properties are positively correlated between each other, in which the relation of grain yields with P, K and S was more significant. In most of the cases, remarkable improvement in the soil fertility status was observed due to the addition of VC (3.0-4.5 t ha-1) with lessened P level (22.5-45.0 kg ha-1). Thus, the results indicate that application of 3.0-4.5 t VC ha-1 reduced the use of phosphatic fertilizer at a substantial level (50-75%) for attainable grain yield with improving soil fertility which ultimately reduced the chemical fertilizer use in rice. So, for long time sustaining yield and soil fertility, VC @ 3.0-4.5 t ha-1 can be employed into the soil that can save inorganic P fertilizer, and it may be an efficient approach for boro rice cultivation.