Efficiency of azolla as an organic N source for rice
1987
Patro, G.K. | Mohanty, K. | Jena, B.K. (Orissa Univ. of Agriculture and Technology, Orissa, Bhubaneswar (India))
A 3-yr experiment at the Cropping Systems Research Centre were laid out during 1983-86 wet and dry seasons. Treatments were azolla alone, azolla in combination with nitrogenous fertilizers, and N fertilizers alone, at three N levels in a randomized block design with four replications. P and K (17.5 kg P, 33 kg K/ha) were constant for all treatments, including control. Chemical analysis established 4% N content of azolla, based on dry weight. Azolla inoculated at 1 t/ha at transplanting, with 3.5 kg P/ha, recorded a fresh weight of 5 t/ha at incorporation 20 d after transplanting. In the wet season, yield with N fertilizer were consistently higher than that of control. Yield with fresh azolla inoculated at 1 t/ha with 3.5 kg P/ha and incorporated 20 d after inoculation were equal to yields with 5 t fresh azolla/ha incorporated before planting. In the dry season, yields with 90 kg N/ha were significantly higher than in all other treatments. Azolla at 5 t/ha yielded 0.6 t/ha more than control. The actual benefit of azolla in combination with fertilizer was rather inconsistent. But azolla alone showed significantly higher yields than control. This study suggests alternative fertilizer strategies when chemical fertilizers are scarce or expensive.
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