Enhancing effect of nitrogen and phosphorus on azolla (Azolla microphylly) in rice production in acid sulphate soil
1996
Adhikary, Bishnu Hari | Prayoon Swatdee | Somsak Vangnai | Tasnee Attanandana | Prapa Sripichitt (Kasetsart Univ., Bangkok (Thailand). Faculty of Agriculture. Dept. of Soil Science)
Experiment was carried out at Pathumthani Rice Research Center in the year 1995/96 to evaluate the effects of 1) Azolla-N and urea-N to rice in acid sulphate soil, and 2) the split application of P on Azolla biomass production. The soil at the experimental site was classified as Sulphic Tropaquepts : isohyperthermic acid in Rangsit Series (RS). To evaluate the effect of P, the Azolla was inoculated 20 days before transplanting and 5 days after transplanting as dual-crop with rice. P was applied as basal or splitted 2 and 4 times at 10 and 5 days intervals, respectively. The results indicated that maximum fresh biomass can be produced with 2 or 4 split application of P. N content and total N production in Azolla was found significantly higher with 4 split applications of P. Azolla doubling time, its biomass production and N content were not affexted by its cultivation methods. Split application of P to Azolla resulted in higher grain yield and total dry-matter production in rice. N-yield (uptake) in rice was found to be increased with increasing number of split applications of P to Azolla.
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