Study on the efficiency of urea and ammonium phosphate fertilizers as a direct use for maize
1988
Charintorn Dajdamrongpreecha
Corn grown on all three soils i.e. Pak Chong, Chok Chai and Warin soil series showed marked response to added fertilizers. The magnitude of response were varied with soil types and fertilizer rates. By average, the maximum responses was obtained at the highest fertilizer rate of 15-15-15 kg. of N-P2O5-K2O per rai respectively. Generally, the relative effectiveness of mixed fertilizer grades 16-20-0, 20-20-0, 11-52-0 (monoammonium phosphate) and 18-46-0 (diammonium phosphate) as well as various application methods i.e. broadcast, sidedress and banded were comparable. Apparently, monoammonium phosphate and diammonium phosphate fertilizers in combination with urea could be used for corn as an alternative sources for mixed fertilizer grades 16-20-0 and 20-20-0 usually recommended for corn. For the greenhouse test, addition of diammonium phosphate fertilizer slightly increased the pH of soils. Besides the content of extractable ammonium-nitrogen in the soil was also increased markedly as compared to the soils treated with 16-20-0 and 15-15-15 mixed fertilizers. Nevertheless, fertilizer sources and application methods exerted no striking effects on the change in exchangeable calcium and extractable phosphorus in the soils. For plant growth, applied diammonium phosphate had slight depressive effect on corn seed germination in Pak Chong soil but not evident in Warin soil. Generally corn grew for 14 days showed marked response to added fertilizers. However, the influence of application methods and fertilizer sources were not striking and consistent.
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