Slow N-release starch and flour coated urea for lowland rice
1993
Lapis, I.B. (Bureau of Soils and Water Management, Ellipitcal Rd., Diliman, Quezon City (Philippines))
A study was conducted at the Bureau of Soils and Water Management [Quezon City, Philippines] last year, 1992 that tested starch and flour as coating materials for slow N-release of urea fertilizer. Appropriate consistency was attained at 20 percent for starch and 25 percent for flour when mixed and heated with distilled water. Mixture ratio of 30 gm of the coating materials for both starch (CUS) and flour (CUF) per 100 mg of urea were observed to be sufficient, resulting in fertilizer materials with total nitrogen content for both to be about 47 percent but with uneven particle sizes and thickness of coating. CUS has lower cumulative nitrogen release in distilled water than CUF, although both were lower than sulfur coated urea (SCU) which released about 24 percent, 52 percent, and 79 percent of its N-content, respectively, 10-days after application. Slow N-release CUS has made available 66 percent of its N-content 50-days after its application in submerged soil compared to 87 percent for CUF. The results of the study evidently showed that commercially available fertilizer materials can still be improved and that locally available starch is so far the best coating material for urea having 34 percent of its N-content remaining 50-days after its application in submerged soil
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