Resumen

TOSQUY VALLE, Oscar Hugo et al. Agro-economic comparison of the fertilization with anhydrous ammonium and urea in rainfed rice. Agric. Téc. Méx [online]. 2008, vol.34, n.4, pp.387-396. ISSN 0568-2517.

During the 2001 spring-summer cycle, an experiment was established at Medellin de Bravo, Veracruz, Mexico, in order to determine the agro-economic effect of two nitrogen sources on grain yield and profitability of rainfed rice, cv. Milagro Filipino. A randomized complete block design with three replications was utilized. Five treatments were evaluated: 1) 0-0-0 as check, 2) 92-46-0, with urea as nitrogen source and triple calcium super phosphate as phosphorus source, 3) 138-69-60, using the same nitrogen and phosphorus sources plus potassium by means of potassium chloride, 4) 92-46-0, using anhydrous ammonium as nitrogen source and triple calcium super phosphate as phosphorus source, and 5) 138-69-60, with anhydrous ammonium, triple calcium super phosphate and potassium chloride. Dry matter production, yield components and grain yield were determined. The fertilization with anhydrous ammonium favored initial plant growth that produced 65.4% more tillers at the onset of the tillering stage and start flowering 6.8 days before that those plants fertilized with urea. Although both nitrogen sources show similar grain yield, the application of 92 kg ha^-1 of nitrogen as anhydrous ammonium and 46 kg ha^-1 of phosphorus, showed the highest net utility, the best profit-cost relationship with 2.01 and a marginal rate of return of 320.81%. This source and dose of nitrogen can withstand a 40% increment in the production costs without a rise in the sale price of the rice grain and still maintain a high marginal return rate of 200.58%. There was no response neither to the application of nitrogen and phosphorus at rates higher than recommended and to potassium fertilization.

Palabras llave : Oryza sativa; economic analysis; nitrogen sources; yield.

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