Resumen

ALFONZO, Nidia et al. Nitrogen use efficiency in upland rice on an acid soil in western Guárico State. Agronomía Trop. [online]. 2011, vol.61, n.3-4, pp.215-220. ISSN 0002-192X.

In order to evaluate absorption efficiency, agronomic use and recovery of N in rainfed rice, Oryza sativa L., cultivars in soil acid condition (acid Kandic Plinthustults), a field experiment was carried out using two cultivars, the CT-102 and FONAIAP-2000 (F-2000) at southeastern of Guárico State. The experimental design was randomized block with three replications. The doses of nutrients (kg ha-1) were 80-100 N, 80 P and 80 K, was used urea, diammonium phosphate and potassium chloride as nutritional sources. 15N-urea (5 atom% excess) was used in the isotopic microplots. At moment of harvest samples were taken of soil and plant (crop and weed) for chemical determinations, were calculated the efficiency of use of nitrogen fertilizer (EUFN), agronomic efficiency (EA) and harvest index (IC). Grain yield ranged from 5.0 to 5.9 t ha-1 significantly higher in F-2000. between cultivars were not observed statistical differences for EUFN and IC. Althought were observed significants differences statistical for N derived from fertilizer and EA. The highest grain yield and N efficiency was observed in F-2000 with high potential to be used in soil acid. The results also show that although the crop had a better response with higher doses of N, efficiency use of N tends to decrease, implying that excess of nitrogen removed of the soil-plant system could cause more environmental pollution.

Palabras clave : acidic soil; efficiency; nitrogen; Oryza sativa L; poorly drained savannas; rainfed.

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