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Agronomy Journal Abstract -

Comparison of Sulphate of Ammonia and Slow-Release Nitrogen Fertilizers for Rice in Trinidad


This article in AJ

  1. Vol. 61 No. 5, p. 730-734
    Received: Feb 17, 1969

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  1. N. Ahmad and
  2. P. T. S. Whiteman2



Two slow-release pelletted N fertilizers manufactured by Esso Engineering and Research Ltd. known as EAP 3032 (17.7% N, 21 days to release 15%) and EAP 3033 (18% N, 63 days to release 75%) were compared with (NH4)2SO4 as sources of nitrogen for the rice variety ‘Bluebelle’ in Trinidad. Nitrogen dressing from all sources was 70 kg/ha applied at transplanting. The slow release materials were buried 5 cm into the soil after transplanting while the (NH4)2SO4 was applied and cultivated into the soil just before transplanting. The effect of these treatments on yield, growth, and N uptake was estimated. EAP 3033 resulted in increased yield of 2,920 kg/ha; EAP 3032, 2,060 kg/ha; and (NH4)2SO4, 1,195 kg/ha. The response was made up by small increases in all yield components but especially panicle weight resulting from more spikelets per panicle and a higher percentage of filled grains. The fertilizers reduced the response to a top dressing of N applied 35 days after transplanting, especially the EAP 3033 treatment. The pattern of N recovery by the crop was closely related to the release of N from the fertilizers. Plants treated with (NH4)2SO4 had absorbed all of their N when they had accumulated only 50% of final dry weight. At the same stage plants treated with slow-release materials had absorbed only half of their final N content and they continued to absorb N to much later stages in growth.

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