ISSN:
1573-0867
Keywords:
Urea prills
;
urea granules
;
floodwater nitrogen
;
grain yield
;
N uptake
;
Oryza sativa L.
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Laboratory and greenhouse experiments were conducted to determine whether the efficiency of broadcast urea in wetland rice cultivation can be improved by using large granules which penetrate the puddled soil. In laboratory experiments the penetration increased with increasing granule size. Penetration was improved by having only a waterfilm on the soil and by the granules entering the soil with speed. In pot experiments with rice, N concentrations in the floodwater were lower with large granular urea (LGU, 6 to 8 mm diameter) dropped from a height of 2 m or shot with force into the puddled soil than with either prilled urea (PU) or LGU placed on top of the soil (+0cm). N concentrations in the floodwater were reduced even further by placement of LGU at 1 and 4 cm depths (−1 and −4cm, respectively). At all rates of N, the N uptake by grain plus straw increased with decreasing N concentrations in the floodwater. The apparent recovery of N in grain plus straw increased in an experiment on sandy soil from 61 to 85% in the order PU +0cm, LGU +0cm, LGU dropped, LGU −1cm, LGU shot and LGU −4cm. In an experiment on clay soil apparent recovery increased from 47 to 90% in the order PU +0cm, LGU +0cm, LGU dropped, LGU −0cm, LGU shot, LGU −1cm and LGU −4cm. LGU placed at −1 and −4cm resulted in significantly greater N uptake by grain plus straw than the other treatments. The experiments showed that the efficiency of broadcast urea is improved by using large urea granules, at least when conditions are favourable for penetration into the puddled soil.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01080682
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