Efficiency of N15 labelled urea applied to rice at reducing water regime
2009
Khanif, Y. M. | Sherihazlin, A.
Water shortage could be a threat to increasing rice production. This study was conducted to determine the effect of reducing flood water in rice production on fertilizer N balance and rice yield using Nsub15 labeled urea. Five water treatments with four replications were arranged in Completely Randomized Design (CRD) as follows: W1 (flooding at 5cm); W2 (flooding at 1cm); W3 (flooding at 5cm then 1cm after 3 weeks); W4 (flooding at 5cm then 1cm after 6 weeks) and W5 (flooding at 5cm then 1cm after 9 weeks). The Bakau Series Soil was filled in each cylindrical concrete culvert. The MR 220 rice variety were sown at the rate of 150 kg/ha. Urea labeled with Nsub15 were applied at 120 kg N/ha in three splits, 60 kg P2O5/ha as Triple Super Phosphate and 60 kg K2O/ha as Muriate of Potash as basal dressings. The standard agronomic practices were applied and rice was harvested after 110 days. The Nsub15 atom excess in plant parts and in soil at different depth was determined by using an emission spectrophotometer. The NDFF (nitrogen derived from fertilizer) were calculated using isotopic dilution technique. The fertilizer N uptake ranged between 48.2 to 57.2 kg/ha fertilizer N recovered in soils ranged between 39.4 to 58.5 kg/ha. The reduction of water input did not have any significant effects on rice yield and fertilizer N balance as in earlier study. Reducing flooding water did not cause detrimental effect on rice yield, fertilizer N efficiency and N uptake. Thus there is a potential to produce rice under low water input to increase water use efficiency.
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