Improvement of Application Method of Liquid Fertilizer with Irrigation Water for Uniform Topdressing and Change in Nitrogen Concentration of Flooded Water after Application
- Other Title
- ミズグチ リュウニュウ セヒキ オ モチイタ ダイ クカク スイデン ニ オケル スイトウ エキヒ リュウニュウ ノ キンイツ セヒ コウカ ト コウリツテキ セヒ ジョウケン ノ ケントウ
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The application method of liquid fertilizer with irrigation water was tested in large scale paddy fields using a newly developed fertilizer supplier which can make a supplying rate of liquid fertilizer constant. Uniformity of fertilization, change in the nitrogen concentration of flooded water and absorption of applied nitrogen by paddy rice were examined. High uniformity of fertilization was achieved with this method as compared with a conventional broadcast application of granular fertilizer, or an inflow fertilization of granule-like fertilizer with irrigation water. When urea was applied as liquid fertilizer, the fertilizer-N disappeared quickly from ponding water under shallow conditions of ponding water depth. In the case of the same depth of ponding water, the rate of reduction was large under conditions of large permeability of water. The nitrogen utilization rates of urea and ammonium sulfate labeled with ^<15>N were not related to the depth of ponding water at the time of fertilization. When ammonium sulfate was supplied the nitrogen utilization rate was around 50% regardless of fertilization conditions; however, the urea-N utilization rate fell to 40% or less at a permeability of ponding water of 0.8cm day^<-1> or less, while it increased to 50% equivalent to ammonium sulfate, at 0.8cm day^<-1> or more permeability.
- Japanese Journal of Soil Science and Plant Nutrition
Japanese Journal of Soil Science and Plant Nutrition 76 (6), 811-816, 2005
Japanese Society of Soil Science and Plant Nutrition