Efficiency of nitrogen fertilizers and a nitrification inhibitor
1987
Yadvinder Singh | Bijay-Singh | Maskina, M.S. (Punjab Agricultural Univ., Ludhiana (India). Soils Dept.)
The relative efficiency of urea, ammonium sulfate, and potassium nitrate were studied during 1986 kharif (Jun-Sep). Nitrification inhibitor 4-amino-1,2,4-triazole (ATC) was applied at 5% by weight of urea. To restrict NH3 volatilization, urea-nitrification inhibitor and urea alone treatments were applied in bands (3 cm below surface) between the rows. N at 110 kg/ha was applied in three equal splits: 7, 21, and 42 d after transplanting with no standing water. Soil of the experimental field was Fatehpur loamy sand (Typic Ustipsamment) with pH 8.5, 0.23% organic C, 7 kg Olsen's P/ha and 71 kg ammonium acetate extractable K/ha. Soil percolation rate was about 6 mm/h. Treatments were laid out in a randomized complete block design with four replications. Six-week-old seedlings of rice variety PR 106 were transplanted the third week of June. Urea and ammonium sulfate top dressed in three equal splits did not differ significantly. Band application slightly increased grain yield and N uptake over top dressing. Additional benefit with band placement was probably due to the low rate of nitrification. Application of ATC, a water soluble chemical recommended for nitrification inhibition, did not influence yield and N uptake of rice, even at higher rates. This may be due to ineffective coating and leaching of the chemical from the bands. Potassium nitrate was the most inefficient N source. Recovery of N from potassium nitrate was about half that from ammonium sulfate and urea.
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