Evaluation of XDE‐474 as a soil nitrification inhibitor

Abstract

This study was conducted to evaluate the effectiveness of XDE‐474 as a nitrification inhibitor in two soils that differed significantly in organic carbon (C) and texture. The results were compared with those obtained by using nitrapyrin [N‐Serve: 2‐chloro‐6‐(trichloromethyl)pyridine]. In the first experiment, a 10 g sample of surface soil treated with 1 mL ammonium sulfate [(NH₄)₂SO₄] solution containing 2 mg nitrogen (N) and increasing concentrations of 0.05, 0.10, 0.20, or 0.40 μg active ingredient (AI)/g of the inhibitors was incubated at 20°C for 14 days. In the second experiment, the soil sample treated with (NH₄)₂SO₄ and 0.40 μg AI/g inhibitor was incubated at 10, 20, or 30°C for 14 days. The results showed that application of XDE‐474 to soils induced nitrification of indigenous soil organic N. Nitrification rate decreased significantly as inhibitor concentrations increased. The superiority of XDE‐474 over nitrapyrin in controlling nitrification of (NH₄)₂SO₄ added to soils was clearly demonstrated. Nitrapyrin was much less effective than XDE‐474 in controlling nitrification rate when soil temperatures increased to the 10 to 30°C range. The temperature coefficients (Q₁₀) for nitrate‐nitrogen (NO₃‐N) produced as affected by inhibitors ranged from 0.81 to 10.5. The effectiveness of nitrapyrin and XDE‐474 was considerably affected by inhibitor rate, soil type, and soil temperature. In general XDE‐474 was more effective than nitrapyrin and warrants consideration as an important management tool for effective utilization of N fertilizers.

Notes

Journal Paper No. J‐15897 of the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa 50011–1010. This study was funded, in part, by a grant from DowElanco.

Postdoctoral Research Associate and Professor, Extension Agronomist, respectively.