Differential Mobility of Nitrapyrin and Ammonium in a Sandy Soil and Its Effect on Nitrapyrin Efficiency
1979
Rudert, B. D. | Locascio, S. J.
Nitrification inhibition by 2-chloro-6-(trichloromethyl) pyridine (nitrapyrin) has not been consistent on sandy soils. This study was conducted to evaluate movement of nitrapyrin and N in a fine sand as influenced by water rate and leaching period. In greenhouse studies, nitrapyrin reduced NO₈-N loss from a Kanapaha fine sand (loamy, siliceous, hyperthermic Grossarenic Paleaquult) for only the first 2 weeks of a 5-week leaching period. In segmented soil columns, nitrapyrin was placed in the soil at a depth from 13 to 15.5 cm. After the soil was leached at water rates of 0, 2.5, and 5 cm/week for 2 and 4 weeks, soil samples were incubated with NH₄-N. Nitrification bioassay of soil above and below nitrapyrin placement showed that nitrapyrin movement was affected more by volatility than by water rate. Movement of NH₄-N from a 13.0 to 15 cm depth was studied in soil columnsthat contained 20 ppm nitrapyrin in the soil. After leaching, NH₄-N and NO₃-N levels were determined at various soil depths. With increases in the rate of water applied and in the leaching period, higher levels of NH₄-N moved to lower depths than nitrapyrin. Movement of NH₄-N away from nitrapyrin may account for the reduced nitrapyrin effectiveness often observed for sandy soils.
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