Nitrogen Fertilization I. Nitrate Accumulation and Losses Under Continuous Corn Cropping1
- H. C. H. Hahne,
- Wybe Kroontje and
- J. A. Lutz2
Selected treatments were chosen from three field experiments with corn (Zea mays L.) to determine effects of N rates on the vertical distribution of nitrates in the soil. The experiments were located on three different soil types and corn was grown for 5 consecutive years. Irrigation was a variable in two of the experiments.
Appreciable amounts of NO3-N accumulated in the soils when the optimum rate of 140 kg N/ha at Blacksburg and Charlotte Courthouse and 168 kg N/ha at Orange had been exceeded. Amounts of vertical distributions of NO3-N accumulations were highly dependent on soil type, and on amounts of irrigation and rainfall. Lowest NO3-N accumulations and highest NO3-N losses were encountered in the Cecil fsl. An increase in NO3-N was found in the Davidson clay loam whereas no loss or gain was observed in the Groseclose silt loam.
Irrigation markedly reduced the maximum NO3-N accumulation in the Davidson clay loam especially in the 120 to 195-cm depth. Irrigation on the Cecil fine sandy loam had less influence on NO3-N and hardly affected the spread of the accumulation zone. The data indicated that proper irrigation of soils with high internal drainage can markedly reduce NO3-N loss through leaching; the reduction in NO3-N loss in the Cecil fine sandy loam was from 48 to 5% at near optimum N rate of application.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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