Nitrate-N Accumulation in the Soil Profile Under Alfalfa1
- David L. Schertz and
- D. A. Miller2
A study was conducted to determine the influence of various levels of ammonium nitrate applications of NO3--N accumulations under alfalfa (Medicago sativa) and whether alfalfa has the ability to utilize excessive amounts of nitrate in the soil. Eight split applications of N totaling O, 224, 448, and 672 kg/ha (O, 200, 400, and 600 pounds/acre) were studied at the Agronomy South Farm, Urbana, 111. at various depths on six sampling dates. Soil was sampled at depths of O to 15, 15 to 30, 30 to 60, 60 to 90, and 90 to 105 cm or to the water table, which was never lower than 105 cm. Soil samples were dried, finely ground, and analyzed for NO3--N. NO3--N concentrations were greatest in March 1970 at the 30- to 60-cm depth. No more than 1 ppm was found at the 90- to 105-cm depth (water table) for any N treatments on Nov. 11, 1970. Highest concentrations of NO3--N were found at the 15- to 30-cm depth for all N treatments at the end of the growing season, Nov. 11. Although total amounts of NO3--N were lower in March than in November, the highest accumulations were found at the 30- to 60-cm depth in March, but at the 15- to 30-cm depth in November. The only treatment on Nov. 11 that did not show a significant difference when compared to the check was the 224 kg N/ha. Alfalfa would have some value in a rotation for reducing NO3--N, which may accumulate under continuous corn (Zea mays L.) after excessive N applications.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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