Evaluation of the nitrogen fertilizer value of plant materials to spring wheat production.
1993
Mahler R.L. | Hemamda H.
Use of green manure crops has become a preferred alternative source of N. The objectives of this 3-yr field study were to evaluate the N supplying power of 1, 2, and 3 Mg ha-1 of Austrian winter pea (Pisum sativum ssp. arvense L.) Poir), alfalfa (Medicago sativa L.), and wheat (Triticum aestivum L.) residue. Residues were incorporated in September and the N contribution of each amendment to a subsequent spring wheat crop was calculated. We measured inorganic soil N levels and wheat yields in northern Idaho on Latahco silt loam fine-silty, mixed, mesic Pachic Ultic Haploxeroll) soils. Soil samples were taken during July of each year to determine residual inorganic N. Plant material addition and incorporation affected spring wheat yield and soil inorganic N level in each study. Pea and alfalfa material applied at 3 Mg ha-1 resulted in the highest spring wheat yields. Austrian winter pea residue at 3 Mg ha-1 provided a N credit of 51 to 63 kg ha-1 to spring wheat, compared to 1 to 36 kg ha-1 for alfalfa applied at the same rate. Based on inorganic soil N in July, application of 3 Mg ha-1 of Austrian winter pea, alfalfa, and wheat residue provided an N credit of 16 to 24, 21 to 26, and - 1 to - 25 kg ha-1, respectively. Average total N credits (soil + plant uptake) for the 3 Mg ha-1 application of Austrian winter pea, alfalfa, and wheat materials were 76, 47, and -35 kg ha-1, respectively. Estimated N recovery of Austrian winter pea material after 10 mo of incorporation was 77% (58% in wheat and 19% in soil).
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