Influence of Drying Method and Fertility Treatments on the Total and Water Soluble Nitrogen Contents of Alfalfa
1966
Burns, J. C. | Noller, C. H. | Rhykerd, C. L.
An established stand of Ranger alfalfa was fertilized with various combinations of nitrogen, phosphorus, and potassium. One sample of freshly harvested material was immediately immersed in liquid nitrogen, freeze-dried, and stored in a refrigerator. A second sample was weighed" and dried to a constant weight. Forage was analyzed for total nitrogen and water soluble nitrogen (WSN). Freeze-dried forage was found to be significantly higher (P<.01) in WSN but significantly lower (P<.01) total nitrogen than the oven-dried material. Total nitrogen was not significantly affected by fertilizer treatments in the freeze-dried forage. However, harvest date had a significant effect. Oven-dried forage showed both a significant fertilizer and harvest effect. The WSN content of forage subjected to freeze-drying was not altered significantly by either fertilizer treatments or harvest date. Identical samples of oven-dried material showed contrary results with significant effects for both fertilizer treatments and harvest date. The variance estimates showed chemical analyses from the freeze-dried forage to be more variable than similar oven-dried material. Since the method of drying had a definite effect on the total and water soluble nitrogen constituents of forage plants, analyses on oven-dried samples may not be representative of green plant material.
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