The Nitrogen Distribution in Alfalfa Hay Cut at Different Stages of Growth

Abstract

Analyses were made of alfalfa hays cut at six different stages of growth during the course of one growing season. For the determination of the soluble forms of nitrogen encountered in this study, the method developed by Wasteneys and Borsook for the fractional analysis of incomplete protein hydrolysates was applied. This procedure ensured the securing of more definite information concerning the exact gradations of protein synthesis and breakdown than is obtained by the usual amino and amide nitrogen determinations.The data for total nitrogen show a relatively steady decrease with advancing maturity of the harvested material. Also, the second and third cuttings of hay exhibit a distinctly higher total nitrogen content than the first cutting.Total soluble nitrogen tends to exhibit considerable fluctuation throughout the growing period. Cuts made later in the season show a progressive decrease in the proportionate amounts of this fraction. Particularly striking is the finding that, in all cuttings, total soluble nitrogen tends to be present in very large amounts during the early part of flowering.Results obtained from the application of the method of Wasteneys and Borsook make possible the presentation of a relatively clearly defined pictur of protein synthesis and degradation throughout the growing period. These data further strengthen the assumption that the period between bud formation and the commencement of flowering represents a very critical stage in the life history of the plant.