Influence of Residual Nitrogen on Wheat Straw Decomposition in the Field

Plant material decomposition appears to be mainly controlled by the C/N ratio of the plant material under soil moisture, temperature, and aeration conditions that support plant growth in the field. Harmsen and VanSchreven (4) reported, "Numerous earlier papers were devoted to the study of this problem .... Fairly close agreement was obtained by all these investigators as to the N content limits of the added material, below which no N mineralization may be expected. This is 1.5 to 2.0 per cent of the dry matter, corresponding to a C/N ratio of 20 to 25." Similar values were also reported by Broadbent (2) from laboratory studies; and Allison (1), in a recent review, cited several reports that are in general agreement