The results obtained from turf samples indicate that growing plants are mainly responsible for the accumulation of soil organic nitrogenous compounds. Mixing of the soil of turf samples containing living plants did not stimulate the release of soil organic N.Addition of unlabeled (NH 4 ) 2 SO 4 did not promote the liberation of labeled nitrogen (N 15) recently immobilized in turf samples with living grass plants. This labeled part was mineralized more readily than the originally present soil organic matter upon killing of the grass plants.The amino acid patterns of the hydrolysates of pasture soil, arable land and the humic acids of these soils were rather similar, resembling the amino acid composition of the hydrolysates of the 'humic acids' produces by streptomycetes in a glycerol-nitrate medium.Soil organic matter was used as the only N source for the growth of a proteolytic Pseudomonas strain. The results obtained suggest that more protein-like material is incorporated in the soil organic matter of pasture than in that of arable land. The availability of N of 'humic acids', synthesized by a Streptomyces strain, to the Pseudomonas sp. was similar to that of humic acids extracted from grassland by NaOH.
|Qualification||Doctor of Philosophy|
|Award date||3 Nov 1972|
|Place of Publication||Wageningen|
|Publication status||Published - 1972|
- carbon-nitrogen ratio
- nitrogen cycle