Further Studies on the Effect of Long-time Organic Matter Additions on the Physical Properties of Sassafras Silt Loam
1952
Russell, M. B. | Klute, A. | Jacob, W. C.
The objectives of the investigation were to determine the effects of long-time differential manure applications on physical properties, organic matter, and nitrogen content; to provide a “bench-mark” for future studies on the permanence of the observed differences following the discontinuance of the treatments; and to study the distribution of variance among the experimental, sampling, and determination error terms as a guide for planning future studies involving the same plots and measurements. Composited soil samples were taken at three depths from plots representing three replications of each of four treatments. Organic carbon, total nitrogen, moisture equivalent, 15-atmosphere percentage, aggregate stability, and percent sand were determined on all samples. Proctor compaction and penetrability measurements also were made. Twenty-five annual applications of manure at rates of 0, 10, 20, and 40 tons per acre have resulted in highly significant differences in organic carbon and nitrogen percentages, aggregate stability, and susceptibility to compaction of Sassafras silt loam. Highly significant positive correlation coefficients were obtained between the organic matter content and the moisture equivalent, 15-atmosphere percentage, and aggregate stability. Sampling and determination variances were in general well below the corresponding experimental variances.
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