Effect of corn, soybeans, their residues, and a straw mulch on soil aggregation
1946
Stauffer, R.S.
1. A study was made of soil aggregation as affected by growing, corn, growing soybeans, a mulch of wheat straw, corn stalks broken down across the slope after harvest, soybean straw spread on the respective plots after threshing, and season. A comparison was also made of the aggregation in the thin surface layer of soil, about 3/8 inch thick, with that in the 3/8 to 5-inch layer. 2. The thin surface layer of soil, approximately 3/8 inch thick, contained a smaller percentage of aggregates, particularly of the larger sizes, than the 3/8 to 5-inch layer. These results confirm the conclusions of others that the surface soil becomes dispersed, particularly if there is no protective cover on the soil. 3. The mulch of wheat straw definitely favored the formation of the larger aggregates. The soybean straw and the corn stalks remaining on the soil over winter seemed to favor aggregation but did not increase significantly the percentage of aggregates. 4. The soil on the corn plots contained a higher percentage of aggregates larger than 0.50 mm than that of the soybean plots. 5. On the corn plots the percentage of aggregates larger than 0.50 mm increased during the four years the experiment was in progress. On the soybean plots there was a decrease except on those plots receiving a mulch of wheat straw.
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