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Soil Aggregation as Affected by Certain Crops and Organic Materials and Some Chemical Properties Associated with Aggregation
Author(s) -
Hide J. C.,
Metzger W. H.
Publication year - 1940
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1940.036159950004000c0004x
Subject(s) - soil water , citation , soil conservation , service (business) , agriculture , chemistry , mathematics , computer science , environmental science , soil science , library science , geography , archaeology , economics , economy
For this study a soil was selected which was known to possess relatively poor structure. In order to obtain a uniform sample the soil was passed through a J4inch screen and thoroughly mixed. It was then placed in 2-gallon pots in the greenhouse, triplicates of each treatment being provided. Before determining the degree of aggregation of the soil in any jar the plant residues were removed and the soil again passed through a J^-inch screen. The pots were handled in two groups, group I preceding group 2 by about 6 weeks. Both groups were subjected to treatment for a period of approximately four months. The treatments were as shown in Table I in which are presented the averages of triplicate determinations. The bluegrass stand on the pots was obtained by transplanting sod from which the soil had been fairly well removed by shaking. Other crops were grown from seed. The ground alfalfa and wheat straw were mixed through the soil at the rate of 2, tons per 2,000,000 pounds of soil. Aggregate determinations were made by use of the soil tube designed by Cole and Edlefsen (2). In examining the data with regard to aggregation a low summation percentage indicates a well aggregated soil and vice versa. The two groups of data are probably comparable since the two sets of fallow pots give similar values. The high degree of aggregation found in the fallow pots is in agreement with a previous greenhouse study (3). The previous study also showed extended periods of fallow under field conditions to be destructive to soil aggregation. Since no facilities for drainage were provided in the pots, the aggregation may have resulted from an accumulation of decomposition products that would normally be leached from the soil. Growth of wheat and of sweet clover were found to produce similar effects on aggregation but alfalfa, which had not been included in the previous greenhouse study, had a more favorable effect than either of the other crops. It was previously reported that alfalfa and sweet clover had similar effects after 2 years growth under field conditions (3). In the former paper it was reported that soils which had grown grasses for a short period of time possessed a lower degree of aggregation than those which had grown any of several other crops. This result was