Effects of aeration, compaction, and water-logging on soil structure and microflora
1948
Hubbell, D.S. | Gardner, J.L.
Laboratory investigations on effects of water-logging, aeration, and compaction on soil aggregation and microflora were carried out with two calcareous soils--Gila clay and Tucumcari sandy loam. Three particle sizes were used, and the imposed treatments comprised increased and reduced aeration, submersion in water, and compaction at 35 pounds per square inch. The samples were incubated for periods of 30, 60, and 90 days. Determinations of numbers of fungi, actinomycetes, and bacteria, of pore space, and of water-stable aggregates were made at the end of each incubation period. Reduction of initial particle size reduced amounts of aggregation at the end of 90 days of incubation. In the finest particled samples where all existing aggregates larger than 0.12 mm had been destroyed, aggregation was always lower than in the coarser particled samples. No effect on number of organisms was apparent. Increased aeration was, in general, accompanied by aggregation lower than that of the controls. Number of organisms was not consistently affected. Aggregation in sealed samples was depressed, as was number of organisms. Water-logging reduced aggregation and number of bacteria but had little effect on numbers of fungi and actinomycetes. Compaction produced the greatest lowering of aggregation and microbial population. Aggregation and microbial populations showed some correlation with noncapillary pore space, the former only in the 90-day incubation period.
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