COMPARATIVE CHANGES IN SOIL-PHYSICAL PROPERTIES INDUCED BY ADMIXTURES OF MANURES FROM VARIOUS DOMESTIC ANIMALS
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Laboratory admixtures of soil with manures from domestic animals decreased bulk densities of a fine sandy loam soil. Water holding capacities of both sandy and clay soils were increased in proportion to quantities of admixed manures. Fibrous components of manures from beef cattle and horses dramatically enhanced water flow through saturated soils, whereas poultry manures gave little or no response. Admixtures of 5 percent animal manure induced water-stable soil-particle aggregation and higher shrinkage limits of a clay soil. Dairy and beef cattle manures were more effective than chicken manure in decreasing bulk densities of soils when subjected to compaction. Soil strength as indicated by modulus of rupture was reduced progressively with increased rates of admixed manure. The fibrous materials in manures play a major role in altering physical properties of soils.