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- Davidson, J.
- Agronomy journal 1915 v.7 no.5 pp. 221-238
- Triticum; coumarin; phytotoxicity; root exudates; seed germination; soil toxicity; soil fertility; fertilizers; nitrogen content; clay loam soils; crop yield; New York
- ... The evidence offered in favor of the theory of soil toxicity is not sufficient to establish the fact that roots of higher plants excrete substances harmful to themselves or to other plants. Neither is the evidence sufficient to establish the presence in the soil of organic substances harmful to plants under normal field conditions. The concentrations of 600 parts per million of cumarin and of 3,00 ...
- Brown, P.E.; Johnson, H.W.
- Agronomy journal 1915 v.7 no.5 pp. 216-220
- soil; crushing; soil pH; sandy loam soils; Iowa
- ... The results of these tests lead to the following conclusions: When acid soils are ground before being tested by the Veitch method the acidity is reduced and frequently the reaction becomes basic. The development of basicity increases with the grinding of the soil. The increase in basicity is greater the greater the percentage of sand and it is greater in coarse sandy soils than in fine sands. To d ...