The effect of the vetch cropping history and chemical properties of the soil on the longevity of vetch nodule bacteria, Rhizobium leguminosarum
1940
Andrews, W.B.
Ninety-two samples of soil were obtained from fields or woods which had different vetch histories. Fifteen of the soils had never been planted to vetch and no related cultivated plants had been grown. Seventy-seven soils had grown vetch for one or more years, and it had been from none to several years since vetch had been grown. The soil was used to inoculate vetch at the rate of one fruit jar top full (about 60 grams) of soil per 30 feet of row. The soil inoculation was compared to commercial and no inoculation. The data show that: 1. Twenty per cent of soils which had not previously grown vetch and 50% of the soils which had grown vetch, with the quantity of soil used, were probably equal to or superior to commercial culture for inoculating vetch. 2. Twelve of the soils produced over 1,000 pounds more vetch than commercial culture. 3. Vetch nodule bacteria were present in 96% of the soils which had previously grown vetch. The data suggest that: 1. Sixty-nine per cent of the soils would not need inoculation when vetch is planted on them. 2. Ninety-six per cent of the soils which had grown vetch probably would not need inoculation. 3. Four per cent of the soils which had grown vetch previously would need inoculation. 4. Nodule bacteria apparently do not thrive as well in sandy soils as in heavier soils. Soils which produce a good crop of vetch without the addition of lime in the drill do not need inoculation when vetch is planted on the field again. Soil inoculation where excellent vetch has been grown is equal to or superior to commercial culture. A heavy suspension of clay from soil which has previously grown good vetch is a satisfactory method of inoculating vetch.
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