A study was made of the relations between the protein, phosphoric acid, and lime contents of forty-nine samples of Bermuda and sixty-one samples each of young and mature bluestem and the nitrogen, active phosphoric acid, and active lime in the soils on which they grew.
Coefficients of correlation between the composition of the plant and that of the soil were calculated. In Bermuda, a significant correlation with respect to nitrogen was secured when the nitrogen content of the soil was less than .110%, but not when sixteen soils containing over .110% were included. Significant correlations for phosphoric acid and for lime were secured when all of the soils were used in the comparisons, but the correlations were not significant when soils containing more than 30 parts per million of active phosphoric acid or more than 5,000 parts per million of active lime were excluded. In bluestem, the relation with respect to nitrogen in the soil and protein in the plant was significant whether all of the soils were included or soils containing more than .130% or .110% were excluded. In young bluestem, significant correlations with respect to phosphoric acid were secured when all of the soils were included, but the correlation was not significant when soils containing more than 30 parts per million of active phosphoric acid were excluded. In mature bluestem, there was no significant relation between the phosphoric acid in the plant and the active phosphoric acid in the soil. In young bluestem, significant correlations with respect to lime were secured in all comparisons. In mature bluestem, the correlation with respect to lime was highly significant when all soils were included in the comparison, but was doubtful when soils containing more than 5,000 parts per million of active lime were excluded and was not significant when soils containing more than 2,500 parts per million of active lime were excluded.
Within a given forage group, significant positive correlations between protein and phosphoric acid occurred in all groups, and between protein and lime in young bluestem; a significant negative correlation between phosphoric acid and lime occurred in mature bluestem. Partial correlation resulted in additional significant correlations between protein and lime in Bermuda and between phosphoric acid and lime (negative) in Bermuda on soils of low fertility.
Both young and mature bluestem grasses were deficient in phosphoric acid, and mature bluestem was deficient in protein.
The relation between the chemical composition of the soil and that of the forage was much closer in the case of bluestem than in the case of Bermuda.