The calcium, phosphorus, and nitrogen content of grasses and legumes and the relation of these elements in the plant
1934
Daniel, H.A.
The chemical composition of 368 samples of grasses and 335 samples of legumes were studied. These samples were representative of 23 species of grasses and 10 different legumes. The grass samples averaged 0.351% calcium, 0.103% phosphorus, and 0.868% nitrogen, while the legumes averaged 1.373% calcium, 0.180% phosphorus, and 2.283% nitrogen. These data indicate that the legumes on the average contained 3.91 times as much calcium, 1.74 times as much phosphorus, and 2.64 times as much nitrogen as the grasses. It was found that the mineral content of plants which are low in calcium and phosphorus remains low when these plants are grown on fertile soil. Crops which are high in calcium and phosphorus always contain large amounts of these elements, even though they are produced on poor soil. The relation existing between the calcium, phosphorus, and nitrogen within the plants was studied. The legumes have low nitrogen-calcium and high calcium-phosphorus and nitrogen-phosphorus ratios, while the grasses, on the other hand, have high nitrogen-phosphorus and low calcium-phosphorus and nitrogen-calcium ratios. A very poor correlation exists between the calcium and the phosphorus content of the grass, and these elements show a negative correlation in mature legumes. Plants extremely low in phosphorus were usually high in calcium, and vice versa. A poor correlation existed between nitrogen and calcium content of the plants, while the nitrogen and phosphorus in the plants were closely correlated.
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