The Influence of Nitrogen on the Uptake of Phosphorus by a Tomato Test Crop from Three Crop Residues

Abstract

AbstractThe uptake of phosphorus from wheat straw, tomato vine, and lettuce residues by a tomato test crop as influenced by different rates of nitrogen additions was studied under greenhouse conditions. The residues were grown in sand‐nutrient cultures at different levels of phosphorus containing the radiophosphorus. The residues were then incorporated into two calcareous soils in greenhouse pots at rates equivalent to 50 and 100 pounds of P2O5 per acre. Nitrogen was applied at rates ranging from 0 to 400 pounds of N per acre 6 inches. The tomato test crop was grown for 9 weeks before harvesting and analyzing.The results indicated that the percentage of P in the tomato test crop derived from the different residues was not significantly affected by the rate of application of nitrogen to the soil. This circumstance occurred despite the fact that the percentage of nitrogen and phosphorus, and the dry weight of the test crop was influenced by the rate of application of nitrogen fertilizer. The percentage of P in the test crop derived from the crop residues was not affected by nitrogen additions either in a soil deficient in plant‐available phosphorus or one adequately supplied with indigenous available phosphorus. However, the total uptake of plant residue phosphorus by the test crop was significantly influenced by the concentration of phosphorus in the residue.