The effect of sodium humate upon phosphorus nutrition of plants with variable doses of iron and calcium in tomato water cultures

Studies were carried out on the effect of sodium humate upon content of P, Fe, Ca, and dry weight yield of tomato seedlings in water cultures. Nutrient solutions contained 10 times more or 10 times less P, Fe, and Ca than the control (nutrient solution according to Hampe). Sodium humate was effective only in relation to phosphorus at lowered amount of Fe, and supplied the plants with Fe when phosphorus content remained in excess. At lowered Ca content humate was not more effective in relation to phosphorus. Sodium humate protected the plants against inhibiting effects of excessive Ca content, and supplied them with phosphorus