EFFECT OF FREQUENCY OF IRRIGATION ON SEWAGE SLUDGE-AMENDED SOIL AND CORN NUTRITION

A greenhouse experiment was conducted to evaluate yield, nutrient uptake, and concentration of nutrients in corn (Zea mays L.) tissue under different irrigation frequencies in sluge-amended soil. Sewage sludge was applied at four rates (0, 20, 40, and 80 t ha-1). Pots were watered either once or twice a week with the same amount of water. Six sequential harvests of corn were made. Frequent irrigation (twice a week) was more effective in increasing dry weight and nutrient uptake by the shoot than once a week irrigation. The increase in dry weight was 54, 66, and 110% at 20, 40, and 80 t sludge ha-1, respectively. The uptake of N, P, K, Fe, Zn, Mn, and Cu was also more than doubled at the highest rate of sludge application (80 t ha-1). Concentrations of nutrients in the plant and the soil were not affected by the frequency of irrigation. An increase in the sludge application rate considerably increased dry weight, nutrient uptake by the shoots, and the availability of P, Fe, Zn, Mn, and Cu in the soil. Concentrations of P and Zn in corn tissue were also increased by sludge application, but were within the range considered normal for corn.