TRICKLE IRRIGATION OF SUNFLOWER WITH MUNICIPAL WASTE-WATER

A field experiment was carried out for three years on a Calcaric Lithosol to study the influence of treated municipal wastewater in comparison with freshwater, supplemented with four N or P levels, on soil fertility and on growth and yield of trickle-irrigated sunflower (Helianthus annuus L.). The N concentrations in irrigation water were nil, 30, 60, or 90 mg 1(-1). An efficient use of N, with no residual NO3-N in soil, occurred with the additional 30 and 60 mg N 1(-1) in wastewater and freshwater, respectively. The maximum seed yield obtained was significantly greater in the effluent-irrigated treatments supplemented with N up to 30 mg 1(-1); with the freshwater, maximum yield was obtained with the 60 mg N 1(-1). The P levels were nil, 15, 30, or 45 mg 1(-1). With the effluent no supplementary P was needed for high yield of good quality. It was concluded that with treated wastewater less N and no P fertilizers are needed by sunflower for high yield of good quality.