Abstract

                                Field experiments were conducted at AC & RI, Madurai to study the effect of sewage effluent on nutrient availability in soils besides improving the fodder yield and quality" of bajra napier hybrid grass (BN 2). Field experiments were conducted in a spilt plot design with two irrigation sources viz., ordinary water (1,) and sewage effluent (1) as main plots and four N leves viz., 0, 50, 75 and 100 kg N ha as sub plot treatments with three replications. BN 2 grass was grown as a test crop. The analyses of sewage effluent collected at periodic intervals showed that the sewage effluent was alkaline in reaction (pH 8.3). non-saline (EC: 1.1-1.5 dSm-1). The total N, P, K, Ca and Mg contents ranged from 220-700 ppm, 3-14 ppm, 16-268 ppm, 18-292 ppm and 19-134 ppm, respectively. The micronutrients like Zn, Cu, Mn and Fe ranged from traces 0.18, traces- 0.06, 0.03- 0.21 and traces-12.84 ppm respectively. The heavy metals like selenium and cadmium were absent whereas lead, chromium and nickel were present in trace amounts. The bacterial, fungi and actinomycetes population in sewage water were 3.55 x 10'ml-1, 2.68 x 10'ml-1 and 5.55 x 10'ml, respectively. Periodic soil samples were taken after 2nd, 4th and 8th cuts during first year and after 4th and 8th cuts during second year. Addition of increased levels of N increased the available N content in soil. Irrigation with sewage effluent increased the organic carbon content (0.96%) compared to ordinary water (0.65%). A built up in soil available N, K and organic carbon content was observed due to sewage effluent irrigation.

Key words : Bajra Napier Hybrid Grass, Sewage effluent, Nutrient availability, Organic carbon, Micro nutrients