Effect of Primary Treated Biomethanated Spentwash on Soil Properties and Yield of Sunflower (Helianthus annuus L.) on Sodic Soil

The field experiment on effect of primary treated biomethanated spentwash (PBSW) on physiochemical and biological properties of soil and yield of sunflower (Helianthus annuus L.) on sodic soil was conducted at the Postgraduate Farm, Mahatma Phule Agricultural University, Ahmednagar, India, during 2008-9. The experiment was laid out in a randomized block design (RBD) with nine treatments [control, varying doses of PBSW (30, 60, 90, 120, 150, and 180 m(3) ha(-1)), farmyard manure (FYM) + recommended dose of fertilizer (RDF), and FYM + gypsum at 50% gypsum requirement (GR) + RDF] with three replications. The FYM dose was 5 Mg ha(-1). The experimental soil was sodic calcareous, being of the Sawargaon series of isohyperthermic family of Vertic haplustepts with high exchangeable sodium percentage (ESP), low available nitrogen (N) and phosphorus (P), and high available potassium (K). The results revealed that the physical properties [bulk density, mean weight diameter (MWD) of water-stable aggregates, and hydraulic conductivity] of soil were improved in both layers of sodic soil (0-30 and 30-60 cm) as a result of the addition of increased doses of PBSW. The significant reduction in pH, calcium carbonate (CaCO3), ESP and increase in organic carbon, cation exchange capacity (CEC) and electrical conductivity (EC) were observed in both soil layers as a result of the addition of PBSW at 180 m(3) ha(-1). The changes in chemical properties were also seen in the treatment of FYM + GR + RDF, but it was at par with lower doses of PBSW (30 to 90 m(3) ha(-1)). The microbial populations [bacteria, fungi, actinomycetes, azotobacter, and phosphate-solubilizing bacteria] increased with an increase in the levels of application of PBSW. However, it was maximum in FYM + GR + RDF treatment, and it showed an overall increase up to the flowering stage and thereafter reduced at harvest. The soil basal respiration as mg carbon dioxide (CO2) increased with the increase in levels of PBSW application but it was the greatest in the FYM + gypsum + RDF treatment. Among the PBSW treatments, the greatest activities of soil enzymes (urease, dehydrogenase, and acid phosphatase) under the treatment of 180 m(3) ha(-1) PBSW were observed at the flowering stage. The available N, P, and K after harvest of sunflower crop were significantly greater in the PBSW treatment applied at 180 m(3) ha(-1); however, N, P, and K uptake and yield of sunflower were significantly greater in FYM + RDF + gypsum treatment followed by FYM + RDF and 180 m(3) ha(-1) of PBSW.