Effects of application of filter cake, biochar and PGPR bacteria as organic- and bio-fertilizers on some soil quality indices and wheat growth

Due to the undesirable effects of using long-term chemical fertilizers and the defection of organic matter in Iranian soils, it is necessary to use of organic fertilizers. Many of the plant remains, including sugar cane, can be transformed into biochars and used as organic fertilizers in the soil. Also, the filter cake is a component of the purification products of sugar that can be used as organic material. Therefore, the present study was conducted with the aim of investigate the effect of organic- and bio-fertilizers on some soil characteristics and wheat yield and to investigate the best combination of organic fertilizers and stimulating bacteria on wheat growth. This research was done in greenhouse in a completely randomized design with factorial arrangement. Factors including organic fertilizer (control, filter cake as 20 (F20) and 40 ton ha-1 (F40), and biochar as 36 (B36) and 72 ton ha-1(B72)) and bacteria (control, Enterobacter Cloacae and Paenibacillus Lactis). Five kg pots were prepared and 10 grains of Chamran variety were cultivated. Harvest was carried out after grain filling and some soil properties such as basal and substrate-induced respirations (BR and SIR respectively), soil organic carbon (SOC), microbial biomass carbon (MBC), permanganate oxidable carbon (POC), cold and hot water soluble carbon (CWC and HWC), Olsen phosphorus and also the dry biomass of the plant grains and the amount of P of them were measured. The results showed that bacterial inoculation reduced the amount of electrical conductivity and pH in compared to non-inoculated treatments. The highest amount of BR (75.0 mg kg-1day-1), Olsen phosphorus (35.7 mg kg-1), and SOC (1.13%) were observed in the treatment of F40 inoculated with Bacillus and the highest amount of MBC (78.1 mg kg-1) was observed in soil treated with F40 inoculated with Enterobacter. Also, the highest amount of CWC (2706 mg kg-1), HWC (3596 mg kg-1) and POC (173 mg kg-1) were related to the treatment of B72 inoculated with Entrobacter. The highest amount of dry weight (5.23 g pot-1) and seed phosphorous amount (1.04 %) were related to F40 inoculated with Bacillus. However biochar was applied to soil in higher weight; but, regarding with plant dry weight, soil olsen phosphorus and SOC, filter cake was more efficient and more proper to improve soil quality indices. Also, the results show that Bacillus had better effects than Enterobacter and it is recommendable to use the F40 as organic fertilizer and inoculation the soil with Bacillus for better growth of wheat.