Influence of boron and organic matter on the changes in soil biological properties and yield of rape (Brassica campestris) in an aeric endoaquept

Field experiments were conducted during winter seasons of 2006 -07 and 2007-08 to study the influence of boron and organic matter application on the changes in soil biological properties in an aeric endoaquept (pH,7.5;organic carbon content, 0.61%; CaCl 2 –extractable boron 0.32 mg/kg) growing rape (Brassica campestris L.) as a test crop. The results reveal that non-symbiotic nitrogen fixing bacteria (NFB), non symbiotic nitrogen fixing capacity, phosphate solubilising micro-organisms (PSM), phosphate solubilising capacity (PSC) and microbial biomass carbon (MBC) have been found to be influenced with different treatments, being recorded highest (90.45, 69.29 × 105/g soil; 11.73, 9.63; 80.29, 63.28 mg of N 2 fixed/g of soil/g of sucrose; 0.038, 0.032 mg/g dry soil and 159.48, 149.58 μg/g dry soil respectively) in the treatment T 4 where lower level (0.5 kg/ha) of boron as calbor and organic matter at 5 tonnes/ha was applied along with recommended levels of N, P 2 O 5 and K 2 O (80:40:40) in both rhizosphere (R) and nonrhizosphere (NR) soils. The yield of rape was also recorded highest (8.95 q/ha) in the treatment T 4 (lower level (0.5 kg/ha) of boron as calbor,organic matter at 5 tonnes/ha and recommended levels of N, P 2 O 5 and K 2 O (80:40:40 ). From the stepwise technique of multiple regression it was revealed that the NFB at R and NR, PSC at R and NR, PSM at R and NR and MBC at NR are only important predictors which can explain 99 % of total variance.