The effects of inorganic salts, inoculum concentration, aeration rate and shaking speed on insoluble phosphate solubilization by Pseudomonas fluorescens RAF15 were investigated. Soluble phosphate production was dependent on the presence of MgCl₂·6H₂O and MgSO₄·7H₂O in the medium. Supplementation of medium with 0.01% CaCl₂·2H₂O and 0.01% NaCl slightly increased soluble phosphate production. The optimal medium compositions for the solubilization of insoluble phosphate by P. fluorescens RAF15 were 1.5% glucose, 0.005% urea, 0.3% MgCl₂·6H₂O, 0.01% MgSO₄·7H₂O, 0.01% CaCl₂·2H₂O and 0.01% NaCl, respectively. Optimal inoculum concentration was 2.0%(v/v). Maximum soluble phosphate production was obtained with 20-50 ml/250-ml flask and 200 rpm of shaking speed, respectively. The addition of EDTA decreased cell growth and soluble phosphate production.

The aquatic fern Azolla spp. is of value as a bio-fertilizer for wetland paddy. It is popular and cultivated widely in other countries like China, Vietnam, and the Philippines, but has yet to be taken up in Korea, in a big way. It fixes nitrogen as high as 3-5kg N per day, because it contains nitrogen fixing blue-green algae, Anabaena azollae. Azolla's ability to create a light-proof mat that suppresses other weeds has been used for centuries in rice production. Azolla spp. has also the capacity to take up the heavy metals such as Mercury and Chromium (75~100%) and may be used as a bioaccumulator in the phytoremediation. Azolla meal also can be used as an unconventional feed resource has a potential as a feedstuff for livestock.

A field experiment was conducted to investigate effects of application time and rate of biofertilizer alone and in combination with chemical NPK fertilizer on growth, yield and quality of rice. The biofertilizer used composted food waste as substrate and added with effective microorganism. The treatments included recommended NPK fertilizer(RF, 11-5.5-4.8kg~;10a-1 ), half recommended NPK fertilizer(HRF, 5.5-2.8-2.4kg~;10a-1 ), half recommended NPK fertilizer plus 250kg~;10a-1 biofertilizer(HRF+Bio 250) and 500kg~;10a-1 biofertilizer(HRF+Bio 500). The biofertilizer treatments were applied at 0, 5 and 10 days before transplanting(DBT). Grain yield of HRF+Bio 250 at 5 DBT(648.4kg~;10a-1 ) was statistically similar to the highest obtained in the RF(654.1kg~;10a-1 ). Tiller numbers at HRF plus biofertilizer treatments were already high during the maximum tillering stage, and were similar with that of the RF and higher than that of the HRF during heading stage. Likewise, ripening ratio at HRF plus biofertilizer treatments was similar with that of the RF and higher than that of the HRF. Furthermore, all the biofertilizer treatments improved protein content but reduced the amylose content and palatability compared to treatments with chemical NPK fertilizer alone. Thus, HRF+Bio 250 at 5 DBT can be used to save 50% chemical NPK fertilizer and at the same time obtain an improved rice grain yield and quality.

The effect of biofertilizer in enhancing nutrient quality and antioxidant property of rice grain was investigated. The experiment was carried out in a randomized complete block design with 3 replications and 7 treatments namely : RF = N-P2O5-K2O(11-5.5-4.8kg~;10a-1); half of the recommended fertilizer rate, HRF=N-P2O5-K2O(5.5-2.75-2.4kg~;10a-1): HRF+Bio 250=HRF combined with 250 kg Biofertilizer 10 a-1 ; HRF+Bio 500=HRF combined with 500 kg Biofertilizer 10 a-1; Bio 250=250 kg Biofertilizer 10 a-1; Bio 500=500 kg Biofertilizer 10 a-1; and NF=No Fertilizer. Results showed that HRF+Bio 500 obtained a significantly higher protein content but a significantly lower amylose content compared with RF and NF treatments. Highest phytic acid content was recorded in NF treatment while the lowest was observed in HRF+500 treatment. The highest values in both electron donating ability and reducing power were obtained in HRF+Bio 500 treatment. All treatments obtained higher reducing power than that of the RF treatment and that NF treatment showed comparable values in both electron donating ability and reducing power with those of the treated plots. Highest antimutagenicity property was also observed in HRF+Bio 500 treatment followed by Bio 500 treatment. This study showed the possibility of using biofertilizer to enhance nutritional quality and antioxidant property of rice.

The aim of this study was to isolate mesophilic chicken feather-degrading bacteria and to evaluate feather hydrolysate as alternative biofertilizer. Isolate RS7 was isolated from compost and identified as Bacillus pumilus according to API analysis and 16S rDNA sequencing analysis. Chicken feathers were completely degraded after 5 days of cultivation at 30℃. Feather hydrolysate treated by B. pumilius RS7 positively influenced Helianthus sannuus L. (sunflower) growth (e.g. growth rate, number and dry weight of leave, and flowering rate). These results suggest that feather hydrolysate prepared using B. pumilius RS7 could successfully be used as alternative biofertilizer, thereby reducing the environmental impact of feather waste from the poultry industry.

The effect of biofertilizer (compound of microbial inoculants or groups of micro-organisms) on growth and yield of rice was investigated. The experiment was carried out in a randomized complete block design with 3 replications and 7 treatments namely: RF=N-P2O5-K2O (11-5.5-4.8 kg 10a-1 ); half of the recommended fertilizer rate, HRF=N-P2O5-K2O (5.5-2.75-2.4 kg 10a-1 ); HRF+Bio 250=HRF combined with 250 kg biofertilizer 10a-1 ; HRF+Bio 500=HRF combined with 500 kg biofertilizer 10a-1 ; Bio 250=250 kg biofertilizer 10a-1 ; Bio 500=500 kg biofertilizer 10a-1 ; and NF = No Fertilizer. Results showed that the recorded values of plant height, tiller number and chlorophyll content at 40 to 60 days after transplanting (DAT) in HRF+Bio 500 were significantly higher than those recorded in the RF treatment. Similar observations between these two treatments were only recorded from 60 DAT onwards. Yield components were also superior in HRF+Bio 500 treatment and comparable to that of RF. The highest grain yield obtained in HRF+Bio 500 treatment (785.8 kg 10a-1 ) was statistically similar to that of RF (739.8 kg 10a-1 ) but significantly higher than that of NF (506.7 kg 10a-1 ). Finally, head grain recovery (90.9) was low while chalkiness (0.03) was high at HRF+Bio 500 treatment as compared with RF, which were (96.1) and (0.3), respectively. Results showed that combined treatment of HRF and 500 kg biofertilizer 10a-1 has similar effects on the growth and yield of rice with that of RF.