Studies On The Utilization Of Compost From Agricultual Wastes For Production Of Rice Nursury Substrates

While the acreage of rice increases in recent years and uplandly raising rice seedlings becomes popular for mechanizedly planting rice in field, a large number of soil resources have been consumed for production of rice seedlings; meanwhile, many rice seedling diseases occur seriously during seedling nursery. On the other hand, tremendous agricultural wastes from rapid expansion of animal farms and mushroom industries as well as other agricultural industries enter into evironments. Improper disposition of agricultural wastes not only lead to severe environmental pollution, but also waste a lot of valuable biomass resources. However, few researches have been reported on utilization of agricultural wastes to reduce consumption of soil in formulation of rice seedling nusery media, which can control seedling diseases and enhance plant growth. This paper is aimed to formulate rice seedling nursery media by using cow manure compost, worm excrement, spent mushroom compost, Chinese medicine residue compost and inorganic minerals for reduction the consumption of soil; and to isolate and screen bacteria antagonists against damping-off disease of rice seedlings for formulation of plant pathogen suppressing and plant growth enhancing rice seedling nursery media. The main results of this research are listed as follows.1. The primary experiment on screening organic fertilizers showed that the basic media made of60%organic fertilizers and40%inorganic minerals (vermiculite and perlite) were more suitable for rice seedling growth than the media made of100%cow manure compost, worm excrement, spent mushroom compost or Chinese medicine residue compost alone or mixed with any two of the organic fertilizers. Among all basic media, the medium, which was made of30%cow manure compost,30%spent mushroom compost,30%vermiculite and10%perlite, gained the highest biomass and leaf SPAD value and the most evenness of shoot establishment. 2. The further raising seedling experiment showed that the seedling quality from media that was made of60-75%organic fertilizer were better than anyone of the two tested commercial media whereas the media that contained more than80%organic fertilizer performed with poor seedling quality. The media TA, which was made of30%cow manure compost,30%spent mushroom compost,30%vermiculite and10%perlite, and the media TB, which was made of20%cow manure compost,30%spent mushroom compost,25%vinegar residue compost,20%vermiculite and5%perlite, gained better seedling quality than the other media. For regulation of medium acidity, nitro-humic acid and fertilizer grade calcium superphosphate were added to nursery media. Seedling growth in the media that were added with nitro-humic acid was better than in the media that were added with fertilizer calcium superphosphate. Water holding porosity and electric conductivity had good correlation with shoot biomass and could be the key indicators for evaluation of the quality of nursery medium that was made from agricultural waste compost.3. Laboratory microbiological assay showed the plant pathogen that was isolated from the samples of rice seedlings with damping-off symptom from Heilongjiang Province, China, belonged to Fusarium species. Greenhouse seedling nursery experiment showed that the rice seedlings inoculated with the pathogen grew poor when compared with the rice seedlings without inoculation.4. A Bacillus species strain P9that could suppress the growth of the rice seedling damping-off pathogen was isolated and screened from soil samples. Greenhouse seedling nursery experiment showed that under the condition that rice seedling nursery media were pre-inoculated with the damping-off pathogen, rice seedlings grown in the medium inoculated with strain P9had no noticeable damping-off symptoms, whereas almost all of those grown in the media without strain P9had damping-off symptoms. This suggested strain P9could be used in biological control of damping-off disease in raising rice seedlings.5. Composts which used for rice seedling nursery can prevent control rice seedling wilt.