Effects Of Inoculating Soil Functional Organisms On Soil Properties And Peanut Growth In Upland Red Soil

It is well known that earthworms are the most typical soil macrofauna (invertebrate) and bacterial-feeding nematodes are the most abundant metazoa group in soil. Numerous findings revealed that their activities and interactions with other soil fauna and microorganisms can modify soil physical, chemical and biological properties in terrestrial ecosystem through which they play an important role on the material cycling and energy flow. Phosphate-solubilizing microorganisms (PSM) is a kind of bacteria which can transform phosphoric ions adsorbed in soil into soluble phosphate so that it can be easily utilized by the plants.Due to the degradation of soil fertility and ecosystem function of upland red soil in Southern China, based on a pot experiment in greenhouse and a plot experiment, this research investigated the feasibility that soil biological resource could self-regulate soil ecosystem foundation such as to elevate the crop yield. By typical biotic inoculation technology, this research investigated the effects of earthworms, bacteria-feeding nematodes and phosphate-solubilizing bacteria (PSB) and their interactions on the characters of red soil (physical, chemical and biological properties) and the growth and yield of peanut. Our objective is to further elucidate the role of earthworms, bacteria-feeding nematodes and PSB in the fertilization of red soil ecosystem, providing scientific basis for the sustainable management of upland red soil ecosystem. The pot experiment was designed with eight treatments:earthworms only (E); bacteria-feeding nematodes only (N); PSB only (P); earthworms and bacteria-feeding nematodes (EN); earthworms and PSB (EP); bacteria-feeding nematodes and PSB (NP); the combination of earthworms, bacteria-feeding nematodes and PSB (ENP) and the control (CK). The plot experiment use chemical fertilization as the control (CK), with rice straw mulched (R), added earthworms only (RE); nematodes only (RN); PSB only (RP); the mix of them (RENP). With peanuts stalk mulched (H) and bio-organic fertilizer added (B) respectively, we inoculated the combination of earthworms, bacteria-feeding nematodes and PSB (HENP and BENP), ten treatments in all. The main results were as follows:1In the pot experiment, the inoculation of earthworms, bacteria-feeding nematodes, PSB, and the combination of them could improve the microbial properties of red soil, promoting the content of available phosphorus, nitrogen, potassium, and eventually enhance the of peanuts growth of all four sampling seasons. Repeated-measure ANOVA results showed that earthworms, bacteria-feeding nematodes, PSB had significant (P<0.05) or highly significant (P<0.01) effects on MBC, MBN, BR, URE and APE; there’s remarkable interaction between earthworms, bacteria-feeding nematodes, and PSB on MBN, URE, APE. Together, the mixed inoculation improved the microbial properties better than the single inoculation. The treatment ENP which inoculated with earthworms, bacteria-feeding nematodes and PSB affected the MBC, MBN, URE, APE more than other treatments; its MBC increased24.00、89.67、42.27�'�42.20mg·kg-1, the growth rate increasedly25.4%、52.0%、24.3%and27.2%than CK of all four sampling seasons; Soil fauna can also improve the soil available phosphorus, and nitrogen; particular the treatment PSB only (P) significantly enhanced the available phosphorus contents. Thanks to better soil properties improved by the soil fauna, peanut yield increased by2.27g·plant-1, and the average growth rate increasedly27%.2In the field experiment, each different biological manipulation remarkably increased the amount of soil nematodes and PSB, the treatments BENP, B and RN significantly increased the amount of soil nematodes (P<0.05), they were respectly554.357and317indvidues every100g dry soil than CK, the growth rate increasedly183%,121%and107%. Biological manipulation could enhance soil available phosphorus, potassium and promote the biological properties of red soil, particularly URE and BR. With single or combined inoculation, the root length, area, volume, numbers of tips were improved than the control, while nodule number, branch number of peanut showed no efferts. The peanut yield of each treatment was enhanced except rice straw and peanut stalk mulched ones (R and H). With rice straw and peanut stalk mulched and bio-organic fertilizer added, peanut yield was significantly enhanced. The same as the pot experiment, combinated inoculation influenced soil properties, growth and yield of peanut more remarkable than single inoculation with rice straw and peanut stalk mulched.