| The field experiment in this study was in Jiaxing Academy of Agricultural Science in Taihu Lake region of southeast of China. During 2005-2014, swine manue amendment was adopted as a base fertilizer. We studied the 1000-grain weight, rice yield, soil physicochemical properties and characterization of soil caoolidal particles. P forms in soil, floodwater and rice straw and grain were determined by 31P NMR spectroscopy, dissolved P and colloidal P released from soil solution, floodwater, paddy runoff were determined. During the transformation of swine manure to pyrolyzed swine-manure-derived biochar, we utilized 31P NMR and P K-edge XANES to characterize the properties and P forms in swine manure and temperature-dependent biochars; Simultaneously, we studied the solubility of swine manure and manure-derived biochar in different extracts and the most fitable dynamic equations. Based on pot experiment in labs, rice plants were planted in two kinds of soils (clay loam and silt loam). Manure biochar pyrolyzed at 400℃ were introduced into the two soils and their effects on soil P forms, soil phosphatase, microbial community structure, uptake of heavy metals by rice plant were studied. We hope the results of this paper will supply its value in optimizing the swine manure amendment rates in field experiment, strengthening the knowledge of pyrolysis effects on properties of swine manure and manure biochar, and furthermore, the feasibility of applying manure biochar to field soils.The detailed results were as follows:(1) The ripening percentage,1000-grian weight and yiled of rice increased with increasing swine manure amendment rates. The optimized swine manure amendment rates were 39 kg P ha-1, which increased 27.9% of rice yield than no fertilizer control. In 0-20 cm, soil pH showed an increasing tendency with swine manure amendment rates, but no significant differences were detected between M2 and M3 treatments。 Beneath the 20-cm depth, soil pH was hardly affected by swine manure amendment rates. Soil CEC was significantly increased in 0-5 cm, which ranged from 7.92 in Mo treatment to 12.77 cmol kg-1 in M3 treatment, however, CEC in the 40-60-cm depth was not affected. Long-term swine manure amendment did not bring significant difference on distribution of soil particles. In 0-5,5-20, and 20-40 cm, increased soil total C, N, P, organic C and Olsen-P were observed with increasing swine manure amendment rates. Contents of organic P in 0-20 cm depth were increased, while the ratio of organic P in total P reduced. The morphology of soil colloidal particles appeared as flakes, with elements of Al、Fe、Mg、K、 Ca on them, as detected by SEM-EDS. Radicals on soil colloidal particles were slightly influenced by swine manue amendment rates, but contents of soil kaolinite and muscovite were increased in the 0-20-cm surface layer. Contents of released colloidal particles increased with soil depth. Moreover, contents of colloidal particles wer not significantly increased among four swine manure amendment rates in 0-5 and 5-20 cm, but were increased in 20-40 and 40-60 cm.(2) Orthophosphate was the dominant P species in all soil samples from 0-60-cm soil profile, which was followed by phytate. Abundant P species were detected in 0-20-cm layer, and contents of all P species were increased with swine manure amendment rates; Below the 20-cm layer, no other P species were detected except for orthophosphate and phytate. In all layers, contents of dissolved P (DP) and colloidal P (Pcoll) increased with swine manure amendment rates; DP decreased with soil depth. In 0-20-cm layer, contents of DP were higher than Pcoll, and in 20-60 cm depth, contents of Pcoll were higher than DP. Orthophosphate was the dominant P species in paddy floodwater. After fertilization, small amounts of monoesters were detected in M3 and M2 treatments. One day after swine manure amendment, contents of particle P, DP and Pcoll increased rapidly and they all decreased with time, but the percentage of Pcoll was relatively stable. Swine manure amendment increased the uptake of total N and total P in rice straw and grain, but no significant differences were detected between M2 and M3 treatments. Orthophosphate and phytate were the major P species in rice straw and grian, respectively. Swine manure amendment increased the contents of phytate in rice grian, and increased the contens of orthophosphate and phytate in rice straw. Moreover, swine manure amendment increased the activities of four phosphatases, which are good indicators of contents of soil orthophosphate and myo-IHP.(3) In the process of pyrolyzing swine manure into manure-derived biochar, the basic physicochemical properties were significantly influence by temperature. With higher pyrolysis temperature, comes higher amounts of total heavy metals contents, larger specific area and smaller averaged pore diameter. Results of 31P NMR spectroscopy and P K-edge XANES showed that the most abundant inorganic and organic P species in swine manure were orthophosphate and phytate, respectively; phytate were gradually transformed into orthophosphate and pyrophosphate in pyrolysis process. In MB700, orthophosphate became the sole P species, and it might be binding with Ca element. The extraction efficiency of four extracts was in the following order:ammonium oxalate> NaOH-EDTA> Deionized water> Mehlich 3 solution. Kinetics of P release from swine manure and manure-derived biochar were different. That is, the Elovich model was more fitting for swine manure, the zero-order kinetics model was more fitting for MB700 and a combination of Elovich model and zero-order model might be used to describe to the release of P from MB400.(4) In pot experiment, addition of 400℃ manure biochar significantly increased pH, CEC, AEC, total C, total N, total P, Olsen-P and available K, moreover, significant differences were detected between 0.5% and 1.5% manure biochar treatments. Results from 31P NMR integration showed that manure biochar amendment increased the contents of orthophosphate and pyrophosphate in two soils, but significantly decreased the contents of monoesters. Due to the differences of pH in two studied soils, manure biochar amendment decreased the activities of soil acid phosphomonoesterase but have a different effect on activities of soil alkaline phosphomonoesterase. Manure biochar amendment increased the complexity of two soils’microbial community structure, the PLFAs contents of soil aerobic bacteria and fungi, but showed a different effect on PLFAs of soil actinomycetes; it significantly increased the PLFAs content of Gram- but not G+. Swine manure biochar amendment increased the uptake of N, P and K in rice grain and straw. It should be note that manure biochar may reduce the accumulation of heavy metal (loid) Pb, Cu and As, but increase the content of Cd, Zn. However, both 0.5% and 1.5% of manure biochar amendment did not lead heavy metal (loid) Cd, Pb and As to exceed the limitation of food safety published by China’s Health ministry. |
PDF Full Text Request