生物炭和AM真菌提高矿区土壤养分有效性的机理

Mechanism of the improvement effect by biochar and AM fungi on the availability of soil nutrients in coal mining area

【目的】矿区土壤贫瘠、有效养分含量低,而生物炭和丛枝菌根(arbuscular mycorrhizal, AM)真菌能够改善土壤养分,提高植物对环境胁迫的抗性和养分的利用。因此探究生物炭和AM真菌对矿区土壤的改良效果,可为矿区污染土壤生态恢复和新型肥料的开发提供参考。【方法】温室盆栽试验的土壤采自河南省洛阳市新安县江春矿区,以玉米"弘单897"为试验材料。试验设计4个处理,分别为原状土壤对照(CK)、添加生物炭(B)、接种AM真菌(M)、添加生物炭和接种AM真菌(BM),每处理重复8次,完全随机区组设计,玉米于矿区土壤中培育2个月后收获,测定根系生长、生理特性和土壤养分含量。【结果】施用生物炭和接种AM真菌均能够促进玉米生长,提高玉米叶片的净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、叶色值(SPAD值)和抗氧化酶活性,提高土壤养分含量。接种AM真菌对促进玉米生长、改善生理特性和磷吸收的效果优于生物炭,而生物炭提高土壤pH值和玉米对钾吸收的效果较好。生物炭和AM真菌联合处理玉米的总根长、根部和地上部干重分别较CK增加了84.22%、176.67%和45.84%,玉米叶片的净光合速率、蒸腾速率、气孔导度分别较对照提高35.42%、56.44%和88.31%,叶色值比CK提高了22.77%,菌根侵染率较CK提高234.20%,菌丝密度可达到4.37 m/g,总球囊霉素和易提取球囊霉素分别达到4.32 g/kg和1.60 g/kg,有机质、碱解氮、有效磷、速效钾含量分别较对照提高24.23%、43.26%、98.63%和33.93%。【结论】生物炭和AM真菌单独或复合处理均能够促进玉米生长和提高土壤养分有效性,生物炭和AM真菌联合处理可促进玉米生长、改善生理特性、促进养分吸收、提高土壤养分效果,可作为退化土壤生态修复和农业生产安全的一项有效措施。

【Objectives】The soil of mining area is infertile and lack of available nutrients, biochar and arbuscular mycorrhizal(AM) fungi play critical roles in driving soil nutrient cycling processes, and improving plant resistance to environmental stress and nutrient utilization. Therefore, this study evaluated the synergy of biochar and AM fungi, in order to find a better measurement for ecological restoration and the efficient agriculture production in mining areas.【Methods】A pot experiment was conducted to investigate the effects of biochar amendment and AM inoculation on maize(Zea mays) growth and nutrient uptake, and soil nutrient contents in heavy metal pollution soil. The soil used for the pot experiment was collected from the "Jiangchun" mining area in Xin’an, Luoyang City, Henan Province. Maize cultivar of Hongdan 897 was used as test materials in Henan University of Science and Technology. There were 4 treatments: without biochar or AM inoculation, base application of biochar 20 g/kg, AM inoculation 20 g/kg, wheat-straw biochar and AM inoculation together,denoted as CK, B, M and BM, respectively. Pots were randomly arranged in the greenhouse with eight replicates per treatment. After two months of growth, maize was harvested, dry weight was measured, nutrients and antioxidant enzyme activities were analyzed, and the content of soil nutrients was determined.【Results】The results showed that biochar or AM inoculation alone or their combination significantly increased maize growth and improved net photosynthetic rate(P_n), transpiration rate(T_r), stomatal conductance(G_s), leaf color value(SPAD value), and antioxidant enzymatic activities(P < 0.05). AM fungi inoculation played a better role in promoting maize growth, physiological biochemistry characteristics and phosphorus(P) absorption than biochar,while biochar amendment alone was more effective in improving soil pH and potassium(K) absorption in maize.Amending soil with biochar and AM inoculation together produced the largest increase in maize growth and soil improvement with 176.67%, 45.84% increase of biomass of root and shoot, 84.22% greater of total root length,35.42%, 56.44%, 88.31% and 22.77% higher of P_n, T_r, G_s and SPAD value in maize leaves respectively. The combined treatment also had a synergistic effect on inducing the root AM fungi colonization rates with 234.20%increase compared with CK, the mycelium density could reach 4.37 m/g, and the total glomalin(TG) and easy extraction glomalin(EEG) could reach 4.32 and 1.60 g/kg, respectively. In addition, biochar amendment and AM inoculation together increased the contents of organic matter, alkaline hydrolysis nitrogen, available phosphorus and readily available potassium by 24.23%, 43.26%, 98.63% and 33.93%, respectively.【Conclusions】On the whole, biochar and AM inoculation alone or their combination all improved maize growth, nutrient uptake, and the availability of soil nutrients. The combined treatment of biochar and AM fungi showed the best effect on maize growth, nutrient uptake, showing promising measurement for ecological restoration and efficient agriculture production in mining areas.