基于土壤重金属风险和经济效益的双孢蘑菇菌渣还田量估算

为确定既能避免较高的土壤重金属污染风险,又满足农业生产较大经济效益的双孢蘑菇菌渣还田量,设置不施肥对照(CK),常规化肥(CF),双孢蘑菇菌渣分别提供25%、50%、75%、100%和125%的N(M1~M5)共7个施肥处理,研究两年稻麦轮作周期土壤重金属Cu、Pb、Zn、Cd含量及污染指数和作物投入产出比。结果表明,随着菌渣年施用量的增加,Cu、Pb和Zn年净增加值呈上升趋势,而Cd年净增加值表现出先减小后增加的趋势。土壤重金属潜在生态风险系数、综合污染系数和投入产出比均与菌渣年施用量存在明显的二次函数关系(P0.05)。基于土壤重金属生态风险和经济效益考虑,双孢蘑菇菌渣适宜还田量应为11 763~12 850 kg·hm~(-2)。

Assessment of Agaricus bisporus residue application rate based on soil heavy metal risk and economic benefit

It was important for agriculture waste recycling that what the annual waste application rate should be estimated based on soil heavy metal safety and economic benefits. The experiment contained seven treatments with fertilizer and Agaricus bisporus residue, including CK(the control, no fertilizer), CF(conventional fertilizer), M125% N from mushroom residue(MR)], M2(50% N from MR), M3(75% N from MR), M4(100% N from MR), M5(125% N from MR), in Chengdu Plain from 2014 to 2016. The concentrations of Cu, Cd, Pb and Zn in soil(0~20 cm) were determined by atomic absorption spectrophotometer. The results showed that Cu, Pb and Zn concentrations showed increase trend with increasing MR application rates. Moreover, Cd concentrations first increased then decreased with adding MR application rates. Furthermore, the relationships among potential ecological risk index, comprehensive pollution index and economic benefits and annual MR application rate showed significant quadratic functions, respectively(P<0.05). Therefore, the MR rates from 11 763 to 12 850 kg·hm^-2 were recommended to be the annual MR application rate based on soil heavy metal safety and economic benefits.