耕层重构对小麦籽粒镉累积的影响和应用风险

EFFECT AND APPLICATION RISK OF PLOUGH-LAYER RECONSTRUCTION ON ACCUMULATION OF CADMIUM BY WHEAT GRAIN

小麦富镉(Cd)问题受到广泛关注,耕层重构技术具备降Cd潜力。通过大田实验,探究耕层重构和深翻耕技术对土壤-小麦系统Cd污染的控制效果及其风险。结果表明:土壤耕作层(0~20 cm)中的Cd总量是影响小麦籽粒Cd含量的关键因子。耕层重构技术通过互换深层土壤(30~60 cm)和表层土壤(0~30 cm),能够显著降低耕作层(0~20 cm)土壤Cd总量和Cd有效态含量,并使小麦籽粒Cd含量降低17.3%~24.6%。深翻耕技术通过混匀0~30 cm土壤,能够降低耕作层土壤Cd总量,但会导致土壤Cd有效态含量升高,进而促进小麦籽粒Cd富集。耕层重构和深翻耕对小麦营养元素吸收影响均较小。耕层重构技术的处理深度较大而深翻耕处理深度不足,因此耕层重构技术的土壤降Cd能力、小麦降Cd能力和不确定性均优于深翻耕处理,适用于中轻度Cd污染[ρ(Cd)>1.2 mg/kg]农田修复。耕层重构技术与补施Ca、Mg肥等农艺措施的组合应用可有效提高降Cd效率。

The enrichment of cadmium(Cd)in wheat has attracted extensive attention,while plough-layer reconstruction(PR)has the potential for reducing Cd in wheat grain.The present study investigated the ability of PR and deep-ploughing(DP)to control Cd pollution in the soil-wheat system and potential risk through field experiments.Results showed that Cd in plough-layer(0 to 20 cm)soil was the key factor affecting Cd in wheat grain.PR reduced total Cd concentration in plough layer(0 to 20 cm)soil significantly by switching 0 to 30 cm soil layer with 30 to 60 cm soil layer,in which total Cd and available Cd concentration in soil decreased significantly,and Cd concentration in wheat grain dropped by 17.3% to 24.6%.Through mixing soil in depth of 0 to 30 cm,DP decrease total Cd but led to increased available Cd concentration in soil and Cd in grain.Both PR and DP posed little negative impact on the nutrient elements of wheat grain.The treatment depth of DP was insufficient compared with PR,leading to PR’s better soil and wheat Cd-reducing capacity and lower uncertainty over DP.PR was suitable for mild to moderate Cd-polluted farmland remediation.PR could be combined with agronomic measures,such as Ca-and Mg-fertilizers,for higher Cd-reducing efficiency.