广西典型红壤旱地施用钙镁磷肥对玉米产量及其镉累积的影响

Effect of calcium-magnesia phosphate fertilizer on maize yield and its cadmium accumulation in upland red soil in Guangxi

在广西典型类型红壤旱地布置玉米磷肥施用量的田间试验,研究不同钙镁磷肥施用量(磷肥Cd含量为0.0651 mg/kg)对玉米产量及地上部Cd累积的影响。结果表明,与不施磷肥处理(CK)相比,施磷肥可分别显著提高春、秋玉米籽粒产量8.2%—13.1%和13.7%—20.0%。高磷(600 kg P2O5/hm2)处理的春玉米秸秆产量比CK显著提高11.4%;施磷处理春、秋玉米秸秆Cd含量分别下降2.7%—45.8%和11.0%—43.6%;而籽粒Cd含量分别下降13.0%—40.6%和9.9%—31.5%,且秸秆和籽粒的Cd含量及累积量均随施磷量的增加而逐渐降低,其中以高磷处理最为显著。玉米秸秆及籽粒Cd累积量在高磷处理下(600 kg P2O5/hm2)分别比低磷处理(75—300 kg P2O5/hm2)降低13.6%—41.5%和8.8%—29.3%。相关分析表明,玉米Cd含量与土壤pH呈显著负相关,与土壤有效Cd含量呈显著正相关。施磷提高土壤pH,而降低土壤有效Cd含量。高量磷肥施用降低土壤Cd的有效性进而降低玉米对Cd的吸收累积。

A filed experiment was carried out to evaluate effects of calcium-magnesia phosphate fertilizer application rate on maize yield and its cadmium accumulationin in representative red soil of Guangxi province. Phosphate fertilizer with 0.0651 mg Cd/kg was applied at five rates （0, 75, 150, 300 and 600 kg P2O5/hm2）. In comparison with CK, phosphate fertilizer significantly increased the grain yield by 8.2%--13.1% for spring maize and 13.7%--20.0% for autumn maize, and the straw biomass of spring maize increased by 11.4% under high phosphate treatment （600 kg P2O5/hm2）. Phosphate fertilization decreased Cd contents in straw by 2.7%--45.8%and 11.0%--43.6%, while decreased Cd contents in grain by 13.0%--40.6% and 9.9%--31.5% for spring and autumn maize, respectively. Moreover, the Cd concentration and accumulationin in straw and grain decreased with the increasing phosphate fertilizer. Compared with low phosphate treatments （75--300 kg P2O5/hm2）, the Cd accumulation in straw and grain under high phosphate treatment （600 kgP2O5/hm2） reduced by 13.6%--41.5% and 8.8%--29.3%, respectively. Correlation analysis showed that there was a negative linear relationship between Cd Concentration in maize and soil pH, but positive linear relationship between Cd concentration and soil available Cd. High phosphate fertilizer could reduce the Cd phytoavailability, thus attributed to the lower Cd accumulation in maize.