铜对土壤酶和碱解氮及甘蔗生长影响

【目的】研究土壤Cu浓度对土壤性状动态变化规律及甘蔗生长的影响,为农产品安全生产和重金属污染治理提供依据。【方法】以甘蔗为试验材料,采用盆栽法,设置不同土壤Cu浓度处理（44.15、61.65、79.15、86.65、94.15、269.15、444.15mg/kg）,在甘蔗不同生长期采样分析土壤性状及蔗株的生长情况。【结果】土壤脲酶随Cu浓度的增加（44.15-444.15mg/kg）呈先增加后降低的趋势,当Cu浓度为86.65或94.15mg/kg时达最大值;甘蔗各生长期土壤碱解N随土壤Cu浓度的增加呈先增加后降低的趋势;土壤脲酶活性与Cu浓度呈负效应,其中分蘖期和伸长期达到极显著和显著负相关;土壤碱解N与Cu浓度呈正、负效应,其中分蘖期和伸长期呈显著正相关;甘蔗株高、茎径、产量、蔗汁锤度随土壤Cu浓度的增加先增加后降低,甘蔗Cu受害临界值为土壤全Cu269.15mg/kg或蔗茎Cu7.82mg/kg。【结论】适宜的土壤Cu浓度可提高土壤脲酶活性、碱解N含量及甘蔗产量、品质;土壤脲酶活性与Cu浓度呈负效应,土壤碱解N与Cu浓度呈正、负效应。

Effect of copper on soil enzyme, alkali-hydrolyzable N and sugarcane growth

Objective]The present experiment was conducted to study the effects of Cu content on soil properties and sugarcane growth in order to provide information for safe agricultural production and to develop control measures for heavy metal pollution. Method]A pot experiment was conducted for growing sugarcane plants. The soil was mixed with different concentrations of copper （44.15, 61.65, 79.15, 86.65, 94.15, 269.15, 444.15 mg/kg）, and samples of both soil and plants were taken for analyses at different growth stages of sugarcane plants. Result]The results showed an initial increase in activity of urease in soil with increasing Cu concentration, which later decreased to its minimum at 86.65 or 94.15 mg/kg Cu;Alkali-hydrolyzable N content in soil at each stage of sugarcane growth increased initially and then decreased with increasing Cu concentration in the medium; The Cu content in soil significantly and negatively affected the urease activities for whole duration of plant growth as revealed by the significant negative correlations of Cu content with urease activity at tillering and elongating stages; Cu content positively （at tillering and elongating stages） and negatively affected the alkali-hydrolyzable N content of soil. The plant height, stalk diameter, cane yield and juice brix of sugarcane increased initially and then decreased with increasing Cu concentration. The critical value of Cu for plants was found as 269.15 mg/kg soil and 7.82 mg/kg cane stalk dry weight. Conclusion]Urease enzyme activity, alkali-hydrolyzable N content in soil and yield and quality of sugarcane were improved with the increase in Cu content in soil up to critical level, above which plants were severely affected; The Cu content negatively affected the activities of urease in soil.