长期不同施肥对红壤碳、氮、磷循环相关酶活性的影响

Effects of different long-term fertilization on the activities of enzymes related to carbon,nitrogen,and phosphorus cycles in a red soil

试验采用微孔板荧光法,选取不施肥（CK）、单施氮肥（N）、化学施肥（NPK）、单施粪肥（M）和粪肥与化学肥料混施（MNPK）5个处理,研究了长期不同施肥对祁阳旱地红壤碳、氮、磷循环相关酶[β-1,4-葡萄糖苷酶（βG）、纤维二糖水解酶（CBH）、β-1,4-木糖苷酶（βX）、β-1,4-N-乙酰基氨基葡萄糖苷酶（NAG）和酸性磷酸酶（AP）]活性的影响.结果表明：与CK处理相比,长期N处理对βG、βX、CBH和NAG活性无影响,但降低了AP活性,而NPK、M、MNPK处理均显著增加了5种酶活性;相关性分析表明,5种土壤酶活性与硝态氮（0.465-0.733）、有效磷（r=0.612-0.947）、土壤呼吸（r=0.781-0.949）和作物产量（r=0.735-0.960）均呈显著正相关,βG、CBH和AP与p H显著正相关（r=0.707-0.809）,而仅有AP与土壤可溶性有机碳显著相关（r=-0.480）.表明所测5种土壤酶活性可作为评估不同施肥处理对红壤生产力影响的重要指标,但5种酶对氮肥引起的严重酸化的指示作用均非常有限.

Using a microplate fluorimetric assay method,five fertilization treatments,i.e. no-fertilizer control（ CK）,sole application of nitrogen（ N）,balanced application of nitrogen,phosphorus,and potassium fertilizer（ NPK）,application of pig manure（ M）,and combination of pig manure with balanced chemical fertilizer（ MNPK） were selected to investigate the effects of different longterm fertilization regimes on the activity of five enzymes（ β-1,4-glucosidase,βG; cellobiohydrolase,CBH; β-1,4-xylosidase,βX; β-1,4-N-acetylglucosaminidase,NAG; acid phosphatase,AP） in a red soil sampled from Qiyang,Hunnan Province. The results showed that compared with CK treatment,N treatment had no impact on βG,βX,CBH,and NAG activities but reduced AP activity,while NPK,M and MNPK treatments increased the activities of all the five enzymes. Correlation analysis indicated that all the five enzyme activities were positively correlated with the content of nitrate（ r = 0.465-0.733）,the content of available phosphorus（ r = 0.612-0.947）,soil respiration（ r = 0.781-0.949） and crop yield（ r = 0.735-0.960）,while βG,CBH and AP were positively correlated with p H（ r = 0.707-0.809）,only AP was significantly correlated with dissolvable organic carbon（ r =- 0. 480）. These results suggested that the activities of the measured enzymes could be used as indicators of red soil fertility under different fertilization regimes,but the five enzymes tested provided limited information on the degree of acidification induced by application of mineral nitrogen.