滴灌施肥蔗田土壤氧化亚氮排放与反硝化酶活性的关系

Relationship between Nitrous Oxide Emission and Denitrifying Enzyme Activities in Sugarcane Field Soilunder Drip Fertigation

对不同滴灌施肥处理下甘蔗不同生育期蔗田土壤氧化亚氮(N2O)排放通量和反硝化酶活性间关系进行了探讨。田间试验设2种滴灌灌水量水平和4种施肥量水平。2种灌水量水平分别为W0.6:180 m3 hm-2和W1.0:300 m3 hm-2。4种施肥量水平F1.0:N 250 kg hm-2,P2O5150 kg hm-2,K2O 200 kg hm-2;F0.9:施肥量是F1.0的90%;F1.1:施肥量是F1.0的110%;F1.2:施肥量是F1.0的120%。测定不同处理甘蔗4个生育期蔗田土壤N2O排放通量以及土壤硝酸还原酶(NR)、亚硝酸还原酶(NiR)和羟胺还原酶(HyR)活性。结果表明:W0.6F1.2和W1.0F1.2处理甘蔗产量较高,分别为117.7 t hm-2和124.0 t hm-2。在分蘖期,所有处理土壤NR、NiR和HyR活性均达到最大值,其中W0.6F1.2和W1.0F1.2处理反硝化酶活性较高。采集土样当天蔗田土壤N2O排放通量与土壤NiR活性之间呈极显著正相关,相关系数为0.472(r0.01=0.449,n=32),说明蔗田土壤NiR活性显著影响N2O的排放通量。因此,W0.6F1.2处理,即滴灌灌水量为180 m3 hm-2及施肥量为N 300 kg hm-2、P2O5180 kg hm-2和K2O 240 kg hm-2,在提高产量的同时对蔗田N2O的减排也有积极意义。

The relationship between nitrous oxide(N2O)flux and denitrifying enzyme activities in sugarcane fieldsoil under different drip drip fertigation treatments was explored.Two drip irrigation amount of 180 m3 hm-2(W0.6)and 300 m3 hm-2(W1.0)and four fertilization levels were designed in the field experiment,including 250 kg N hm-2,150 kg P2O5 hm-2 and 200 kg K2O hm-2(F1.0);the amount(F0.9)of 90%of F1.0,the amount(F1.1)of 110%of F1.0 and the amount(F1.2)of 120%of F1.0.N2O emission flux in sugarcane field,soil nitrate reductase(NR),nitrite reductase(NiR)and hydroxylamine reductase(HyR)activities were determined in four growth stages of sugarcane in different treatments.W0.6F1.2 and W1.0F1.2 treatments respectively had sugarcane yields of 117.7 t hm-2 and 124.0 t hm-2.At the tillering stage,soil NR,NiR and HyR activities in all treatments reached the maximum,and W0.6F1.2 and W1.0F1.2 showed higher denitrifying enzyme activities.There was a significant positive correlation between the N2O emission flux in sugarcane field and soil NiR activities,with correlation coefficient of 0.472(r0.01=0.449,n=32),which showed that the soil NiR activities significantly affected N2O emission flux.Therefore,the drip irrigation water at amount of 180 m3 hm-2 and the fertilization at amount of N 300 kg hm-2,P2O5180 kg hm-2 and K2O 240 kg hm-2 had a positive significance for N2O emission reduction as well as yield increasing.