长期施肥对小麦-玉米作物系统土壤颗粒有机碳和氮的影响

Effects of long-term fertilization on soil particulate organic carbon and nitrogen in a wheat-maize cropping system

通过对华北平原小麦-玉米轮作农田生态系统18年田间施肥试验,研究了长期不同施肥处理对耕层(0～20cm)土壤颗粒有机碳和氮及矿质结合有机碳和氮的影响.施肥处理包括化肥NPK不同组合(NPK、NP、NK、PK)、全部施用有机肥(OM)、一半有机肥+化肥NPK(1/2OMN)及不施肥(CK)共7个处理.结果表明:各施肥处理均能在不同程度上增加土壤颗粒有机碳和氮及矿质结合有机碳和氮含量,提高土壤颗粒有机碳和氮分配比例及颗粒有机质C/N.施肥处理颗粒有机碳和氮储量较不施肥处理分别增加11.7%～196.8%和13.0%～152.2%,土壤颗粒有机碳对总有机碳储量增加的贡献率为31.5%～67.3%,土壤颗粒有机氮对全氮储量增加的贡献率为14.3%～100.0%;矿质结合有机碳和氮储量较不施肥处理分别增加2.0%～75.0%和0.0%～69.8%.各处理颗粒有机碳和氮及矿质结合有机碳和氮储量均以OM处理最高,且有机肥与化肥NPK配施高于单施化肥各处理,而化肥处理中NPK均衡施用效果最好.说明施用有机肥、有机肥与化肥NPK配施及化肥NPK均衡施用是增加土壤颗粒有机碳和氮及矿质结合有机碳和氮的关键.

0-20 cm soil samples were collected from an 18-year wheat-maize rotation field on the North China Plain to study the effects of long-term fertilization on the contents and storages of soil particulate organic carbon （POC）, particulate organic nitrogen （PON）, incorporated organic car- bon （IOC）, and incorporated organic nitrogen （ION）. The long-term fertilization experiment was designed to include 7 treatments, i. e., chemical NPK （NPK）, organic manure （OM）, 1/2 organic manure plus 1/2 chemical NPK （1/2OMN） , chemical NP （NP）, chemical PK （PK）, chemical NK （NK）, and control （CK）. After 18 years experiment, all the fertilization treatments showed higher contents of soil POC, PON, IOC and ION, higher proportions of soil POC to soil total organic carbon （TOC） and of soil PON to soil total nitrogen （TON）, and higher C/N ratio of soil particulate organic matter. The storages of soil POC and PON under fertilization treatments were increased by 11.7%-196. 8% and 13.0%--152.2%, respectively, compared with the control. The contribution of soil POE to the increased storage of soil TOC ranged from 31.5% to 67.3%, and that of soil PON to the increased storage of soil TON ranged from 14. 3% to 100. 0%. The storages of soil IOC and ION under fertilization treatments increased by 2. 0%-75.0% and 0. 0%-69. 8%, respectively, compared with the control. Among the fertilization treatments, treatment OM had the highest storages of soil POC, PON, IOC and ION, followed by treatment 1/2OMN, and the treatments of applying chemical fertilizers alone. Balanced application of chemical fertilizers （treatment NPK） showed higher storages of soil POC, PON, IOC and ION than imbalanced application （treatments NP, PK, and NK）. It was suggested that applying organic manure or its combination with chemical NPK and the balanced application of chemical NPK could be the keys for the increase of soil POC, PON, IOC and ION contents and storages.