长期施肥下黑土活性有机质和碳库管理指数研究

EFFECT OF LONG-TERM FERTILIZATION ON LABILE ORGANIC MATTER IN AND CARBON POOL MANAGEMENT INDEX OF BLACK SOIL

基于东北黑土长期定位试验,研究不同施肥措施对黑土活性有机质及其碳库管理指数的影响。结果表明：在不同施肥措施的影响下土壤有机质得到了不同程度的提高。撂荒处理（CK0）土壤有机质较初始值提高了35.62%;单施化肥处理有机质提高最小,为10%~15%;其次为秸秆还田处理提高了20%;有机肥和化肥配施处理土壤有机质提高效果最显著,为66.38%~92.13%。黑土活性有机质分布规律为高活性有机质、中活性有机质、低活性有机质分别占有机质含量的3.80%~10.28%、1.59%~12.32%、8.71%~27.45%。以撂荒处理为参考土壤,有机肥和化肥配施处理高活性有机质、中活性有机质碳库管理指数高于参考土壤;氮磷钾肥配施处理（NPK）高活性有机质及其高活性有机质碳库管理指数与参考土壤较为接近;单施氮肥处理（N）、施用氮肥和磷肥处理（NP）、施用氮肥和钾肥处理（NK）、施用磷肥和钾肥处理（PK）高活性有机质、中活性有机质及总活性有机质碳库管理指数均低于参考土壤。采用有机肥无机肥配施对提高黑土活性有机质含量,提高土壤碳库管理指数具有比较好的效果。

Black soil plays a crucial role in food security and sustainable development of the ecology in China. In the past 50 years the content of soil organic matter （SOM） in the black soil in Northeast of China has been decreasing, thus posing a critical problem of how to maintain its productivity, which has become a hot spot in agricultural science. Based on the long-term stationary fertilization field experiment, variation of soil fertility of and fertilizer efficiency in black soil as affected by long-term fertilization was explored and effects of long-term fertilization on content of soil labile organic matter and carbon pool management index were evaluated. This experiment was laid out in 1990 and designed to have 12 treat- ments, i.e. CK0, CK, N, NP, NK, PK, NPK, SNPK, MNPK, MNPKW2, 1.5MNPK and2MNPK. All the treatments have the same cropping pattern, mono-cropping of maize, except for Treatment MNPKW2, which follows a maize-maize- soybean rotation system. In 2013, soil samples were collected from the topsoil （0 - 20cm） layer for analysis of labile soil organic matter. Contents of three fractions of labile organic matter, namely highly labile organic matter （H-LOM） , moder- ately-labile organic matter （M-LOM） and low-labile organic mmol L-1 and 333 mmol L-j KMnO4, respectively. Results matter （L-LOM） were determined using 33 mmol L-1, 167 show that contents of soil organic matter in all the fertilized treatments increased to a varying extent. Compared with the initial content （23.3 g kg-1 ） of soil organic matter （SOM） , it increased by 35.6% in Treatment CK0, by 10%-15% in Treatments N, NP, NK, PK and NPK, the least in incre- ment, by 20% in Treatment SPNK （ NPK plus straw incorporation） , and by 66.38% ~ 92.13% in Treatments MNPK, MNPKW2, 1.5MNPK and 2MNPK, the most significant increment. The content of H-LOM, M-LOM and L-LOM were 0.94 - 4. 18 g kg-1 , 0.39 - 5.10 g kg-1 and 2.45 ~ 11.36 g kg-1 , respectively, accounting for 4%~ 10% , 1.59% ~ 10.28% and 8.71% ~ 27.45% of the total organic matter, re- spectively. The content of H-LOM, M-LOM and L-LOM in organic fertilizers treatments, were higher than their corre- sponding ones in the other treatments, and the more the organic manure applied, the higher, the contents of SOM. The contents of the three fractions of SOM were low mere chemical, fertilizers and Treatment CK, and did not vary much be- tween those treatments. However, Treatment CK0 and Treatment MNPK did not differ much in content of H-LOM, M-LOM and L-LOM, suggesting that fallow had a significant SOM increasing effect. Carbon pool management index （CPMI） is an important parameter to characterize status of soil nutrients. Treatment CKo. did not have much improvement in CPMI of LOM, whereas Treatment 2MNPK exceeded 200, the highest among all the treatments. For M-LOM, CPMI was 22.08 in Treatment CK, lower than any other treatments. Compared with Treat- ment CK, Treatments N, NK, NP, and PK did not improve much in CPMI, but Treatments NPK, SNPK, MNPK, MN- PKW2, 1.5MNPK, 2MNPK and CK0 did quite significantly, with the highest CPM｜ being 176.64 in Treatment 2MNPK. On the whole, in terms of CPMI, the treatments followed an order of organic fertilizers 〉 fallow land 〉 straw incorpora- tion （SNPK） 〉 mere chemical fertilizers （N, NP, NK, PK, NPK）. For organic treatments, the more the organic ma- nure applied, the higher the CPMI. CPMI was higher in Treatment MNPKW2 than in Treatment MNPK, suggesting that the maize-maize-soybean rotation system is a good way to improve CPMI.