施肥措施对黄土旱塬区小麦产量和土壤有机碳积累的影响

利用中国科学院长武农田生态试验站的长期田间试验（1984～2007年），研究了小麦产量，耕层有机碳变化，评价了土壤管理和气候因素对土壤有机碳（Soil organic C，SOC）变化的影响。研究涉及6个处理:休闲地（F）、不施肥（CK）、有机肥（M）、氮肥（N）、磷肥（NP）和氮、磷、有机肥（NPM）处理。结果表明，施肥可以显著提高作物产量和SOC积累，CK、M、N、NP、NPM处理平均产量依次为1.5、2.6、2.0、3.3、4.0 t/hm2，2007年F、CK、M、N、NP、NPM处理0—20 cm土层SOC积累量依次为-1.09、0.76、8.59、1.02、3.42和9.5 t/hm2。作物产量与SOC含量呈显著的正相关关系（r=0.80），有机碳输入量与SOC含量相关性更好（r=0.97），外源有机碳的输入也是提高SOC的重要措施。施肥措施对作物固碳和SOC影响存在显著（P0.05）差异。土壤固碳速率（Y）与SOC输入量（X）符合线性方程Y=0.231X﹣0.0813（r=0.98）。施肥可以提高黄土高原半干旱地区土壤生产力和SOC的积累，且无机肥和有机肥配施效果最佳。

Effects of fertilization on wheat yield and soil organic carbon accumulation in rainfed loessial tablelands

Wheat yield and soil organic carbon(SOC)change at the surface layer were investigated by a long．Term field experiment with six treatments at the Changwu Ecological Station of the Chinese Academy of Sciences started from 1984 to 2007．The six treatments are fallow(F)，control(CK)，organic manure(M)，nitrogen(N)，nitrogen and phosphorus (NP)，and nitrogen and phosphorus with organic manure(NPM)．The resets show that the crop productivity and SOC accumulation ale significantly increased under the fertilizer applications．The averaged winter wheat yields of Ihe 23 years are 1．5，2．6，2．0，3．3，and 4．0 t／ha for the CK，M，N，NP，and NPM treatments,respectively．Cumulative amounts of SOC at 0-20 cm soil layer in 2007 are-1．09，0．76，8．59，1．02，3．42 and 9．5 t／ha for the six treatments．There is a significant correlation between crop yield and SOC content(r=0．80)，and moreover，there is a significant correlation between carbon application amount and SOC content(r=0．97)，which indicates carbon from farm yard manure plays an important role in improving SOC content．There is a significant difference between the effects of fertilization on carbon sequestration(P<0．05)by crop and SOC，and the relationship between soil carbon sequestration rate(Y) and soil organic carbon input(X)can be expressed by a linear equation of Y=0．231X-0．0813(r=0．98)．Fertilization can increase soil productivity and SOC accumulation in the semiarid regions of the Loess Plateau，especially with the combined application of organic and inorganic fertilizer．