长期施肥下新疆灰漠土有机碳及作物产量演变

为明确长期不同施肥下新疆灰漠土有机碳和作物产量演变特征,依托始于1990年的灰漠土肥力长期定位监测试验,选择对照(CK,不施肥)、施氮磷肥(NP)、氮磷钾平衡施肥(NPK)、氮磷钾配合常量有机肥(NPKM)、氮磷钾配合高量有机肥(h NPKM,有机肥施用量为NPKM的2倍)、氮磷钾配合秸秆还田(NPKS)6个处理,分析不同处理下土壤有机碳和小麦、玉米产量演变特征,探讨碳投入及有机碳与作物产量的关系。结果表明:1)长期耗竭种植(CK)、连续施用NP或NPK肥,灰漠土有机碳含量持续下降,年均下降速率分别为0.094 g·kg~(-1)、0.043 g·kg~(-1)和0.053 g·kg~(-1),表明施化肥(NP、NPK)不能维持土壤有机碳含量,不利于土壤肥力的保持。NPKM和h NPKM处理,土壤有机碳显著增加,年均增加0.360 g·kg~(-1)和0.575 g·kg~(-1),增施有机肥是快速提高灰漠土肥力的重要措施。秸秆还田处理(NKPS),土壤有机碳年均增幅0.006 g·kg~(-1),与NPK处理对比,秸秆还田虽没有大幅度提高土壤有机碳,但维持了土壤肥力。2)较CK,长期化肥有机肥配施(NPKM、h NPKM)显著增加了作物产量(P0.05)。与NP和NPK比较,长期化肥有机肥配施显著提高了小麦产量(P0.05),但玉米产量与施化肥处理差异不显著(P0.05),玉米产量以平衡施肥(NPK)的增幅最高,达到220 kg·hm~(-2)·a~(-1)。小麦的产量变异系数(29.1%~43.9%)高于玉米产量变异(19.0%~32.7%)。化肥配合秸秆还田(NPKS)处理的小麦增产幅度与高量施用有机肥(h NPKM)处理接近,喻示了秸秆还田对作物增产的作用不可忽视。3)碳投入与土壤有机碳和小麦、玉米产量有显著线性正相关(P0.05)。基于以上分析,在干旱区灰漠土增加土壤碳投入(有机肥或秸秆)仍然是最基本的土壤培肥措施。

Evolution of soil organic carbon and crop yield under long-term fertilization in grey desert soils

With a cropping area of 1.76 million hectares, the grey desert soil (hapliccalcisol) is crucial for agricultural development in Xinjiang, Northwest China. The use of chemical and manure fertilizers has been an effective way of increasing crop production. However, there has been limited information on crop yield and soil organic carbon evolution in the region under long-term fertilization using both organic and inorganic fertilizers. Thus this study was conducted to determine the relationship among carbon input, soil organic carbon and crop yield in grey desert soil in Modern Agricultural S&T Demonstration Garden of Xinjiang Academy of Agricultural Sciences. The study also analyzed the trends in variations in crop yield and soil organic carbon under different long-term fertilization practices. The results of the study will provide scientific database which can be used to improve soil fertility and promote sustainable development of crop production in the study area. A long-term experiment was conducted using various fertilizations in 1990-2013 in wheat (Triticum aestivium) and maize (Zea mays) crop rotation system in grey desert soil. The fertilization treatments included the control without fertilization (CK), chemical nitrogen plus phosphate fertilization (NP), chemical nitrogen plus phosphate and potassium fertilization (NPK), NPK plus animal manure (NPKM), two times animal manure of NPKM (hNPKM), and NPK plus straw (NPKS). The results showed that: 1) soil organic carbon contents of CK, NP and NPK decreased by 0.094 g·kg-1·a-1, 0.043 g·kg-1·a-1 and 0.053 g·kg-1·a-1, respectively, from 1990 to 2013. Although chemical fertilization increased crop production, but decreased soil fertility. Annual rates of soil organic carbon increase under NPKM and hNPKM treatments were 0.360 g·kg-1 and 0.575 g·kg-1, respectively, from 1990 to 2013. Therefore the application of manure played an important role in improvement of soil fertility for crop cultivation. 2) Compared with CK, long-term application of chemical fertilizers with manure (NPKM and hNPKM) increased crop yield. However, compared with NP and NPK treatments, chemical fertilizers with manure (NPKM and hNPKM) significantly increased wheat yield (P < 0.05). There was, however, no significant difference in maize yield between observed manure treatments and chemical fertilizers treatments (P > 0.05). The highest maize yield was 220 kg·hm-2·a-1 under NPK treatment. The coefficient of variation of wheat yield (29.1%-43.9%) was higher than that of maize yield (19.0%-32.7%). There were no differences between NPK with straw and NPK with manure, which suggesting that the effects of straw return on crop yield was not negligible. 3) Carbon input was significantly positively correlated with soil organic carbon and crop yield (P < 0.05). Thus increasing carbon input (manure or straw return) was a key of improving soil fertility in the grey desert soil region.