不同有机物料对苏打盐化土有机碳和活性碳组分的影响

【目的】在大同盆地苏打盐化土上,研究不同有机物料对春玉米产量、土壤有机碳及活性碳组分的影响,明确土壤有机碳及活性碳组分与主要盐碱指标的相关关系,为苏打盐化土改良及有机物料资源化利用提供理论支撑。【方法】2016-2017年在山西省北部怀仁县开展田间定位试验,设对照(CK)、风化煤、生物炭、牛粪和秸秆5个处理,各处理有机物料施用量按照每年9000 kg/hm^2等有机碳投入量折算,收获时对春玉米进行测产。2017年春玉米收获后,采集土壤样品测定土壤有机碳总量(SOC)和水溶性有机碳(WSOC)、易氧化有机碳(EOC)、轻组有机碳(LFOC)含量,分析土壤活性碳组分占有机碳的比例、土壤有机碳及活性碳组分与盐碱指标之间的关系。【结果】与CK相比,生物炭和秸秆处理春玉米产量无明显差异,而风化煤和牛粪处理春玉米产量则分别显著提高30.2%和30.3%。添加有机物料促进了0-20 cm土层SOC累积,其中以风化煤和牛粪处理效果最佳,较CK分别提高47.6%和36.1%。在有机碳组分方面,风化煤和牛粪处理提高WSOC、EOC含量的效果显著高于生物炭、秸秆处理;风化煤、牛粪和秸秆处理的LFOC含量显著高于生物炭处理。四类有机物料处理的WSOC占总有机碳的比例差异不显著,牛粪处理的占比显著高于CK。EOC占总有机碳的比例以牛粪处理最高,风化煤次之,且二者均显著高于CK处理;LFOC占总有机碳的比例则表现为秸秆、牛粪>风化煤、生物炭> CK。此外,添加有机物料能有效降低0-20 cm土层土壤pH、电导率(EC)和碱化度(ESP),其中以风化煤和牛粪处理降幅最大。相关分析表明,土壤SOC与pH、EC和ESP呈显著负相关。【结论】通过有机物料改良效果比较,发现牛粪和风化煤处理能促进苏打盐化土有机碳累积,提高可溶性、易氧化态及轻组有机碳组分在总有机碳中的占比,降低土壤pH、EC和ESP,明显提高春玉米产量。因此,风化煤和牛粪是山西北部苏打盐化土良好的改良剂。

Effects of organic materials on soil organic carbon and fractions of active carbon in soda saline soil

【Objectives】We compared the effects of four kinds of organic materials on increment of soil organic carbon quality and quantity, and studied the correlation between soil organic carbon and active carbon fractions and main salinity and alkali indexes in the soda saline soil of Datong basin,northern Shanxi Province, to provide a reference for the biological remediation of the soils.【Methods】The field experiment was conducted in Huairen County of northern Shanxi from 2016 to 2017. The tested organic materials included weathered coal, biochar, cattle manure and corn stalk, all the organic materials were applied at rate of 9000 kg/hm2 organic carbon annually, and no organic material addition was served as control (CK). The spring maize yield was investigated, the content of soil organic carbon (SOC), water-soluble organic carbon (WSOC), easily oxidizable organic carbon (EOC) and light fraction organic carbon (LFOC) were measured.【Results】Compared with CK, addition of biochar and corn stalk did not increase the maize yield significantly, while weathered coal and cattle manure treatments markedly increased the yield by 30.2% and 30.3%, respectively. All organic material addition enhanced the SOC accumulation in 0–20 cm soil layer, and weathered coal and cattle manure increased 47.6% and 36.1%, respectively, which were significantly higher than those of corn stalk and biochar. Similarly, all organic material addition significantly increased the contents of WSOC, EOC and LFOC in 0–20 cm soil layers. WSOC and EOC contents in weathered coal, cattle manure treatments were significantly higher than those in biochar and corn stalk treatments. Addition of biochar had the lowest LFOC content. The WSOC/SOC in cattle manure treatment was significantly higher than CK in 0–20 cm layer, while those in the four organic material treatments were not significantly different. The EOC/SOC in cattle manure treatment was highest, followed by weathered coal, both were significantly higher than CK. The LFOC/SOC appeared in a descending order as corn stalk, cattle manure > weathered coal, biochar > CK. Organic material addition also resulted in a decrease of soil pH, electrical conductivity (EC) and exchange sodium percentage (ESP) in 0–20 cm soil layer, and such decrease effects in weathered coal and cattle manure treatments were stronger. SOC and fractions of soil active carbon were negatively correlated with soil pH, EC and ESP.【Conclusions】Addition of cattle manure and weathered coal could markedly increase SOC quality and quantity, reduce soil pH, EC and ESP, and further increase maize yield, so are thought to be suitable amendment materials for soda saline soil of northern Shanxi.