【作者】 张永春； 汪吉东； 许仙菊； 宁运旺； 张辉； 沈其荣；

【Author】 Zhang Yong-chun~(1,2,3),Wang Ji-dong~(1,2),Xu Xian-ju~(1,2),Ning Yun-wang~(1,2),Shen Qi-rong~(3+) (1.Institute of Agricultural Resource and Environmental Sciences,Jiangsu Academy of Agricultural Sciences,Nanjing 210014; 2.Scientific observing and experimental station of Arable Land Conservation(Jiangsu),Ministry of Agriculture,Nanjing 210014; 3.College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095)

【机构】 江苏省农业科学院农业资源与环境研究所； 农业部江苏耕地保育科学观测实验站； 南京农业大学资源与环境学院；

【摘要】 利用江苏地区典型水稻土和潮土长期定位试验,研究了施肥对土壤酸化速率及酸碱缓冲体系的影响,并结合土壤添加秸秆、猪粪等培养试验、施氮及模拟酸沉降试验,对土壤酸化的关键影响因素及不同致酸因子的具体贡献进行了系统的研究。主要结果如下:太湖地区水稻土经26年施肥处理,土壤pH降低了0.38～1.39。土壤酸化速率为0.50～1.74 kmol H⁺hm^-2a^-1,酸化修复所需CaCO₃用量为（24.7～87.1）kg·hm^-2a^-1。各处理土壤酸化速率以施磷钾肥（CPK）处理最低,施氮肥结合有机肥及秸秆（MRN）处理最高,施用氮肥基础上增施有机肥促进土壤酸化,其酸化速率大于单施化肥处理;各处理土壤pH以施磷钾肥处理（CPK）为最高（pH 6.42）,对照（CO）次之（pH6.38）,施氮肥结合有机肥及秸秆处理（MRN）最低（5.41）。增施有机肥及秸秆处理土壤缓冲容量保持稳中有升,这主要与土壤有机质的提升有关;而pH的下降则与盐基离子含量的下降有关。30年连续不同施肥下,徐州石灰性潮土土壤pH降低0.41～0.70;不同施肥处理耕层土壤酸碱缓冲容量为（15.82～21.96）cmol·kg^-1,施用化肥促进土壤酸化加速,单施氮肥酸化程度最高,而化肥配施有机肥处理则缓解土壤酸化加速。长期不同施肥下石灰性潮土仍处于碳酸钙缓冲体系,该体系下,有机质对石灰性潮土土壤酸碱缓冲体系影响较弱。长期不同施肥显著改变0～40 cm层土壤的碳酸钙和活性碳酸钙含量,且活性碳酸钙含量在剖面中的分异变化比碳酸钙大,其含量与土壤酸碱缓冲容量达到极显著正相关关系,暗示长期施肥管理下,土壤活性碳酸钙更能敏感反应土壤基本理化性状的变化。室内比较了3个pH梯度降雨和3水平施氮量对水耕铁渗人为土土壤酸化的影响。不同pH降雨及施氮处理土壤的酸度累积量为每柱（4.73～15.57）mmol H⁺,以pH 6.5降雨不施氮处理、pH 2.5添加高氮量（N2）处理酸化速率为最低和最高;相同pH降雨下,致酸量随施氮量增加而上升;不施氮处理土壤酸度累积随降雨pH降低而增加,但中施氮量(150 mg kg^-1土)和高施氮量(300 mgkg^-1土)下,pH 4.5处理土壤酸度累积量则小于pH 6.5处理;不同降雨及施氮处理NO₃^-淋溶致酸量为每柱（4.32～12.88）mmol H⁺,NH₄⁺淋溶消耗H⁺量为每柱（0.01～0.29）mmol;正常酸沉降（pH 6.5）下,中施氮量和高施氮量处理致酸量都大于各梯度pH降雨的致酸量。以上结果表明,单施氮处理的致酸量大于单纯的酸沉降处理,而无论是降雨还是施氮,NO₃^-淋溶在加速土壤酸化进程中占主导作用。总之,对于江苏省太湖地区的黄泥土,土壤酸碱缓冲体系处于硅酸盐和盐基离子缓冲体系,该体系下在施用化肥基础上增施有机肥对土壤酸化的加速主要受土壤盐基离子的耗竭影响,而保持土壤酸碱缓冲容量稳中有升则主要受土壤有机质的提升影响;江苏淮北潮土则处于碳酸钙缓冲体系,在施用化肥的基础上增施有机肥土壤减缓酸化趋势;和模拟不同pH降雨相比,施氮的致酸强度大于降雨,且NO₃^-为致酸量的关键因素。更多还原

【Abstract】 Soil acidification is a naturally occurring phenomenon and is usually caused by long-term addition of protons to the upper layers of soil and subsequent leaching of exchangeable bases.In recent decades,due to the rapid development of chemical and petroleum industries and frequent agricultural practices including fertilization and crop rotation,soil acidification has been accelerated,which is one of the important soil degradation.In this paper,incubation experiments as well as long-term field experiments in typical paddy soil and alluvial soil in Jiangsu Province were carried out to study acid deposition and nitrogen application on soil acidification rates,the key factors of soil acidification,the characteristics of various factors and their contributions to soil acidification. Over 26 years of different fertilization,the acidification rate of the paddy soil in Tai Lake region was 0.50¹.74 kmol H⁺ hm^-2 a^-1,and lowest and highest soil acidification rates appeared in the control treatment（no fertilizer） and the treatment of urea plus pig manure and rice straw application,respectively. The required amounts of CaCO₃ were 24.7-87.1 kg·hm^-2a^-1 among all treatments.The pH of major plot of chemical fertilizer（6.10） was 0.33 higher than the main plot of organic fertilizer addition.Na⁺,K⁺,Ca²⁺ and Mg²⁺ concentrations in chemical fertilizer plots were 5.24,2.05,39.87 and 9.04 mmol·kg^-1,which were 2.7%,54.1%,3.1%and 13.4%higher than the corresponding organic fertilizer addition plots, irrespectively.Significant differences were found in K⁺ and Ca²⁺ concentration between the two major plots. The soil pH was highest in P and K fertilizer application treatment（pH 6.42）,followed by the control treatment（pH 6.38）,the treatment of N plus organic fertilizer and rice straw addition was the lowest（pH 5.41）,and the main plot with pig manure additional got a low concentration of cation,indicating that the lower pH in the major plot of organic fertilizer amendment might be due to transfer of base cations from soil to plant.The exhaustion of base cations occurred when the yield increased.The buffer capacity of soil amended by organic fertilizers(2.18 cmol kg^-1) was slightly higher than the chemical fertilizer treatment (2.14 cmol kg^-1).Soil buffer capacity was positively correlated to soil organic matter content,and soil pH value decline was due to cation depletion. Soil pH,CaCO₃ and active CaCO₃ contents,soil buffer capacity significantly changed over continuous 30-year fertilization on alluvial soil in Xuzhou City.The topsoil pH was decreased by 0.41～0.70.The soil buffer capacity,ranging from 15.82 to 21.96 cmol·kg^-1,was lowest in sole N treatment and highest in the treatment of manure plus NPK.The soil buffer capacity of chemical fertilizer treatments（except NP） was lower than the control,while the manure treatments had higher soil buffer capacity than the control.The soil buffer capacities of the treatments of MN,MNP and MNPK were 3.23,1.56 and 4.33 cmol·kg^-1 higher than those of N,NP and NPK,irrespectively.The soil buffer capacity was significantly positively correlated to soil CaCO₃ content,but had no significant correlation with organic matter content and CEC,indicating that Alluvial soil was still in the CaCO₃ mediated buffer system,in which organic matter had a small role over long term fertilization.Different long term fertilizations altered CaCO₃ and active CaCO₃ contents notably in the 0～40 cm soil layer,and the contents of active CaCO₃ which was very significantly positively correlated to soil buffer capacity,showed a greater variation along soil profile than that of CaCO₃, suggesting that soil active CaCO₃ could more sensitively reflect variation of soil physical and chemical properties than CaCO₃,and the CaCO₃ mediated buffer system could be subdivided into the active CaCO₃ mediated buffer system. Indoor simulation experiment was carried out to compare the effects of 3 pH values and 3 nitrogen application rates on soil acidification.Soil acidification accumulation varied from 4.73 to 15.57 mmol H⁺/column,among which the highest and lowest soil acidification accumulation occurred on the treatments of pH 6.5 depositions without N and pH 2.5 depositions with high N input,respectively.Soil acidification accumulation was elevated with the increase of N input under the same pH deposition.Soil acidification accumulation increased with the decrease of pH in zero N application treatment,when the same amounts of N were provided.However,within medium(150 mg kg^-1 soil) and high(300 mg kg^-1soil) N input,soil acidification accumulation was lower in pH 4.5 deposition than pH 6.5 deposition.Nitrate-induced soil acidification accumulation was 4.32¹2.88 mmol per column,and ammonia leaching consumed H⁺ by 0.01～0.29 mmol per column.In case of normal deposition（pH 6.5）,soil acidification accumulation was greater than other pH deposition treatments under medium and high N inputs.The above results indicated that soil acidification accumulation induced by N input was greater than acid deposition.Nitrate leaching played a leading role in the acceleration of soil acidification. In conclusion,Hapli-Stagnic Anthrosols was silicate and cations buffering system,soil acidification induced either by matter single application of chemical fertilizer,or of chemical fertilizer,or by combined application of chemical fertilizer and organic fertilizer,or by mixed application of organic fertilizer,rice straw and chemical fertilizer,was influenced by soil buffering capacity which in turn was affected by soil organic matter content;Accumulation or depletion of base cations was a major factor to the in-consistent acidification trend between different fertilization treatments.The content of calcium carbonate was a key factor affected pH_BC for the sandy loam calcareous fluvor-aquic soil,and the active calcium carbonate more sensitively response to different fertilizer treatments,calcium carbonate buffering system can be further broken down into the soil active calcium carbonate buffering system.Compared to different pH rainfall, nitrogen application contributed more to soil acidification and nitrate was the key acidity inducing factor.更多还原