氮肥施用是引起土壤酸化的主要原因之一,酸性环境促进紫色母岩的风化过程,并影响紫色母岩风化产物的理化性质,然而氮肥施用对风化产物的盐基离子和酸缓冲容量(pH Buffer Capacity,pHBC)的影响尚不明晰.因此,以蓬莱镇组(J_(3)p)紫色泥岩...氮肥施用是引起土壤酸化的主要原因之一,酸性环境促进紫色母岩的风化过程,并影响紫色母岩风化产物的理化性质,然而氮肥施用对风化产物的盐基离子和酸缓冲容量(pH Buffer Capacity,pHBC)的影响尚不明晰.因此,以蓬莱镇组(J_(3)p)紫色泥岩为研究对象,设置3组氮肥施用水平(280,560,840 kg/hm^(2))以及不施肥处理(CK),通过淋溶试验模拟母岩风化,以探明氮肥施用对紫色泥岩风化产物盐基离子及pHBC的影响.结果表明:与CK处理相比,氮肥施用处理下风化产物的化学蚀变指数(Chemical Index of Alteration,CIA)增加0.9%~4.7%,且风化产物的CIA随施肥水平的增加而呈现先增加后减小的趋势.氮肥施肥处理下风化产物的pHBC较CK处理降低4.0%~8.9%,且风化产物的pHBC随氮肥施用水平的增加呈现先减小后增加的趋势.风化产物的交换性盐基离子、水溶性盐基离子和盐基离子的淋失总量表现为:Ca^(2+)>Mg^(2+)>Na^(+)>K^(+),且风化产物的二价盐基离子(Ca^(2+)和Mg^(2+))含量远高于一价盐基离子含量(K^(+)和Na^(+)).基于多元线性逐步回归分析和结构方程模型分析结果表明:氮肥施用对风化产物水溶性K^(+)(R^(2)=0.75)和Na^(+)(R^(2)=0.99)含量存在显著负效应(p<0.05),而水溶性K^(+)和Na^(+)含量对风化产物pHBC(R^(2)=0.44)存在正效应,进而导致氮肥施用对风化产物pHBC存在负效应,这可能是氮肥施用影响风化产物pHBC的主要机制之一.研究结果表明:为了紫色土肥力的可持续发展,紫色土区域的氮肥施用量应小于280 kg/hm^(2).展开更多
Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultiv...Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultivation and heavy chemical N input in the Huang-Huai-Hai Plain, the impact extent of induced proton input on soil pH in the long term was not yet clear. In this study, acidification rates of different soil layers in the soil profile （0-120 cm） were calculated by pH buffer capacity （pHBC） and net input of protons due to chemical N incorporation. Topsoil （0-20 cm） pH changes of a long-term fertilization field （from 1989） were determined to validate the predicted values. The results showed that the acid and alkali buffer capacities varied significantly in the soil profile, averaged 692 and 39.8 mmolc kg-1 pH-1, respectively. A significant （P〈0.05） correlation was found between pHRC and the content of calcium carbonate. Based on the commonly used application rate of urea （500 kg N ha-1 yr-1）, the induced proton input in this region was predicted to be 16.1 kmol ha-1 yr-1, and nitrification and plant uptake of nitrate were the most important mechanisms for proton producing and consuming, respectively. The acidification rate of topsoil （0-20 cm） was estimated to be 0.01 unit pH yr-1 at the assumed N fertilization level. From 1989 to 2009, topsoil pH （0-20 cm） of the long-term fertilization field decreased from 8.65 to 8.50 for the PK （phosphorus, 150 kg P205 ha-1 yr-1; potassium, 300 kg K20 ha-1 yr-1; without N fertilization）, and 8.30 for NPK （nitrogen, 300 kg N ha-1 yr-1; phosphorus, 150 kg P2Os ha-1 yr-1; potassium, 300 kg K20 ha -1 yr-1）, respectively. Therefore, the apparent soil acidification rate induced by N fertilization equaled to 0.01 unit pH yr-1, which can be a reference to the estimated result, considering the effect of atmospheric N deposition, crop biomass, field management and plant uptake of other nutrients and cations. As protons could be consumed by some field practices, such as stubble return and coupled water and nutrient management, soil pH would maintain relatively stable if proper management practices can be adopted in this region.展开更多
文摘氮肥施用是引起土壤酸化的主要原因之一,酸性环境促进紫色母岩的风化过程,并影响紫色母岩风化产物的理化性质,然而氮肥施用对风化产物的盐基离子和酸缓冲容量(pH Buffer Capacity,pHBC)的影响尚不明晰.因此,以蓬莱镇组(J_(3)p)紫色泥岩为研究对象,设置3组氮肥施用水平(280,560,840 kg/hm^(2))以及不施肥处理(CK),通过淋溶试验模拟母岩风化,以探明氮肥施用对紫色泥岩风化产物盐基离子及pHBC的影响.结果表明:与CK处理相比,氮肥施用处理下风化产物的化学蚀变指数(Chemical Index of Alteration,CIA)增加0.9%~4.7%,且风化产物的CIA随施肥水平的增加而呈现先增加后减小的趋势.氮肥施肥处理下风化产物的pHBC较CK处理降低4.0%~8.9%,且风化产物的pHBC随氮肥施用水平的增加呈现先减小后增加的趋势.风化产物的交换性盐基离子、水溶性盐基离子和盐基离子的淋失总量表现为:Ca^(2+)>Mg^(2+)>Na^(+)>K^(+),且风化产物的二价盐基离子(Ca^(2+)和Mg^(2+))含量远高于一价盐基离子含量(K^(+)和Na^(+)).基于多元线性逐步回归分析和结构方程模型分析结果表明:氮肥施用对风化产物水溶性K^(+)(R^(2)=0.75)和Na^(+)(R^(2)=0.99)含量存在显著负效应(p<0.05),而水溶性K^(+)和Na^(+)含量对风化产物pHBC(R^(2)=0.44)存在正效应,进而导致氮肥施用对风化产物pHBC存在负效应,这可能是氮肥施用影响风化产物pHBC的主要机制之一.研究结果表明:为了紫色土肥力的可持续发展,紫色土区域的氮肥施用量应小于280 kg/hm^(2).
基金financially supported by the National Basic Research Program of China (2011CB100506)the China Agriculture Research System-Wheat (CARS-03-02A)+1 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences (KSCX2-EW-N-08)Research Fund of State Key Laboratory of Soil and Sustainable Agriculture, Nanjing Institute of Soil Science, Chinese Academy of Sciences (Y412201401)
文摘Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultivation and heavy chemical N input in the Huang-Huai-Hai Plain, the impact extent of induced proton input on soil pH in the long term was not yet clear. In this study, acidification rates of different soil layers in the soil profile （0-120 cm） were calculated by pH buffer capacity （pHBC） and net input of protons due to chemical N incorporation. Topsoil （0-20 cm） pH changes of a long-term fertilization field （from 1989） were determined to validate the predicted values. The results showed that the acid and alkali buffer capacities varied significantly in the soil profile, averaged 692 and 39.8 mmolc kg-1 pH-1, respectively. A significant （P〈0.05） correlation was found between pHRC and the content of calcium carbonate. Based on the commonly used application rate of urea （500 kg N ha-1 yr-1）, the induced proton input in this region was predicted to be 16.1 kmol ha-1 yr-1, and nitrification and plant uptake of nitrate were the most important mechanisms for proton producing and consuming, respectively. The acidification rate of topsoil （0-20 cm） was estimated to be 0.01 unit pH yr-1 at the assumed N fertilization level. From 1989 to 2009, topsoil pH （0-20 cm） of the long-term fertilization field decreased from 8.65 to 8.50 for the PK （phosphorus, 150 kg P205 ha-1 yr-1; potassium, 300 kg K20 ha-1 yr-1; without N fertilization）, and 8.30 for NPK （nitrogen, 300 kg N ha-1 yr-1; phosphorus, 150 kg P2Os ha-1 yr-1; potassium, 300 kg K20 ha -1 yr-1）, respectively. Therefore, the apparent soil acidification rate induced by N fertilization equaled to 0.01 unit pH yr-1, which can be a reference to the estimated result, considering the effect of atmospheric N deposition, crop biomass, field management and plant uptake of other nutrients and cations. As protons could be consumed by some field practices, such as stubble return and coupled water and nutrient management, soil pH would maintain relatively stable if proper management practices can be adopted in this region.
