秸秆及其配施有机物料对黄灌区盐碱土淋洗效果的影响

Effects of straw and its application on different organic materials on the leaching effect of saline-alkali soils in an irrigation area in the South bank of the Yellow River

为了分析比较玉米秸秆及其配施不同有机物料对盐碱土壤淋洗过程中盐分和溶解性有机物的影响,以黄河南岸灌区中度和重度两种盐碱土壤为研究对象,分别设置对照(CK)、3%玉米秸秆(W1)、2%玉米秸秆配施1%牛粪(W2)和2%玉米秸秆配施1%生物炭(W3)共4个处理,通过测定淋洗液的可溶性盐和溶解性有机碳(DOC)含量、淋洗前后土壤电导率(EC)和盐基离子,探究淋洗过程中不同有机物添加下土壤盐分和有机物分解过程的变化。结果表明:秸秆及其配施不同有机物料均显著降低了两种盐碱土淋洗后土壤的EC和可溶性盐离子含量。与淋洗前相比,W1、W2和W3处理下,中度盐碱土的脱盐率分别为65.02%、67.22%和66.21%,重度盐碱土分别为73.85%、66.14%和69.55%。W1、W2和W3处理下,中度盐碱土中可溶性Na^(+)、Ca^(2+)和Mg^(2+)的降幅范围分别为48.38%~69.32%、70.89%~75.86%和73.00%~74.45%,重度盐碱土中可溶性K^(+)、Na^(+)、Ca^(2+)和Mg^(2+)降幅范围分别为14.86%~23.39%、70.98%~85.84%、86.63%~92.39%和93.72%~95.42%。有机物料的输入会增加两种盐碱土的DOC含量,但不同处理在两种盐碱土中腐殖化程度表现不同。中度盐碱土中,不同物料淋洗液中溶解性有机物的特定紫外吸光度(SUVA254)和光谱斜率比值(SR)在处理间均无显著差异,SUVA254随淋洗次数增加而降低,而SR均增大;重度盐碱土中,添加有机物料处理下溶解性有机物的SR均较小,但W1处理的SUVA254低于W2和W3处理。秸秆配施不同有机物料均提高了土壤持水量,中度盐碱土中以W1效果最好,提高了31.00%,重度盐碱土中W1、W2分别提高了76.46%、74.33%。综上,在相同淋洗状态下,外源有机物料的添加均不同程度地减少了两种盐碱土的可溶性盐基离子含量,有效降低了土壤盐碱程度,尤其是重度盐碱土。同时,外源有机物料的添加也增加了土壤DOC的输入来源,提高了土壤持水能力,弥补了淋洗对盐碱化土壤造成的养分损失。在给定淋洗条件下,中度盐碱土中W2处理的脱盐、降Na+效果最好,重度盐碱土中以W1处理较好。

To analyze and compare the dynamic changes of salt and dissolved organic matter during the leaching of saline-alkali soils under the addition of different organic materials,control(CK),3%corn stover(W1),2%corn stover with 1%cow dung(W2),and 2%corn stover with 1%biochar(W3)were applied to moderate and severe saline-alkali soils in an irrigation area in the south bank of the Yellow River.Subsequently,the soluble salt and dissolved organic carbon(DOC)content of the eluent,soil electrical conductivity(EC)and saltbased ions before and after leaching were analyzed,to explore the changes in soil salt and organic decomposition processes under the addition of different organic matter during the leaching process.The results showed that:the EC value and water-soluble salt ion content of the soil after the leaching of the two saline-alkali soils were significantly reduced by straw and its application on different organic materials.Compared with before leaching,under the treatment of W1,W2,and W3,the desalination rates of moderate saline-alkali soil were 65.02%,67.22%,and 66.21%,and the heavily saline-alkali soil were 73.85%,66.14% and 69.55%,respectively.Under the treatment of W1,W2,and W3,the reductions of water-soluble Na^(+),Ca^(2+),and Mg^(2+)in moderately saline-alkali soil ranged from 48.38%-69.32%,70.89%-75.86%,and 73.00%-74.45%,respectively,and the reduction ranges of water-soluble K^(+),Na^(+),Ca^(2+),and Mg^(2+)in heavily saline-alkali soil were 14.86%-23.39%,70.98%-85.84%,86.63%-92.39%,and 93.72%-95.42%,respectively.The input of organic materials increased the content of DOC in the two saline-alkali soils,but the degree of humification in the two saline-alkali soils was different under different treatments.In moderate saline-alkali soil,there were no significant differences between special UV absorbance of 254 nm(SUVA254)and spectra slope(SR)in eluents of different organic material treatment,and SUVA254 decreased with the increase in leaching frequency,while SR increased.In severe saline-alkali soil,SR of the dissolved organic matter under the treatment of added organic materials was low,but SUVA254 of the treatment with 3% straw was lower than that of the treatments with cow dung or biochar.The application of different organic materials to straw increased the soil's water holding capacity.W1 was the best in moderate saline-alkali soil,with an increase of 31.00%;W1 and W2 in severe saline-alkali soil increased by 76.46% and 74.33%.In summary,the addition of exogenous organic materials in the same leaching condition reduced the soluble salt-based ion content of the two saline-alkali soils to varying degrees,and effectively reduced the salinity of the soil,especially the severe saline-alkali soil.Simultaneously,the addition of exogenous organic materials also increased the input source of soil DOC,improved the soil's water holding capacity,and made up for the nutrient loss caused by leaching on saline-alkali soils.Under the given leaching conditions,W2 in desalination and Na+reduction was the best in moderate saline-alkali soil,while W1 was better in severe saline-alkali soil.