| Soil salinization is an important factor to restrict agricultural production.At present,the problem of soil salinization along the Yellow River beach in Inner Mongolia is prominent.Various factors lead to soil hardening,fertility decline,low grain output,and seriously restrict the local economic development.Therefore,it is imperative to find a simple and effective way to improve saline alkali soil.In this paper,two kinds of agricultural wastes,corn straw and sunflower straw,were used to make biochar,and humic acid was used as the improver.Indoor soil culture test and pot experiment were used to study the improvement effect of physical and chemical properties of saline alkali soil and the growth of corn.The main research results are as follows:The results showed that humic acid,mixed biochar,sunflower straw biochar and corn straw biochar were the best way to improve saline alkali soil.There was no significant difference in soil pH between biochar alone and blank soil in a short period of time(P < 0.05).There was no significant change in soil pH within 60 days.Within80 days,the pH was only reduced by 0.12 units,which had a significant effect on the improvement of soil fertility and nutrition index,CEC was 2.8 times higher than CK.Humic acid had a significant effect on soil pH during 80 days It can reduce 0.33 units,and it has a good effect on the conservation and utilization of phosphorus.At the same time,it can reduce the soil salt content,and reduce EC by 21.8%.The results showed that the change of soil index with time was significant difference after mixed application of biochar and humic acid,the pH of soil decreased by 13.98% as compared with CK,the effect decreased with the increase of biochar application,EC decreased by 35.1% as compared with CK,the effect of soil fertility andwater conservation was significantly improved by the combination of biochar and humic acid,CEC increased by 3.48 times as compared with CK,and the effect of soil pH and water conservation was significantly improved by the combination of biochar and humic acid Carbon and humic acid are helpful to improve soil fertility: the highest total phosphorus is 4.69 times of CK,the utilization efficiency of phosphorus is improved,and the effective phosphorus is 3.17 times of CK;the alkali hydrolyzed nitrogen and available potassium are improved,1.01 times and 5 times of blank respectively,and the organic matter is increased by 1.68 times;it can be seen that the soil improvement effect of combined application is better than that of single application.The application of biochar and humic acid improved the soil environment,provided more suitable living environment and more abundant nutrients for microorganisms,increased bacteria,actinomycetes and fungi by 26.4%,29.5% and 19.7% respectively in80 days,reduced soil return salt,decreased soluble salt by 38.06% compared with CK,decreased soil ESP compared with CK,and significantly improved soil alkalization,among which a3b2 was lower than CK 73.6%,the soil was transformed into mild saline alkali soil;pot experiment showed that the application of biochar and humic acid could inhibit the growth of plants with the increase of humic acid amount.After planting corn,the utilization efficiency of phosphorus was increased up to 67.8%,plant growth was promoted,and the content of chlorophyll was increased up to 76.2%,and the resistance of plants was significantly increased,and the content of ascorbic acid was increased by1.6 times.The results showed that the application of biochar and humic acid(GB)had a more significant effect on reducing ESP and water-soluble salt content,esp decreased to 5.6%,soluble salt content decreased by 15.9% compared with CK,soil nutrients increased,element transformation efficiency increased,total phosphorus increased by 2.1 times and effective phosphorus increased by 6.62 times;Compared with CK,pot experiment showed a more significant effect,not only increased the emergence rate of corn,but also increased the chlorophyll content of corn plants by about 50%,ascorbic acid by 3.3times,and increased the plant growth period The conversion efficiency of P was 83.4%.The correlation analysis shows that biochar and humic acid are feasible to improve the saline alkali soil.At the same time,the combination of them can use the microporous structure of biochar to discharge salt and retain water,which can promote the improvement of the saline alkali degree of soil.The results of this study provide a theoretical basis for the utilization of agricultural waste and the effective improvement of salinized soil along the Yellow River beach in Inner Mongolia. |
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