Study on Improvement Effect of Saline-alkali Soil by Cationic Modified Biochar

Abstract

The severe soda-alkali soil in the western Songnen Plain was used as the experimental object. Compared with the application of common biochar, the effects of modified biochar on the basic physical and chemical properties, agglomerate distribution, organic carbon and total nitrogen distribution of saline-alkali soil were analyzed. The experiment adopts the indoor culture method, and the use of common biochar (B) and iron modified biochar and calcium modified biochar is 0, 1.5%, 5% . A total of 7 treatments: CK, B1.5, B5, FBS1.5, FBS5, CBS1.5, CBS5. The results show: 1. Modified biochar significantly reduced soil pH with a maximum reduction of 12.2%. Both biochar and modified biochar significantly reduce soil ESP. The reduction effect of FB5 was the most significant in each treatment, which was 58.2% lower than CK, followed by FB5, which was 41.8% lower than CK. The introduction of cations and the significant reduction of ESP showed strong Na+ substitution and adsorption capacity, thereby alleviating soil salt accumulation and improving soil basic physical and chemical properties. 2. Both modified biochar and ordinary biochar increased the content of soil microaggregates (0.053-0.25mm). The modified biochar was significantly higher than ordinary biochar, and the function of improving soil structural stability was stronger. Among them, CBS improvement effect is better than FBS. The ratio of CBS5 treatment increased the microaggregate to the highest, with an increase of 66.4%; the increase of CBS1.5 treatment was 56.2%; the proportion of FBS5 and FBS1.5 microaggregates increased by 51.1% and 32.2% respectively. The geometric mean diameter (GMD) of all treatments was higher than that of CK treatment, in which CBS5 treatment significantly increased GMD by 18.6%; modified biochar treatment increased mean weight diameter (MWD), of which CBS5 significantly improved MWD. The increase was 8.8%.