Effects of Continuous Biochar-based Fertilizer Replacement on Soil Properties and Bacterial Community Structure in Vegetable Garden

Abstract:

In order to understand the field long-term effect of biochar-based fertilizer instead of chemical fertilizer, the vegetable yield, soil physical and chemical properties and bacterial community structure with biochar-based fertilizer replacement for 5 consecutive years were studied by localization experiment. The results showed that soil pH increased 0.13-0.25 after 5 years, and the contents of organic matter, alkali-hydrolyzable nitrogen and available phosphorus in soils increased 2.1%-62.2%, 5.8%-86.0% and 0.4%-103.1%, respectively. The yield of Capsella bursa-pastoris with biochar-based fertilizers increased by 4.0%-14.8% than that of the control, but the yield under 75% replacement was lower than that of 50% replacement. The indexes of Sobs, Shannon, Ace and Chao of soil bacteria with biochar-based fertilizer were higher than those of chemical fertilizer, and those under 75% replacement were the highest. Compared to chemical fertilizer, the abundances of Nitrolancea, Amycola- topsis and Gemmatimonas with biochar-based fertilizer decreased significantly, and the abundances of cellulose-degrading bacterial increased, such as Planifilum and Saccharimonadales. There were significant correlations between the abundances of Gemmatimonas, Ilumatobacteraceae, Methyloligellaceae, and soil total nitrogen, total phosphorus, organic matter. Therefore, the replacement of continuous biochar-based fertilizer significantly improved soil physical and chemical properties, and caused the changes in bacterial community structure and diversity. Appropriate replacement of biochar-based fertilizers could increase vegetable yield, but the effect of long-term continuous application on soil pH and C/N should be paid attentions, so as to avoid excessive application inhibiting nutrients uptake and utilization by crops.

Key words:Vegetable garden;Biochar-based fertilizer;Chemical fertilizer;Soil;Bacterial community