Abstract
The degradation of the grassland system has severely threatened the safety of the ecological environment and animal husbandry. The supplement of key substances lost due to degradation is widely used to accelerate the restoration of the degraded grassland ecosystem. In this study, we investigated the effects of biochar and nitrogen addition on soil properties and microorganisms of degraded alpine grassland. The experimental treatments consisted of the control without any addition, only nitrogen addition (10 gN/m2), only biochar addition (4.00 kg/m2 biochar), and the mixed addition of biochar and nitrogen (4.00 kg/m2 biochar and 10 gN/m2 nitrogen, respectively). Adding N alone did not significantly change the pH, total organic carbon (TOC), total nitrogen (TN), microbial biomass (MB), and the composition proportion of microbes of the soil, but increased the contents of soil water content (SWC), NH4+-N, NO3–-N, available phosphorus (AP), and the biomass of bacteria and fungi. The addition of biochar or the mixture of biochar and nitrogen increased the contents of pH, TOC, TN, MB, SWC, NH4+-N, NO3–-N, AP, bacteria, and fungi in the soil and changed the structure of the soil microbial community. The increasing intensity of AP, bacteria, and fungi under the addition of biochar or the mixture of biochar and nitrogen was significantly greater than that under N addition alone. These results indicated that the separated addition of nitrogen and biochar and the mixed addition of biochar and nitrogen all improved the soil condition of the moderate–severe degraded alpine grassland, but the mixed addition of biochar and nitrogen could be a better strategy to remediate the degraded alpine grassland.
Highlights
The alpine grassland ecosystem in the Qinghai-Tibet Plateau is a unique ecosystem formed in a high-altitude environment, accounting for 50.9% areas of the Qinghai-Tibet Plateau and 44% areas of China grasslands (Piao et al, 2012)
In the 0–10 cm soil layer, pH had no significant change among treatments in 2017, but pH was significantly higher in the treatments of biochar application than that in CK in 2018 and
In the first experimental year (2017), electrical conductivity (EC) in the 0–20 cm soil layer was much higher in the treatments of N addition, biochar addition, and the mixed addition of nitrogen and biochar than that in CK
Summary
The alpine grassland ecosystem in the Qinghai-Tibet Plateau is a unique ecosystem formed in a high-altitude environment, accounting for 50.9% areas of the Qinghai-Tibet Plateau and 44% areas of China grasslands (Piao et al, 2012). The deterioration of soil habitat caused by grassland degradation is mainly due to the destruction of soil structure and the sharp loss of soil nutrients, especially soil nitrogen and carbon, which destroy the soil biological system and the growth environment of plant roots (Liu et al, 2020; Sun et al, 2020; Wu et al, 2021). In the degraded grassland, the soil generally has high bulk density, low porosity, low organic matter, and unstable aggregate structure (Ma et al, 2020; Zhang et al, 2020). These traits make soil difficult to retain the introduced nutrients and result in the loss of nutrients and the decrease of utilization efficiency (Yagüe et al, 2016; Zhang et al, 2018)
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