Drought and salt stress negatively affect soil fertility and plant growth. Application of biochar, carbon-rich material developed from combustion of biomass under no or limited oxygen supply, ameliorates the negative effects of drought and salt stress on plants. The biochar application increased the plant growth, biomass, and yield under either drought and/or salt stress and also increased photosynthesis, nutrient uptake, and modified gas exchange characteristics in drought and salt-stressed plants. Under drought stress, biochar increased the water holding capacity of soil and improved the physical and biological properties of soils. Under salt stress, biochar decreased Na+ uptake, while increased K+ uptake by plants. Biochar-mediated increase in salt tolerance of plants is primarily associated with improvement in soil properties, thus increasing plant water status, reduction of Na+ uptake, increasing uptake of minerals, and regulation of stomatal conductance and phytohormones. This review highlights both the potential of biochar in alleviating drought and salt stress in plants and future prospect of the role of biochar under drought and salt stress in plants.

Biochar soil amendment on alleviation of drought and salt stress in plants: a critical review

Soil, the living terrestrial skin of the Earth, plays a central role in supporting life and is home to an unimaginable diversity of microorganisms. This review explores key drivers for microbial life in soils under different climates and land-use practices at scales ranging from soil pores to landscapes. We delineate special features of soil as a microbial habitat (focusing on bacteria) and the consequences for microbial communities. This review covers recent modeling advances that link soil physical processes with microbial life (termed biophysical processes). Readers are introduced to concepts governing water organization in soil pores and associated transport properties and microbial dispersion ranges often determined by the spatial organization of a highly dynamic soil aqueous phase. The narrow hydrological windows of wetting and aqueous phase connectedness are crucial for resource distribution and longer range transport of microorganisms. Feedbacks between microbial activity and their immediate environment are responsible for emergence and stabilization of soil structure-the scaffolding for soil ecological functioning. We synthesize insights from historical and contemporary studies to provide an outlook for the challenges and opportunities for developing a quantitative ecological framework to delineate and predict the microbial component of soil functioning.

Biophysical processes supporting the diversity of microbial life in soil.

Salinity stress is one of the major abiotic stresses limiting crop production in arid and semi-arid regions. Interest is increasing in the application of PGPRs (plant growth promoting rhizobacteria) to ameliorate stresses such as salinity stress in crop production. The identification of salt-tolerant, or halophilic, PGPRs has the potential to promote saline soil-based agriculture. Halophytes are a useful reservoir of halotolerant bacteria with plant growth-promoting capabilities. Here, we review recent studies on the use of halophilic PGPRs to stimulate plant growth and increase the tolerance of non-halophytic crops to salinity. These studies illustrate that halophilic PGPRs from the rhizosphere of halophytic species can be effective bio-inoculants for promoting the production of non-halophytic species in saline soils. These studies support the viability of bioinoculation with halophilic PGPRs as a strategy for the sustainable enhancement of non-halophytic crop growth. The potential of this strategy is discussed within the context of ensuring sustainable food production for a world with an increasing population and continuing climate change. We also explore future research needs for using halotolerant PGPRs under salinity stress.

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Mining Halophytes for Plant Growth-Promoting Halotolerant Bacteria to Enhance the Salinity Tolerance of Non-halophytic Crops.

Climate change is not only altering weather patterns but also accelerating sea-level rise, leading to increased inundation and saline contamination of soils. Given projected sea-level rise, it is imperative to examine the extent to which farmers in coastal Bangladesh can adapt by diversifying economic activities before resorting to migration within and across borders. Here, to identify patterns in how households adapt to increased sea/freshwater flooding and soil salinity, we analyse nationally representative socioeconomic and migration data against a suite of environmental variables constructed at the sub-district level. Our results show that inundation alone has negligible effects on migration and agricultural production. However, gradual increases in soil salinity correspond to increasing diversification into aquaculture and internal migration of household members. Salinity is also found to have direct effects on internal and international migration even after controlling for income losses, with mobility restricted to certain locations within Bangladesh. Our study suggests that migration is driven, in part, by the adverse consequences of salinity on crop production. Projected sea-level rise and increased flooding threaten coastal agriculture. Gradual increases in soil salinity, but not inundation alone, are shown to correspond to increasing diversification into aquaculture and higher levels of internal migration.

Coastal climate change, soil salinity and human migration in Bangladesh

Performance evaluation of anaerobic digestion technology for energy recovery from organic fraction of municipal solid waste: A review

Influence of salinity and water content on soil microorganisms

Response of erosion reduction effect of typical soil and water conservation measures in cropland to rainfall and slope gradient changes and their applicable range in the Chinese Mollisols Region, Northeast China

Soil erosion causes topsoil loss of more than 75 billion tons per year globally. It results in reduced crop yields and other economic losses totaling approximately US$400 billion. The ecological and environmental issues, such as land degradation and water pollution, are aggravated, posing a serious threat to ecological security, river and lake health, and sustainable human development (Food Agriculture Organization of United Nations, 2015; Montgomery, 2007; Quinton et al., 2000). Soil erosion in China is particularly stern and the country has tackled this challenge unremittingly for over 70 years. The outcome speaks for itself: the national soil erosion area (with soil erosion modulus exceeding soil loss tolerance of corresponding region, e.g., 1000 t/km·a in the Northwest Loess Plateau, 500 t/km·a in the Southern Red Soil Area, and 200 t/km·a in the Northeast Black Soil Area) (MWR, 2008) has dropped from 3,670,300 km in the mid‐to‐late 1980s to 2,949,100 km in 2011 and further to 2,674,200 km in 2021, registering an accumulative reduction of over 1/4; and the proportion of soil erosion area at “moderate and above” level (with soil erosion modulus exceeding 2500 t/km·a) has decreased from 49.32% to 35.58%, meaning both erosion area and the intensity have declined (MWR et al., 2010; MWR, 2013, 2021). The Chinese government has attached great importance to ecological improvement amid its rapid economic and social development throughout the years. Both the understanding of this issue and the investment for it are growing. In 2017, China called for “fundamentally improving the ecological environment and largely achieving the goal of a beautiful China by 2035; and comprehensively advancing ecological progress by 2050”; and the ecological civilization concept of “pursuing green development and promoting harmony between humanity and nature” was again highlighted in 2022. As a fundamental measure for the ecological protection and restoration of rivers and lakes systems, soil erosion and water loss control is taken as an important element of pursuing ecological progress and has become a fundamental state policy to be upheld in the long run. Therefore, to what extent is soil erosion control considered adequate to meet China's goal of achieving ecological progress and the vision of a beautiful China by 2035 and 2050 is a question that warrants speedy response. In the meantime, as global ecological protection and governance continue to progress, studies have been carried out on appropriate targets for regional vegetation restoration (Feng et al., 2016), trade‐ offs for ecosystem services (Ouyang et al., 2016), and evolution and spillover effects of the social‐ecological system (Wu et al., 2020). These studies have shown that single ecological elements, processes, and their effects at a certain spatial and temporal scale may have relatively stable or reasonable threshold intervals for the system as a

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/rvr2.43

Wenhong Cao

Papers

Influence of salinity and water content on soil microorganisms

Response of erosion reduction effect of typical soil and water conservation measures in cropland to rainfall and slope gradient changes and their applicable range in the Chinese Mollisols Region, Northeast China

Appropriate targets for soil erosion control at the national scale determined in China