REVIEW ARTICLE Biochar soil amendment on alleviation of drought and salt stress in plants: a critical review Shafaqat Ali 1 & Muhammad Rizwan 1 & Muhammad Farooq Qayyum 2 & Yong Sik Ok 3 & Muhammad Ibrahim 1 & Muhammad Riaz 1 & Muhammad Saleem Arif 1 & Farhan Hafeez 4 & Mohammad I. Al-Wabel 5 & Ahmad Naeem Shahzad 6 Received: 28 March 2016 /Accepted: 20 March 2017 # Springer-Verlag Berlin Heidelberg 2017 Abstract Drought and salt stress negatively affect soil fertil- ity and plant growth. Application of biochar, carbon-rich ma- terial 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 in- creased 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, increas- ing uptake of minerals, and regulation of stomatal conduc- tance 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. Keywords Abiotic stress . Soil reclamation . Soil salinity . Soil remediation . Black carbon . Charcoal . Slow pyrolysis Introduction The world population is increasing at an alarming rate and is expected to reach 9.6 billion by 2050 (FAO 2009). Additional food required to feed this increasing population is putting pressure on existing natural resources. Agricultural crops are frequently exposed to abiotic stresses such as salinity, drought, and heavy metal stress (Osakabe et al. 2014; Parihar et al. 2015; Rizwan et al. 2016a). Among the abiotic stresses, drought and soil salinity are the most critical threats to agri- cultural production. At the world level, ∼800 × 10 6 million ha of land is affected by salt with an annual increase of ∼1–2% (Munns and Tester 2008). Land degradation due to salinity is causing an annual economic loss of USD 27.2 billion in terms of crop loss in irrigated agriculture (Qadir et al. 2014). Loss in revenue is estimated to accelerate to 69%, if no action is taken to prevent the land degradation. In addition, higher emission of carbon (C) from degraded lands further adds to the cost of reclamation. The excess soluble salts have negative effects on the soil physicochemical and biological properties through various ways. Sustainable crop production depends on the interaction between salinity and soil moisture conditions (Maas and Grattan 1999). The major effect of salinity is the decrease in the biomass production leading to lower C inputs, Responsible editor: Hailong Wang * Muhammad Rizwan mrazi1532@yahoo.com 1 Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, Faisalabad 38000, Pakistan 2 Department of Soil Sciences, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan, Pakistan 3 Korea Biochar Research Centre and Department of Biological Environment, Kangwon National University, Chuncheon 24341, South Korea 4 Department of Environmental Sciences, COMSATS Institute of Information Technology, Abbottabad, Pakistan 5 Soil Sciences Department, College of Food and Agricultural Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia 6 Department of Agronomy, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan, Pakistan Environ Sci Pollut Res DOI 10.1007/s11356-017-8904-x