This foreword provides a summary of papers included in this special issue on biochar and fertiliser interactions for crop and pastures productivity. This special issue includes published papers on how biochar and fertiliser affect soil health and crop yields and overcome soil constraints such as acidity, salinity, low fertility and remediation of metal and pesticides contaminated soils.

Biochar application improves soil properties which helps in proper plant growth. Biochar improves the plants’ tolerance to adverse effects of abiotic stress. Biochar modifies plant physiology towards the survival under stressful condition.

The use of biochar in combination with soil phosphate fertilisers is an important strategy in increasing crop yields and sustainability. Adding biochar improves soil fertility and protects it from degradation. The addition of biochar with phosphate fertilisers increased the wheat yield and improved its fertility in semiarid regions.

Biochar significantly decreases nutrient and pollutant leaching in soils. Biochar application could decrease P loss from applied P fertilisers due to leaching, reducing the pollution risk from P in water and soils. The present study assessed the effect of biochar and nitrogen–phosphorus–potassium (NPK) fertilisers on wheat yield, other agronomic parameters and selected soil properties under raised- and flat-bed cultivation. The study would be useful for further enhancing wheat yield in irrigated and rainfed areas on a sustainable basis.

This study investigated the effect of a traditionally prepared organic biochar from banana, i.e. kolakhar was used individually and in combination with commercial biochar for ameliorating soil, growing few traditional rice cultivars, with regard to tolerability of Al toxicity and P deficiency. The rice seedlings treated with kolakhar showed significant response in terms of biomass, photosynthetic efficiency and antioxidant protection mechanisms which was further authenticated by histochemical and ICP-OES analysis, paving the way to overcome the acidic soil stress.

Boron is an essential micronutrient that stimulates plant metabolic and developmental processes. This study aimed to enhance boron availability through the development of biochar- and boron-coated diammonium phosphate (BC-BDAP) for use in biochar-amended alkaline calcareous soils. Data showed improved nutrient (boron and phosphorus) uptake with application of BC-BDAP in 2% and particularly 4% biochar-amended soil, which further improved the growth, yield and oil content of sunflower relative to DAP alone or boron + DAP without biochar amendment.

A healthy soil is required for healthy crops, and plants growing on salt-affected soils have inadequate supply of nutrients. Application of biochar may help to mitigate salinity stress. Our pot study showed that biochar application at 10 t ha⁻¹ significantly promoted nutrient availability, enzyme activities and crop growth of marigold in soils at various salinity levels, thus avoiding crop failure.

The application of co-composted biochar is an emerging mean of increasing agricultural productivity while sustaining soil health. However, it is unknown whether co-composted biochar applied in the previous season or its fresh application at increasing rates could promote the performance of a legume when grown under different levels of salinity. Co-composted biochar, applied in or previous season, increased mungbean yield through alleviating salt stress suggesting that it could be one of the sustainable means for legume production in saline-prone areas.

Use of inorganic material is the main cause of soil pollution globally, hindering efforts toward sustainable and safe agriculture. In this regard, heavy metals pollute the soil and endanger food quality, but biochars with very high surface area are effective in absorbing toxic heavy metals. In this study, various sizes of biochar were tested for phyto-stabilisation of heavy metals, and the finest biochar (<3 mm) proved most effective.

The application of soil amendments to immobilise pesticide residues is a promising technology for meeting human health requirements, environmental protection and cost-effective remediation. The addition of biochar with compost increased the canola growth and decreased the concentrations of pesticide residues. Spectroscopy analysis indicated that the π–π interaction, pore filling, hydrophobic effect, H-bonding, and degradation are the dominant mechanisms of the studied pesticide residues with rice straw of biochar and compost amendments in the alkaline soils.

Soil contamination with heavy metals adversely affects plant growth and soil fertility. We applied biochar, slag and ferrous manganese ore as amendments to contaminated soil into which water spinach was sown, to assess their effects on soil physicochemical and biological properties, bioavailability of lead and cadmium, and plant growth. Application of the amendments, especially biochar, significantly enhanced soil properties and plant growth and reduced bioavailability of lead and cadmium.