Biochar derived from papermill factories improves soil physical and hydraulic properties in no-till cotton fields

Authors: LI, YUANYUAN - Zhengzhou University; Feng, Gary; Tewolde, Haile

Submitted to: Biochar
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2023
Publication Date: 6/25/2023
Citation: Li, Y., Feng, G.G., Tewolde, H. 2023. Biochar derived from papermill factories improves soil physical and hydraulic properties in no-till cotton fields. Biochar . 5:35. https://doi.org/10.1007/s42773-023-00235-9.
DOI: https://doi.org/10.1007/s42773-023-00235-9

Interpretive Summary: Our results imply that the long-term application of biochar derived from papermill plants to the field surface has beneficial effects on soil physical and hydrological properties at the depth of 0-10 cm in commercial cotton fields of Mississippi State, USA. With added biochar, the soil bulk density and degree of soil compactness decreased with increasing times of yearly biochar addition. The application of biochar effectively promoted the formation of >0.25 mm aggregates and enhanced the aggregate stability in soil. Biochar addition also modified the soil pore size distribution and increased total porosity, contributed to great increase of field capacity and permanent wilting point and slight increase of plant available water. The increases in soil physical properties resulted in improvement of soil health scores and SPQI. The degree of biochar effects on soil aggregation, available water, and properties was greatly related to the soil depth and the times of annual biochar addition. Overall, the impact increased with increasing the times of biochar addition, and the effect in 0 to 5 cm layer was greater than that in 5-10 cm layers as comparing their SPQI. The beneficial effect of biochar on soil physical and hydrological properties confirmed that the application of biochar produced from papermill to commercial farm field had considerable potential alternative to landfilling.

Technical Abstract: Biochar, known as boiler ash, produced in large quantities as a by-product of the pulp and paper, sawmill, and bioenergy industries under limited O2. Its application to the land soils is a viable alternative to landfilling but knowledge of the long-term impact of biochar produced from papermill on soil physical and hydrological properties is limited under commercial farm field conditions. The objectives of this study are to investigate whether biochar can be beneficial for improving soil physical properties, revealing how biochar affects the hydrological properties, and ultimately determine whether biochar impacts soil physical quality. Disturbed and undisturbed soil samples were taken from 0-5 and 5-10 cm layers in five commercial no-tilled farm fields that continuously received 6.7 Mg ha-1 biochar for 0, 2, 3, 5 and 10 years, respectively, in northern part of Mississippi, USA. The results showed that biochar addition reduced the degree of soil compactness, and increased soil aggregate and structural stable index of 0-5 and 5-10 cm soils, particularly for biochar consecutive application for 10 years. Compared with control, biochar treatments increased soil total porosity which was mainly contributed from small pores, and consequently, resulted in the greatest average increase of field capacity (26%) and permanent wilting point (43%).Plant available water was increased by 17% over the control treatment at a depth of 0-5 cm. Biochar addition increased the scores of soil physical and hydrological indicators and soil physical quality index which was positively correlated with the number of years of application Biochar addition significantly affected soil physical properties in 0-5 cm topsoil though it also improved, to some extent, physical properties of soils in 5-10 cm layer. These results indicated that spreading biochar from papermill to the surface of cotton field improved the physical and hydrological properties of agricultural soils, thereby leading to an improvement in physical health in top 0-5 cm soils.