Effects of different irrigation amounts and biochar application on soil physical and mechanical properties in the short term

Biochar application, as a kind of soil amendment, significantly influences soil physical and mechanical properties. This study revealed the effects of biochar application on the physical and mechanical properties of a clay‐type soil at different irrigation levels. Soil was treated with three levels of biochar application: B0 (0 t ha⁻¹), B1 (25 t ha⁻¹) and B2 (50 t ha⁻¹), and three levels of irrigation: T0 (1.2 pan evaporation Ep), T1 (1.0 Ep) and T2 (0.8 Ep). The results indicated that other treatments reduced the soil bulk density compared with the control treatment (CK) (B0T1). Compared to CK, the highest reduction in soil bulk density was 18%. Irrigation did not improve the soil bulk density and porosity at the same biochar application in the short term. Biochar enhanced the stability of the soil aggregates. Compared to CK, the largest MWD (mean weight diameter) was enhanced by 9%. The addition of biochar and decreasing irrigation could decrease soil cohesion. The addition of biochar and increasing irrigation could increase the soil internal friction angle. The soil cohesion first increased and then decreased as the soil water content increased. According to the fitting formula, the soil cohesion was found to be minimum at B2T2, which was a decrease of 39% compared to B0T1. At the same irrigation level, the soil internal friction angle decreased with increasing soil water content. Soil penetration resistance showed a decreasing trend with the application of biochar. The more irrigation there is, the larger the soil penetration resistance. Résumé L'application du biochar en tant qu'amendement du sol exerce un impact significatif sur les propriétés physiques et mécaniques du sol. Cette étude a révélé les effets de l'application de biochar sur les propriétés physiques et mécaniques d'un sol argileux à différents niveaux d'irrigation. Le sol a été traité avec trois niveaux d'application de biochar: B0 (0 t ha⁻¹), B1 (25 t ha⁻¹) et B2 (50 t ha⁻¹), ainsi que trois niveaux d'irrigation: T0 (1,2 évaporation pan Ep), T1 (1,0 Ep) et T2 (0,8 Ep). Les résultats ont indiqué que d'autres traitements ont réduit la densité apparente du sol par rapport au traitement témoin CK(B0T1). Comparativement à CK, la plus forte réduction de la densité apparente du sol était de 18%. L'irrigation n'a pas amélioré la densité apparente et la porosité du sol pour une même application de biochar à court terme. Le biochar a amélioré la stabilité des agrégats du sol. Par rapport au CK, l