Effects of Biochar Applications and Irrigation Regimes on the Temporal Dynamics of Soil Temperature and Soil Moisture in Silage Maize Cultivation
Abstract
In this study, the effects of biochar applications and different irrigation regimes on the temporal dynamics of soil temperature and soil moisture in second-crop silage maize cultivation under semi-arid conditions were investigated during the 2021 and 2022 growing seasons. In addition, the relationships between soil temperature and soil moisture with dry matter yield, evapotranspiration and irrigation water amount were evaluated. The experiment was established as a factorial experiment with four irrigation levels and four biochar doses arranged in a randomized complete block design with three replications. The biochar treatments were B0 (control without biochar), B1 (10 t ha⁻¹), B2 (20 t ha⁻¹), and B3 (30 t ha⁻¹ biochar application). The mixture ratio for the biochar consisted of equal parts, 50% paddy stalk and 50% maize waste. Irrigation treatments were defined as follows: I100, replenishment of the entire soil moisture deficit within the 0–60 cm soil depth when 30 ± 5% of available water was depleted; I75, application of 75% of the water supplied to I100; I50, application of 50% of the water supplied to I100; and I0, rainfed conditions without irrigation. The results showed that biochar applications increased soil moisture and reduced soil temperature under all irrigation levels, with stronger effects at higher doses (B2 and B3). The highest mean soil temperature was observed in the I0-B0 treatment, whereas the highest pre-irrigation soil moisture was obtained in the I100-B3 treatment. Under full irrigation conditions (I100), mean soil temperature in 2021 and 2022 decreased from 21.7–22.2 °C, respectively, in B0 to 18.9–19.1 °C in B3, while mean soil moisture increased from 35.1–35.8% to 37.6–38.1%. Under rainfed conditions (I0), mean soil temperature in 2021 and 2022 decreased from 24.0–24.1 °C in B0 to 19.7–20.0 °C in B3, whereas mean soil moisture increased from 22.8–23.4% to 24.2–24.6%. Biochar applications moderated soil temperature and improved soil moisture conservation under all irrigation levels. Compared with the non-biochar control, biochar applications increased the mean dry matter yield by 3.9–25.6% and the mean soil moisture content by 0.7–7.1%. These findings demonstrate the potential of biochar to enhance crop productivity and improve soil water conservation under water-limited conditions. While weak relationships were determined between soil temperature and dry matter yield, evapotranspiration, and irrigation water amount, strong positive relationships were found between soil moisture and these parameters. Overall, biochar improved soil hydrothermal conditions and supported sustainable agricultural production under limited water availability in semi-arid regions.