Effects of irrigation and fertilization with biochar on the growth, yield, and water/nitrogen use of maize on the Guanzhong Plain, China

Excessive water and nitrogen inputs in agricultural production can result in resource wastage and environmental pollution. This makes it imperative to identify effective farmland management strategies to ensure sustainable agriculture development, and it remains to be explored whether biochar can be an effective solution. In this study, a 2-year (2021 and 2022) field experiment was conducted with two irrigation levels, W100 (ET) and W80 (0.8 ET), and three nitrogen fertilizer levels, NH (270 kg ha−1), NM (180 kg ha−1), and NL (90 kg ha−1), in full combination with biochar (30 t ha−1). The NM and N0 treatments without biochar at both irrigation levels were set as controls. The results of the study showed that there was no significant difference in maize yield between the high and medium N treatments. Further, maximum water productivity (WP), nitrogen agronomic efficiency (NAE), and nitrogen recovery efficiency (NRE) were obtained in NM treatments when water and nitrogen were kept consistent. Deficit irrigation was effective in reducing water consumption and increased WP by 15.54% and 11.06% in 2021 and 2022, respectively. Biochar application increased WP, nitrogen use efficiencies, and significantly increased the yield by 7.02% and 6.46% in 2021 and 2022, respectively. Therefore, the application of biochar can be an effective measure to promote crop growth and resource use. Based on the results of this experiment, an irrigation level of 0.8 ET in combination with NM and biochar application is recommended to ensure the sustainability of agricultural production.