Sustainable Soil Management in Alkaline Soils: The Role of Biochar and Organic Nitrogen in Enhancing Soil Fertility

Biochar (BC) serves a vital function in sequestering carbon, improving nutrient cycles, and boosting overall soil quality. This research investigated how both biochar and nitrogen, derived from both organic and inorganic sources, influence the physical and chemical properties of alkaline soils in semi-arid regions. The study particularly emphasized the effects on nitrogen availability. A field experiment was carried out from 2015 to 2017 using a randomized complete block design (RCBD) with a split-plot arrangement. The study involved applying biochar at various rates (0, 10, 20, and 30 t ha⁻¹) and nitrogen at different levels (0, 90, 120, and 150 kg ha⁻¹) using urea, farmyard manure (FYM), and poultry manure (PM) as nitrogen sources. The application of biochar at the highest rate (30 t ha⁻¹) significantly increased soil organic carbon (SOC), soil organic matter (SOM), and soil moisture content (SMC) by over 120%. Additionally, it led to increases in total soil nitrogen (STN) by 14.16% and mineral nitrogen (SMN) by 9.09%. Conversely, biochar applications at this rate decreased soil bulk density (SBD), pH, and electrical conductivity (EC) by 28.52%, 3.38%, and 2.27%, respectively, compared to the control group. Similarly, applying nitrogen at 150 kg ha⁻¹ using FYM significantly improved SOC, SOM, SMC, and SBD. Using PM as a nitrogen source at the same rate enhanced STN and SMN while lowering soil pH and EC. In conclusion, the study demonstrated that combining biochar at a rate of 30 t ha⁻¹ with nitrogen at 150 t ha⁻¹, derived from either PM or FYM, holds significant promise for enhancing soil fertility and promoting carbon sequestration in alkaline soils within semi-arid environments. These findings underscore the value of integrating BC and organic N sources to enhance agroecosystem sustainability. Thus, the study provides a promising pathway to enhance soil quality, improve crop productivity, and support sustainable agricultural practices in challenging environments.