Frequent Irrigation in Manure-fertilized Soil Reduces CO2 Emissions Per Unit Yield by Increasing Maize Silage Yield

In agricultural areas where manure is used as fertilizer, the rapid mineralization of soil carbon upon rewetting, along with increased microbial activity, results in a significant release of CO₂ emissions. This process leads to substantial soil carbon depletion, which has negative environmental impacts. This study aims to examine which irrigation regime reduces soil carbon loss to optimize CO₂ emissions per unit yield for sustainable production. Soil CO₂ emissions were measured using an infrared gas analyzer in soils fertilized with mineral (F) and cattle manure (M) under three irrigation regimes in the research. Irrigations were conducted at different intervals based on the difference between estimated cumulative plant water consumption and precipitation (25, 50, and 75 mm, respectively) in the IR1, IR2, and IR3 regimes. The consistent emissions of CO₂ during the growing season were due to the ongoing depletion of organic carbon in the soil. Increasing soil moisture and decreasing soil temperature contributed to emission increases. The application of manure increased CO₂ emissions per unit area, water consumption, and yield by 2.7, 2.8, and 2.0 times, respectively, compared to mineral fertilization. This was attributed to the higher seasonal carbon emission, lower water consumption, and higher yield associated with manure application. The IR1 treatment, which enhanced the mineralization of organic matter, resulted in a 1.08 times increase in CO₂ emissions per unit area and a 1.16 times increase in emissions per unit water consumption compared to the IR3 treatment. On the contrary, it caused a 1.41 times decrease in emissions per unit yield with the yield contribution. Although CO₂ emissions per unit yield were 75.4% higher than in FIR1, the MIR1 treatment was the most successful in reducing emissions, showing a 1.57 times decrease compared to MIR3. In conclusion, frequent irrigation in soil fertilized with manure decreases CO₂ emissions per unit yield in silage maize. Higher yields with frequent irrigation management can lead to a greater reduction in CO₂ emissions per unit of yield.