CO2 Emission from Soils Under the Influence of Calcium Carbonate Addition and Polymer Superabsorbent Application

Superabsorbents are crosslinked polymer networks composed of ionic and non-ionic monomers. Among these, polyacrylates are notable for their capacity to absorb and retain water solutions amounting to several hundred times their own weight. These superabsorbents serve various purposes, particularly in agriculture, where they are employed as soil additives to enhance physical properties and improve moisture retention. Soil respiration is a critical metric that measures the rate of organic matter decomposition and carbon cycling within the soil, both of which are vital for ecosystem functionality. Consequently, assessing the base respiration rate is one of the most prevalent microbiological analyses conducted to evaluate soil quality. This process involves quantifying the amount of carbon dioxide (CO2) released from a soil sample over a specified duration. This study demonstrates that the incorporation of polyacrylates into sandy soils, in conjunction with calcium carbonate, results in increased carbon dioxide emissions and a significant elevation in soil pH. Such alkalinization may adversely affect the health of cultivated plants, underscoring the need for careful consideration in soil management practices. In acidic loam/silt loam soils, PAA addition did not further increase CO2 emissions or pH beyond liming alone, whereas in neutral sandy soil, the combination caused a strong CO2 flush and marked alkalisation.