Impact of Paper Mill Waste on Physicochemical Properties of Soil, Crop Yield, and Chemical Composition of Plants.

Paper production is among the industrial branches generating significant amounts of waste. Organic waste from paper manufacturing is mostly used in gardening and agriculture or converted for energy purposes, while inorganic waste, including green liquor dregs (GLD), is usually deposited on landfills. GLD has a highly alkaline reaction, suggestive of its possible utilization for land reclamation or for improvement of soil's physico‐chemical properties. The research results originate from a pot experiment with maize as the test plant. GLD was added to soil in doses 10–40 t ha−1. The trials consisted of two series: with and without tree bark (TB). GLD contributed to neutralization of the soil's acidic pH, enrichment of the sorption complex with alkaline cations, and to greater salinity of the soil. In the series with TB, it is demonstrated that GLD led to a decrease in the soil content of total organic carbon; while the content of total nitrogen increased, the C:N ratio is considerably narrowed. In response to GLD, the greenness of leaves significantly improves, but this does not translate into an increase in the yield of plants. Regarding the chemical composition of plants grown in soil treated with elevated GLD doses, the content of N and Na is demonstrably higher, although no such effect is discernible in the case of P and K. For the environment, safe doses of the applied waste, not causing significant deterioration of soil properties or depressing crop yields, are 10 and 20 t GLD ha−1. [ABSTRACT FROM AUTHOR]