Assesment of compost and Technosol as amendments to increase nutrient contents in a mine soil vegetated with Brassica juncea

Abstract

Abandoned mines pose potential risks to the environment and human health, and the reclamation of these areas is difficult. Soils from mining areas are usually characterised by degraded structure, high concentration of potentially toxic elements and deficiencies in nutrients. A greenhouse experiment was carried out in cylinders with the mine soil from the settling pond of the depleted copper mine of Touro (Galicia, Northwest Spain) amended with compost or technosol made from organic and inorganic wastes, and planted with <em>Brassica juncea</em> for 11 months. The aim of the study was to evaluate the effect of compost and technosol amendments on nutrient concentrations at different depths in a mine soil planted with <em>Brassica juncea</em>. The results revealed that at depths 0-15 and 15-30 cm, soil+technosol+<em>Brassica juncea</em> (STP) and soil+compost+<em>Brassica juncea</em> (SCP) treatments had higher pH than untreated mine soil S at the end of experimental. At depths 0-15 and 15-30 cm, SCP had the highest carbon total content. The nitrogen was only detected at depth 0–15 cm and only in the treated settling pond soil. STP and SCP had higher percentage of base saturation (V%) and lower percentage of aluminum saturation (Al%) than S and SS (sand). At depth 0-15 cm, soil+technosol+<em>Brassica juncea</em> (STP) and soil+compost+<em>Brassica juncea</em> (SCP) did not show generally significant differences on the nutrients values. At time 3, <em>Brassica juncea</em> plants cultivated in soil+compost+<em>Brassica juncea</em> (SCP) had the highest biomass. Soil+technosol+<em>Brassica juncea</em> (STP) treatment was the most effective increasing soil pH. Soil+compost+<em>Brassica juncea</em> treatment was the one that produced the greatest increase in total carbon. The treatments increased the cation exchange capacity (CEC) at depth 0-15 cm. Both treatments corrected the CEC by increasing the V% and decreasing the Al%. The application of technosol and <em>Brassica juncea</em> plants, or compost and <em>Brassica juncea</em> to a mine soil improved the soil quality.