The Effect of Organic Materials with Different Degrees of Decomposition on the Content of Nickel in the Lettuce Leaves Cultivated in Mineral Soil

Studies were carried out in order to verify the research hypothesis that “the introduction of organic matter in the form of high peat, brown coal, and wheat straw to the mineral soil contaminated with nickel will reduce the content of this metal in the lettuce”, the main purpose of which was to determine the impact of various organic materials with varying degrees of decomposition on the content of nickel in lettuce leaves. The factors of the experiment were different types of organic material that were added to the mineral soil (loamy sand), such as high peat, brown coal, and wheat straw. The substrates in which lettuce was grown were contaminated with increasing doses of nickel: 0, 50, 75, and 100 mg Ni·dm−3 of the substrate. This research shows that the type of organic material introduced into the mineral soil as a source of soil organic meter has a significant impact on the content of nickel in lettuce leaves.