Changes in the Content of Humic Substances, Reaction and Sorption Properties Occurring in Reclaimed Land in Post-Mining Areas

Abstract

The paper presents selected results of analyses of the properties of post-mining land of the former lignite mine „Przyjaźń Narodów” in the region of Łęknica in the Lubusz Voivodeship. The land formed in that area had very unfavourable properties: its granulometric composition (light clay sand) was susceptible to water erosion, the reaction of the formations was highly acid, the contents of total organic carbon and total nitrogen were varied and highest on the surface level of the profiles. The Ckh:Ckf ratios increased as the sampling depth increased.
The development of opencast mining in the region of Łęknica (the Lubusz Voivodeship) has resulted in geomorphological changes. The post-mining land of the post-mining areas of the former lignite mine „Przyjaźń Narodów”, which started operating at the beginning of the 1970s, was subjected to reclamation processes. Reclamation in that area consisted of the following actions [7]: (a) land levelling with bulldozers; (b) soil deacidification with magnesium lime in the Zink Mill „Miasteczko Śląskie” in a dose of 50 Mg ha-1; (c) mineral fertilisation: phosphorus powder in a dose of 5 Mg ha -1, nitro-chalk in a dose of 200 kg ha -1, ammonium phosphate in a dose of 200 kg ha -1 and potash salt in a dose of 400 kg ha -1; and (d) forestation of the area with Scots pines.
Accumulation of organic matter is very important for restoring fertility in post-mining soils and improving their physical, chemical and biological properties [4]. Organic matter in soils undergoes complicated processes which often depend on oxygen-environmental conditions, and produce as a result a number of mineralization products. During the process of humification, humic substances are produced, various fractions of which differ in terms of their immunity to decomposition, time of existence in the environment, and at the same time they determine soil properties [6]. Those processes occur with the participation of microorganisms. Microorganisms in soils are both decomposers participating in the decomposition of organic matter produced by autotrophic organisms and organisms responsible for soil formation processes [1]