  Citation: Kacprzak, M.; Kupich, I.; Jasinska, A.; Fijalkowski, K. Bio-Based Waste’ Substrates for Degraded Soil Improvement—Advantages and Challenges in European Context. Energies 2022, 15, 385. https:// doi.org/10.3390/en15010385 Academic Editor: Gabriele Di Giacomo Received: 22 November 2021 Accepted: 1 January 2022 Published: 5 January 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). energies Review Bio-Based Waste’ Substrates for Degraded Soil Improvement—Advantages and Challenges in European Context Malgorzata Kacprzak 1, * , Iwona Kupich 2 , Anna Jasinska 2 and Krzysztof Fijalkowski 2 1 Institute of Civil Engineering, Faculty of Civil Engineering, Mechanics and Petrochemistry, Warsaw University of Technology, Lukasiewicza 17, 09-400 Plock, Poland 2 Department of Environmental Engineering and Biotechnology, Faculty of Infrastructure and Environment, Czestochowa University of Technology, 42-200 Czestochowa, Poland; iwona.kupich@pcz.pl (I.K.); anna.jasinska@pcz.pl (A.J.); krzysztof.fijalkowski@pcz.pl (K.F.) * Correspondence: malgorzata.kacprzak@pw.edu.pl Abstract: The area of degraded sites in the world is constantly expanding and has been a serious environmental problem for years. Such terrains are not only polluted, but also due to erosion, devoid of plant cover and organic matter. The degradation trends can be reversed by supporting remediation/reclamation processes. One of the possibilities is the introduction of biodegradable waste/biowaste substrates into the soil. The additives can be the waste itself or preformed substrates, such composts, mineral-organic fertilizers or biochar. In EU countries average value of compost used for land restoration and landfill cover was equal 4.9%. The transformation of waste in valuable products require the fulfillment of a number of conditions (waste quality, process conditions, law, local circumstances). Application on degraded land surface bio-based waste substrates has several advantages: increase soil organic matter (SOM) and nutrient content, biodiversity and activity of microbial soil communities and change of several others physical and chemical factors including degradation/immobilization of contaminants. The additives improve the water ratio and availability to plants and restore aboveground ecosystem. Due to organic additives degraded terrains are able to sequestrate carbon and climate mitigate. However, we identified some challenges. The application of waste to soil must comply with the legal requirements and meet the end of use criteria. Moreover, shorter or long-term use of bio-waste based substrate lead to even greater soil chemical or microbial contamination. Among pollutants, “emerging contaminants” appear more frequently, such microplastics, nanoparticles or active compounds of pharmaceuticals. That is why a holistic approach is necessary for use the bio-waste based substrate for rehabilitation of soil degraded ecosystems. Keywords: soil degradation; biodegradable waste; compost; biochar; remediation; revegetation; soil organic matter; plant ecosystem restoration contamination immobilization/degradation 1. Introduction Soil degradation is the modification of its physical, chemical and biological properties that worsen the biological activity of the environment, with particular emphasis on food production, water quality, ecosystem services, flooding, eutrophication, biodiversity and carbon stock shrinkage. Soil degradation has many forms and genesis: (i) geotechnical soil degradation caused by deformation of the relief resulting from the activities of opencast and underground mining as well as construction (including road, rail and water). This form of soil degradation covers the entire territory, but the greatest damage should be noted in the areas of high concentration of the mining industry and in large urban agglomerations. Soil geotechnical changes are usually accompanied by changes in soil structure; (ii) physical degradation of soils consists primarily of water and wind erosive action. It is caused by negative changes in the soil structure, compaction of the soil mass, excessive soil drainage Energies 2022, 15, 385. https://doi.org/10.3390/en15010385 https://www.mdpi.com/journal/energies