The book focuses on the impact of different long-term cropping systems and tillage on the biologically active substances "allelochemicals" of a well-known and unknown structure in soils. The negative effects of continuous cropping (decreased crop yields in the fields in which the same plant species have been grown continuously) are well-known. There are also indications that in soil under continuous cropping of rye, phenolic acids and other phytotoxins accumulate and inhibit the development of cultivated plants. The following cropping systems are described in this book: (i) continuous cropping of rye, (ii) crop rotation, (iii) no tillage, and (iv) conventional tillage.§§The book focuses on free and bounded biologically active substances such as amino acids, auxins, humic and fulvic acids, transient radicals, enzymes in light sand soils fertilized with different mineral and organic fertilizers. Moreover, the book centers on soil's enzymes involved in the cycle of nitrogen and contributing to the transformations of sulfur organically bound in soil. The authors also shed light on new aspects of chemical and biochemical processes in organic soils, the utilization of peat and peatlands in agriculture, the impact of different organic fertilizers prepared on the basis of peat and sapropels/gyttja on the content of phytohormone - auxin in soils, and the influence of secondary transformation of peat soil on the content of hydrophilic and hydrophobic organic compounds of a well-known and unknown structure. The chapters also outline the function of biogeochemical barriers such as shelterbelts - mild field rows of trees in agriculture landscape and peatlands and their impact on ground water.§§The book addresses fundamental chemical and biochemical questions that are relevant to the environmental challenges we face today and will undoubtedly deal with in the future. The results involve asking basic questions motivated by soils chemical and biochemical processes, leading to the improvement of the quality of soil's organic matter. Therefore, the chapters are connected by the pervasive goal of understanding the fundamental relationship between ecological processes, and the effect of environmental change on individual levels of biocomplexity as well as on system in their entirety.§Current approaches on soil allelochemicals emphasize the identification of allelochemicals using methods with ecological relevance, appropriate for allelopathic research. The discipline of allelopathic plant-soil interactions has developed recently, hence, this book was written to depict the comparative aspects, which will be useful to research workers in this field.§§This book is for students and teachers for laboratory practical classes worldwide. It can be also useful to soil scientists, biochemists, chemists, plant ecophysiologists, "Natural Products" organic chemists and other environmental scientists and specialists.§§
