This book collates updated knowledge about algal species which are present in the terrestrial environment particularly in soil. Contributions in this volume covers different topics such as morphology, ecology and applications of soil algae. Ecological significance of soil algae and their biotechnological importance are the key features of this book. Algae are ubiquitous and occur in almost all terrestrial environments and in soil, they majorly belong to the member of Chlorophycophyta, Cyanochloronta, Rhodophycophyta Euglenophycophyta, and Chrysophycophyta. The role of soil algae as fertilizer and for reclaiming the saline soil is well studied. Algae in soil benefits agricultural production, increase water retention capacity, reduced soil erosion, reduction of nutrient runoff, and provides nutrients. The added algae increase soil biodiversity, organic biomass, and the total humus content of the soil, beneficial for healthy soil. These soil algae diversities also have many biotechnological and industrial importance. This book is of interest and use to researchers of phycology, molecular biology, agriculture and biotechnology and also to scientists working on soil biology, agronomy and crop research. Also, the book serves as reading material for undergraduate and graduate students of microbiology, agriculture, molecular biology, and biotechnology. Researchers from biotechnological and biofertilizers companies will also find this to be a useful read.