Preface

Soil is a fundamental component of Earth's environment. It is one of the subsystems of the Earth, being the interface between the hydrosphere, the atmosphere, and organisms that inhabit it. As its main functions, soil regulates natural material and energy cycles and is extremely sensitive to the effects of climate change and human and historical activities [1].

The genesis of soils is closely related to the changes undergone by the materials that make up the Earth's crust in proximity to the topographic surface. Subject to environmental conditions other than those that originated them, on the Earth's surface, rocks undergo a wide range of weathering processes, phenomena that essentially promote the breakdown of rocks, transforming them into detritic materials and chemical solutions.

Subjected to a diverse set of factors, soils undergo a degrading process, much of them of anthropic origin, which promote its erosion [2].

Soil erosion is an extremely serious environmental problem, widespread on practically the entire land surface, with direct and indirect effects on its productivity and thus human survival [3].

The consequences of this phenomenon are especially serious if we consider that the average rate of soil formation is around 1 t/ha/year, and the soil loss values are greater than 15 t/ha/year in China, 6 to 7 t/ha/year in the United States [4], and greater than 14 t/ha/year in Europe, in agricultural areas, vineyards, or soils without vegetation [5].

In addition, soil erosion can lead to the loss of 75% to 80% of its carbon content, causing the emission of carbon into the atmosphere [6].

It is a global problem and, although it is more serious in developing countries, it currently concerning in technologically more advanced countries.

Soil erosion is a phenomenon that occurs on practically the entire land surface, and in some areas, erosion and consequent deposition are essential for maintaining the soil's natural fertility.

However, the erosion action that occurs in the slopes also promotes the removal of the superficial part of the soil, precisely that where the highest concentration of nutrients is present [7]. When this process occurs at rates faster than those necessary for weathering and soil formation, its loss is irreversible.

If we realize that soil is responsible for 99% of the world's food production [8] then we will easily understand that it is critical to develop and implement soil

**II**

**Chapter 7 121**

Biochar: A Sustainable Approach for Improving Soil Health

*by Shreya Das, Samanyita Mohanty, Gayatri Sahu, Mausami Rana* 

and Environment

*and Kiran Pilli*

erosion mitigation strategies and measures for protecting our soil while ensuring a sustainable and food-secure world.

Considering the importance and relevance of this topic for all societies, we have put forth much effort in developing this book. Written by authors from across the globe, the seven chapters in this volume reflect the authors' experiences of implementing different methodologies for soil erosion evaluation as well as soil conservation strategies.

Chapter 1 by Gil and Pacheco evaluates some RGB indexes for protecting the soil from erosive processes by vegetation cover, considering an area with agricultural use and based on images collected by Unmanned Aerial Vehicles (UVA). The objective of the proposed methodology, which was tested in Ecuador, is to offer the possibility of quickly differentiating vegetation from other types of coverage on the ground. The evaluation allowed to define which indexes present the best results and adaptation to the type of crop or plant mass mapped and to propose their use for zoning of risk of erosion under the agro-ecological conditions of the study area.

Chapters 2 and 3 propose the implementation of the Revised Universal Soil Loss Equation (RUSLE) to evaluate soil erosion in two African regions with different characteristics: Algeria and Ethiopia. In Chapter 2, Benchettouh et al. evaluate erosion in the wadi Mina catchment (Northwest Algeria) and its impact on silting up of dams built for human consumption and economic activities. The results of this study indicate that a significant part of the wadi Mina catchment (36.1%) is affected by high-to-dangerous erosion risk, revealing the urgent necessity of implementing soil conservation measures. In Chapter 3, Ahmed and Asmamaw propose the implementation of RUSLE to quantify the amount of soil loss in Bahir Dar Zuria district, Ethiopia, concluding the existence of a high correlation between soil loss and high slopes.

In Chapter 4, Pambudi presents a model for evaluating the Erosion Hazard Level (EHL) in the Lesti Sub-Watershed, Indonesia, considering population pressure to determine the priority conservation areas.

In Chapter 5, Okou et al. propose the evaluation of the impacts of soil degradation effects on phytodiversity and vegetation structure on the Atacora mountain chain in Benin, West Africa, concluding that physical soil degradation induced modification of floristic composition, phytodiversity loss and modification of vegetation structure.

In Chapter 6, Rutebuka presents some successful stories of sustainable landscape management and soil erosion control developed in Rwanda. These initiatives include intensive erosion control interventions as well as participatory landscape management, both promoted by the Government of Rwanda, to optimize land productivity in a sustainable manner.

In the final Chapter 7, Das et al. propose a revision of agronomic and environmental impacts of biochar on soil amendment, showing that biochar can play an

**V**

important role in the modification of nutrients dynamics, soil contaminants, and microbial functions, which can give benefits to the soil, also strengthening soil

**António Vieira**

University of Minho, Guimarães, Portugal

Uberlândia, Brazil

**Sílvio Carlos Rodrigues** Institute of Geography,

CECS, Department of Geography,

Federal University of Uberlândia,

erosion management.

important role in the modification of nutrients dynamics, soil contaminants, and microbial functions, which can give benefits to the soil, also strengthening soil erosion management.

> **António Vieira** CECS, Department of Geography, University of Minho, Guimarães, Portugal
