Impact of Agriculture on Soil Degradation I: Perspectives from Africa, Asia, America and Oceania 3031321677, 9783031321672

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The Handbook of Environmental Chemistry 120 Series Editors: Damià Barceló · Andrey G. Kostianoy

Paulo Pereira Miriam Muñoz-Rojas Igor Bogunovic Wenwu Zhao   Editors

Impact of Agriculture on Soil Degradation I Perspectives from Africa, Asia, America and Oceania

The Handbook of Environmental Chemistry Volume 120 Founding Editor: Otto Hutzinger Series Editors: Dami
a Barcelo´ • Andrey G. Kostianoy

Editorial Board Members: Jacob de Boer, Philippe Garrigues, Ji-Dong Gu, Kevin C. Jones, Abdelazim M. Negm, Alice Newton, Duc Long Nghiem, Sergi Garcia-Segura, Paola Verlicchi, Stephan Wagner, Teresa Rocha-Santos, Yolanda Pico´

In over four decades, The Handbook of Environmental Chemistry has established itself as the premier reference source, providing sound and solid knowledge about environmental topics from a chemical perspective. Written by leading experts with practical experience in the field, the series continues to be essential reading for environmental scientists as well as for environmental managers and decisionmakers in industry, government, agencies and public-interest groups. Two distinguished Series Editors, internationally renowned volume editors as well as a prestigious Editorial Board safeguard publication of volumes according to high scientific standards. Presenting a wide spectrum of viewpoints and approaches in topical volumes, the scope of the series covers topics such as • • • • • • • •

local and global changes of natural environment and climate anthropogenic impact on the environment water, air and soil pollution remediation and waste characterization environmental contaminants biogeochemistry and geoecology chemical reactions and processes chemical and biological transformations as well as physical transport of chemicals in the environment • environmental modeling A particular focus of the series lies on methodological advances in environmental analytical chemistry. The Handbook of Environmental Chemistry is available both in print and online via http://link.springer.com/bookseries/698. Articles are published online as soon as they have been reviewed and approved for publication. Meeting the needs of the scientific community, publication of volumes in subseries has been discontinued to achieve a broader scope for the series as a whole.

Impact of Agriculture on Soil Degradation I Perspectives from Africa, Asia, America and Oceania Volume Editors: Paulo Pereira
Miriam Mu~ noz-Rojas
Igor Bogunovic
Wenwu Zhao

With contributions by M. F. Adame
A. Almagro
E. Argaman
A. R. Becker
E. C. Brevik
C. B. Colman
A. P. Cuervo-Robayo
F. A. Dadzie
R. de Faria Godoi
C. C. du Preez
E. Egidi
D. J. Eldridge
F. Escusa
G. Eshel
D. S. Ferna´ndez
M. Francos
M. Gong
M. d. T. Grumelli
M. Guevara
R. R. Gutierrez
M. Hu
L. La Manna
G. J. Levy
P. Ma
A. Maor
K. Z. Mganga
A. Molesworth
J. S. Motta
M. Mu~noz-Rojas
P. T. S. Oliveira
D. I. Ospina-Salazar
P. Pereira
S. Periasamy
M. E. Puchulu
M. Quintero-Angel
M. A. Rosas
C. M. Rostagno
N. S. Santini
H. F. Schiavo
R. S. Shanmugam
B. K. Singh
J. S. Sone
J. Stewart
C. W. van Huyssteen
E. Volk
Y. Yu
Q. Zuo

Editors Paulo Pereira Environmental Management Laboratory Mykolas Romeris Univerisity Vilnius, Lithuania

Miriam Mu~ noz-Rojas Department of Plant Biology and Ecology University of Seville Seville, Spain

Igor Bogunovic Faculty of Agriculture University of Zagreb Zagreb, Croatia

Wenwu Zhao Faculty of Geographical Science Beijing Normal University Beijing, China

ISSN 1867-979X ISSN 1616-864X (electronic) The Handbook of Environmental Chemistry ISBN 978-3-031-32167-2 ISBN 978-3-031-32168-9 (eBook) https://doi.org/10.1007/978-3-031-32168-9 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Series Editors Prof. Dr. Dami
a Barcelo´

Prof. Dr. Andrey G. Kostianoy

Department of Environmental Chemistry IDAEA-CSIC Barcelona, Spain and Catalan Institute for Water Research (ICRA) Scientific and Technological Park of the University of Girona Girona, Spain [email protected]

Shirshov Institute of Oceanology Russian Academy of Sciences Moscow, Russia and S.Yu. Witte Moscow University Moscow, Russia [email protected]

Editorial Board Members Prof. Dr. Jacob de Boer VU University Amsterdam, Amsterdam, The Netherlands

Prof. Dr. Philippe Garrigues Universite´ de Bordeaux, Talence Cedex, France

Prof. Dr. Ji-Dong Gu Guangdong Technion-Israel Institute of Technology, Shantou, Guangdong, China

Prof. Dr. Kevin C. Jones Lancaster University, Lancaster, UK

Prof. Dr. Abdelazim M. Negm Zagazig University, Zagazig, Egypt

Prof. Dr. Alice Newton University of Algarve, Faro, Portugal

Prof. Dr. Duc Long Nghiem University of Technology Sydney, Broadway, NSW, Australia

Prof. Dr. Sergi Garcia-Segura Arizona State University, Tempe, AZ, USA

Prof. Dr. Paola Verlicchi University of Ferrara, Ferrara, Italy

Prof. Dr. Stephan Wagner Fresenius University of Applied Sciences, Idstein, Germany

Prof. Dr. Teresa Rocha-Santos University of Aveiro, Aveiro, Portugal

Prof. Dr. Yolanda Picó Desertification Research Centre - CIDE, Moncada, Spain

Series Preface

With remarkable vision, Prof. Otto Hutzinger initiated The Handbook of Environmental Chemistry in 1980 and became the founding Editor-in-Chief. At that time, environmental chemistry was an emerging field, aiming at a complete description of the Earth’s environment, encompassing the physical, chemical, biological, and geological transformations of chemical substances occurring on a local as well as a global scale. Environmental chemistry was intended to provide an account of the impact of man’s activities on the natural environment by describing observed changes. While a considerable amount of knowledge has been accumulated over the last four decades, as reflected in the more than 150 volumes of The Handbook of Environmental Chemistry, there are still many scientific and policy challenges ahead due to the complexity and interdisciplinary nature of the field. The series will therefore continue to provide compilations of current knowledge. Contributions are written by leading experts with practical experience in their fields. The Handbook of Environmental Chemistry grows with the increases in our scientific understanding, and provides a valuable source not only for scientists but also for environmental managers and decision-makers. Today, the series covers a broad range of environmental topics from a chemical perspective, including methodological advances in environmental analytical chemistry. In recent years, there has been a growing tendency to include subject matter of societal relevance in the broad view of environmental chemistry. Topics include life cycle analysis, environmental management, sustainable development, and socio-economic, legal and even political problems, among others. While these topics are of great importance for the development and acceptance of The Handbook of Environmental Chemistry, the publisher and Editors-in-Chief have decided to keep the handbook essentially a source of information on “hard sciences” with a particular emphasis on chemistry, but also covering biology, geology, hydrology and engineering as applied to environmental sciences. The volumes of the series are written at an advanced level, addressing the needs of both researchers and graduate students, as well as of people outside the field of vii

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Series Preface

“pure” chemistry, including those in industry, business, government, research establishments, and public interest groups. It would be very satisfying to see these volumes used as a basis for graduate courses in environmental chemistry. With its high standards of scientific quality and clarity, The Handbook of Environmental Chemistry provides a solid basis from which scientists can share their knowledge on the different aspects of environmental problems, presenting a wide spectrum of viewpoints and approaches. The Handbook of Environmental Chemistry is available both in print and online via https://link.springer.com/bookseries/698. Articles are published online as soon as they have been approved for publication. Authors, Volume Editors and Editors-in-Chief are rewarded by the broad acceptance of The Handbook of Environmental Chemistry by the scientific community, from whom suggestions for new topics to the Editors-in-Chief are always very welcome. Dami
a Barcelo´ Andrey G. Kostianoy Series Editors

Preface

Agricultural soil degradation is a pervasive phenomenon related to agricultural intensification and increasing food demand. There are some areas of the world more vulnerable than others. For instance, semi-arid and arid areas are extremely vulnerable to soil degradation. Therefore, agriculture practices in these ecosystems need to be planned carefully. Agricultural soil degradation is a consequence of multiple pressures, such as land use changes (e.g., conversion of grasslands, scrublands, or forests into agriculture areas), use of deep tillage methods, tractor trafficking, and the use and abuse of agrochemicals and plastics. These practices dramatically impact soil compaction, erosion, pollution, salinity, or acidification [1]. Climate change is also expected to exacerbate soil degradation [2]. When soil is degraded, several functions, ecosystem services, and habitat support are hampered.1 They lost their capacity to regulate soil erosion, floods, and climate, purify water and supply food, fodder, and medicinal plants [3]. Food security is becoming one of the most important issues in these turbulent times when inflation skyrockets and global food trade are severely affected [4]. Therefore, looking at the soil as a vital resource to our survival is essential. 95% of the food that we eat comes from soil.2 Although this is recognized, the current picture could be more encouraging. Approximately 40% of soils in the world are degraded, which represents a loss of US$44 trillion.3 If nothing is done, the situation can be even more dramatic, and by 2050, 90% of the world’s soil will be degraded.4 Soil compaction decreases crop yields by 60%.5 Also, soil erosion is accelerated about 1000 times through anthropogenic activities, including intensive agriculture. Soil salinization makes unproductive 1.5 million

1

https://www.fao.org/global-soil-partnership/resources/highlights/detail/en/c/1539317/. https://www.fao.org/about/meetings/soil-erosion-symposium/key-messages/en/. 3 https://www.unccd.int/news-stories/press-releases/chronic-land-degradation-un-offers-starkwarnings-and-practical. 4 https://news.un.org/en/story/2022/07/1123462. 5 https://www.fao.org/3/i6473e/i6473e.pdf. 2

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Preface

hectares of farmlands per year and has an annual cost of US$31 million.6 Soil acidification also has substantial costs. In Australia, it is estimated that the annual loss due to soil acidification is AUS $8.7 million per year [5]. Examples across the world are multiple international agencies, such as the United Nations, which claim that stopping soil degradation (e.g., erosion) is key to “save our future”.7 Soil degradation is a severe problem in the global South, and there are several reports8 [6] that highlight that the populations are vulnerable to soil conditions and poor harvest yield. For instance, in Africa, “More Than Half of Africa’s Arable Land ‘Too Damaged’ for Food Production.”9 This is too dramatic to be true. It is time to act urgently. The time to think or to wait has already passed. Sustain global food security can no longer be at the expense of agriculture intensification. It is essential to understand this. To understand it is key to know the causes of in different countries for agricultural soil degradation. This was at the core of our motivation to develop the compendium of different case studies worldwide focused on global agricultural soil degradation in “The Handbook of Environmental Chemistry.” This project was divided into two volumes. One focused on Africa, America, Asia, and Oceania (Volume I) and Europe (Volume II). In the first volume, Argentina, Australia, Bolivia, Brazil, Chile, China, Colombia, India, Israel, Kenya, Mexico, Peru, South Africa, and the USA participated in this work. Vilnius, Lithuania Seville, Spain Zagreb, Croatia Beijing, China

Paulo Pereira Miriam Mu~ noz-Rojas Igor Bogunovic Wenwu Zhao

References 1. Pereira P (2019) Soil degradation, restoration and management in a changing environment. Elsevier, Amsterdam, p 249 2. Lal R (2020) Regenerative agriculture for food and climate. J Soil Water Conserv 75:123A–124A 3. Pereira P, Bogunovic I, Munoz-Rojas M, Brevik E (2018) Soil ecosystem services, sustainability, valuation and management. Curr Opin Environ Sci Health 5:7–13 4. Pereira P, Zhao W, Symochko L, Inacio M, Bogunovic I, Barcelo D (2022) Russian-Ukrainian armed conflict impact will push back the sustainable development goals. Geogr Sustain 3:277–287

6

https://www.fao.org/global-soil-partnership/areas-of-work/soil-salinity/en/. https://news.un.org/en/story/2019/12/1052831. 8 https://news.un.org/en/story/2021/09/1101632. 9 https://reliefweb.int/report/world/more-half-africa-s-arable-land-too-damaged-food-production. 7

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5. Government of South Australia (2018) Soil acidity status report 2018 – SAMDB NRM Region. https://cdn.environment.sa.gov.au/landscape/docs/mr/regionalsoil-acidity-baseline-2018-rep.pdf 6. DeValue K, Takahashi N, Woolnough T, Merle C, Fortuna S, Agostini A (2022) Halting deforestation from agricultural value chains: the role of governments. FAO, Rome

Acknowledgments

The editors appreciate the support of Prof. Damia Barcelo and Sofia Costa in developing this book. Their encouragement was crucial to bring this project to light. We would like also to acknowledge the support of the project No. 42271292, funded by the National Natural Science Foundation of China.

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Contents

Agricultural Soil Degradation in Argentina . . . . . . . . . . . . . . . . . . . . . . Diego S. Ferna´ndez, Marı´a E. Puchulu, Ce´sar M. Rostagno, Ludmila La Manna, Analı´a R. Becker, Marı´a del T. Grumelli, and Hugo F. Schiavo

1

Agricultural Soil Degradation in Australia . . . . . . . . . . . . . . . . . . . . . . . Frederick A. Dadzie, Eleonora Egidi, Jana Stewart, David J. Eldridge, Anika Molesworth, Brajesh K. Singh, and Miriam Mu~ noz-Rojas

49

Agricultural Soil Degradation in Peru and Bolivia . . . . . . . . . . . . . . . . . Ronald R. Gutierrez, Frank Escusa, Miluska A. Rosas, and Mario Guevara

69

Agricultural Soil Degradation in Brazil . . . . . . . . . . . . . . . . . . . . . . . . . Paulo Tarso S. Oliveira, Raquel de Faria Godoi, Carina Barbosa Colman, Jaı´za Santos Motta, Jullian S. Sone, and Andre´ Almagro

97

Agriculture Soil Degradation in Chile . . . . . . . . . . . . . . . . . . . . . . . . . . 129 Marcos Francos Agricultural Soil Degradation in China . . . . . . . . . . . . . . . . . . . . . . . . . 153 Yang Yu, PanPan Ma, Qilin Zuo, Ming Gong, Miao Hu, and Paulo Pereira Agricultural Soil Degradation in Colombia . . . . . . . . . . . . . . . . . . . . . . 177 Mauricio Quintero-Angel and Daniel I. Ospina-Salazar Agricultural Soil Degradation in India . . . . . . . . . . . . . . . . . . . . . . . . . . 219 Shoba Periasamy and Ramakrishnan S. Shanmugam Agricultural Soil Degradation in Israel . . . . . . . . . . . . . . . . . . . . . . . . . 259 Gil Eshel, Elazar Volk, Alon Maor, Eli Argaman, and Guy J. Levy Agricultural Soil Degradation in Kenya . . . . . . . . . . . . . . . . . . . . . . . . . 273 Kevin Z. Mganga

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Contents

Agricultural Soil Degradation in Mexico . . . . . . . . . . . . . . . . . . . . . . . . 301 Nadia S. Santini, Angela P. Cuervo-Robayo, and Marı´a Fernanda Adame Agricultural Soil Degradation in South Africa . . . . . . . . . . . . . . . . . . . . 325 C. W. van Huyssteen and C. C. du Preez Agricultural Soil Degradation in the United States of America . . . . . . . 363 Eric C. Brevik

Agricultural Land Degradation in Argentina Diego S. Fernández, María E. Puchulu, César M. Rostagno, Ludmila La Manna, Analía R. Becker, María del T. Grumelli, and Hugo F. Schiavo

Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Types of Land Degradation in Argentina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3 Characteristics of Land Degradation in the Main Regions of the Country . . . . . . . . . . . . . . . . . . 7 3.1 Northwest Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2 Northeast Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.3 Pampas Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

D. S. Fernández (✉) Grupo de Investigación en Geología Ambiental, Cátedra de Pedología, Facultad de Ciencias Naturales e IML, Universidad Nacional de Tucumán, San Miguel de Tucumán, Argentina SEGEMAR (Centro Regional Tucumán), San Miguel de Tucumán, Argentina e-mail: [email protected] M. E. Puchulu Grupo de Investigación en Geología Ambiental, Cátedra de Pedología, Facultad de Ciencias Naturales e IML, Universidad Nacional de Tucumán, San Miguel de Tucumán, Argentina e-mail: [email protected] C. M. Rostagno Instituto Patagónico para el Estudio de los Ecosistemas Continentales (IPEEC) – CCT CENPAT, CONICET, Puerto Madryn, Chubut, Argentina e-mail: [email protected] L. La Manna Centro de Estudios Ambientales Integrados, Facultad de Ingeniería, Universidad Nacional de la Patagonia San Juan Bosco (UNPSJB), Esquel, Chubut, Argentina Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Esquel, Chubut, Argentina e-mail: [email protected] A. R. Becker Departamento de Geología, Universidad Nacional de Río Cuarto, Córdoba, Argentina Paulo Pereira, Miriam Muñoz-Rojas, Igor Bogunovic, and Wenwu Zhao (eds.), Impact of Agriculture on Soil Degradation I: Perspectives from Africa, Asia, America and Oceania, Hdb Env Chem (2023) 120: 1–48, DOI 10.1007/698_2022_917, © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022, Published online: 17 December 2022

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3.4 Cuyo Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 Patagonia Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Abstract Land degradation is a serious and widespread problem in Argentina. Argentina is one of the largest agricultural goods producers of the world with large-scale agricultural and livestock industries and generates a great pressure over natural ecosystems. Main drivers of land-degradation processes are the advance of agricultural frontier through fragile ecosystems (e.g., dry forests) and intensive and simplified farming systems without an adequate rotation planning. Currently around 40% of the country’s lands are affected by degradation processes, a percentage that increases to 60% if only the crop lands are considered. This situation generates a decrease in land productivity and an increase in environmental costs due to loss of ecosystem services. Although successful examples of conservation practices for erosion control exists, the reality is that agricultural management practices must consider other degradation processes that are acting in different regions. This chapter reviews the recent studies regarding the types of land degradation and their drivers that affect the different regions of Argentina. Proper management practices oriented to soil conservation appear as a priority for local authorities and producers, especially in the context of climate change, which can exacerbate the negative effects. Keywords Argentina, Deforestation, Land use change, Soil degradation processes, Sustainable land management

1 Introduction Argentina is one of the main exporters of agricultural products in the world along with countries such as the USA, Brazil, Australia, Uruguay, among others. This support the fact that agricultural production is the main economic activity of the country, and until today, the principal driving force of the country development. In

Instituto Académico Pedagógico de Ciencias Básicas y Aplicadas, Universidad Nacional de Villa María, Córdoba, Argentina Centro de Investigación y Transferencia CONICET, UNVM, Córdoba, Argentina e-mail: [email protected] M. d. T. Grumelli and H. F. Schiavo Departamento de Geología, Universidad Nacional de Río Cuarto, Córdoba, Argentina Instituto de Ciencias de la tierra, Biodiversidad y Ambiente (ICBIA) CONICET-UNRC, Río Cuarto, Córdoba, Argentina e-mail: [email protected]; [email protected]

Agricultural Land Degradation in Argentina

3

2018, the agro-food sector, primary plus processed agricultural and livestock products, accounted for 58.8% of total exports [1]. The great influence of the agricultural activity in the Argentina is based on a big natural comparative advantage for the production of many agricultural products: 33.5 million hectares of arable land, deep and fertile soils, fairly regular rainfall distribution, and direct access to the sea [2]. The agricultural activity has been changing through the history of the Argentina, taking the period of 1860–1880 as starting point. Agriculture in Argentina dominantly consists of cereal crops and livestock that was carried out in a traditional way for a period of 100–120 years following patterns similar to those adopted in Europe. Agriculture and livestock grazing expanded until the mid-twentieth century by cultivating new lands, largely employing low-intensity agricultural practices [3]. Due to the climatic characteristics of the plains of the country, with alternating wet-dry periods and high-intensity rainfalls of short duration, the historical agricultural practices elevated soil water and wind erosion [4]. This speeds up an adoption and spread of no-tillage management during the 1970s [5]. Since then, there has been a great increase in production driven by the adoption of new technologies and changes in the form of organization of production, accelerating the process of agriculturization [6]. Since the 1990s, the agricultural frontier has expanded to the north-east, the north-west, and the west, moving into areas with drier climates and/or less fertile soils [3, 7, 8]. The expansion of agriculture frontier outside the pampas was possible due to an increase in rainfall during 1977–2005 period and the price growth of agricultural commodities (principally soybean). Large dry forests areas have been cleared in the Semi-arid Chaco Region of Argentina for cultivation [9]. The cultivated area increased from about 15 to 40 million ha since 1988–2020, and bulk grain production shot up from about 27 to nearly 140 million tons in the same period [10]. Soybean, maize, and wheat have become the primary grain field crops in Argentina [11]. The soybean harvested area has increased dramatically in the country from 980 ha in 1961 to 16 Million ha in 2019 [12]. Argentina is the third soybean producer of the world behind the USA and Brazil [13]. Due to this extraordinary increase in agricultural production associated to the land use changes, Argentina faces serious problems of land degradation that are reviewed in this chapter.

2 Types of Land Degradation in Argentina Land degradation has been defined as a negative trend in land condition, caused by direct or indirect anthropic actions that lead to a loss of actual or potential biological productivity [14, 15]. Land use changes into agricultural land generally negatively affect the soil and ecosystem services. For example, overgrazing leading to wind erosion. Deforestation and tillage methods leading to water erosion. Salinization triggered by water table-level rises as a consequence of irrigation. The landdegradation processes in Argentina are triggered by rapid land-cover changes and poor conservation policies [16–19].

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Fig. 1 Main drivers and land-degradation processes in different regions of Argentina

Argentina presents great diversity in climate, physiography, vegetation, and land use that lead to variations in land degradation type and intensity [20]. Main drivers of land degradation in different regions of Argentine are shown in Fig. 1. In northwest region the most widespread types of degradation are soil erosion, salinization, and

Agricultural Land Degradation in Argentina

5

Fig. 2 Spatial distribution of the number (a) and types (b) of land-degradation processes in arable lands of Argentina. Data sources: affected areas (Prâvâlie et al. [21]); arable land extension (Volante et al. [22])

aridity. In northeast region main degradation processes are water erosion and soil compaction. In pampas region soil erosion, salinization, nutrient depletion, and aridity are the main degradation processes. In Cuyo and Patagonia regions soil erosion and salinization are the main degradation processes. Sometimes a combination of two or more degradation processes occurs in the same territory. In a recent study Prâvâlie et al. [21] recognized up to three different processes acting in a same area of Pampas Region (Fig. 2a). These authors analyze the land-degradation footprint on global arable lands applying geostatistical techniques that are representative for identifying the incidence of five land-degradation processes: aridity, soil erosion, vegetation decline (vegetation loss/damage), soil salinization, and soil organic carbon decline. Figure 2b shows the result of the spatial analysis of landdegradation processes in arable lands of Argentina and reveals that significant part of Argentina soils suffers from combined effect of several degradation processes. Although Argentina’s image is generally linked to the green prairies of the Pampas, it actually may be defined as an arid country. An estimated 70% of its area is in arid, semi-arid, or dry-sub-humid (drylands) environment, where only 12% of the country’s water resources are located [23]. Desertification is a process that affects drylands that consist in a loss of biological complexity and economic productivity of a region, and involves vegetation degradation, water balance alteration, and soil erosion [24]. In the case of Argentina’s dry lands, main land degradation causes are overgrazing and land-use change, enhanced by long dry periods [25]. In humid and sub-humid regions, main land degradation causes are

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Table 1 Evolution of soil erosion affected area (Mha) in Argentina

Year 1956a 1990b 2015c 2017– 2019d,

Total land area affected by soil erosion 34.2 58.0 100.7 136.6

Total area affected by wind erosion 16.0 28.0 37.6 41

Total area affected by water erosion 18.2 30.0 63.1 95.6

Area affected based on mean rate of soil loss Moderate (2– Severe 10 t ha-1 (>10 t ha-1 -1 year ) year-1) 27.1 7.1 22.4 24.0 67.4 33.3 90.8 45.9

e

Data sources: aInstituto de Suelos y Agrotecnia [28], bINTA-SAGyP [29], cCasas [30], dGaitán et al. [27], eColazo et al. [31]

linked with agricultural practices used in agricultural intensive systems. Agricultural intensification refers to two general processes: (1) changes in the vegetation diversity (including crop species and varieties and other vegetation components such as trees, trap crops, and weeds) and (2) changes in management practices and intensity of production including soil amending, chemical use, tillage, and irrigation, among others [26]. Due to the affected area and severity, the processes of soil erosion, desertification, and physical and chemical degradation are the most important in Argentina. Main driving factors of soil erosion in the country are deforestation and the advance of agriculture frontier, overgrazing, and land-use change [27]. The area affected by erosion processes at national level has showed an increasing trend since the 1950s decade. Table 1 shows the evolution of the total land area affected by water and wind erosion at country level through studies made in 1956, 1990, and 2015. Moreover, the increment in total land area affected by erosion processes accelerated during the period 1990–2015 by 73% with respect to the 35% observed during 1956–1990 period. This trend agrees with the results of the GloSEM (Global Soil Erosion Modelling) project based on RUSLE (Revised Universal Soil Loss Equation) model, that showed an increment of 41.6% of the surface affected by erosion in Argentina during the period 2001–2012 as a consequence of deforestation and land-use change [32]. Nevertheless, despite the increase of total affected area by erosion, the soil erosion occurrence and level were mitigated by the adoption of extended conservation practices in the Argentina [32]. The mean annual soil loss due to water erosion was estimated in 6.2 t ha-1 year-1, while 12% of the country lands suffer from severe soil loss rates (>10 t ha-1 year-1) concentrated principally in dry lands of Patagonia, Cuyo, and Northwest regions [27]. In humid and sub-humid areas of the country severe soil losses were reported in high slopes lands like Tandil and Ventana ranges and rolling Pampas in Buenos Aires province, ranges of Córdoba province, and deforested lands in Misiones province. According to data obtained for the period 1950–2000, 33% of the country lands present a rate of potential soil loss due to wind erosion greater than 150 t ha-1 year-1 [33]. Estimations made for the 2020–2050 period have showed that wind erosion risk will remain

Agricultural Land Degradation in Argentina

7

stable compared to the 1950–2000 period [34, 35]. Nowadays, there are 41 Mha of soils eroded by wind, of which 12.5 Mha are severely eroded. Most of the eroded soils match with the area of high risk of wind erosion as Patagonia, the Northwest Region, and Semi-Arid Pampas [31]. Soil salinization constitutes one of the most important soil degradation processes and a major threat to agricultural productivity in arid and semi-arid areas of the world. According to FAO [36] more than 70 Mha are affected by salinization processes and at least 600,000 ha (one third of the total) of the irrigated soils suffer from excessive salinization. The regions that were pointed out as the most affected by soil salinization in the country are the semi-arid Chaco, the Salado River depression, and the northwest of Buenos Aires province [37]. Complementary demands of irrigation for crops such as soybean, maize, and wheat have increased, partly due to climatic change, but mainly due to the shallow root development, derived from soil compaction [38]. In Argentina, agricultural soils have decreased soil organic matter (SOM) content and aggregate stability and increased bulk density in addition to pristine soils. Soils with less than 10 years of continuous agriculture had 83%, 62%, and 106% of the pristine SOM content, aggregate stability, and bulk density, respectively, while soils with 10–20 years of continuous agriculture had 64%, 48%, and 116% of the pristine values, respectively [11]. These findings indicate that SOM decreased by approximately 18% per decade due to agricultural use. The main land-degradation processes in the different regions of Argentina and their current situation related to them are described below.

3 Characteristics of Land Degradation in the Main Regions of the Country 3.1

Northwest Region

The Northwest region of Argentina covers an area of approximately 23 Mha and includes the provinces of Jujuy, Salta, Catamarca, Tucumán, and Santiago del Estero (Fig. 1). It is one of the most affected regions by deforestation during the advance of agricultural frontier. Clearance for agriculture or cattle ranching was the dominant land-cover change during the last two decades in this region [39, 40]. Deforestation and cultivation in the region are carried out using heavy machinery, the burning of remaining vegetation, and the plowing. These practices expose soil to abiotic factors, resulting in an elevated soil vulnerability [9]. According to the Dry Chaco Forest Deforestation Monitoring Project [41], during 1976–2019 period deforested land in northwest region increased from 5.8% to 31.8% of the total region area (Fig. 3). This percentage reached 32.4% of the total area according to the 2020 deforestation data (142,604 ha) from the early alert system of deforestation of the federal government [42]. The 2000–2010 period

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Fig. 3 Clearing forest temporal trend in Northwest Region of Argentina. (a) Historical spatial distribution of the deforested areas in the different provinces of the region. (b) Evolution of the land areas affected by deforestation in the region

Agricultural Land Degradation in Argentina

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showed the highest rate of deforestation with 2.35 Mha, approximately 10.2% of Northwest Region (Fig. 3). Such a vast land clearing process was triggered by two factors: (1) the increase of global demand of soybean and (2) a 20–30% increase in precipitation [43, 44]. Most important crops of the region are sugar cane, citrus, soybean, bean, wheat, and maize. In dry lands area predominates soybean, bean, wheat, sorghum, and pasture for cattle farms. Monoculture farming of bean and soybean contributes to water erosion due to unprotected topsoil and the occurrence of intense rainfall during summer season. High soil losses as a consequence of gully and rill erosion processes are frequent in piedmont areas and intermountain valleys of the region [45, 46] while in the oriental plains, sheet erosion predominates due to unrestricted cultivation or overgrazing in relatively poor soils, previously covered by the Chaco forest [47]. In the province of Salta, land-use changes enhance runoff due to intensive agricultural practices. The expansion of soybean crop area, with narrow crop rotation with wheat and sorghum, has exacerbated land degradation by water erosion processes [48]. Soil losses higher than 10 t ha-1 year-1 in area of 941,950 ha (15.3% of the total area under study) were estimated under arable sloped ( pasture 87.9 mg ha-1 > continuous cropping more than 20-year (77.3 mg ha-1) > continuous cropping less than 10-year (71.9 mg ha-1). Moreover, in the transition between the humid Yungas and dry Chaco forests, in Jujuy Province, a decrease in SOC by 37% and greater soil penetration resistance was noted in rangeland compared to deciduous forest rangeland [52].

10

3.1.1

D. S. Fernández et al.

Soil Salinization in Northwest Region

Northwest Region contains extensive areas of salt-affected soils. Approximately 28% of the irrigated soils of Argentina are located in arid and semi-arid areas of Northwest Region [53]. Salt-affected soils of these areas correspond to occurrence of Aridisols, Entisols, and Alfisols with excessive irrigation, inefficient drainage, or specific hydromorphic processes. The Chaco plain is a very flat and extensive plain with a sub-humid to semi-arid climate, where conditions for salt accumulation in topsoil and subsoil can be expected in most of its territory. The pervasive salt retention of different natural vegetation formations in the dry sedimentary plains of the Chaco plain ends with the onset of annual crop cultivation [54]. Salt retention is no longer sustained under agriculture, as multiple paired site comparisons of chloride profiles have revealed [55]. The rapid and intense land clearing occurred in the plains of Northwest Region in the last two decades has produced changes in unsaturated zone groundwater dynamics. Vadose salts that were not interacting with plants or groundwater become dissolved and get moved closer to the surface by rising groundwater level leading to soil and water salinization [54]. This ecohydrological behavior was observed in the semi-arid plains of Salta and Santiago del Estero [56, 57]. This process can be exacerbated with the irrigation in agricultural lands located in these areas. In the Northwest region, 494,528 ha are under irrigation where 11% of them are affected by secondary salinization [53]. Catamarca and Santiago del Estero are the most affected with 21.2% and 11.3% of the total irrigated area affected, respectively. In the province of Tucumán, soil salinization is observed in the depressed plain of the southeast where a shallow water table with saline composition (sodium bicarbonate type) were reported [58]. Locally, salinity problems were registered in Mollisols (Ustolls) affected by temporary floods due to the active dynamic of the rivers in the area during humid season [59].

3.1.2

Situation of the Arid Areas of Northwest Region

In the arid valleys of the west of the region land degradation is linked with desertification processes like wind and water erosion, dune mobilization, aridity, and salinization. The Santa María River Basin, a large basin that occupy part of the provinces of Catamarca, Salta, and Tucumán, suffers from the expansion of desertification during the period 1997–2012 [60]. According to Navone et al. [61], 15% of the basin area (approximately 25,000 ha) suffer from severe problems of desertification. Main drivers of desertification in the area are climate change (drier conditions), water and wind erosion, and deforestation [62, 63]. The Puna region covers plateaus, high plains, and slopes of the Andes at elevations between 3,200 and 6,000 m a.s.l. from Bolivian border to about 28°S. It is an arid region with annual rainfalls between 100 and 300 mm concentrated during summer. Features of this region are the characteristic endorheic basins with the

Agricultural Land Degradation in Argentina

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development of saline playas. The predominant soils are Aridisols and Entisols that are in a fragile environmental balance [64]. Regarding the area affected by the degradation process, approximately 74% of the study area (120,000 km2) is affected by ongoing land-degradation processes [65]. The magnitude of the different types of soil degradation affecting the Puna region varies among provinces. Puna region of Jujuy and Salta provinces showed a severe degree of land degradation. Soil erosion by wind, chemical soil deterioration, and livestock rearing drive land degradation in the dryer areas while water soil erosion became more important in the more humid eastern part [61, 65].

3.1.3

Soil Contamination Evidences

Soil contamination evidences were recorded in some local areas of Northwest region associated to industrial and mining activities [66–68]. Chemical soil degradation refers to the accumulation of toxic chemicals and chemical processes which impact on chemical properties that regulate life processes in the soil [69]. Soil salinization and alkalinization due to wastes from pulp and paper industry were registered in a rural area of Tucumán province [67]. Solid wastes were buried in agriculture lands producing an increase in soil electrical conductivity and pH and a decrease in SOC (Table 2). High concentration of heavy metals in topsoil were reported by Fernández Turiel et al. [66] in lands around a lead smelter plant in Lastenia, province of Tucumán. Soil and plant patterns of Pb, Cd, Ag, Zn, and Cu demonstrated the effects of pollutant dispersion plumes over the area. The high Pb concentration in soil (>5,000 mg kg-1) caused serious health problems in children from Lastenia locality [70]. Soil contamination by abandoned mine tailings was reported in western part of Northwestern Region where an intense mining activity took place [71]. The tailings usually have elevated levels of heavy metals or other toxic elements. In Catamarca province, high concentrations of Cu (20–1600 mg kg-1), Zn (25–600 mg kg-1), As (5–4,900 mg kg-1), and Sn (40–1,900 mg kg-1) were found in soils of surroundings of ancient mine tailings [72]. Other example of soil contamination by heavy metals in adjacent lands to tailings was reported in the abandoned mines of Concordia and La Poma in Salta province with high concentrations of As (200–613 mg kg-1) and Pb (230–5,000 mg kg-1) [68].

3.2

Northeast Region

The Northeast region of Argentina covers an area of approximately 29 Mha and includes the provinces of Formosa, Chaco, Corrientes, and Misiones (Fig. 1). Formosa and Chaco share the Chaco forest, second largest forest region in South America, with the provinces of Salta and Santiago del Estero of the Northwest Region. Mean annual rainfall varies in this forest region from 450 mm to 1,200 mm and decreases from east to west, resulting in a division into the wet

Soil sample Non-affected soil Buried industrial waste Affected soil

Electrical conductivity (dS m-1) 0.70 2.42

2.05

pH 6.68 8.95

7.99

3.76

Carbonate (%) 0.79 52.45 0.13

Salts content (mg l-1) 0.04 0.15 1.42

Organic matter (%) 2.24 0.82 2.25

Calcium content (meq 100 g-1) 0.17 0.65

0.80

Sodium content (meq 100 g-1) 0.19 0.32

Table 2 Comparison of the chemical properties between soil samples in a contaminated area of the Lules department, Tucumán province. Data source: Puchulu et al. [65]

12 D. S. Fernández et al.

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Chaco (900–1,200 mm) and dry Chaco (450–900 mm) [43]. Soybean cultivation and cattle ranching are the most important proximate drivers of deforestation in the Chaco, although their relative importance varies across the region on a base of the annual rainfalls [73]. Soybean crops are currently limited to areas above 500 mm rainfall [74]. Other important crops in the area are cotton, sunflower, and maize. In the case of Corrientes and Misiones provinces, they present more humid conditions with mean annual precipitations that vary from 1,200 mm in Corrientes to more than 2,000 mm in Misiones. In consequence, native vegetation in Corrientes is represented by a dry subtropical forest and shrubs called The Espinal, while in the more humid areas of Misiones the Paranaense rainforest is located. Principal crops in these provinces are yerba mate, tea, and rice. In Misiones it is also important the forestry industry.

3.2.1

Land-Degradation Processes in Northeast Region

Chaco forest clearing for agricultural activities impacted in great manner in Chaco and Formosa provinces. According to the Dry Chaco Forest Deforestation Monitoring Project [41], during 1976–2019 period, deforested areas in the provinces of Chaco and Formosa increased from 1.6% to 12.1% of their area. The evolution of deforestation in the period 1997–2016 shows that until 2006, the deforested areas were led by the province of Chaco. From this year, the province of Formosa began a very marked increase in deforestation, surpassing Chaco province and leading the Northeast region in the period 2012–2016 (Fig. 4). The general trend of deforestation in the provinces of the region is downward with the exception of the province of Formosa. During the 2010–2015 period, 188,660 ha of Chaco dry forest were deforested in Formosa province mainly in Matacos and Patiño departments for agricultural land use [41]. Land use change from forest to agriculture and cattle ranching is the most important drive factor for land degradation in this region. Main land-degradation process in Northeast Region is water erosion. Water erosion is particularly important Fig. 4 Deforestation trend in provinces of Northeast region

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Table 3 Areas affected by water erosion in Northeast region of Argentina

Province Misiones Corrientes Chaco Formosa Total

Total land area affected by water erosion (ha) 841,091 962,625 1,776,726 570,306 4,150,748

Area affected based on mean rate of soil loss (ha) Moderate (2–10 t ha-1 Severe (>10 t ha-1 year-1) year-1) 105,136 735,955 864,580 98,045 1,666,308 110,418 524,682 45,624 3,160,706 990,042

Data source: Gaitán et al. [27]

in Misiones province where tropical rains and moderate to high gradient slopes converge. In this province 24.5% of its area presents soil loss rates higher than 10 t ha-1 year-1, that is approximately 735,955 ha [27]. Gully and rill erosion are the main types of water erosion that affect red soils, Ultisols and Oxisols, formed in a hilly terrain with 5–15% slopes [75]. In Formosa and Chaco provinces sheet erosion predominates due to agriculture advance or overgrazing in fine soils (Mollisols and Alfisols). In the central parts of both provinces water erosion processes are affecting soybean, sunflower, and cotton crops where severe soil losses were reported [76]. Table 3 shows the areas affected by water erosion processes in the region. Estimates show that a total of 4,150,000 ha present moderate to severe soil losses due to water erosion (14.3% of the total area), where 990,000 ha present soil losses higher than 10 t ha-1 year-1. Agricultural expansion and intensification and overgrazing affect soil structure altering the water and gaseous movement. Soils from Chaco and Formosa provinces are silty with shallow water table which gives high vulnerability to soil sealing, compaction, and waterlogging [77]. Approximately 770,000 ha are affected by soil sealing, waterlogging, and floods in the central part of Chaco province affecting principally cotton and sunflower crops [78]. Physical soil degradation processes in Northeast region are a consequence of agriculturization that includes deforestation (clear cutting, slash burning, and plowing), technological improvements with heavy machinery use, and monoculture [79]. Total organic carbon, particulate organic carbon, bulk density, and structural stability are the most affected soil properties by agriculturization [80, 81]. In semi-arid areas of the province of Formosa, with severe weather, and for 10 years of continuous agriculture, the losses of organic carbon, total nitrogen, and light carbon have been significant [82]. In order to face this situation long-term crop rotation was suggested as an alternative to monoculture in order to increase chemical and physical quality of the soils of the region [83]. Land use change from natural woodlands to agriculture and livestock can alter the hydrologic balance and salinity of soils that influence productivity and sustainable land use [84]. Chaco forest and natural pastures naturally grow in moderate saline soils. Land use management/change must be adjusted to this area; otherwise soil salinization will tend to desertification. This is the case with livestock production in

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the south of the Chaco province where overgrazing in natural pastures usually tends to forming bare soil patches with high salt content interspersed with non-saline soils. Saline and sodic soils in this area cover an area of 950,000 ha [76]. In the east part of the region with sub-humid to humid conditions irrigation is not widely used. Only 5% (117,000 ha) of the total irrigated lands of Argentina are located in this region [85]. The affected area by salinity in irrigated lands is 8,350 ha, mostly located in Corrientes province [53].

3.3

Pampas Region

The Pampas region is the most productive and highest-income area in the country. The region has an approximate area of 60 Mha formed by the provinces of Córdoba, Santa Fe, Entre Ríos, Buenos Aires, and La Pampa (Fig. 1). It can be divided into six sub-regions on a base of climatic and geomorphological settings [86, 87]: Southern pampa, flooded or depressed pampa, rolling pampa, sub-humid or sandy pampa, semi-arid pampa, and Mesopotamian pampa (Fig. 5).

Fig. 5 Principal subdivisions of Pampas Region with indication (blue squares) of annual rainfall spatial distribution

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Pampas region is one of the largest temperate grasslands in the world with great variability in environmental conditions. Annual average precipitation ranges from 1,100 mm in the east to less than 600 mm in the southwest, especially in springsummer and autumn period with more frequent deficits during summer. The average annual temperature varies from 12.5°C in the south to 17.5°C in the northeast. The natural biome is the grassland with dominant prairie vegetation, followed by the steppe, belonging to the Pampean phytogeographic province [29]. It is an extensive plain where loess sediments outcrop, partially reworked by fluvial action and modified by pedogenesis [88]. The dominant soils are Mollisols, with smaller areas covered by Alfisols, Entisols, Vertisols and in a very subordinate way Aridisols, as well as in a specific places Inceptisols [89]. Among the Mollisols, predominate Argiudolls (to the east) and Hapludolls, Haplustolls (to the west) [90]. The aptitude of the lands is agricultural-livestock in similar proportions, depending on whether it is elevated and stable landscapes or dunes or lowland areas [89, 91, 92]. Pampas region has very favorable environmental and pedological conditions for agriculture (cereals and oilseeds). Currently the main crops are soybeans, maize, wheat, and sunflower, as well as barley, sorghum, and canola.

3.3.1

Physical Soil Degradation in Pampas Region

Before the conversion to agricultural land, this region was covered by grasslands without large herbivores and a low human population. Agriculture and livestock began to develop slowly from the arrival of immigrants with an increase in the human population. Natural grasslands were grazed until the last quarter of the nineteenth century when forage crops and mercantile crops began to grow. Since then, agriculture expands the region and nowadays represents the dominant activity [93]. The expansion of the agricultural and livestock frontier in Argentina and the use of agricultural technology are factors that explain the increase in biological and economic productivity of rural sector in the last five decades [94]. Historically, farmers have made business decisions based on an economic relationship between benefits and costs, and has generally ignored the relationship between the economic benefit and the environmental cost of such a decision [95]. The increases in gross production in the pampas prairie were marked by an expansion over new lands until the 70s and 80s [96], and from then on, the productive jump can be explained by a more intensive agricultural practices. Since the 70s, there has been an important increase in the area under arable crops, with the cropped area increasing relative to the pasture area at an annual rate of 4% [97]. In recent years, there has been an extreme simplification of the Pampean production systems with a gradual replacement of traditional rotations by monoculture. This trend toward the production of a single crop had an unfavorable impact on the soil functions and the agroecosystem sustainability, such as the loss of organic matter and clay by water erosion [98]. In different sectors of this region, as a response to monoculture, physical degradation of the soil is observed [99] that strongly induces wind and water erosion processes [35, 91, 100–105].

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Fig. 6 (a) Aerial photograph of soil water erosion processes in the locality of Río Cuarto, Córdoba province. (b) Rill erosion in soils of the locality of General Cabrera, Córdoba province. (c) Gully erosion in soils of the locality of General Deheza, Córdoba province. (d) Laminar and rill erosion in soils of the locality of General Cabrera, Córdoba province. Photos: (a) M Cantú, November 2011. (b) A Becker, September 2017. (c) Analía Becker, October, 2018. (d) Analía Becker, April 2019

For these reasons, the most relevant soil degradation process is wind and water erosion. Long history of conventional tillage promotes sediment movement and loss of the surface horizon can usually be observed [106] (Fig. 6). The widespread adoption of no-tillage in the last two decades has slowed down the deterioration process [107]. However, in areas under monoculture, mainly soybean, no-tillage method was not enough to reverse soil degradation [108], although the inclusion of cover crops is mentioned as an alternative in no-tillage systems [109–111]. According to Casas [5] in the last three decades, Buenos Aires province has greater intensity of agricultural land use and a greater concentration of livestock (Feedlot). The lack of rotations, the outsourcing of land use, and the excessive demand for stubble by concentrated livestock farming contributed to the presence of a new scenario where the processes of soil degradation are showing a different dynamic. In general, compaction and structural deterioration processes are being developed that help reduce infiltration, percolation, and retention of water in the soil. Consequently, in flat areas, surface waterlogging tends to increase, and in undulating areas surface runoff and water erosion increase [112]. In areas of the west and southwest of the Pampas region, where the occurrence of drought periods is frequent, the processes of wind erosion increase. According to Casas and Puentes [113], the province of Buenos Aires has 35.5% of their lands affected by water erosion. In the rolling pampa, with slopes that varies from 0.3 and 3%, highly

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evolved Typic Argiudolls develop on loess material [91]. In this area, processes of water erosion, degradation of the surface horizon due to loss of organic matter, compaction and acidification due to continuous agriculture are observed. Naturally or anthropogenic-induced compacted layers that present difficulties for root growth, tillage, water and gaseous movement, and engineering uses were described in the Pampean region [112]. In addition, these authors [112] point to the occurrence of fragipan distribution in the soils on approximately 500 km2 in some regions. In the southwest of Buenos Aires, compaction processes are recorded that could be attributed to the loss of macroporosity in soils under no-tillage management [114] since this system has not been able to reverse the problems of physical degradation. Important compaction processes were reported by Agostini et al. [115] in soils with high organic matter (OM) content and loamy texture in the southeast of Buenos Aires province. Soils with physical degradation processes due to compaction were reported in the rolling pampas in Buenos Aires province due to the high silt content, long agricultural history and their management, with a predominance of no-tillage management [116]. In cultivated fields of the sandy Pampas, sectors with chlorotic less developed plants are observed called “overos” or “spotted” fields. Spotted fields occur mainly due to severe compaction at variable depths caused by cementing of silica or Fe, very hard Bt horizons, high apparent density, or excessively alkaline reaction [117]. The central-west part of Córdoba province is affected by processes of water erosion, mainly linked to change and intensification of land use in fragile environments [118] where the simplification of rotations and soybean monoculture contributed to increase in the erosive process. The gullies represent one of the most severe forms of erosion due to their impact on road infrastructure and due to their high sediments production [119]. Migration of peanut production (3,500 ha sown in 1998 to 116,000 ha in 2012) to south-central part of province increased susceptibility of soils and frequency occurrence of phenomenon of “blast” (dust flying by wind), particularly in dry years [120]. Waterlogging affects a total area of 1.7 Mha in the province of Córdoba, of which 880,000 ha correspond to agricultural land, and the rest to natural shallows suitable for livestock use or wetlands (usually used for biodiversity reserve and flood control). Soils under agricultural and livestock use in south-central Córdoba province present anthropogenic-induced evidence of compaction [121] where reduced infiltration favoring surface runoff and water erosion that negatively affect the behavior of crops in the area. These soils present natural susceptibility to compaction due to high silt and low organic matter content [121, 122]. In the current depressed areas of south eastern Córdoba province, the presence of subsoil compacted layers, together with the climate and the relief is the cause of great periodic floods and long period of permanence of the surface water. It is important to mention that fragipans interfere regionally in the dynamics of water infiltration when they are close to the surface [123]. Water erosion processes in Mesopotamian pampa are manifested with greater intensity in the western half, extreme south west of the Entre Ríos province, and in

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part of the south east sector. Water erosion affects 42% of the province with soil losses higher than 2 t ha-1 year-1 [27]. This means that around 4.5 Mha can be eroded and therefore must be managed using conservation practices. To mitigate soil degradation caused by water erosion, conservation tillage systems were developed and adopted, mostly reduced and no-tillage. However, in some regions, depending on the type of soil, slope and intensity of rainfall, the use of conservation tillage systems is insufficient to mitigate the erosion. Therefore, farmers and land managers have to implement technologies such as systematization of land and construction of terraces to control water erosion [124]. Soil compaction problems in center and north Santa Fe province were reported by Imhoff et al. [125], whose causal agents would be silt high content and organic matter loss that is manifested in high bulk density (>1.3 g cm-3) in topsoil. Entre Ríos province under Vertisols used mainly for rice cultivation is highly susceptible to compaction due to high content of expandable clay (>40%). Moreover, harvest is often performed under saturated conditions by heavy harvesters [126]. Currently, in La Pampa province water erosion has a greater magnitude in the central and south east zone, occupied by the natural ecosystem of the Caldenal and dedicated to extensive cattle ranching. However, there is pressure from agriculture to force clearings and transform extensive silvopastoral systems into agricultural ones. In the zones affected by wind erosion like the east of La Pampa province the area occupied by highly susceptible soils usually exceeds 50% [127]. Approximately 51% of the total area of the provinces of the region is affected by soil erosion according to the latest estimates, with more than 8.8 Mha with soil loss rate higher than 10 t ha-1 year-1 (Table 4). In north and center of La Pampa province studies carried out by Duval et al. [128] indicate that agricultural use has generated a non-critical compaction of soils at expense of 12% decrease in macropores. In relation to soil type, Argiudolls are vulnerable to agricultural practices intensification increasing degradation processes by compaction. Regardless of soil type, Table 4 Soil erosion affected areas (Mha) in Pampas Region

Province Buenos Aires Santa Fe Córdoba Entre Ríos La Pampa Total

Area affected based on mean rate of soil loss Moderate (2– Severe (>10 t ha10 t ha-1 -1 1 year ) year-1) 13,918,068 3,882,217

Total land area affected by soil erosion 17,800,285

Total area affected by wind erosiona 6,987,000

3,429,567 13,355,133 3,314,134

– 4,764,000 –

3,429,567 8,591,133 3,314,134

3,123,831 10,177,550 2,277,486

305,736 3,177,583 1,036,648

4,034,381

2,498,162

1,536,219

3,606,315

428,066

41,933,500

14,249,162

27,684,338

33,103,250

8,830,250

Data sources: aCasas [30], bGaitán et al. [27]

Total area affected by water erosionb 10,813,285

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agricultural activity generated decreases in total organic carbon (TOC) levels, negatively affecting most of physical properties evaluated with increases in bulk density and decrease in total porosity, mainly due to lower volume of macropores which decreased 12% on average. In the 1990s, the agricultural intensification advanced towards simplified production schemes under no-tillage cropping, with spring-summer species, especially soybean and maize. As a consequence, concern about negative nutrient balances in the Pampas and the importance of considering these deficits in land management and fertilization decisions have been expressed [129, 130]. Studies in croplands of the Argentine Rolling Pampa demonstrated that the technology (reduced tillage, no-tillage) was unable to maintain existing soil organic matter stocks with losses of 15–20% after 30 years [108, 131].

3.3.2

Salt-Affected Soils in Pampas Region

The Pampa region contains several areas with salt-affected soils as a consequence of waterlogging in lowlands or the presence of a shallow saline water table. According to Taboada et al. [132], there are 11.6 Mha of soils with some degree of alkalinization/sodification in the region. These soils are located principally in the meridional lowlands of the north of Santa Fe province, in depressed pampa in the center of Buenos Aires province and in the south-east of Córdoba province. Irrigation plays a key role in the intensification of agricultural systems of sub-humid areas. In the case of the Pampas Region, agricultural lands use pressurized irrigation systems. Soil salinization problems were reported in irrigated crop lands as a consequence of the use of sodic bicarbonate type groundwater for irrigation purposes [133]. The use of sodic bicarbonate water produces an increment of soil pH and ESP (exchangeable sodium percentage) with little or no variation of electrical conductivity. As a result, soil sodification is the highest risk for these areas [134]. According to statistical data, the region has more than 500,000 ha of crop lands under irrigation where 163,000 ha (29.3%) are affected by soil salinization [53]. The province of Buenos Aires is the most affected part of the region with 40% of the irrigated lands with soil salinization evidence (Table 5). Table 5 Irrigated and salt-affected soils area in the different provinces of Pampas region Province Buenos Aires Córdoba Santa Fe Entre Ríos La Pampa Total for the region

Irrigated land area (ha) 317,720 102,000 62,508 69,000 4,600 555,828

Data source: Sánchez et al. [51]

Area affected by soil salinization (ha) 128,560 17,710 6,000 10,350 460 163,080

Area affected by soil salinization (%) 40.4 17.3 9.5 15.0 10.0 29.3

Agricultural Land Degradation in Argentina

3.3.3

21

Agrochemical Contamination in Pampas Region

The Pampa region is characterized by no-tillage management and intensive use of agrochemicals. Glyphosate (N-phosphono-methylglycine) is the most commonly used herbicide in transgenic soybeans whose main metabolite, due to microbial degradation, is aminomethyl-phosphonic-acid (AMPA). In maize crops and soybean-maize crop-rotation sequence Atrazine (2 chloro 4 ethylamino 6 isopropyl amino 1,3,5 triazine) is used in conjunction with Glyphosate in agricultural lands of Argentina. Glyphosate (GLP), AMPA, and Atrazine (ATZ) residues were detected in the upper 10 cm of soils in different provinces of Pampa region [135–138]. A summary of several studies about GLP, AMPA, and ATZ residues in soils of the Pampas region is shown in Table 6. In cultivated soils, GLP was detected in concentrations between 8 and 5,200 μg kg-1, while AMPA concentration ranged from 3 to 6,550 μg kg-1. The GLP and AMPA levels detected in soils of the provinces of Buenos Aires and Santa Fe were not significantly different having concentrations that ranged from 2 to 1,500 μg kg-1. The province of Córdoba has showed remarkable differences between different areas, while the highest concentrations were measured in the province of Entre Ríos with an average concentration of 2,299 μg kg-1. ATZ residues were measured in Buenos Aires and Córdoba provinces in concentrations between 4 and 66 μg kg-1. The difference in herbicide concentrations could be related to some physicochemical properties of the soils, like organic matter and clay content, and different types of crops. Some papers dealt with the study of the environmental fate of GLP and AMPA in surface water, groundwater, and suspended particulate matter [137, 141, 143]. The major risk of propagation is linked with runoff and the detachment of soil particles according to studies carried out in Buenos Aires province. In suspended particulate matter, GLP was found in 67% while AMPA was present in 20% of the samples, while in stream sediments were also detected in 66% and 88.5% of the samples, respectively [141]. In the surface water studied, the presence of GLP and AMPA was detected in about 15% and 12% of the samples analyzed, respectively. Similar results were found in the Tapalqué stream basin in the province of Buenos Aires where GLP and AMPA residues were detected in sediments and surface water [138]. Conversely, studies on GLP concentrations in groundwater indicate a lower frequency of detection on shallow aquifers than in surface water [144]. Until now the presence of GLP residues in deep aquifers is still undetectable [136]. Soil wind erosion is other potential transport process of GLP molecules in agricultural soils. Measurable concentrations of GLP and AMPA were detected also in the dust emitted by soils of the central semi-arid region of Argentina, 12 months after GLP application [143]. This indicates that GLP and AMPA can potentially be a source of air contamination in windy regions.

Soybean-wheat, horticultural

Mollisols

Prevalent crop type

Dominant soil type Herbicide (μg kg-1) Mean Min Max Median

Buenos Aires (n = 5)c

Mollisols, Alfisols

Soybean, wheat, maize, oats

Mollisols

System barleysoybean

Olavarría, Tapalqué Quequén Grande River Basin

Buenos Aires (n = 6)b Córdoba (n = 58)a

Balcarce, Necochea, B° Ituzaingó, San Cayetano, Tres Malvinas Argentinas, Marcos Arroyos Juárez, Brinkmann Soybean-wheat, sun- Soybean-maize flower-wheatsoybean Mollisols Mollisols

Buenos Aires (n = 16)d

Mollisols

Mollisols