The Root Systems in Sustainable Agricultural Intensification

Zed Rengel, Ivica Djalovic, Zed Rengel, Ivica Djalovic

• Éditeur: Wiley-Blackwell
• Année: 2021
• ISBN:
  9781119525431
• Édition: 1
• Sujet: Biological Sciences
• Sous-sujet: Botany

Explore an in-depth and insightful collection of resources discussing various aspects of root structure and function in intensive agricultural systems

The Root Systems in Sustainable Agricultural Intensification delivers a comprehensive treatment of state-of-the-art concepts in the theoretical and practical aspects of agricultural management to enhance root system architecture and function. The book emphasizes the agricultural measures that enhance root capacity to develop and function under a range of water and nutrient regimes to maximize food, feed, and fibre production, as well as minimize undesirable water and nutrient losses to the environment.

This reference includes resources that discuss a variety of soil, plant, agronomy, farming system, breeding, molecular and modelling aspects to the subject. It also discusses strategies and mechanisms that underpin increased water- and nutrient-use efficiency and combines consideration of natural and agricultural systems to show the continuity of traits and mechanisms.

Finally, the book explores issues related to the global economy as well as widespread social issues that arise from, or are underpinned by, agricultural intensification. Readers will also benefit from the inclusion of:

• A thorough introduction to sustainable intensification, including its meaning, the need for the technology, components, and the role of root systems
• Exploration of the dynamics of root systems in crop and pasture genotypes over the last 100 years
• Discussion of the interplay between root structure and function with soil microbiome in enhancing efficiency of nitrogen and phosphorus acquisition
• Evaluation of water uptake in drying soil, including balancing supply and demand

Perfect for agronomists, horticulturalists, plant and soil scientists, breeders, and soil microbiologists, The Root Systems in Sustainable Agricultural Intensification will also earn a place in the libraries of advanced undergraduate and postgraduate students in this field who seek a one-stop reference in the area of root structure and function.

1
Sustainable Intensification: Meaning, Need, Components, and Role of Root Systems

P.V.V. Prasad¹, M. Djanaguiraman², and Zed Rengel³

¹ Department of Agronomy; and Feed the Future Innovation Lab for Collaborative Research on Sustainable Intensification, Kansas State University, Manhattan, KS, USA

² Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India

³ UWA School of Agriculture and Environment, University of Western Australia, Perth, Australia

1.1 Introduction

The grand challenge for scholars, policymakers, and citizens is to eradicate poverty and hunger in all forms at all times for all people, and protect our planet from further degradation. There have been significant increases in the global population that has more than doubled in the last 50 years (from about 3.7 billion in 1970 to about 7.6 billion in 2018; FAO 2018). In the past five decades, cereal grain production increased from about 1200 million tons in 1970 to about 2650 million tons in 2018. However, even now about 821 million people – approximately one in every nine people in the world – lacks sufficient food to lead active and healthy life. About 30% of children under five years of age suffer from undernourishment in many parts of Africa and Asia.

All four dimensions of food security: availability (having sufficient quantities of food available); access (having adequate income or resources to access food); utilization/consumption (having adequate dietary intake and ability to absorb and use the nutrients from food); and stability (having availability and access to food at all times) need to be addressed. In general, high food availability leads to lower food insecurity and less undernourishment. However, adequate supply of food does not always lead to food security. Access to food is dependent on household income, food prices, physical infrastructure, and social structure including gender and power hierarchies. Food utilization focuses on nutritional aspects of food security. The ability of the human body to obtain energy and nutrients from food is dependent on diet diversity, nutritional quality, food safety, clean water and environment, and human health. Food stability ensures that people are not exposed to risks of losing access to food due to shocks from climate, financial and social factors, conflict, and/or governance. Limited availability, access, utilization, and/or stability impose tremendous economic and social costs on all countries, irrespective of their economic status.

Food production is related to the harvested area and productivity per unit of that land. The increases in total food production have come from three sources – expansion of agricultural land, rise in yields per unit land area, and increase in the number of crops per unit land area per unit time. In the last five decades, food production was driven primarily by increasing yields per unit land area. However, the annual rate of yield gains of major food grain crops has significantly slowed down in recent decades. There is an urgent need to increase the rate of yield gains to keep up with the expanded demand for food, feed, and fuel from rapidly increasing population. Food and nutritional security are key for ensuring a healthy population. At the contemporary rates of increase in global population and the current changes in consumer preferences for animal source protein/dairy, we will have to increase food production by about 60% to meet the needs of about 9.5 billion people by 2050.

Agriculture uses about 30% of total land area and about 70% of total freshwater withdrawals in the world through irrigation. Even though irrigated agriculture represents only 20% of cultivated land, it contributes up to 40% of global food production.

There have been significant increases in the global greenhouse gas emissions in the last 50 years. The carbon dioxide concentration in the air has increased from 325 μmol mol⁻¹ in 1970 to 410 μmol mol⁻¹ in 2018. In the same timeframe, the concentration of methane increased from 1.35 μmol mol⁻¹ to 1.85 μmol mol⁻¹, and concentration of nitrous oxide increased from 0.295 μmol mol⁻¹ to 0.330 μmol mol⁻¹. The increases in total greenhouse gases were evident in a range of economic sectors. The percentage contributions from the different sectors in the United States in 2017 were 28.9% from transportation, 27.5% from electricity generation, 22.2% from industry, 11.6% from commercial and residential use, and 9% from agriculture (EPA 2019). Hence, agriculture contributes relatively little compared to other sectors. Within the agriculture sector, key contributors are livestock, soils, and rice production. However, agriculture also offsets about 11% of greenhouse gases in the United States and thus is a net carbon sink. Agriculture is a part of the solution to minimize greenhouse emissions and issues related to loss of biodiversity and natural resource management. However, increasing demand for food, feed, fuel, and fibre from humans will put additional pressure on agriculture. Novel methods and broader outlook towards our agriculture and energy production is required to ensure that we are meeting the food demand of growing population as well as safeguarding our planet and natural resources for future generations.

The challenge of increasing food production by about 60% is not new; we were faced with a similar problem in the last century. Agriculture scholars and global community stood up to the challenge and transformed agriculture through Green Revolution that increased the productivity of major crops and livestock species through improved genetics and use of fertilizers, pesticides, irrigation water, and farm machinery. All of these practices led to intensification of agriculture and met the needs and demands of humans, particularly in terms of calorie availability (Pingali 2012). However, there were unintended consequences on natural resources (e.g. water and soil quality), soil degradation (e.g. sub‐soil compaction, waterlogging, and micronutrient deficiencies), and chemical runoff leading to negative environmental impacts (Pingali and Rosegrant 1994). The environmental consequences were not caused directly by these technologies per se, but due to the policies that led to indiscriminate use and overuse of chemicals, and expansion of cultivation into marginal lands (Pingali 2012). The excessive reliance on chemical‐based plant protection and expansion of monoculture of selected crop species also decreased crop, plant, and animal diversity (Singh 2000), including diversity of indigenous crop species (Nelson et al. 2019) and associated ecosystems services. Excessive and unsustainable use of chemical inputs made our agricultural systems less efficient (Murgai et al. 2001; Thrupp 2000).

Despite rapid increases in yield gains at the start of Green Revolution, the recent trends in annual yield gains of major food crops has stagnated in recent decades (Ray et al. 2012; Grassini et al. 2013). There is a need to reverse this trend and make our agricultural systems more diverse, efficient, and productive. There is a global desire for agriculture to produce more food without environmental harm and to make positive contributions to natural and social capital through sustainable agricultural practices (Pretty et al. 2018). This is evident in the development of the 2030 Sustainable Development Agenda with 17 Goals (SDGs) by the United Nations. The SDGs came into force in 2016 and were called into action by all countries to promote prosperity while protecting environment (United Nations 2016). This new agenda recognizes that ending poverty must go hand‐in‐hand with strategies that build economic growth and address a range of social needs, including education, health, social protectio...