Forages, Volume 1

An Introduction to Grassland Agriculture

Michael Collins, C. Jerry Nelson, Kenneth J. Moore, Robert F. Barnes, Michael Collins, C. Jerry Nelson, Kenneth J. Moore, Robert F. Barnes

• Éditeur: Wiley-Blackwell
• Année: 2017
• ISBN:
  9781119300663
• Édition: 7
• Sujet: Technology & Engineering
• Sous-sujet: Agronomy

Forages, Volume I, Seventh Edition is themost comprehensive text available for teachers of undergraduate Forages courses. This edition will provide students with a good balance of scientific principles, to aid in integrating the concepts they learn, and practical information on forage identification, plant characteristics, management, and utilization that can be used by forage management practitioners. Grassland ecosystems are extremely complex, including the plant/animal interface as well as the soil/climate/forage interface and the text must support understanding and integration of all of these considerations. The coverage of the science behind the plant characteristics and responses make the book applicable in many parts of the world, while other region-specific management information relates mainly to North America. This edition has been updated to address emerging areas of study, including the use of forage plants as bioenergy crops. The editors also address the renewed national interest in environmental issues such as water quality, global climate change and eutrophication in the Gulf. This edition also addresses the role of forages for wildlife habitat and food sources, another area of increased interest in recent years. These revisions respond to the generational change taking place among forage scientists and teachers in recent years.

PART I

CHARACTERISTICS OF FORAGE SPECIES

Chapter 1
Forages and Grasslands in a Changing World

C. Jerry Nelson, Kenneth J. Moore, and Michael Collins

Welcome to forages and grassland agriculture. The roles and importance of forages and grasslands for mankind have a long history and continue to change as societies evolve and new technologies are developed for the plant and animal sciences. The foundational grasses, legumes, and other forbs observed today are the result of natural evolution for adaptation and resilience, often with the presence of grazing animals, for over 10,000 years with the advent of sedentary agriculture by humans. These plant resources are fragile; when they are managed or mismanaged beyond their limits, they deteriorate and can be lost.

The focus of this book is to understand and appreciate the plant characteristics and fundamental principles that provide diversity among the major forage and grassland species and to describe their use and optimal management. The goals of this chapter are to provide background and future perspectives for grasslands in the USA and North America.

Grassland Terminology

With any subject, it is important to know and understand the terminology. As with other subjects, the terms and definitions (see Glossary) for grassland agriculture overlap and are intertwined. The main land and plant resources are forage, pasture, range, and grassland. Forage is defined by the International Forage and Grazing Terminology Committee (Allen et al., 2011) as “edible parts of plants, other than separated grain, that provide feed for animals, or can be harvested for feeding.” It includes browse (buds, leaves, and twigs of woody species), herbage (leaves, stems, roots, and seeds of non-woody species), and mast (nuts and seeds of woody species). Thus forage is an inclusive term for plants and plant parts that are consumed in many forms by domestic livestock, game animals, and a wide range of other animals, including insects. Furthermore, production of forage involves several types of land use and is subdivided using more specific terms.

The term pasture is derived from the Latin pastus and is defined by the International Forage and Grazing Terminology Committee (Allen et al., 2011) as “an area in which grass or other plants are grown for the feeding of grazing animals.” This broad context includes pasturage that more accurately means “the vegetation which animals graze.” Thus pasture refers to the land area or grazing management unit, rather than to what is consumed. Pastureland refers to land, usually in humid areas, devoted to the production of both indigenous (i.e., native to the area) and introduced forage species that are harvested primarily by grazing. Permanent pasture refers to pastureland composed of perennial or self-seeding annual plants that are grazed annually, generally for 10 or more successive years. In contrast, rangeland refers to land, usually in arid or semi-arid areas, consisting of tall-grass and short-grass prairies, desert grasslands and shrublands that are managed extensively and grazed by domestic animals and wildlife.

Cropland forage is land devoted to the production of a cultivated crop (e.g., corn or winter wheat) that is harvested for silage or hay. Cropland pasture is cropland that is grazed for part of the year, such as grazing corn stalks after the grain is harvested or grazing leaves of winter wheat during winter and early spring before reproductive growth begins. In addition to grazing, cropland pastures are useful in row crop rotations as winter cover crops to reduce soil erosion. Cover crops such as red clover or winter rye in the north or ryegrass and crimson clover in the south are seeded in fall primarily to provide protective ground cover over winter. The crop can be grazed, harvested, or tilled into the soil in spring. In addition to erosion control and protection of water quality, cover crops have favorable effects on soil fertility, soil quality, water quality, weeds, pests, diseases, and biodiversity and wildlife in an agroecosystem.

Rangeland is land on which the indigenous vegetation consists predominantly of grasses, grass-like plants, forbs, or shrubs and is managed as a natural ecosystem. When non-native plants are seeded into rangeland, they are managed as part of the vegetation mix as if they were native species. Range is a more collective term that includes grazeable forestland or forest range that produces, at least periodically, an understory of natural herbaceous or shrubby vegetation that can be grazed. This use has raised interest in agroforestry, namely the use of cropland agriculture among trees until the tree canopy causes shade. Silvopasture describes an agroforestry practice that combines managed pastureland with tree production.

Cropland, forestland, pastureland, and rangeland are also the basis for land-use mapping units (Fig. 1.1...