Submitted by:
Carlos Garcia, Forage-Livestock Systems Research Specialist II
Liliane Silva, Clemson University Assistant Professor and Forage-Livestock Systems Specialist
Forages are the primary feed source for livestock production systems worldwide due to low production costs, adapted species, and diversity. With the growing population agricultural systems are facing challenges in increasing food and fiber production while minimizing negative environmental impacts. Forage systems play an essential role in delivering ecosystem services, and their management directly affects their ability to do so.
Ecosystem services (ES) are defined as the “benefits people obtain from ecosystems” and they are classified into four categories: cultural, provisioning, regulating, and supporting benefits. Some examples of ES provided by grasslands include carbon sequestration, nutrient cycling, and wildlife and pollinators’ habitat. Management practices affect forage stand production, longevity and resilience, nutrient cycling, animal performance, soil fertility, and health among others. This document will discuss few key points related to ES from forage systems.
Nutrient cycling
Nutrient cycling can be defined as the movement of nutrients within and between the biotic (e.g., pasture, cattle, insects, soil microorganism, etc.) and abiotic (e.g., soil, water, air, light, soil minerals, temperature, etc.) components of a forage-livestock system or other agricultural ecosystems. These components constantly interact with each other.
What does this mean? Forage systems rely on nutrients available in the soil to accumulate forage production and quality. A soil with poor nutrient levels or undergoing degradation (e.g., unproductive soil, high erosion levels, etc.) will affect the forage plant growth and production and may compromise persistence of the forage stand in the long term. Consequently, the livestock grazing in those pastures will have limited forage available for consumption, leading to compromised animal performance (e.g., reduction in milk and meat production). In addition, grazing systems without soil macrofauna present can limit or delay cattle excreta mineralization (the process that transforms organic matter into nutrients available for plant absorption and contributes to increase soil fertility) (Figure1).
Litter decomposition
Litter is defined as the senescent material attached to the plant or already deposited on the soil surface (Figure 2). This process promotes nutrient cycling through the decomposition of plant materials and release of nutrient content into the soil. Leaves, stems, and other plant parts deposited on soil through losses during grazing and/or natural senescence processes occurring in the plant are decomposed, releasing nutrients such as nitrogen, phosphorus, and carbon in the soil. These nutrients become available to plants and other microorganisms which can then use them within the ecosystem. Litter decomposition plays a crucial role in replenishing soil fertility and sustaining plant growth, making it an integral part of nutrient cycling in ecosystems.
Carbon accumulation
Carbon accumulation in the soil arises from the deposition of various carbon-containing sources. This process entails the conversion of carbon captured by plants from the atmosphere into organic carbon stored into the soil. Soils under grasslands are large reserves of carbon. Atmospheric carbon is captured by grasslands in three units: live vegetation [including aboveground and belowground (root systems) biomass], litter, and soil. In Figure 3, a sample of a bahiagrass pasture was collected (left) and washed to assess above- and below-ground biomass contributions as sources of organic carbon. Soil was then collected on the same site to determine carbon accumulation over time in response to management practices implemented.
Forages are important for feeding animals because they are relatively inexpensive and can adapt to different environments. They need to be managed well to keep the environment healthy and help plants grow. This in turn helps animals stay healthy too. Nutrient cycling is very important to keep the soil fertile and help plants grow. Improper management of the soil can lead to less food for animals and make it harder for them to stay healthy. Therefore, prioritizing proper land management and promoting nutrient cycling within our farming systems are essential for maintaining balance and sustainability.
