Drying grass transforms freshly cut forage into a preserved state by removing its moisture. This process, often called curing, reduces water content to allow safe storage without spoilage, while retaining nutritional value. The main goal is to create a stable product for livestock feed when fresh pasture is unavailable.
Methods for Drying Grass
The most common method for drying grass, especially for hay production, is sun-drying, also known as field curing. This process begins with cutting the forage when its sugar content is highest, often in the morning after the dew has evaporated. Freshly cut grass has a moisture content between 75% and 80%, which must be reduced for preservation.
After cutting, the grass is spread into a wide swath across the field. This maximizes exposure to sunlight, keeping the plant’s stomates open and promoting rapid initial moisture loss. Within 12 to 24 hours of mowing, when the forage moisture content is between 40% and 60%, the grass is often raked into windrows. A hay tedder can further spread and fluff the hay, aerating it and speeding up the drying process. For larger-scale operations, a hay conditioner may be employed to crimp and crush the stems, facilitating faster moisture evaporation.
Once the hay is nearly dry, frequent testing prevents over-drying, which can lead to dusty hay with reduced nutritional value. A common method to check for readiness involves hand-flipping the hay in the windrow; if the underside is green or moist, more drying time is needed. The hay is considered ready for baling when it reaches a moisture content of 14% to 18%.
While sun-drying is prevalent, mechanical drying offers an alternative, particularly for large-scale operations or in less favorable weather conditions. This method uses forced hot air to dry the forage. Although it allows more control over the drying process, it is less common due to its higher cost and energy requirements compared to natural field drying.
Factors Influencing the Drying Process
Several factors influence the efficiency and success of drying grass. Environmental conditions play a large role, with low relative humidity being a key factor. When the air holds less moisture, water can more readily evaporate from the grass. Conversely, high humidity hinders moisture loss, making the drying process slower and potentially incomplete.
Temperature and sunlight intensity also affect drying, though their impact can be less pronounced than humidity. Warmer temperatures promote faster evaporation. Sunlight is important for the initial drying phase because it keeps the stomates open, allowing moisture to escape. However, once the grass begins to dry and stomates close, direct sunlight intensity has less effect compared to the movement of air.
Wind speed is another environmental factor that aids drying by moving the moist air away from the cut grass, allowing drier air to absorb more moisture. Without adequate air circulation, humidity can build up within the windrow, slowing the process.
The characteristics of the grass itself also influence drying. Grass with higher initial moisture content requires more time to dry. The type of grass matters too; thin-stemmed, leafy varieties dry faster than those with thick, pithy stems. Conditioning, which involves crimping or crushing stems, can accelerate drying by creating more pathways for water to escape.
Common Uses of Dried Grass
Dried grass, most commonly in the form of hay, serves a variety of purposes, with its primary application being animal feed. Hay is a source of fiber, protein, and other nutrients for livestock such as cows, sheep, goats, and horses, especially during winter months when fresh pasture is scarce. Different types of hay, like timothy or alfalfa, offer varying nutritional profiles depending on the grass or legume species and growing conditions.
Beyond animal feed, dried grass finds uses in gardening and landscaping. It can be applied as a mulch to help retain soil moisture, regulate soil temperature, and suppress weed growth. As it decomposes, hay also contributes organic matter and nutrients back into the soil. It can also be used to create garden paths or as a natural border for garden beds.
Dried grass can also be utilized for other practical purposes. Historically, hay has been used as a building material and for insulation. While less efficient than modern fuels, it can also serve as a biomass resource for energy production or as a natural fire starter.
Storing Dried Grass
Proper storage of dried grass is important to maintain its quality and prevent spoilage. The most important factor is ensuring the hay is adequately dry before storage, with a moisture content below 15%. Baling hay with moisture levels above 20% can lead to problems like mold growth and excessive heating.
Ideal storage environments are dry and well-ventilated, protecting the bales from rain, snow, and direct sunlight. Storing hay indoors in barns is preferable, as it significantly reduces spoilage compared to outdoor storage, where the outer layers of bales can suffer considerable loss due to moisture. If outdoor storage is necessary, covering bales with tarps can offer some protection, but plastic coverings can restrict airflow and increase mold risk.
Elevating bales off the ground helps prevent moisture wicking from the soil, further preserving quality. Proper air circulation within the storage area is also important; bales should not be stacked too tightly, and ample space should be left between rows. Monitoring bale temperatures, especially within the first few weeks after baling, is a good practice. Temperatures exceeding 140°F indicate a high risk of spontaneous combustion, caused by microbial activity and plant respiration generating heat within moist hay.