By Paul Sharpe, Ph.D.

Some weather experts consider drought to be any time in which precipitation falls by 25 percent below average. On a horse farm with seasonal hay and pasture production, this requires attention to the amount of snowfall prior to the growing season and to the rain that falls prior to and during the growing season.

Less snowmelt water and rain contribute to low soil moisture levels. Higher-than-average temperatures contribute to faster evaporation of soil moisture and directly affect plants, including decreasing their ability to make and store carbohydrates.

Drought is inevitable, which should not be surprising considering the variability in weather and, in recent decades, the warming of many climates. If we notice extended or more frequent periods of warming and drying, horse owners should be motivated to ensure they can still grow adequate amounts of the feed their animals need.

Horse managers can learn a lot from neighbours who manage cattle, sheep, or other grazing animals. Some will have a grazing plan, which could have basic components of supply and demand, and be constantly measuring the supply of forages and calculating demand. This amount of awareness of feed supply and demand should make a manager curious enough to recognize an emerging drought. A reasonable manager then needs a plan to respond to the drought. Managers of large herds of grazing animals typically shift the demand for feed during a drought by destocking or selling off animals. Deciding which animals to sell is often driven by a desire to keep the best animals for breeding, so the least valuable animals are sold first.

Related: The Seven Deadly Sins of Haymaking

Try to have animals graze growing, leafy forage without seed heads. Photo: Clix Photography

Horse operations tend to have fewer animals than beef or sheep farms and may not depend on their own breeding programs to supply replacements. As a result, on horse farms it is appropriate to place more emphasis on finding alternate sources of feed and less emphasis on reducing the demand for feed by selling animals.

Horse farm managers who are already using recommended pasture management tasks will find drought management easier than those who just graze areas until they run out of grass, then start feeding whatever hay they have or can buy.

What are these recommended pasture management tasks? For simplicity, I modified four rules presented by Victor Shelton¹, a cattle grazer who frequently writes for The Stockman Grass Farmer.

1. Try to have animals grazing immature, growing, leafy forage plants with no seed heads. If you have horses that are susceptible to equine metabolic syndrome, this needs modification. The idea is to present forages of high quality with levels of protein, minerals, and digestible energy that are optimum for desired health, growth, and performance.
2. Never graze more than seven continuous days on a pasture.  This rule is frequently ignored where the approach is to board a lot of horses, have one pasture, and have all or most of the horses on that pasture nearly every day, ignoring principles and benefits of rotational grazing. This magazine has previously published many excellent articles on pasture management for horse farms. There should be several relatively small pastures, which are grazed for short periods in rotation, so that forages have the opportunity to recover from grazing and then regrow, producing another crop of leaves and storing carbohydrates in their roots or crowns before their next grazing period. Forage quality can be higher with shorter grazing periods, such as three or four days. Some of my colleagues in horse grazing research at US universities have difficulty convincing clients to use grazing periods less than seven days, perhaps because there are so many competing priorities on horse farms.
3. Never graze closer than 3 inches (8 cm). Following this rule helps one to follow rules 1 and 2, although some flexibility is practical. As grass plants are cut or grazed progressively lower, their roots shrink proportionately. Shorter roots extract lower quantities of water and nutrients from the soil each day, so overgrazed plants lose productivity. Leaving more residual grass post-grazing, perhaps 4-6 inches (10-15 cm), is reasonable during drought. In the diagram of tufts of grass (Figure 1), three grazing scenarios are modelled: removal by grazing of 50 percent, 70 percent, and 90 percent of the grass. When only 50 percent of the grass height was removed, roots continued to grow and are shown 17 days later. When 70 percent of the grass height was removed, 50 percent of the roots stopped growing for 17 days. When 90 percent of the grass height was removed, all of the root mass stopped growing. 
4. Never return to a pasture in less than about 30 days. This timeframe can vary significantly depending on factors such as climate, season, rainfall, and plant growth rates. The goal is to allow plants to rest and recover from the loss of photosynthetic tissue and to regrow to a reasonable size and strength before they are grazed or cut again. Most people remember to rest their horses after use but sometimes they don’t understand that plants need to recover too.

Related: Rethinking Horse Paddocks: A Natural Setup Changes Everything

Credit: USDA/SCS, Ag. Handbook no. 389, 100 native forage grasses in 11 Southern states.

Levels of soil moisture, acidity, and nutrient concentrations have significant effects on the rate of growth of forages. However, the goals of these four rules are simple and practical. A manager who attempts to achieve them and keeps records of what they have done, along with records of forage production, will gradually learn their value.

Have you heard that you can’t manage something that you don’t measure? In the textbook, Horse Pasture Management Second Edition by Paul H. Sharpe², there are chapters on determining how much feed to provide to horses each day and on measuring the amount of forage produced at intervals during a grazing season. Fortunately, estimating the yield of forage dry matter per unit of pasture area can be done. There are a few tools available for measuring forage yield. The most practical ones are called “pasture stick” or “grazing stick.” They look similar to a metre stick or yardstick, allowing the average forage height to be determined, and some of them contain tables which allow the user to convert the measurements into yields of forage dry matter per acre or hectare. More complex and expensive tools for forage yield determination are also available. A recent factsheet from the University of Kentucky provides the basics and chapter 7 of Horse Pasture Management Second Edition³ provides more details.

Related: Assess Your Horse Property to Eliminate Potential Dangers

Grass should not be grazed shorter than 3 inches (8 cm) or for more than seven continuous days. Rotational grazing with short grazing periods of three to four days allows forage plants time to recover and can improve pasture quality and productivity.

Drought management requires long-term familiarity with local conditions, frequent measurement of weather patterns, and diligent record-keeping. Reviewing weather records reveals when exceptional conditions are developing. Maintaining a weather station on your farm provides more representative data than getting weather data from another location. Wireless transmission of the weather data to your computer is a very useful feature.

One of the simplest factors that correlates with nutrient needs in animals is their body weight. Since any herd of animals is going to include a variety of body weights, it is convenient to use a term called the “animal unit,” which is approximately 1000 lb or 454 kg of live body weight. In a pasture situation, knowing and using the feed requirements for the calculated number of animal units represented by the horses is simpler than using the individual body weights of the animals. A feed budget can be developed from the daily herd feed requirements (demand) and the productivity of the pastures and hay fields (supply). The more precisely you can match feed supply to feed demand, the more money you can save and the less feed that will be surplus.

Related: Managing Streams on Horse Properties: Safety and Stewardship

Using “animal units” — a standard measure based on 1,000 pounds (454 kg) of live body weight — can simplify feed planning for horse herds of varying sizes. Matching pasture and hay production to the herd’s feed demand as closely as possible helps reduce waste, control costs, and improve overall pasture management. Photo: Pam Mackenzie

Maintaining maps of all the pastures on a farm helps in their management. There are computer programs to facilitate pasture mapping (such as PastureMap | Manage Your Herd From Anywhere).

Steve Kenyon⁴ is an Alberta rancher who frequently gives talks on grazing management. He suggested planning for the next drought as soon as you are finished with one. While he cannot make more rain fall on the pastures he manages, he tries to increase the level of organic matter (compounds containing carbon) on those properties. Soil organic matter (SOM) attracts and holds water, so efforts to increase SOM help to resist the effects of drought. Steve is also concerned with the protective layer of plant litter and thatch on the soil surface, which acts as a sort of armour against the erosion of soil by raindrops and subsequent lateral movement of water. The impacts of raindrops on bare soil destroy soil structure, particularly the existence of aggregates of soil components. This process causes a cap to form on the soil, which inhibits the infiltration of water. So organic matter of plant origin has a two-fold effect on helping pasture soils to acquire and hold water for the benefit of living plants. As the plants grow, their roots exude carbon-containing compounds, which benefit helpful soil microbes. This microbial component, including bacteria, fungi, nematodes, and protozoa, contributes to nutrient cycling, plant growth, and disease suppression. Higher levels of SOM also contribute to the formation of macropores in soil, promoting more infiltration of water from the soil surface.

In addition to keeping the soil moisture concentration high, the water from rainfall and snow melt can be directed into ponds, which are also referred to as dugouts in Western Canada and dams in Australia. Some of this pond water seeps laterally through the soil, keeping up the water table. Captured water can also be used for irrigation and livestock drinking water.

Once a drought has begun, it is worth assessing the cost/benefit ratio of each animal maintained on the pasture. Even if a family member cannot bear to part with a particular horse, it is worth considering whether a friend or relative in an area not affected by drought could manage an extra horse or two for a few months.

A rise in local hay prices and rent for pastureland is inevitable during drought. Frequent monitoring of these prices can assist in making decisions on the purchase of alternative feeds. Hay cubes, beet pulp, and soybean hulls can substitute for some of the forage in horse diets on a temporary basis. Other feeds that can substitute for the pasture and hay you attempt to grow include annual grasses that you plant (if there is enough moisture) and crop residues after harvest. In areas that are relatively far south and have a moderately warm climate, some varieties of warm season or C4 grasses and legumes may be suitable to grow through a drought. Wild C4 grasses are naturally suited to warmer and drier locations. New annual varieties of some C4 grasses have been developed and recommended in temperate parts of the US as substitutes for the cool season forages that are most common in Canada.

In summary, drought should be expected. Horse farm managers can prepare for it through everyday management and specialized efforts. Measuring, calculating, photographing, and record-keeping can facilitate exceptional management when drought occurs, and reduce the negative effects of lower precipitation and higher air temperatures. 

Related: The Role of Mowing in Horse Pasture Management

Related: Horse Fencing: Planning Safe and Practical Paddocks and Pastures 

Footnotes

1. Victor Shelton. Four Rules for Summer Grazing. The Stockman Grass Farmer. Volume 22, #7. July, 2022. 
2. Paul Sharpe, Editor. Horse Pasture Management - 2nd Edition. Elsevier Publishing. Academic Press. 2025. 
3. Paul Sharpe and Edward B. Rayburn. Forage Yield and Its Determination. In: Horse Pasture Management - 2nd Edition. Elsevier Publishing. Academic Press. 2025. 
4. Steve Kenyon. Plan for a Drought after a Drought. The Stockman Grass Farmer. Volume 21, #11. November, 2021. 

Main Photo: iStock/MV Burling