| | Riparian areas are the lands next to streams, rivers, lakes and wetlands that are strongly affected by the water body. These areas usually have moisture-loving vegetation and higher moisture levels than the surrounding landscape. Riparian pastures can be very productive if they are managed with these distinctive characteristics in mind.
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In general, riparian pastures produce at least twice as much forage as the adjacent uplands simply due to access to more moisture. Rotational grazing practices allow you to manage the intensity, duration and timing of riparian grazing to sustain this productivity.
The grazing practices that maintain productive riparian pastures usually also help maintain the vital landscape functions performed by healthy riparian areas. These functions include maintaining water quality, preventing bank erosion, reducing flood damage, and providing habitat in and next to the stream or pond.
The strategies for managing riparian pastures have their own set of economic considerations. Your actual costs and benefits will depend on many factors such as the plant types in your riparian area, soil and landscape features of the floodplain, precipitation patterns, and the characteristics of the water body, as well as the specific grazing strategies you use and how those strategies affect pasture growth, quality and yield.
Grazing management considerations
The key tools for managing any pasture, including a riparian pasture, are: intensity of use; duration of use in one year; and timing of use. Each of these factors plays an important part in the short-term and long-term productivity of your riparian pasture as well as its ability to perform other riparian functions.
Usually the plant species in a riparian pasture are somewhat different from those in the surrounding uplands. You will need to become familiar with the species in your riparian area and how grazing intensity, duration and timing affect their productivity.
The economics of riparian grazing management vary considerably depending on the ecoregion (i.e. the general climate, soil and natural vegetation characteristics of the area). In some ecoregions, woody species dominate in riparian areas, while in other ecoregions, grasses naturally dominate. Generally, grassy areas will have a higher grazing potential than the woody areas. However, there can be large differences in the productivity of woody riparian areas, between one mile of the valley and the next, depending on how deep, flat and wide the floodplain is. Your management strategies will also be influenced by whether native or tame species predominate, because they require different management.
Intensity of use
Grazing intensity is the amount of forage taken at one time. Intensity affects the ability of forage to regrow, and the amount of regrowth determines overall pasture productivity.
The key to managing grazing intensity on any pasture is to leave sufficient above-ground growth after grazing. This allows quicker regrowth because all the root reserves are not depleted. Some examples of rules of thumb for grazing grasses are: take half and leave half; or leave at least 4 to 6 inches of growth, depending on the species. For woody species, at least half of the new annual growth should remain after grazing.
Typically, the amount of growth left behind on a riparian pasture should be somewhat more than on an upland pasture, so the riparian area can continue to perform its landscape functions.
Duration of use
Grazing duration is the amount of time that cattle spend in an area over the course of a year. The less time they spend in a riparian area, the less time they will have to trample the banks and destroy the trees in the area. It is preferable to have more animals for a shorter period of time, than fewer animals for a longer period of time. A good option is to allow the cattle to graze in the riparian area for a day or two and then to move them to another area, so the riparian area has time to rest and recover before regrazing.
The length of the rest period will vary depending on the rainfall, time of year, and the ecoregion. It should be at least three to six weeks. In the drier parts of the province, as long as a year may be needed to allow sufficient litter to accumulate for protection of the soil, filtration of water running to the stream or pond, and adequate regrowth for regrazing. In some cases, riparian areas are only grazed in drought years, leaving them as insurance for shortages in times of drought.
Duration will also depend on the health of the riparian area. A very healthy riparian area has a wide variety of plant species, including many woody species of various ages (if woody species are part of the natural riparian vegetation in the area). If your riparian pasture is very healthy, it will be able to withstand slightly longer grazing durations. If the area is not so healthy, then it will need shorter grazing periods and longer rest periods, as well as a lower grazing intensity, to restore the variety and vigor of plant growth.
Timing of use
Timing is often the most important aspect of protecting riparian health. Since riparian areas are often wetter than the surrounding fields, they are most susceptible to trampling, soil compaction, and pugging. Pugging is the formation of hoof prints and the little mounds beside the hoof prints that are caused by pressure on soft soil, which causes the soil to move upwards around the hoof print, often by 6 inches or more.
Trampling of soft, wet soil destroys roots, buries grass shoots, and generally disturbs plant growth, sometimes leading to weed invasions. Compacting moist soil creates a flat, hard surface. These effects may reduce pasture productivity and/or reduce the riparian area’s ability to perform its other functions.
To minimize damage, the best option is to graze riparian pastures when they are the most dry, and leave them alone when they are the most wet. In many cases, riparian soils are damaged most by spring grazing, when soils are wet. Spring grazing can also damage riparian vegetation, if grazing is too intense or too long to allow plants to replenish their root reserves for future regrowth.
In some situations, the best time to graze some riparian areas may be when they are frozen, when no damage will be done to the soil or the plant roots by trampling. Although they can be used for winter grazing, riparian areas should not be used as winter feeding sites. If cattle stay in these areas for too long, they can do significant damage by using these areas for bedding, rubbing and shelter.
Fine-tuning your management
Rules of thumb are not a substitute for astute observation of your riparian areas before, during and after grazing. Every year will be different, and the riparian vegetation will change and adapt as time goes on. The intensity, timing and duration of grazing will also need to change from year to year, depending on the condition of the riparian area. It is often a good idea to avoid grazing a particular pasture at exactly the same time every year, although this may be less possible with riparian areas that are only dry enough to graze at certain times of the year.
Economics of riparian area grazing
When you calculate the economics of managing your riparian pastures, you’ll need to include the various benefits and costs important for your own operation. Benefits include additional forage productivity and better nutrient distribution. Costs include things such as fencing, watering systems and moving salt blocks. Capital costs, like pumping equipment or fencing materials, can be spread over the life of the equipment and materials, to help you see if your grazing system will pay over the long-term.
Additional forage production
Research and practical experience have shown that it pays to manage upland areas with rotational grazing. And if rotational grazing pays on the uplands, then it certainly pays at least as much on the riparian pastures, since the potential forage production is usually greater.
For upland pastures, poorly managed grazing areas could have production as low as 1000 lb of dry matter per acre, while well managed areas could have production as high as 3000 lb/acre or more (see Grazing Tame Pastures Effectively, Alberta Agriculture factsheet, Agdex 130/53-1). At a value of 2 cents/lb, the additional grazing capacity can be worth an additional $40/acre.
The additional potential in your riparian area may be higher or lower than this, depending on rainfall, present management practices, and types of grasses, forbs (broad-leaved, non-woody plants) and woody plants.
Fencing and watering systems
In many cases, sustainable management of riparian grazing areas requires at least some fencing. The number of fences and paddocks and the associated costs required for good management will depend on the size of your herd. The larger the herd, the larger the paddocks can be, as long as short grazing durations can be maintained in the riparian pastures.
In some cases, simply moving waterers and salt to locations far away from riparian areas will help to reduce the damage to those areas. The cost of this approach varies. However, it is only somewhat beneficial for larger grazing tracts, and does not provide significant protection for riparian areas in smaller pastures where cattle commonly travel the entire pasture in one day. (For information on the costs of watering systems.
Fences along riparian areas do not always need to follow the shorelines exactly. Some amount of upland pasture can be combined with the riparian pastures, as long as the grazing duration is short and the timing is optimum for protection and enhancement of the riparian area. If the adjacent pasture needs to be grazed at a time when the riparian area is not suited for grazing, then a fence is recommended to protect the riparian area. Sometimes only a portable electric wire fence will be required for a short period of time.
Costs for fencing materials can range from $1200 per half mile for four-wire barbed fencing, to $600 per half mile for four-wire high tensile fencing, to $200 per half mile for a single-wire portable or permanent electric fence on rebar posts with insulators, not including the electric fencer charging unit. The single-wire electric fence works for well-trained cows, and it is also used for intensive rotational grazing where cows are moved once a day. Labor and machinery for installation also need to be considered when determining fencing costs.
Manure distribution
Managing riparian pastures separately from upland pastures can also improve manure distribution. When given a choice, cattle often love to bed down in the trees in riparian areas. Keeping them out of there means they will deposit more nutrients on the uplands, which are more nutrient deficient, thus increasing the productive capacity of the upland pastures and adding value to your bottom line.
Take an example of 100 tonnes of manure, with 50 per cent of the manure distributed on upland pastures, rather than wasted in riparian areas. Those 50 tonnes, at a nutrient value of $40/tonne, could add $2000 of nutrient value to that part of the operation. (At 13 lb/day of solid manure/head, it would take 100 cows about 169 days to produce 100 tonnes of manure, or 400 cows about 42 days.)
The actual value of the deposited manure to the growth of pasture grass will vary. It will be higher in the spring and early summer than in the fall, because the growing grass will be able to use it better, and more nutrients will be captured by the forage. Some of the nutrient value will be captured in future years rather than in the first year, and some will be lost to the atmosphere, depending on the weather.
Summary
With good management, riparian pastures can provide abundant forage. Rotational grazing allows you to adjust grazing intensity, duration and timing to suit the distinctive moisture and vegetation characteristics of your riparian pasture.
Managing riparian pastures separately from upland pastures can provide important economic benefits like increased pasture productivity and better nutrient distribution. The actual economic benefits and costs will depend on the specifics of your own operation and the characteristics of your riparian pastures.
Along with the long-term positive effect on your pocket book, maintaining healthy riparian pastures also helps to maintain other riparian functions, like protecting water quality, conserving fish and wildlife habitat, and reducing flooding.
More information
More information on riparian area management and riparian grazing is available on the Cows and Fish website at www.cowsandfish.org and the forage and beef website at www.foragebeef.ca.
Written by John Zylstra, P.Ag.
Environmental Stewardship Branch
Alberta Agriculture and Forestry, original written in 2005, revised in 2016
Acknowledgements: The author thanks the many specialists from Alberta Agriculture and Rural Development who provided assistance and comments in completing this document. |
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