Moisture Management on Perennial Pastures - Risk Management

Maintaining healthy, vigorous forage plants is the key to making the most of available moisture. These plants have deep root systems that are very efficient at using moisture, so they are less affected by short dry spells and initially less affected by drought. Plants stressed by overgrazing, dry conditions or low soil nutrient levels have shallower root systems. Early spring grazing can be especially stressful. Plants need time to replace root reserves used for early growth.

By managing your pastures to deal with your local conditions, you can improve pasture productivity, reduce drought risk and contribute to a healthy environment.

1. Know your local weather and climate

Accurate information on weather and climate can help in managing weather-related risks to forage productivity. Weather information recorded on your farm and data from the nearest weather station provide the best sources of information. Key actions are:

• Measure precipitation and temperature at your farm. You may want to take measurements on several fields because variations between locations can be significant.
• Keep a record of precipitation and temperature, and compare it with forage production to track trends.
• Review long-term weather data for your area to better anticipate weather patterns and understand the variability.

2. Know your local soil

Soils vary across regions and across individual fields. Knowing both the variation in and the capability of your soils is essential for optimum forage production. Key actions are:

• Learn the limitations of your soil group.
• Identify local variations in soil organic matter, fertility, drainage and other soil characteristics that affect plant growth.
• Determine the soil texture in your pastures to better understand water infiltration, drainage, and storage potential and limitations.
• Determine the occurrence and extent of any problem soils in your fields, and manage them appropriately. Choose forage species tolerant of the problem soil’s limitations.

Identify the main forage species in your pastures, and understand their growth patterns, limitations and management. Grow forage species that are productive, adapted to your environment, and suited to your grazing management system. For more information on forage species, refer to Alberta Agriculture’s Forage Species and Perennial Forage Establishment in Alberta (Agdex 9682).

Conduct periodic assessments of your pastures to monitor their health. For more information on health assessments, refer to Alberta Agriculture’s Tame Pasture Scorecard (Agdex130/10-1) and Cows and Fish’s Riparian Health Assessments for Streams, Sloughs, Wetlands and Lakes.

4. Know your riparian areas

Riparian areas are the lands adjacent to streams, rivers, lakes and wetlands, where the vegetation and soils are strongly influenced by the presence of water. Riparian areas provide a buffer and filter to improve and maintain water quality, as well as shelter and habitat for livestock and wildlife. They hold water, which improves forage production and provides drinking water. The key to maintaining healthy riparian areas is to understand how they function.

For more information, as well as specific management strategies, refer to Cows and Fish’s Caring for the Green Zone: Riparian Areas and Grazing Management.

5. Use good pasture management methods

• Delay spring grazing until plants are ready. In general, grazing of perennial pasture species before early to mid June stresses plants because the carbohydrate reserves in their roots are low. Early grazing can reduce forage production significantly for the rest of the growing season. As a rule of thumb, one day’s delay in spring grazing adds three days of grazing in the fall. A general rule is to wait until grass plants have at least three full leaves before grazing in spring. If you cannot delay grazing on all pastures, then alternate the pastures or paddocks grazed first in the spring. Allow the early grazed pasture a long rest period afterwards.
• Set your stocking rates to the average level of forage expected, with adjustment for the present year. Stocking rates are best set conservatively for average forage production. In good years, extra forage can be grazed in the fall or winter, or left to accumulate as litter. In drought years, stocking rates may need to be reduced to match forage supply.
• Provide plant rest periods and graze forage at appropriate stages. A well planned rotational grazing system allocates adequate rest and grazing periods. This increases forage utilization and allows more uniform grazing. Be sure to monitor forage condition and adjust grazing and rest periods throughout the grazing season.
• Manage pasture fertility. Forage production in many pastures in Alberta is limited by low soil fertility. Soil test to determine fertility needs. To increase fertility, apply manure or commercial fertilizer, use winter feeding on pastures, increase manure distribution during grazing, or add legumes to the forage stand.
• Use annuals and winter annuals. Fall-seeded winter annuals, like fall rye, winter triticale or winter wheat, can be used for early spring grazing instead of perennial pastures. In a dry year, spring-seeded winter or spring cereals may provide good quality grazing throughout the season; they respond to light showers with more growth than perennial forages. In a year with more moisture, extra feed can be baled and stored.
• Select forage species adapted to your area. Choose forages recommended for your soil group and average moisture level. In drier areas, select deep-rooted, drought-tolerant species. Alfalfa is generally deeper rooted than tame grasses. In higher moisture areas, clovers make a viable legume alternative to alfalfa. Clovers are more palatable than alfalfa as the plants mature, so they are better for late fall and early winter grazing. Legumes are valuable in pastures because they fix significant levels of nitrogen. In stands with a high proportion of legumes, manage bloat through grazing management.
• Carefully manage grazing of riparian areas. Avoid grazing riparian areas in the early spring and after heavy rains, when the soil is very moist. When saturated, riparian areas are vulnerable to trampling, which damages the health and function of these sensitive areas. Allow adequate time for pasture regrowth on riparian areas prior to winter. Provide off-site watering for livestock, and place livestock shelter, feed and mineral supplements away from riparian areas to protect these areas and to prevent manure build-up near water bodies.
• Distribute livestock evenly. Periodically change the locations of livestock water, shelter, feed and mineral supplements to minimize overgrazing and manure build-up around these areas.

• coordinate grazing with pasture conditions and management events (e.g. weaning),
• account for changes in stocking rates during the grazing season, and
• show when stock will be in each pasture.

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