Author: Dr. Susan Kerr, WSU NW Regional Livestock and Dairy Extension Specialist
Publish Date: Winter 2018A new Extension publication, “The Western Oregon and Washington Pasture Calendar (PMW699),” was created to provide pasture managers and their advisors with a scientific basis for pasture management decisions and the timing of critical actions. A team of Extension educators and NRCS staff recently conducted a series of train-the-trainer workshops throughout western Oregon and Washington to teach fellow professionals and livestock managers how to use this new educational tool. Publication of the Calendar and support for the workshop series were provided by a western regional USDA Sustainable Agriculture Research and Education grant.
Pasture Calendar Contents
The Pasture Calendar starts with the basics: grass terminology, factors controlling perennial forage growth, and plant growth cycles. Maps of Forage Management Zones are included (Fig. 1).
The western Oregon and Washington calendars are divided into 24 management periods consisting of the first and second half of each month (Fig. 2). For each management zone or resource area, a color-coded table indicates what typically happens with grasses during a certain period. These plant growth periods include:
• Steady regrowth
• Declining regrowth
• Very slow growth
• Increasing growth
• Rapid growth—cool soils
• Rapid growth—warming soils
• Slowing growth
• Steady growth
• Slow growth
• DormancyThe Pasture Calendar includes extensive appendices and references. Appendices are:
• How Pasture Plants Grow
• Pasture Clipping
• Sacrifice Areas
• Buffer Strips
• The Nitrogen Cycle
• Nitrates in Forages
• Nutrient Excesses/Deficiencies
• Alternative Forage Crops
• Endophyte Toxins in Forage
The Pasture Calendar emphasizes and explains critical pasture management practices, such as:
• Performing soil tests and addressing fertility issues
• Selecting a forage species and variety well suited to local growing conditions
• Leaving at least three inches of grass stubble at all times
• Rotating pastures to let them rest and regrow to grazing height (> eight inches) before regrazing
• Grazing or mowing grasses to keep them in vegetative phase and vigorous
• Monitoring livestock body condition
• Establishing sacrifice areas for livestock confinement during critical periods.
Fall Is All!
The vital importance of fall pasture management is stressed throughout the Pasture Calendar. In early fall (typically September), grass plants generate new roots to replace the ones shed during the “summer slump.” It takes energy for plants to generate these roots, and roots in turn are needed for plants to obtain water and nutrients from soil. Most importantly, next season’s growing points are being established—overgrazing during this period will cause delayed and reduced pasture growth the following spring.
Protect the Lower 3”
Grasses store their sugar for regrowth in the lowest three inches of above-ground growth, not in their roots as previously believed. This means anytime pasture grasses or grass hayfields are grazed or mowed to less than three inches tall, the plants lose their energy reserves and regrowth will be delayed by up to six weeks (Fig. 3). If this mismanagement occurs month after month, plant vigor is affected and desirable pasture plants die; bare soil and weed incursions result. Expensive pasture renovation is then needed but will be pointless unless pasture management practices are changed.Sacrifice Areas Save Plants
Anytime livestock have the potential to graze pastures below three inches, they should be removed from pastures, confined to a sacrifice area, and fed stored forage such as hay or haylage. The need for a sacrifice area could arise during muddy winter months, the pasture summer slump, or if there is not enough pasture for the livestock under management. Conservation District funding may be available to help develop sacrifice areas, which also help protect soil and water quality.
Where to Get the Pasture Calendar
This 50-page, full color publication will soon be available for free downloading at http://pubs.wsu.edu (search for PNW699).