Reviewing to renovate pastures

Not everything occurs at the same time, but windows open and windows close as the pasture calendar year marches on.

Extension Educator / Washington State University Irrigated Ag Research & Extension Center

A recent extension bulletin that can help you track and respond to local seasonal cycles is The Western Oregon and Washington Pasture Calendar PNW699 . For most livestock pasture-based operations, 2019 was challenging for several reasons: lack of winter from November through January followed by February winter storms that never seemed to end; a cooler and wetter-than-normal spring and summer followed by a very abbreviated fall regrowth period with winter coming earlier than normal. Needless to say, pasture managers and graziers were confused responding to these conditions.

Every pasture is different, and a manager armed with a “good eye” and solid ideas for if and how to renovate abused pastures can heal wounds and repent many of the “sins of overgrazing.”

Years ago, we authored a Washington State University bulletin, Pasture and Hayland Renovation for Western Washington and Oregon. In that bulletin, we explored numerous avenues of pasture renovation that have withstood the test of time by producers in the Pacific Northwest. A few key points, based on current pasture conditions, need to be reviewed again because grazer performance depends on the quality and quantity of forage grown in the new decade.

Somehow, the pasture got into trouble. You know this because you’re considering renovating the pasture. The amount of weeds and bare soil is a result of current grazing patterns and/or soil fertility levels. So how do you figure out which it is (or both)?

Diagnosing the issue

First, collect a soil sample for each grazing area, submit them to a soil testing lab and review the results. Correcting nutrient deficiencies and imbalances results in healthy, desirable pasture plants capable of outcompeting aggressive weeds. Just think, those short, overgrazed plants need extra TLC to bring them back to productive life and compete against existing weeds. How do we accomplish this? Managing nutrients is part of the answer.

Nitrogen often gets all the attention, but other key nutrients are phosphorus and potassium. They are expensive, but each plays a vital role in the plant. Phosphorus is used in small quantities within the plant, but new root system growth and development is dependent upon this essential nutrient.

There are aboveground symptoms to show phosphorus deficiencies, but actually digging a pasture grass plant up, washing the roots free of soil and looking to see if new white roots are growing in spring and fall is fundamental. Cool-season pasture grasses will shed roots, which will transition from white in spring and fall to tan-brown-black in summer and winter. Potassium is taken up by pasture plants in about the same quantities as nitrogen, thus when considering fertilizer applications of nitrogen and sulfur, don’t forget potassium is important to sugar metabolism, starch synthesis, regrowth energy and winterhardiness.

The second step to determine if pasture should be renovated is to walk each pasture and actually measure what types of plants are growing in the field and how they’re doing. One tool to help with this estimation is the USDA-NRCS pasture condition score sheet . To assist in measuring the percentage of desirable and undesirable plants and bare ground, an easy tool is the step-point method of sampling the pasture. This method has been used in range work for decades but seldom is used in tame grass pastures in the western U.S. Visit Sampling vegetation attributes for instructions for the step-point and other methods.

Problems to look for

By walking the pasture and observing plant type and growth in detail, grazing use patterns will also start to become apparent, especially as you answer the questions on the pasture condition score sheet. Is there uneven utilization of pastures? Some areas where plants are grazed too low, and other areas where there is hardly any use? Wetter soil areas and drier areas? Are there pastures where grazing patterns and utilization could be improved with additional cross-fences or water developments? Are there areas where additional fences will keep livestock from pugging or tromping wet soils in the wet season? These winter wet areas are summer’s sub-irrigated pastures, and protecting them from damage will protect summer forage production. Fencing off wet soils from dry soil areas will make both types of pastures easier to manage and more productive over the year.

Plan the next step

After reviewing the soil test and score sheet, better decisions can be made whether to reseed or overseed, and if some infrastructure improvements such as cross-fences or water developments are needed to keep any new seedings productive. There are reasons the current species in a pasture are (or aren’t) present. If those reasons are due to grazing patterns or soil fertility and these aren’t changed, in a very few years the newly reseeded pasture will look exactly as it does today.

Once any infrastructure or soil fertility improvements are made, the time has come to reseed, maybe. Take another walk across the pasture now that a season of implementing the management changes has gone by, and answer the questions on the pasture condition score sheet again. Are there more desirable species? More production? Maybe a reseeding isn’t needed; maybe the plants were there the whole time, just suppressed. Reseeding is expensive, so being able to avoid it is great.

Resolution

Sometimes the evaluation shows reseeding is still needed. In that case, you’ve got the infrastructure in place, the soil fertility corrected and you’re ready to reseed. Don’t do all the pastures at once as weather conditions may cause a stand failure in any particular year, and you don’t want the whole farm out of production at the same time. For seeding methods, listing of adapted species, suggested seeding rates and additional information, use our bulletin online (Pasture and Hayland Renovation for Western Washington and Oregon).