Rain creates pasture challenges

What a spring we have had in the Ohio Valley! All the rain this spring brought its share of challenges to grazing. But I can’t help thinking those difficulties don’t compare with the challenge of trying to make hay this spring.

As often happens in the spring, it has been difficult to stay ahead of the flush of growth in pastures. With summer nearly upon us, here are five steps to promote quality pasture during the summer.

* Control seedheads. At this time of year, grasses that have not been adequately grazed will be reproductive. While this increases yield, quality and tillering are suppressed.

Grasses that are overgrown and mature before clipping will be stagnant in terms of bud development and vegetative tillering. Late clipping will slow regrowth. Early clipping to prevent excessive heading will help keep the plant vegetative, resulting in faster regrowth and higher quality.

Clipping may be done in the form of a hay harvest where there is excessive growth, or by simply mowing the pasture.

Regrowth after clipping or grazing will remain mostly vegetative throughout the rest of the growing season for most of our cool-season grasses. A few grasses, like timothy and smooth brome, will continue to move into seed head formation during the summer.

* Apply fertilizer. Early summer is one of the best times to fertilize pastures. As we move into the summer, we are looking to promote pasture growth. A balanced fertility program can do wonders.

We normally have good rainfall in June, and vegetative plants will really respond to a balanced fertility program that includes nitrogen. Remember to apply nitrogen when the forecast calls for a good rain (1/4 inch or more) to avoid volatilization losses.

I think early spring (late March to early April) is one of the worst times to fertilize pastures. Spreading equipment causes compaction on wet soils, there is higher potential for grass tetany from potassium in early spring, and nitrogen will over stimulate growth at a time when more grass is usually not needed. I relearned this lesson the hard way this spring by putting nitrogen on my lawn. Boy, did I get tired of mowing!

* Increase rotation length. Managed grazing is all about flexibility. As we move into the summer, rest periods should become longer and stubble height after grazing should be taller.

Growth slows in the summer, so plants need extra time for adequate recovery. This promotes healthy root systems, giving plants a greater ability to withstand dry conditions.

As you slow the rotation to lengthen rest periods, the tendency is for closer grazing by livestock. So reduce stocking density per unit of pasture area to prevent overgrazing.

* Increase stubble height after grazing. Maintaining longer forage stubble will shade the soil surface, resulting in lower root temperatures and less evaporation. The longer leaves will capture more sunlight and early regrowth will be less dependent on stored energy reserves.

This is important to maintaining plant health and vigor as the summer becomes hotter and drier. A healthy plant with adequate reserves will be more tolerant of dry conditions.

A good rule of thumb is to graze when plants are 8 to 10 inches tall and remove animals when the height is 4 inches tall. For Kentucky bluegrass, those heights can be lowered.

Continuous or frequent grazing to a short stubble height in the summer is detrimental to grass vigor. Remember that the top growth reflects the condition of the roots.

Longer stubble is also important because it prevents draining stored energy reserves in the plant. Most grasses maintain energy reserves in the 2 to 3 inches of stem base right above the soil surface. Grazing frequently and close will weaken the plant.

* Use deep-rooted species. Maintaining deep-rooted plants in the pasture sward is an important long-term strategy for dealing with the summer slump.

Alfalfa, red clover, chicory, and birdsfoot trefoil are examples of species with deep rooting that have greater capacity to produce in the summer than most of our cool-season grass species. These species also improve quality and animal performance compared with pure grass pastures.

We will have to deal with this strategy in more detail in a future issue because it is such an important step to profitable grazing systems.

Another alternative is to use warm-season species.

Summary. We all know that the weather, especially rainfall, has a huge effect on summer pasture growth. But I also know that healthy and productive pastures don’t happen by accident. The management practices outlined here will help your pastures take advantage of the summer rainfall we do get, and to increase tolerance to stressful conditions when they do occur.

Best wishes to each of you during this summer grazing season. The next time I write in this column, I will be writing from southern Brazil. I hope to share with you some observations from watching the grazing practices of our southern neighbors.

(Mark Sulc is a forage extension agronomist with OSU Extension. Send comments or questions in care of Farm and Dairy, P.O. Box 38, Salem, OH 44460.)