Hay and Pasture Renovation Decisions

Early fall and spring are the best times to assess forage stands in Pennsylvania and determine if improvements should be made for the upcoming growing season. This is done to optimize forage quality and yield, create new forage stands, and restore existing pastures and hay fields that are lagging in yield and productivity. There are several factors to consider when determining which species to plant and to help ensure proper germination, growth, and stand longevity.

This time of year, is ideal for assessment because it can line up with the best planting times for forages as well. Spring brings with it cool temperatures and adequate moisture, sometimes too much, and rapid establishment is crucial to avoid competition from weeds. Fall tends to be the most popular time for seeding because, like spring, we have cooler temperatures, moisture is usually adequate, and there is less weed pressure. That being said, seasons are variable, and fall is sometimes drier than usual, so it is important that there is going to be moisture present for a new seeding to germinate and that it is able to get enough growth before the first frost.

Assess Current Stand Productivity

Determining the productivity of the current perennial forage stand is an essential step in making the decision for improvement. This can be done most often using forage height measurements, cutting and weighing, or with pasture sticks.

Taking forage measurements is used most often and is used in conjunction with a table that associates the height with the pounds of forage dry matter per acre. This is done in combination with estimating the density of the stand, depending on the types of forages growing in the field.

Pasture sticks are available from some grazing organizations, as well as the USDA NRCS, and for those, you take a height measurement, place the stick into the grass canopy, and count the number of visible dots, which represents the density. Using the height and density, the corresponding pounds of dry matter per acre per inch can be found on a chart written on the stick. This number would then be multiplied by the pounds of usable forage per acre. Since we can't remove all the forage from the field, there is always a stubble height left behind.

The most accurate way to determine productivity is by clipping a one foot by one foot section from a few areas in the field and weighing each sample. Then an average can be used. Take the number of acres sampled, divided into 43,560 (sq. ft. in one acre), and then multiply the answer by the weight of the forage. This is the amount of wet forage per acre. To determine dry matter, the weighed samples would need to be dried to determine the percent dry matter.

The NRCS Pasture Condition Score Sheet (PDF) can also be a great tool for assessing both pastures and hay fields for productivity and aid in helping to make the decision for management.

Restoring Current Forage Stands

If keeping the existing vegetation in the field and simply restoring the stand is decided upon, a producer should take soil samples of their fields to determine the current pH and nutrient availability. If weed pressure is high, spraying herbicide(s) to control the weeds prior to planting is suggested. Herbicide efficacy and rates can be found in the Penn State Agronomy Guide or by reaching out to your local agronomy educator.

Planting with a no-till drill to fill in bare ground or to take the place of where undesirable plant species have been killed with herbicide is recommended. Mowing or grazing forages so that there is a residue height of about 3 inches will help to ensure the seeds are placed properly and ensure the best chances of optimal germination.

Soil nutrient amendments based on your soil reports should be made to meet the needs of the desired plant species.

Renovating Pastures and Hay Fields

If, after assessing the current productivity of the forage stand, the manager decides to destroy the field and start over with a complete renovation, burning down the existing stand with herbicide is first recommended before reseeding forages. A soil test should also be conducted to determine soil nutrient needs and recommendations. 

A no-till drill can be used for minimal soil disturbance while planting, or full tillage can be utilized in a complete renovation system. Keep in mind when deciding to burndown or till a field that there will be weed seeds present in the soil seed bank and this process will potentially expose those seeds to ideal conditions and allow for germination. This is why planting during good growing conditions is crucial to allow those forages to rapidly establish and shade out any impending weeds.

Seed-to-Soil Contact and Seeding Rate

Regardless of forage species or method of planting, proper seed-to-soil contact is essential for germination initiation, along with the presence of enough water. Imbibition, or the uptake of water into the seed, is set in motion by seed-to-soil contact and is the first phase in germination.  A firm, clean seedbed is the best way to ensure proper planting depth for perennial forages; however, no-till establishment is just as effective with the option to plant small-seeded forages to the appropriate depth. For most cool-season perennial forage species, no more than ½-inch seeding depth is recommended, with ¼ inch being the most ideal.  A good rule of thumb to know if your seeding depth is correct is that 10% of the seeds should be seen on the soil surface. 

Proper seeding rate for your stand will depend on which forage species you choose and whether it will be a monoculture (pure stand) or a mixture of forage species.

Proper Soil pH

The correct soil pH according to forage species is essential for germination, stand longevity, and optimal yields. This needs to be corrected at least six months prior to planting to allow for limestone to neutralize the soil and then be maintained throughout the life of the stand.

Tolerance of Forage Species to Soil pH

Adapted from Dr. Marvin Hall, The Pennsylvania State University

pH 5.5-6.0

• Tall Fescue
• Reed Canarygrass
• Redtop
• Birdsfoot Trefoil
• Crownvetch

pH 6.0-6.5

• Kentucky Bluegrass
• Orchardgrass
• Smooth bromegrass
• Timothy
• Ladino clover
• Alsike clover
• Red clover

pH 6.5-7.0

• Alfalfa
• Sweet clover

Matching Forage Characteristics to Your Environment

Seedling vigor, tolerance to drought or wet conditions, tolerance to low pH and frequent harvests, and persistence will vary across forage species.  When determining which species would best fit a scenario, all aspects should be considered based on farm management and goals.

H = High; M = Medium; L = Low.  Adapted from Dr. Marvin Hall, The Pennsylvania State University

Forage species differ in their productivity throughout the year. This chart from the Agronomy Guide shows the variation in forage productivity based on forage species. The operational goals and needs for forage should be considered when matching a forage species to the operation.

Growth curves of various pasture components

(Table 1.8-1 from the Penn State Agronomy Guide)

Carefully analyzing the criteria for your situation will enable you to make an informed decision when determining how to go forward with forage management decisions.