Posts Tagged ‘pasture’

Fall Weed Control in Pastures and Hay

Friday, August 31st, 2012

Quintin Johnson, Extension Associate, Weed Science; quintin@udel.edu

Fall provides an excellent opportunity for perennial weed management in pasture and hay with herbicide applications. Most herbicides labeled for use in pasture are translocated, or moved, to various parts of the plant. As fall approaches, perennial weeds like curly dock, Canada thistle, horsenettle, pokeweed, and others are beginning to replenish stored carbohydrates in root structures to prepare for over-wintering and new spring growth. Translocated herbicides are able to reach the rooting structures more efficiently during this period, thus providing more effective perennial weed control. However, if weeds are drought-stressed, herbicide translocation may be slower or incomplete, resulting in less effective control. Delay herbicide applications until after you receive adequate rainfall. Fall applications should be made at least 7 to 10 days before a mowing for greatest effectiveness. In well established perennial weed populations, multiple years of good weed control will be needed to significantly reduce the rootstock of perennial weeds.

There are several things that must be considered when choosing an herbicide for pastures or hay fields including: forage species grown; weed species present; risk of herbicide contact with desirable plants through root uptake, drift, or volatility; residues in composted straw or manure; herbicide rotational, over-seeding, grazing, or harvest restrictions; and cost. Be sure to follow all precautions and restrictions on herbicide labels.

The “Pasture and Hay Weed Management Guide” for Delaware is available from the University of Delaware Cooperative Extension. Access a pdf version on-line at http://www.rec.udel.edu/weedscience/WS_ManagementGuides.html.

Pasture and Hay Crop Nitrogen Fertilization

Thursday, April 26th, 2012

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

The very dry spring that we’ve experienced in 2012 has made it questionable as to whether a second or late spring application of nitrogen (N) might be advisable or economical. Thanks to the rainfall last weekend and the possibility of additional rainfall this week and over the coming weekend, another application of N to pastures and hay fields following the first cutting of hay should have a much reduced chance of injuring your grass crop and should also produce additional grazing or second cutting of hay. However to be on the safe side before you apply that additional N fertilizer, take a soil probe, hand trowel or shovel and check the soil moisture level in your soil. What you would like to find is that the subsoil moisture level has recovered and that the crop will be able to not only draw on soil water from the normal 0-8 inches of soil where most of the roots can be found but also can pull water from the deeper soil layers to support growth when temperatures begin to warm up in May and early June.

Hay producers are at the biggest risk for the current moisture to dissipate before the first hay harvest is taken. If you produce hay, you should be certain to check the soil moisture levels before applying N after the first harvest. Even if inadequate soil moisture is present, N fertilizer will promote more top growth and this growth response under unfavorable conditions can lead to plant death or injury reducing stand longevity. Timothy producers should be especially careful since the first harvest often occurs very late in the spring and unless they are using one of the more heat tolerant varieties such as ‘Derby’ stands can be significantly impacted.

Finally, consider using at least some potash (K) fertilizer when fertilizing in the mid-May to mid-June period. I understand that K has become very expensive but it is the best nutrient to add to help forage grasses and legumes to tolerate the heat and drought stresses of summer. In addition if you are growing orchardgrass, there is a growing concern that we are not adequately fertilizing this crop with enough K to balance the N used to promote yields. There is some evidence that the orchardgrass decline problem that we’ve been experiencing in the Mid-Atlantic may, in part, be caused or at least aggravated by too little K fertilizer in relation to the N rate used.

Getting Your Pastures Off to a Fast Start

Friday, March 2nd, 2012

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

This year, with very high hay prices and short supplies, there is a need for early pasture for grazing to stretch tight budgets and short hay supply. One of the few ways to stimulate growth in pasture is the application of nitrogen (N) at, or just before, pasture spring greenup. Even when N was applied in the early to mid-fall period to stimulate root system expansion and provide pasture grasses with stored N for early spring regrowth, an additional application of N just at greenup can be useful in promoting early pasturage.

A question often asked is whether it’s economical and safe to use granular urea on pastures at this time of year. To answer the economics in the question you need to understand what happens when urea is applied over top of a pasture. If conditions are favorable, urea applied to a pasture can react with water from the soil or vegetation and the ever present enzyme, urease, to convert into ammonium carbonate. Ammonium carbonate is a very unstable form of fertilizer N that breaks down spontaneously into ammonium (NH4+) or ammonia gas (NH3), if the pH is alkaline, water, and carbon dioxide. The ammonium then is either taken up by plants, or it attaches to the cation exchange sites on clay and soil organic matter, or is acted on by the nitrifying bacteria to become nitrate (NO3-). If conditions favor it staying ammonia, this is lost to the atmosphere and effectively raises your cost per pound of N. Urea frequently has the lowest cost per pound of N but if much N loss occurs the savings will be eliminated.

Conditions that favor ammonia loss, besides the presence of plant material that provides the urease enzyme, include warm temperatures (especially 70°F. and higher), high humidity or a moist soil surface, and high soil pH where the prill or urea granule rests on the soil. On Delaware soils where the pH is often maintained between 5.5 and 6.5 for pastures and where air and soil temperatures are cool to cold at this time of year, the loss of N from urea fertilizer is minimal. In fact when I worked in the Deep South, pastures or hay fields were fertilized with urea rather than ammonium nitrate all the way into April as long as the temperatures did not warm up into the mid to upper 70s. Through March at least in Delaware, fertilization with urea should be the most cost effective way to provide N for pastures since losses will be minimal.

What about animal health concerns? Since urea, like other fertilizers, is a salt, animals can become ill if they gain access to bags of urea fertilizer and consume too much of it. As long as the applicator practices safe handling and storage principles and ensures that the fertilizer is evenly spread without large clods, animal safety should be ensured. For those that prefer to err on the side of more caution, we suggest that they keep animals off a fertilized field until it has received from ¼ to ½ inch of rainfall. Rainfall or irrigation water will move the urea quickly into the soil eliminating any concerns for animal health; and, at the same time, will reduce or eliminate the concern with ammonia volatilization.

Another way to get pastures off to a fast start, which also plays into the above health concern, is to keep animals off pastures early in the greenup period to promote more growth. As an analogy, think of a tiny little tomato seedling. It can double in size a number of times but until it reaches a critical size the doubling amounts to only a very small increase in dry weight of the plant. Pastures that are grazed even before the permanent grasses green up in the spring will produce little useable forage compared with a pasture that is fertilized and then allowed to grow to a height of 3 to 4 inches before being lightly grazed, rested a couple of weeks and then grazed again. If the grazing animals are removed when 3 inches of pasture remains, recovery and the pounds of dry matter produced per day will be much greater than that of a pasture kept constantly at a grazed height of 0.5 to 1 inch. It may mean using more hay initially but once the pasture reaches that 3 to 4 inch height, it often will produce more feed per day than your animals will consume.

Once you begin grazing a pasture, the best thing you can do to promote growth is to practice rotational grazing where you allow animals on a subdivision of your pasture for a short period, usually no more than 3 to 5 days at most, and then remove the animals to another subdivision while the plants in the recently grazed subdivision rest and recover and renew growth.

Another suggestion is to take that soil test sample you’ve been meaning to get and send it in for analysis. Soil tests should be taken at least every three years and as often as every year at the same time of year each time. The soil test will help you decide if you need to correct a pH problem or apply nutrients to relieve any nutrient deficiencies. If the pasture soil pH level has declined below 6.0, an application of lime will help both grasses and legumes grow better.

I mentioned N fertilization earlier. How much N should you apply? This does depend a bit on the pasture you are fertilizing and your goal for that pasture. Where you either have too much legume (clover) or where you have so little clover that is isn’t contributing N to the surrounding grass, an application of about 100 lb urea per acre (this is about 46 lb N/acre) will stimulate grass growth helping to reduce the percentage legume in the pasture or will replace the N lacking when legumes are grown with grasses. This rate should be enough to jump start the pasture grasses without a risk of overfertilization and risking damage to the environment. On pastures where maintaining legume presence is important, you should apply only half the rate of urea (50 lb urea per acre). At this rate of N, the legume can continue growing and will not slough off the bacteria nodules that help the legume by fixing atmospheric N (N2 gas) in a plant available form.

Thinking of Renovating or Planting a New Pasture or Hay Field? Part 3: Pasture and Hay Planting Time Has Arrived

Friday, August 19th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

In previous articles, I’ve discussed some of the decisions and planning that needs to be taken ahead of planting hay and pasture fields but we now have entered the ideal planting time for forage grasses and legumes. This holds true at least for those parts of the state that have received the recent rainfall — some areas in southern Delaware still have inadequate soil moisture levels to even think about attempting to seed new forage fields. For those areas that have remained dry and do not receive the rain currently in the forecast over the next five days, the decision to plant will have to be delayed until adequate surface and subsoil moisture is present.

Some species have specific requirements that limit how late in the fall you can plant. For example, reed cararygrass requires at least six weeks between planting and the average date of the first frost, otherwise the crop can be winterkilled or be severely weakened over the winter so that it’s unable to compete with the usual weed competition crops experience in the spring. Other species, such as Kentucky bluegrass, just take a very long time (21 to 28 days) to germinate and begin fall growth and so should not be planted very late in the fall. Before deciding to plant a species or mixture, be sure to study the species in question to avoid problems with late plantings.

In other areas of the state that received some of the recent downpours and that now have adequate soil moisture reserves, planting can begin. Early planting can lead to well established forage seedings that will be able to survive the winter and get off to an early vigorous start the following spring. Early planted stands are much better at competing against weeds the next spring and will often yields much better as well. Work by Dr. Marvin Hall at the Pennsylvania State University showed significant yield decreases for all forage species tested as the date of fall planting was delayed with higher losses occurring the further north the site was located.

If planting into a prepared/tilled seedbed, be sure that all weeds have been killed during soil preparation and that a good smooth (clod-free), firm (your shoe should not sink deeper than the sole level) seedbed is prepared for planting. Seed can then be broadcast over the seedbed and then firmed into the soil with any number of devices but seed should only be pressed into the soil and not buried more than 1/8 to ¼ inch deep. Covering the seed is ideal since the seed will be able to take in water from the soil but not be quickly dried out again by the sun’s rays. Seed can also be planted using a brillion seeder followed by a cultipacker or roller or seed can be placed in the soil using a drill. Since drills place the seed in rows from 4 to 8 inches apart, depending on the drill, I generally recommend that you drill at half the recommended seeding rate and run the drill at about a 45 degree angle across the field. This will help bring the rows closer together and allow the seedlings to more rapidly fill in the space so competing weeds can’t find space to grow.

Another method of seeding is to use a no-till drill following an herbicide burndown program. This is especially useful when perennial weeds with underground rhizome systems are present. Examples of these weeds are hemp dogbane, Canada thistle, and horsenettle. Although several herbicide treatments are often needed to get these weeds under control, one of the best times to apply herbicide is in the fall when the weeds are sending carbohydrates (sugars) down into the underground storage organs (rhizomes). If a systemic herbicide that can move in the plant is used, it will be taken with the sugars down to the rhizomes and help kill the meristem buds or next year’s growing sites in the weed. Read the herbicide label for exact requirements between treatment and seeding but generally for Roundup® or glyphosate you should wait several weeks after herbicide application before planting.

The no-till drills are similar to other grain drills in that the seed is placed in rows and then the open slot in the soil is closed with some type of packer wheels. I again recommend that you calibrate the drill for half the seeding rate and go over the area twice at a 45 degree angle to minimize the distance between rows.

In all cases I’ve talked about above, be certain to calibrate your seeding equipment and make sure the drills or other equipment is clean and functional before entering the field. These days forage seed is quite expensive so make the most of the money you spend by accurately calibrating your equipment. This involves the following procedure: weigh out some seed to add to the planting equipment, determine the width of area covered with seed by the equipment (in feet), run it for a certain number of feet (the length—say 50 or 100 feet); multiplying the two numbers together to get the number of square feet covered by the seed; divide that number by 43,560 (number of square feet in one acre); and finally weigh the amount of seed remaining in the equipment. Subtract the final weight from initial weight and divide that number by the number of acres you covered (usually this will be a number such as 0.15 or even 0.015 or other very small number). If your seed weights were in pounds of seed then the number you calculate at the end will be in pounds per acre or if you had access to an egg scale or something that measures in grams then divide the number of grams of seed used by 454 (grams per pound) to obtain pounds of seed and then divide that number by the number of acres planted in the calibration test. If all else fails, email me or give me a call and I’ll help you do the calculations.

The other articles in this series are:

Thinking of Renovating or Planting a New Pasture or Hay Field? Part 2: Planning to Planting

Thinking of Renovating or Planting a New Pasture or Hay Field? Part 1: The Pre-Planning Process

Fall Pasture and Hay Fertilization

Friday, August 19th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

I had a question this week from a hay producer about whether it was best to apply the soil test recommended fertilizer the first thing in the spring or not. Since his crop was an alfalfa orchardgrass mix, he was not thinking about nitrogen (N) which is the first thing most people think of in the spring. He was asking about potash (K) and phosphorus (P). The answer really lies in the function of these nutrients.

Phosphorus really helps plants establish or grow a better root system and we’ve discovered that root development really goes on for quite some time in the fall for two reasons. First, we generally get more rain in the fall; and, when that is combined with the lower air temperatures and shorter days, it means that soil moisture levels are usually higher in the fall than in the summer months. Secondly in the fall, we’ve found that the soil temperatures stay warm until fairly late in the year unlike spring time when soils start off very cold from winter and tend to warm up slowly throughout the spring. The combination of available moisture and warm soil temperatures and the accumulation of fixed carbohydrates (sugars) and translocation of the sugars down to the roots means that fall applied P will further help plants establish a vigorous root system for better growth during the next spring growing season.

Potash has a number of functions in the plant ranging from enzyme activation to stress reduction to the control of transpiration and water use in the plant. For us, fall K fertilization helps plants lower the freezing point of the cell sap so there will be less winterkill or winter freeze damage to the plant crowns. In addition, fall K helps plants fight off disease problems and other pest injury. For K, I prefer that growers split their application with half going on the pasture or hay field in late May or early June and the other half going on in late August or September.

Finally thanks to research in the turfgrass industry, the forage industry is beginning to discover the benefits of adding at least some N in late summer or early fall to help grasses regrow after summer grazing or summer drought. Some recommendations even suggest a second application in mid-October that the previously N stimulated grass can pick up and store for early green-up growth the next spring. This second application negates the need for an early spring N application and seems to help prevent excessive forage growth the next spring. Too many people apply much of the nitrogen forages need in the spring causing such excessive growth that their grazing plan can’t keep up with it or causing so much yield in the first hay cutting that there is a significant delay in being able to dry and cure the hay. This can lead to poor quality first cut hay or to hay that retains too much moisture so that it either spoils or is at risk for spontaneous combustion.

In conclusion, think about changing your fertilization timing from the early spring to early fall. There are many potential benefits from this change as outlined above.

Thinking of Renovating or Planting a New Pasture or Hay Field? Part 2: Planning to Planting

Friday, July 22nd, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

I wrote about preplanning process two weeks ago (Thinking of Renovating or Planting a New Pasture or Hay Field? Part 1: The Pre-Planning Process) so now it’s on to the planning and planting process. One of the biggest challenges these days, especially if you have a low acreage field, is finding someone with both the right sized equipment to fit the field and a willingness to do the job for you in a timely fashion. Of course even if you’re lucky enough to find the equipment and operator, cost is going to be a critical factor when making the decisions of what parts of the plan are actually doable. Another factor that’s come up recently is the availability of forage seed. Many of the forage seed producers have eliminated production fields in favor of corn or soybeans which now sell for very alluring prices.

In planning the whole procedure, your time will be a valuable asset. With high prices, limited seed supply, and challenges in finding equipment and help to fertilize, lime, control weeds, and plant seeds, the time you take to shop around should pay big benefits and August is the month to do these chores because planting season is rapidly approaching.

For planting date, forage agronomists often list from mid-August through September as being the time to plant as long as soil moisture is adequate. Soil moisture for many hay producers and grazers in the state and region really will be at critically low levels for much of August. This can extend late into September due to the drought and hot weather conditions we usually experience during July and August. With all our pre-planning and planning activities, the final decision on when to plant and even whether to plant on time will be determined by the weather conditions during August and September. You may be tempted to plant as soon as the field receives the first rainfall in the planting window but you should keep in mind that if the deeper layers of soil are deficient in moisture the new planting will likely fail if fall turns dry. Use a shovel or your soil probe to test the soil for moisture at the 6 to 12 inch depth. If the field hasn’t received enough rainfall to supply this soil depth with at least some water, a new planting will be very much at risk if rain events do not continue from planting until winter dormancy takes hold. Only you know the amount of risk you are willing to take to establish the new seeding this season and none of us know what the future weather will be.

What if enough rain to supply water to the deeper soil layers doesn’t fall until very late in September? Certain species, such as low alkaloid reed canary grass, require a specific amount of time between planting and first frost (six weeks minimum for reed canary grass) but almost all species will not only yield less the following year but take a lot more time to reach full establishment if planted late. Again, the hay producer or grazer must evaluate the amount of risk they are willing to take on when deciding to plant after September.

You should maintain frequent contact with your fertilizer/lime dealer, seed dealer, equipment supplier, and others who will be helping you with the process of planting the new pasture or hay field. If you will be using equipment provided through the county conservation districts, be sure to get your name on the list as early as possible since many folks may want to seed about the same time when moisture conditions become favorable.

What’s the best means of seeding fields, no-till or conventional tillage (a prepared, weed-free, firm seedbed)? As with any choice, there are advantages and disadvantages to each method. Both seeding methods allow for weed control activities before seeding but no-till is limited only to herbicide applications. Whenever deciding on an herbicide to use, read the label carefully to be sure there are no rotation restrictions of what can be seeded following the herbicide application or how many days or months must separate the application and seeding activities. Also use the label to determine if a single application will be all that is needed or whether you will need follow-up applications and if you will at what stage of growth must the new seedlings reach before the next application is applied. This latter concern is especially important for perennial and hard to kill weeds such as hemp dogbane, Canada thistle, horsenettle, and others.

No-till drills must be calibrated properly to deliver the correct amount of seed per acre as well as be set to place the seed at the correct seeding depth with adequate soil to seed contact for fast germination and emergence. Never assume that the last person to use the drill set it up properly for your seeding. When you spend a hundred or more dollars per acre just for seed, you need to be sure the seed is being planted as best as possible to ensure a successful establishment. No-till drills also place the seed in rows usually from 7 to 10 inches apart so it often is useful to cover the seeded area in two directions making a cross hatch pattern over the field to help the plants fill in the space quicker. Brillion seeders that broadcast seed over a prepared seedbed and then press the seed into the soil have the advantage of achieving canopy closure much sooner than no-till seedings.

Canopy closure is when the new plants get large enough that they are able to shade the underlying soil and therefore reduce the ability of weeds to germinate and establish in the field. Fields seeded with no-till drills can take many years (if ever) to fill in, so that a full canopy exists during normal grazing activity. This is one disadvantage to the no-till drill although it is offset by the soil conservation advantage of no-till when a field has enough slope to allow significant water erosion or enough exposure to allow wind erosion problems if the weather turns dry again.

Which method is best? Since each has both advantages and disadvantages, it will depend on your situation. No-till helps conserve the soil in situations where soil can be lost; it reduces moisture loss since the soil is not disturbed; it doesn’t encourage new weed growth since buried weed seeds aren’t brought to the surface; it does not introduce oxygen into the soil causing the soil organic matter to be reduced via oxidation; and when done correctly it ensures rapid germination and emergence, since seeds are placed in the soil and soil is firmed around the seeds. From the negative side, no-till does not allow nutrients and lime to be worked into the soil profile; no-till does not help break up compaction issues from previous grazing or haying equipment use; and no-till seedings are often in rows that can be seen for years in some cases.

Conventional tillage does allow nutrients and lime to be incorporated in the soil; it allows tillage during the summer to help with weed control issues; it allows for the summer establishment of annual smother crops for weed control and to introduce organic matter into the soil; it allows you to rip fields to help alleviate compaction issues; and it allows seed to be broadcast to ensure rapid canopy closure. Some of the disadvantages include the loss of soil moisture during the tillage operation as well as the loss of soil organic matter during tillage. The above lists of advantages and disadvantages are not meant to be exhaustive but to point to some of the important factors you should consider when deciding on seeding method.

The other articles in this series are:

Thinking of Renovating or Planting a New Pasture or Hay Field? Part 3: Pasture and Hay Planting Time Has Arrived

Thinking of Renovating or Planting a New Pasture or Hay Field? Part 1: The Pre-Planning Process

Thinking of Renovating or Planting a New Pasture or Hay Field? Part 1: The Pre-Planning Process

Friday, July 8th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

I have received several requests over the past several weeks concerning overseeding or renovating pasture and hay fields and feel it’s a good time to begin a discussion on the process. All too often, we find ourselves moving into mid to late fall without having taken the time to really consider all decisions that have to go into improving the odds that the planting will be successful. You need to keep in mind that seed costs alone can equate to a hundred dollar an acre investment; and, if we really take into account all the variable costs, that new pasture or hay field can easily represent an investment of hundreds of dollars per acre.

So in the pre-planning process, what’s first? I know many get tired of hearing the phrase but testing the fertility of your soil far ahead of time is still the number one issue. If the field will not be tilled and you have not been applying significant quantities of commercial nitrogen (N) fertilizer to the field, sample at 0 to 4 inches deep in each field or management zone (an area of the field treated in a similar fashion and not much different from other areas of the field in soil type).

If you have used large quantities of commercial N fertilizer in the past, you really should take both a 0-2 inch depth sample for determining the soil acidity in the upper soil layer as well as a 0 to 4 inch depth sample for nutrient content (phosphorus, potassium, calcium, magnesium and other essential elements).

The reason for this distinction is that the ammonium or urea N forms that we apply as fertilizer are converted by soil bacteria into nitrate and in the process acidity is released into the soil. Since the N is all surface applied, the release of acidity near the soil surface can create a condition known as ‘acid roof’ where the top inch or two of soil is much more acidic than the deeper layers of soil. A second reason involves the very slow movement of limestone down through the soil. Studies on pastures in Connecticut many decades ago showed that lime moves at a rate of about 1 inch per year so it takes a very long time to have an impact on the entire rooting zone of forage grass and legume plants.

For fields that will be tilled and a new planting established, the traditional plow layer sample (0 to 8 inches) for both soil pH (acidity) and essential nutrient status will be the correct choice. If the soil sample indicates that the soil must be limed, apply the recommended amount of limestone and work it into the soil as soon as possible to allow time for the limestone to neutralize soil acidity before planting time. Although, if it remains dry, lime may not completely react, and a second soil test still would be useful to determine if any additional lime will be needed. Additional agricultural lime and the recommended phosphorus (P) and potassium (K) and any other needed nutrients can be applied and worked into the soil shortly before planting the field.

Everyone asks the question of whether to apply N at the time you plant a new field or seed a field you are renovating. My preference is that you should wait until the new grass is several inches tall and has enough biomass and roots to compete for the applied N and to store any extra N for future growth. Until forage plants have enough leaf area to rapidly capture the sun’s energy and convert it into more plant tissue or into sugars for storage, weeds in new plantings or the current vegetation in renovations are likely to outcompete the new seedlings for N and then for light, water, and other nutrients. When waiting to apply N although weeds and current vegetation will still be present, the new seedlings will at least be in a better competitive position when the N is finally available to stimulate growth.

Now that you’ve taken care of any soil fertility issues that can reduce the chance for a successful stand, the next decision involves choosing the right seed to plant. I’ve had the opportunity over the years to read many seed labels on various pasture mixes offered for sale. I understand the convenience of buying a prepared pasture mix and the allure of these mixes. The buyer often assumes that the seller has spent the time and energy studying the issue and has come up with a mixture that in their opinion and experience has the best chance of success. I certainly can’t speak to motivation of the seller but keep in mind that from a business point of view, seed that is mixed and offered for sale need to be sold over as large an area as possible to justify the expense of wholesaling large quantities of seed, blending, packaging, and labeling the seed. In my opinion, this nullifies the expectation that the seller has designed the mix for your particular field or location.

After looking at the species of forages used in the prepared pasture mixes, I find that these mixes are more like a shotgun approach to seeding where you plant a little of everything in hopes that something will establish in all areas of the field. Usually they contain a quick establishing grass such as ryegrass that can germinate in as little as 5 to 7 days so the buyer can feel comfortable with the new seeding. The mixes also usually contain the feel-good or highly recognized grasses such as timothy and Kentucky bluegrass in horse pasture mixes and at least some orchardgrass and probably an endophyte-free tall fescue to provide more permanent cover. Finally, a legume such as white or ladino clover, red clover, or alsike clover will be in a pasture mix to provide the N-fixing legume everyone would like in a pasture.

The convenience of these mixtures comes from not having to mix them yourself before you fill the seed drill and the allure comes from not having to make a decision other than how much seed per acre to plant and not having to choose individual species to plant. For most buyers, the convenience and allure end up costing them many, many dollars per acre in seed costs for seed of grasses that won’t survive in grazing situations or won’t survive more than a season or two at best or will be unproductive for much of the grazing season.

So what should you do? I prefer going with a simpler mixture using forage species that are adapted to our region. In most cases, the only species that will survive for many years in our transitional zone climate is tall fescue. Because of endophyte (an fungus growing in some tall fescue plants) issues, many growers have tried the endophyte-free tall fescue varieties and some have had success with keeping a stand for many years while others have seed stands decline or disappear quickly. The newest chapter in this issue has been the development of novel or friendly endophyte tall fescue varieties. The novel endophyte tall fescue varieties do not produce the chemical compound (alkaloids) that interfere with animal performance but still provide benefits to the tall fescue plants helping them survive in many stressful environments. A limitation still in evidence with these new tall fescue varieties is that horse owners who breed horses do not all accept tall fescue as a feed source for their animals. This limits tall fescue’s acceptance.

What other species can you include in your simple mixture? Orchardgrass is another grass that many producers like to include in a pasture mixture but you should be aware that many orchardgrass fields are failing due to a disease/insect/environment/management complex interaction we’ve been calling orchardgrass decline. If you choose to include orchardgrass, keep it as a small proportion of your mixture. The other grass to include at least on the heavier soils is Kentucky bluegrass. Be sure to include several varieties of the Kentucky bluegrass to help with disease resistance. It will be most productive early in the year (early spring to early summer) and mid- to late-fall. Finally, add in a legume to help with providing N for the grass to use as well as to improve the protein and forage digestibility of the pasture. For grazing, most people prefer a ladino-type of white clover. Although slobbers (the animal produces excessive amounts of saliva) is a potential concern with all clovers, it seems to be mostly associated with red clover. Often included in commercially sold horse pasture mixtures, alsike clover is known to cause photosensitivity (sunburn) especially in horses and should not be included in your pasture mix.

You will find it useful to talk to your seed dealer about the various varieties of each species that are available. Once you decide on the varieties to use and you purchase seed, you can mix your own pasture mix by either purchasing or renting a cement mixer and combining the seed in the proportions you decide are best for your purpose and field. Since many legumes now come pre-inoculated with the N-fixing bacteria and often are coated with a fine limestone, do not over mix the seed and when you re-bag it store it where it is protected from high temperatures and humidity. Stored properly, the seed can be held over the winter if something prevents you from seeding this fall but you should plan to plant as soon as possible after purchasing seed. Not only are the N-fixing bacteria alive; but, if you use a novel endophyte tall fescue variety, the endophyte has a limited storage time (around a year under good conditions) before it should be planted. Although the tall fescue seed will germinate after longer storage times, the endophyte fungus may no longer be alive. The fungus only lives in the plant and is not soil-borne.

Next time, I’ll cover some of the other management issues to consider, such as planting date.

The other articles in this series are:

Thinking of Renovating or Planting a New Pasture or Hay Field? Part 3: Pasture and Hay Planting Time Has Arrived

Thinking of Renovating or Planting a New Pasture or Hay Field? Part 2: Planning to Planting

 

Mowing Techniques for Pastures Following Heading

Friday, June 24th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Last year there were a number of questions concerning the use of a technique called top cutting, in which the tops of the seed heads of cool-season grasses were removed using a bush hog or rotary mower raised high enough to clip the upper 1/3 to ½ of seed stalk. The word going around was that it would stimulate new growth and improve both forage quality and quantity. I asked a number of forage experts about the practice last year and the consensus was that the practice was unlikely to offer any benefits to grazers at all.

This year I was surprised this past week when another unique practice was employed on a very large area of pastures near my home. In this case, the mower was lowered to remove the top 2/3 of matured growth but instead of mowing the whole pasture random paths were cut through the pasture (see Photos 1 and 2).

The question on my mind is what advantage this type of mowing pattern offers the grazer? The many pastures on this farm are used to graze both cows and horses in a continuous grazing system. One idea was that the paths gave the livestock pathways to move around the pasture but in observing the pastures during the past week I have not seen any tendency of the cows or horses to preferentially use the pathways. As visible in the photos, regrowth of the pasture grasses is occurring so that some improvement in quality forage is occurring and at some point the livestock will make use of the new growth which will be much higher in crude protein, digestible dry matter, and lower in acid and neutral detergent fiber.

Another less serious idea raised by a producer that I asked about this type of practice was that the person mowing the pastures was less than sober or was out having fun. I did watch the mowing process long enough to determine that the mowing was being done deliberately; and, considering the number of acres mowed, it was done purposely.

Photo 1. Random paths mowed through beef and horse pastures

I do have a question for the grazers who may read this article. That question is whether they can think of some reason for this type of mowing process. If you can think of a purpose for this procedure, please email me with your thoughts as I would like to know what this type of procedure can accomplish.

Photo 2. Random paths mowed through beef and horse pastures and showing regrowth of pasture grasses

While on the topic, mowing pastures is one of the very useful management techniques a grazer has to both improve pasture and feed quality and to stimulate new production from the pasture grasses. When continuously grazing as is done in the above situation, mowing is most effective when done shortly after full emergence of the seed head on the majority of the pasture grass plants although many producers do not mow until full flowering or even later. Delaying the mowing operation too late can delay new tiller development and deplete root and crown energy reserves as seeds begin to develop and draw energy from the storage organs. In rotationally grazed pastures, mowing is often replaced by hay making on any unused grazing cells or paddocks. In cells used for several grazing cycles, mowing is often needed to remove grass that is overly mature due to preferential grazing of some grasses or to avoidance of dung areas. In all these cases, mowing removes old growth and stimulates new tiller development and improved forage quality and productivity.

 

Hay and Pasture Fertilization This Spring

Thursday, April 14th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

In many areas of the state, pastures and hay fields are either just beginning to green-up (northern sections) or while having started the process of greening-up several weeks ago are making slow growth with the cool, often cloudy and rainy weather. Now that calendar-wise, we are into mid-April, it’s time to apply nitrogen (N) fertilizer to hay and pasture grasses to boost production.

With fertilizer prices still high and the threat of frequent showers in the forecast, growers will want to limit their application rates of N to ensure maximum plant uptake and minimum loss to leaching or denitrification (wasted fertilizer dollars). The slow start to forage growth this year suggests that at least some N will be useful in encouraging forage (grass) production for grazing animals and reducing the need for supplemental hay or grain.

For pastures or hayfields that contain a significant proportion of legumes (clover, alfalfa, Birdsfoot trefoil, or lespedeza), N application rate should not exceed 30 lb N/acre/application. Otherwise, the N-fixing value of the legume will be lost to the grower.

On pure grass pastures not fertilized with N last fall, an application of 30 to 50 lb N/acre will be sufficient to boost grass productivity. On pastures fertilized with N last fall, the N stored in the plants should be adequate for much of the early grazing season but watch the pastures carefully for the first sign of slowing growth and then apply additional N at that time, probably in mid- to late-May.

For hay fields, research from The Pennsylvania State University and Dr. Marvin Hall suggests that an application of 40 to 60 lb N/ton of expected yield will maximize production of most forage grasses while minimizing the risk of nitrate toxicity. I would suggest going with the lower rate this year because of the growing conditions we’ve experienced so far this season.

 

Evaluating Alfalfa Stands in the Spring

Friday, March 11th, 2011

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

This season I’ve already had a couple of questions asked as to when and how to evaluate alfalfa stands. Below are descriptions of two methods that can be used to determine the viability of an alfalfa stand. An alfalfa producer should use not only one of these methods but their feel for the vigor of the particular stand they wish to evaluate, as well as the production history of that field.

The first method consists of counting the number of plants per square foot. Current research information suggests that when stand counts fall below 3 to 5 plants per square foot, it’s time to either rotate out of pure alfalfa or interseed a grass crop such as orchardgrass, festulolium, tetraploid ryegrass, or annual ryegrass or interseed another legume not hurt by the autotoxicity seen in year old or older alfalfa stands. Red clover is the legume of choice and should be planted at 6 to 8 lbs pure live seed per A either by broadcasting it on in very early spring or seeding it with a no-till drill (plant either in very early spring or in early to mid-Sept after the last harvest of the season).

The second evaluation method derives from research out of Wisconsin by Dr. Dennis Cosgrove that indicates that stem number, rather than plant number, is a more accurate determination of when to plow down or interseed an alfalfa stand. Cosgrove suggests using a value of 55 or more stems per square foot to indicate that the stand will produce maximum yield. A reduction in stem number per square foot to 40 stems or less will result in a 25 percent yield reduction. At this critical level, alfalfa fields begin to lose profitability and should be rotated to another crop for one or two years.

Although you can get some idea on the potential of your alfalfa stand by counting either the number of plants or the number of tillers per square foot, you will need also to consider checking on the health of those plants to have an accurate basis for a decision on keeping or destroying an alfalfa stand. To do this, in the spring when new growth is about 4 to 6 inches tall, check a random one square foot site for each 5 to 10 As of alfalfa or at least 4 to 5 sites on small fields. Dig up several plants at each site and slice open the crown and root (longitudinally) with a sharp knife to determine the health of the crown and tap root. Healthy roots and crowns will be firm and white to slightly yellow in color. Diseased roots will have dark brown areas extending down the center, especially if crown rot is a problem. Reduce your counts of plants per square foot or tillers per square foot so only the healthy plants present are counted. Plants with roots that are mushy or soft are likely to die; and although those with a few brown spots may survive, the overall vigor of the stand will be compromised by the presence of disease.

If you must decide on whether to reseed before growth begins in the spring (and you do not plan to take a first harvest of alfalfa before planting another crop) or after a very hard winter with significant heaving or winter injury, base your decision to reseed on the number of plants per square foot (Table 1). If a decision to reseed can be made during the growing season or after about 4 to 6 inches of growth has occurred in the spring, either evaluation method can be used (Table 1). In Table 1 below, I’ve modified various estimates for good, marginal, and poor stands to give the grower possible guidelines to consider in making a decision on keeping the stand or interseeding a grass or other legume.

Table 1. Suggested plants per square foot or tillers per square foot (#) criteria for evaluating alfalfa stands on Delmarva.

Age of stand

Good stand Marginal stand Consider replacement1 or renovation2 with interseeded grass or red clover
Plants per square foot with spring tillers per square foot in parentheses
New 25-40 plts (> 75) 15-25 plts (< 55) < 15 plts (< 50)
1 year old > 12 plts (> 60) 8-12 plts (< 55) < 8 plts (< 45)
2 years old > 8 plts (> 55) 5-7 plts (< 50) < 5 plts (< 40)
3 years old > 6 plts (> 50) 4-6 plts (< 45) < 4 plts (< 40)
4 years old or older > 4 plts (> 50) 3-4 plts (< 40) < 3 plts (< 40)

1 If the stand is to be plowed for replacement, growers often find it economically favorable to take a first cutting and then plow and plant a rotational crop that can use the nitrogen mineralized from the decomposing alfalfa plants. Rotate out of alfalfa at least until the next fall (14 to 18 months) but preferably for 2 to 4 years. This will allow time for a reduction in the potential for alfalfa diseases and provide the grower the opportunity to correct soil nutrient and pH (acidity) problems as well as make use of the residual N mineralization potential that exists in a field following an alfalfa crop.

2 If you consider renovation or extending the stand life, try no-tilling a grass crop such as orchardgrass, tetraplpoid annual or perennial ryegrass, or one of the new varieties of festulolium (a cross between meadow fescue and one of the ryegrasses). The grass will increase your tonnage especially if you fertilize for the grass with nitrogen fertilizer. This also has the effect of driving out alfalfa at the same time as production levels are maintained for an additional year or two. Another option for extending an alfalfa stand’s life for 1 to 2 years is to seed in 6 to 8 lbs of red clover per A. This option will maintain the higher protein production from the field.