Posts Tagged ‘hay & pasture nutrition’

Fertilizer Management on Hay Fields

Friday, June 1st, 2012

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

For those producers very worried about the impact of the shortage of rainfall so far this year, I suggest a two-pronged approach. First, soil test your fields to determine if any phosphorus (P), potassium (K), or limestone (to adjust soil pH) will be needed this year. If P is required, all of it can be applied at this time as well as limestone to both correct soil pH and to make nutrients such as P more available to the forage plants. If K is also required, it should be applied either all at this time, if less than 100 lb/acre is recommended, or should be applied in two equal applications when the recommendation is for more than 100 lbs/acre. For K, the second application should occur in late August or early September and is designed to help the forage grasses and legumes better tolerate winter weather.

Unless you are using manure or compost on your hay fields, you will not be using a soil test to check on nitrogen (N) recommendation rates. In general, the suggested rates for nitrogen range from 40 to 60 lbs of N per acre for each expected ton per acre of hay produced. Especially in drier years when drought may be a serious concern, the lower suggested rate should be used to avoid the possibility that high levels of nitrates will accumulate in the grass. My suggestion for N fertilization is to apply it very sparingly between each hay harvest or to evaluate the soil moisture levels and if they are adequate for a good period of growth the N can be applied at that time. A number of folks have recently completed their first hay harvest and in the fields I’ve check the soil moisture level is severely limited. The rain earlier this week was insufficient to refill the soil moisture holding capacity and I would suggest waiting a bit longer to see if more rain will come out way before applying N to stimulate grass growth. In the past few years, we’ve seen damage to grass hay fields when N was applied during hot, dry weather. Finally, don’t forget to consider fertilizing with N in a fashion similar to the turf industry and by that I mean applying N in early and mid-fall to encourage fall root growth to help the grass be in better shape for growth during the following spring and summer.

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.

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.

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.

 

Hay and Pasture and Potash

Thursday, May 6th, 2010

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Although it’s a little earlier than normal, I think it’s time to start thinking of applying spring potash (K) and phosphorus (P) fertilizer to your pasture and hay fields. For the hay fields, you will want to wait until after the first harvest, but I’ve seen a number of fields at heading (grasses) or late bud (alfalfa) which is a good time to harvest a good to excellent quality hay. For those more interested in tonnage, you’ll be holding off harvest for a few more weeks but you can still plan ahead for when your fields will be ready to fertilize with P and K and another shot of nitrogen (N). The warm weather of the past week and the period of very warm weather earlier this spring has orchardgrass and many other cool-season grasses heading out already. Early May is also, on average, a time when we have the greatest chance of a period of warm sunny weather long enough to dry hay.

Potassium or potash is a very critical element that helps plants tolerate the stresses of heat, drought, insects, and diseases that attack cool-season grasses in the summer. Although the price of K is high at the present time, the corresponding benefits of K fertilization will help you afford the cost of fertilizing with K. Many growers have chosen to either lower their K fertilization rates or eliminate them completely during the past couple of years when the price of fertilizer has been very high. If you have a current soil test, check the recommendations for how much K might be needed. If your soil test is not current you should get one as soon as possible to determine how much K you should apply or to see if the soil test levels are falling too rapidly.

In general if both P and K are needed by your hay or pasture field, add the P and half the K after the first hay harvest or in late-May or early June and then add the second half of the K recommendation in late August or early September. This timing will allow the plant to prepare for the stresses of summer and then for the stresses of winter.

Spring Pasture Fertilization

Thursday, April 22nd, 2010

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

While preparing to teach my Soil Fertility and Plant Nutrition course this week, I came upon some information that will be of interest to those who have pastures where they graze livestock. Most grazers are aware of the inherent springtime problem with grass tetany which is caused by low blood magnesium (Mg) levels. The rapid growth of forages in the spring plus cool, cloudy and sometimes rainy weather can restrict both root growth and transpiration in forages to the point that magnesium levels in the grass are too low for animal health.

However, another complicating factor is that we often try to stimulate early growth of pastures with nitrogen (N) fertilizer and with the blending capabilities of many fertilizer companies we can easily add in the extra potassium (K) that the soil test might suggest. Nutrients can actually be what is called antagonistic; where one or more nutrients act together to depress the uptake of another nutrient. This is the case for N and K, which if applied in too large amounts can depress further the uptake of Mg by forages in the spring. The depressed uptake of Mg then puts the grazing animals at risk for grass tetany. To avoid the possibility, hold off K applications until late May or early June since K applied at this time will be much less likely to increase the incidence of grass tetany and will improve the tolerance of the grass to the various stresses encountered during the hot summer months.

Nitrogen application in very early spring is useful in getting enough pasture growth to begin grazing a week or two earlier than you otherwise could. If the soil test indicates that soil Mg levels are low, use only a small amount of N in early spring and wait until mid-May to apply larger amounts. This should help reduce the chance for grass tetany but still provide plenty of early season grazing.

Spring Wake-Up of Pasture and Hay Fields

Friday, March 27th, 2009

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

It’s hoped that your pastures and hay fields have made it successfully through another winter. Now it’s time to get pastures actively growing for the needed grazing to extend your hay supplies or reduce the need to buy more hay and it’s time for hay fields to green up and be ready for the first good hay making weather later this spring. Many of our hay and pasture fields have had a relatively hard winter with little snow cover and some very cold temperatures.

If the stands have thinned a little or if you just want to speed up growth this spring to be able to graze earlier or boost spring hay yields, now is the time to add a bit of nitrogen (N) to give the grasses a boost. If the field has a good amount of legume present, you should restrict the amount of N applied at any one time to no more than about 30 lbs N/acre. However if few legumes are present in the field, then addition of 50 to 75 lbs N/acre will stimulate the grass to grow and fill in bare spots or at least tiller out fully to help shade out weeds that might try to fill in any void spots.

Unless your soil test shows low to very low levels of phosphorus (P) and potassium (K), you should wait until after the first hay harvest or early to mid-June to apply the P and K that might be required according to your soil test recommendations or your nutrient management plan. Generally, the freezing and thawing and other reactions that occur over the winter months will release enough available K and P to support spring forage growth.

Planning for the Second Hay Harvest

Friday, May 9th, 2008

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

 With a weather forecast indicating the likelihood of several inches of rainfall over the next five to seven day period, the soil surface moisture levels will be recharged so that hay producers either finished with, or about to begin their first hay harvest need to begin planning for the second hay harvest. In particular, as soon as the first harvest is removed from the field, nitrogen (N) fertilizer and the recommended amount of potassium (potash) and phosphorus should be applied to boost the yield potential for the second harvest cycle. Nitrogen, of course, is the key to promoting extra yield potential but potash also will be essential to help the forage grow well during the early summer high temperatures and with low available subsoil moisture. The latest research results from The Pennsylvania State University suggest adding 50 lb N/acre per ton of expected yield for orchardgrass, 60 lbs N/acre per ton of expected yield to timothy, and as much as 70 lbs N/acre per ton of expected yield to tall fescue. With all of these species, if drought conditions develop, the grower needs to carefully monitor any hay harvested for nitrate levels to prevent potential problems with nitrate toxicity.

Update on Hay and Pasture Crop Irrigation

Friday, April 18th, 2008

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

Many of our hay and pasture species are just beginning the rapid growth phase that occurs each spring. More and more hay and pasture fields are set up to receive irrigation. The limited rainfall the southern half of the state has received so far this spring means that the soil water supply will be rapidly depleted as the cool-season hay and pasture grasses enter the rapid growth phase. Orchardgrass, in particular, since it matures earlier than many of the other species we grow, will be using large quantities of water during the next few weeks. If you are set up to irrigate hay and pasture fields, now is the time to begin the irrigation system. Try not to let the soil moisture levels be lowered to the point that water stress symptoms actually show up on the crop. As the species enter the rapid growth phase of spring, water use will increase from about a tenth of an inch of water per day to a quarter inch or more water per day. To keep fields actively growing, be sure to replace that quantity of water each week. When warmer temperatures occur in June, water use can increase to that approaching corn (about a third of an inch per day) so your irrigation regime will need to increase as summer approaches. Keep in mind that you will need to stop irrigation long enough for the soil to dry enough to support haying and baling equipment without causing significant compaction. It’s also usually best to wait until the crop begins regrowth before resuming irrigation so that you do not encourage weeds.

It also is time to get nitrogen (N) out on irrigated and non-irrigated hay and pasture fields. For hay, the latest research from Pennsylvania State University and Dr. Marvin Hall’s team shows that you should be applying about 50 lbs of N per acre per ton of expected yield. This is a good compromise between maximum economic yield from the hay and the risk of high nitrate levels in the hay if the crop becomes very drought stressed. For pastures, our N recommendations still vary based on the amount of legume in the pasture. If pastures contain a one to one ratio of legume to grass (50 percent of the biomass-forage-comes from the legume), additional N fertilizer will not be needed. If the legume component makes up between 25 and 50 percent of the forage, then apply about 25 lbs N/acre and if there is less than 25 percent legume in the forage, you may need as much as 50 lbs N/acre to maximize productivity of the pasture.