PA Farm News
August 28, 2007
Extension News:
Fall
Considerations
By Delbert G. Voight, Jr., Regional Agronomy Educator
CARLISLE – Trying to determine topics in agriculture to write about is more challenging these days. High grain and hay prices, increased prices for nitrogen, potassium, drought impacts, biofuels, fall cover crops for forage just a few topics of interest. I chose to discuss the return of the rains and alfalfa cutting management due to the limited capacity of the article. Rains finally returned just in time to interfere with the harvesting of many crops. I don’t think anyone will complain about the rain! In some case growers planted emergency forages (Teff, sorghum/sudan) that are now ready to harvest and the rains that saturated soils will leave producers little option other than to compact and make ruts in the soil during harvest. Corn silage harvest is commencing in many areas and most growers reported that the best way to determine proper timing was to chop and see what the moisture is rather than using a timing method or using the milk line methods. After silage it would be great to see plenty of cover crop rye, oats, crimson clover or some sort of cover to protect the soil and or be an emergency forage.
It is amazing how quickly grass perked up after the rains came. One timothy grower near Hershey reported that he was able to make a big bale per acre(500lb dry) on the re growth and plans to make another cutting in a month. The point here is rain is so important to the profitability on farms and brings about some decisions. What I would like to focus on for this short article however is the timing of the fall harvest of alfalfa. Alfalfa stores its food in a tap root and normally the plant needs between 4- 6 weeks before a killing frost in the fall to produce the food required to allow it to regrow vigorously in the spring. The drought however has allowed a long time between cuttings and in most cases enough food is stored for spring emergence and therefore changes the decision of when to cut. Here are some key points that Dr. Marvin Hall Extension Agronomist relates to fall alfalfa management.
1. Young stands are less susceptible to winter injury due to fall harvesting than older stands.
2. Length of harvest interval during the growing season is more important than date of fall harvest in determining alfalfa stand survival. Taking at least one harvest during the growing season at 50% bloom reduces the risk of fall harvest compared to taking all harvests at late bud or first flower.
3. Maintaining soil fertility levels is extremely important in reducing risks associated with fall harvesting.
4. Use of disease resistant and winter hardy alfalfa varieties will greatly decrease the risk of winter injury due to fall harvesting.
5. Environmental conditions will moderate or aggravate the effects of fall harvesting. These include:
a. Temperatures of 5 to 15 °F will injure alfalfa crowns and roots. Fortunately, the soil and snow generally insulates the crown and root from dangerously low temperature.
b. Amount of snow cover determines the amount of crown and root protection from cold temperatures. Snow cover greater than 6 inches is usually adequate to insulate the crowns and roots from low air temperatures.
c. Soil moisture is important because water is a better conductor of heat than is air. Wet soils cool faster than dry soils which may lead to lower soil temperatures. In addition, wet soils will freeze and thaw more extensively which increases the potential for frost heaving.
d. Summer drought stress of alfalfa will reduce the risk of harvesting during the 4 to 6 week dormancy period.
These are some things to keep in mind when considering whether to fall harvest alfalfa. Rains returned and with a long fall more forage may be harvested and make up for lost forage over the summer.
By Delbert G. Voight, Jr., Regional Agronomy Educator
CARLISLE – Trying to determine topics in agriculture to write about is more challenging these days. High grain and hay prices, increased prices for nitrogen, potassium, drought impacts, biofuels, fall cover crops for forage just a few topics of interest. I chose to discuss the return of the rains and alfalfa cutting management due to the limited capacity of the article. Rains finally returned just in time to interfere with the harvesting of many crops. I don’t think anyone will complain about the rain! In some case growers planted emergency forages (Teff, sorghum/sudan) that are now ready to harvest and the rains that saturated soils will leave producers little option other than to compact and make ruts in the soil during harvest. Corn silage harvest is commencing in many areas and most growers reported that the best way to determine proper timing was to chop and see what the moisture is rather than using a timing method or using the milk line methods. After silage it would be great to see plenty of cover crop rye, oats, crimson clover or some sort of cover to protect the soil and or be an emergency forage.
It is amazing how quickly grass perked up after the rains came. One timothy grower near Hershey reported that he was able to make a big bale per acre(500lb dry) on the re growth and plans to make another cutting in a month. The point here is rain is so important to the profitability on farms and brings about some decisions. What I would like to focus on for this short article however is the timing of the fall harvest of alfalfa. Alfalfa stores its food in a tap root and normally the plant needs between 4- 6 weeks before a killing frost in the fall to produce the food required to allow it to regrow vigorously in the spring. The drought however has allowed a long time between cuttings and in most cases enough food is stored for spring emergence and therefore changes the decision of when to cut. Here are some key points that Dr. Marvin Hall Extension Agronomist relates to fall alfalfa management.
1. Young stands are less susceptible to winter injury due to fall harvesting than older stands.
2. Length of harvest interval during the growing season is more important than date of fall harvest in determining alfalfa stand survival. Taking at least one harvest during the growing season at 50% bloom reduces the risk of fall harvest compared to taking all harvests at late bud or first flower.
3. Maintaining soil fertility levels is extremely important in reducing risks associated with fall harvesting.
4. Use of disease resistant and winter hardy alfalfa varieties will greatly decrease the risk of winter injury due to fall harvesting.
5. Environmental conditions will moderate or aggravate the effects of fall harvesting. These include:
a. Temperatures of 5 to 15 °F will injure alfalfa crowns and roots. Fortunately, the soil and snow generally insulates the crown and root from dangerously low temperature.
b. Amount of snow cover determines the amount of crown and root protection from cold temperatures. Snow cover greater than 6 inches is usually adequate to insulate the crowns and roots from low air temperatures.
c. Soil moisture is important because water is a better conductor of heat than is air. Wet soils cool faster than dry soils which may lead to lower soil temperatures. In addition, wet soils will freeze and thaw more extensively which increases the potential for frost heaving.
d. Summer drought stress of alfalfa will reduce the risk of harvesting during the 4 to 6 week dormancy period.
These are some things to keep in mind when considering whether to fall harvest alfalfa. Rains returned and with a long fall more forage may be harvested and make up for lost forage over the summer.
Del Voight is the Penn State Cooperative Extension Educator for Field Crop Management serving the Capital Region. Penn State is committed to affirmative action, equal opportunity, and the diversity of its workforce. Penn State Extension in Cumberland County is located at 1100 Claremont Road, Carlisle, PA 17015, phone 717-240-6500, or e-mail
Cumberlandext@psu.edu.
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