By Daniel Davidson
DTN Contributing Agronomist
Producing high corn and soybean yields grabs most of the headlines and farmers' attention. Alfalfa, on the other hand, is too often left to fend for itself.
Yet of all the crops, alfalfa is one that most readily responds to fertility and foliar programs. Results are quickly available and easy to see during summer harvests. What we need to keep in mind is that pushing the crop to increase tonnage in the spring and summer can also stress the crop and send it into winter in a weakened state.
The timing of final cutting, amount of regrowth before a hard frost, fertilizer applications and weed-control measures all factor in to making the right fall management decisions. My personal goal for alfalfa is 6 tons [per acre] this year, and I'd like to produce another 6 or 7 tons [per acre] next year. To get that, I have to set up the crop this fall for success next spring.
Evaluate Timing. Growers typically take three or four cuttings per year, depending on the weather when they take the first cutting and the cutting cycle (25, 30 or 35 days, for example). How late you can cut in the fall depends on how much time remains before the first hard frost. Harvesting alfalfa too late into autumn increases the risk of winterkill. Alfalfa needs time to store carbohydrates in the roots, so it has enough nutrients to survive winter and jump-start regrowth the following spring.
My rule of thumb is to leave about 25 to 30 days between the last cut and the first expected hard frost. I also like 4 to 6 inches of regrowth to occur before that frost. However, it's also important to consider the number of growing degree days (GDDs). A very warm September requires fewer calendar days than a cool September.
University of Wisconsin forage specialist Dan Undersander says in his newsletter (bit.ly/1LDYprI) that alfalfa needs 500 GDDs (base temperature 41 degrees Fahrenheit) after the last cutting to regrow sufficiently for good winter survival and yield the following year. However, another option is to cut late with only 200 GDD remaining before the first hard frost. By waiting, there is very little regrowth, and alfalfa won't use up significant stored reserves.
Alfalfa will remove about 50 pounds of potash, 15 pounds of phosphate and 5 pounds of sulfur for every ton harvested. Removing 5 tons of forage annually (dry weight removes about 250 pounds of potash, 75 pounds of phosphate and 25 pounds of sulfur), you should plan to apply what you remove if the soil reserves aren't there. I like to provide that fertility boost in the fall after final cutting to improve winter survival. Monitor your soil-test levels and track the tonnage you harvested to help determine how to replace what you've removed.
A great spring alfalfa stand comes by giving the alfalfa time to go into dormancy and store reserves, replenishing needed nutrients and applying weed-control measures in the fall.
If you have a question, e-mail Dr. Daniel Davidson at askdrdan@dtn.com.
(PS/SK)
Producing high corn and soybean yields grabs most of the headlines and farmers' attention. Alfalfa, on the other hand, is too often left to fend for itself.
Yet of all the crops, alfalfa is one that most readily responds to fertility and foliar programs. Results are quickly available and easy to see during summer harvests. What we need to keep in mind is that pushing the crop to increase tonnage in the spring and summer can also stress the crop and send it into winter in a weakened state.
The timing of final cutting, amount of regrowth before a hard frost, fertilizer applications and weed-control measures all factor in to making the right fall management decisions. My personal goal for alfalfa is 6 tons [per acre] this year, and I'd like to produce another 6 or 7 tons [per acre] next year. To get that, I have to set up the crop this fall for success next spring.
Evaluate Timing. Growers typically take three or four cuttings per year, depending on the weather when they take the first cutting and the cutting cycle (25, 30 or 35 days, for example). How late you can cut in the fall depends on how much time remains before the first hard frost. Harvesting alfalfa too late into autumn increases the risk of winterkill. Alfalfa needs time to store carbohydrates in the roots, so it has enough nutrients to survive winter and jump-start regrowth the following spring.
My rule of thumb is to leave about 25 to 30 days between the last cut and the first expected hard frost. I also like 4 to 6 inches of regrowth to occur before that frost. However, it's also important to consider the number of growing degree days (GDDs). A very warm September requires fewer calendar days than a cool September.
University of Wisconsin forage specialist Dan Undersander says in his newsletter (bit.ly/1LDYprI) that alfalfa needs 500 GDDs (base temperature 41 degrees Fahrenheit) after the last cutting to regrow sufficiently for good winter survival and yield the following year. However, another option is to cut late with only 200 GDD remaining before the first hard frost. By waiting, there is very little regrowth, and alfalfa won't use up significant stored reserves.
Alfalfa will remove about 50 pounds of potash, 15 pounds of phosphate and 5 pounds of sulfur for every ton harvested. Removing 5 tons of forage annually (dry weight removes about 250 pounds of potash, 75 pounds of phosphate and 25 pounds of sulfur), you should plan to apply what you remove if the soil reserves aren't there. I like to provide that fertility boost in the fall after final cutting to improve winter survival. Monitor your soil-test levels and track the tonnage you harvested to help determine how to replace what you've removed.
A great spring alfalfa stand comes by giving the alfalfa time to go into dormancy and store reserves, replenishing needed nutrients and applying weed-control measures in the fall.
If you have a question, e-mail Dr. Daniel Davidson at askdrdan@dtn.com.
(PS/SK)
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