The winter of 2008 has been one of extremes in both temperature and snowfall. We have seen temperatures range from 15 below F. to 60 degrees this winter. These extreme temperature changes and the resulting ice standing in low areas could potentially result in some damage to alfalfa fields in Green County.
Fixed costs such as land, taxes, and machinery depreciation now account for more than half the annual cost of growing a crop. These fixed costs are the same regardless of whether the alfalfa yield is high or low. In addition, forage harvesting costs are about the same whether we are in a high-yield range or low. For example, mowing and raking costs are about the same for a 1-ton-per-acre (t/a) yield as for a 2 t/a yield. Chopping or baling cost may only be about 10 percent higher for the 2 t/a yield than a 1 t/a yield.
From studies done in the Midwest, alfalfa varieties generally begin to decline in yield in the third production year (about 11 percent from the first two production years) and by the fourth year may be yielding 25 percent less than they did the first two years. These yield declines are averages, and it is important to assess the yield potential of your alfalfa stands.
As stands begin to green up in this spring, it is important to walk fields and see if stands are good enough to keep. In the past, we assessed stand viability by plants per square foot. Today, we realize as stands age, larger plants with more stems dominate. That means stem numbers are more critical.
Recent research findings show that 55 stems per square foot are needed to have optimal alfalfa yields. Fewer stems per square foot mean lower yields. You can count the dead stems from the last cutting last year or you can count the stems as they green up this spring. After counting one spot, you can usually walk fields and visually assess stem density without further counting.
One additional indication of a poor stand is dandelions. Dandelions do not crowd out alfalfa, they only fill holes. Spraying dandelions will not increase yields. In fact, spraying may reduce yield because holes in the stand will remain. Stands with two to four dandelions per yard will generally be yielding 25 to 30 percent less than optimum and should have been turned over.
symptoms of winter injury
• Slow Greenup. If other fields in the area are starting to grow and yours are still brown, you should check your stand for injury. Digging up roots can tell a lot about the health of the plant. You want a nice solid white tap root. If it is soft or discolored the plant yield will be reduced or may not even survive.
• Uneven growth. Uninjured buds will start growth early, while killed buds must be replaced by new buds formed in the spring. This results in alfalfa stems of different heights on the same plant. This is particularly visible when the tallest stems have grown about 6 inches tall. The second growth (shorter stems are from buds formed in the spring) will thicken the stand but represents lost yield.
• Stem density. Once the alfalfa stand is at least six inches tall, determine the average number of stems per square foot in at least four representative areas per field. Stands with an average stem density of more than 55 stems per square foot are in good shape and have potential for continued high production. Stands with less than 40 stems per square foot should be replaced. Stands with between 40 to 55 stems per square foot are probably in their last year of economic production.
Fixed costs such as land, taxes, and machinery depreciation now account for more than half the annual cost of growing a crop. These fixed costs are the same regardless of whether the alfalfa yield is high or low. In addition, forage harvesting costs are about the same whether we are in a high-yield range or low. For example, mowing and raking costs are about the same for a 1-ton-per-acre (t/a) yield as for a 2 t/a yield. Chopping or baling cost may only be about 10 percent higher for the 2 t/a yield than a 1 t/a yield.
From studies done in the Midwest, alfalfa varieties generally begin to decline in yield in the third production year (about 11 percent from the first two production years) and by the fourth year may be yielding 25 percent less than they did the first two years. These yield declines are averages, and it is important to assess the yield potential of your alfalfa stands.
As stands begin to green up in this spring, it is important to walk fields and see if stands are good enough to keep. In the past, we assessed stand viability by plants per square foot. Today, we realize as stands age, larger plants with more stems dominate. That means stem numbers are more critical.
Recent research findings show that 55 stems per square foot are needed to have optimal alfalfa yields. Fewer stems per square foot mean lower yields. You can count the dead stems from the last cutting last year or you can count the stems as they green up this spring. After counting one spot, you can usually walk fields and visually assess stem density without further counting.
One additional indication of a poor stand is dandelions. Dandelions do not crowd out alfalfa, they only fill holes. Spraying dandelions will not increase yields. In fact, spraying may reduce yield because holes in the stand will remain. Stands with two to four dandelions per yard will generally be yielding 25 to 30 percent less than optimum and should have been turned over.
symptoms of winter injury
• Slow Greenup. If other fields in the area are starting to grow and yours are still brown, you should check your stand for injury. Digging up roots can tell a lot about the health of the plant. You want a nice solid white tap root. If it is soft or discolored the plant yield will be reduced or may not even survive.
• Uneven growth. Uninjured buds will start growth early, while killed buds must be replaced by new buds formed in the spring. This results in alfalfa stems of different heights on the same plant. This is particularly visible when the tallest stems have grown about 6 inches tall. The second growth (shorter stems are from buds formed in the spring) will thicken the stand but represents lost yield.
• Stem density. Once the alfalfa stand is at least six inches tall, determine the average number of stems per square foot in at least four representative areas per field. Stands with an average stem density of more than 55 stems per square foot are in good shape and have potential for continued high production. Stands with less than 40 stems per square foot should be replaced. Stands with between 40 to 55 stems per square foot are probably in their last year of economic production.
