Alfalfa and grass must be confused. March started out fairly warm and dry. Alfalfa, which very much develops according to heat, took off. Then April was cold and quite wet and things quit growing. May has been dryer but still cold with a few warmer days. Growth has been by stops and starts.
When will first cutting be ready? It depends. The variability from year to year on maturity for alfalfa can be considerable. Maturity depends on Growing Degree Days, micro-climate (elevation, closeness to lake), soil drainage, what grass is planted with it and to a lesser extent variety. Calendar date at 40 NDF can sometimes vary by two weeks between years and micro-climates.
Grasses don’t tend to fluctuate from the calendar date from year to year quite as much as alfalfa. However, maturity will depend on all of the above and also fall cutting management and fertilization. Grass cut late last fall will be later maturing than fields last cut in September. Fields with nitrogen applied in early April will likely mature quicker. Of course, orchard grass will be ahead of most fescues, Reed Canarygrass and Timothy.
When to mow is obviously a complex question with many variables. But don’t wait for your governor to tell you when to mow. It will be best for you and your crop advisor to monitor fields and consult the following table from Dr. Jerry Cherney of Cornell. From my experience, it is the best place to start in determining your window to mow.
Use this table by evaluating the height of the tallest alfalfa in different areas of the field and the percentage of grass in the stand.
Table – Estimated NDF of a mixed alfalfa-grass stand based on alfalfa height and the percent grass in the stand. Target NDF for each mixture is highlighted. Using the table below, a field with 40% grass and 60% alfalfa will be ready to mow when the tallest alfalfa stems in the field are 26” tall. For straight grass fields, look at the stage of maturity on the grass (boot stage is ideal) and the height of the tallest alfalfa in the area.
It's May 1st. The forecast shows some unseasonably cool temperatures this coming week. By the calendar we should be safe to plant corn now, right? Indiana growers were asking the same question about two weeks ago. The following are some excerpts from an article on imbibitional chilling injury by Dr. Bob Nielson from Purdue that may help you make a decision:
While farmers are free to plant corn whenever they choose to do do, there are risks associated with "early" planting (Nielsen, 2020). The primary risk is that associated with "cold" soil temperatures. Soils that hover around 50 degrees (F) for days or longer after planting delay germination and slow emergence of the young seedlings. More importantly, soil temperatures lower than about 50F increase the risk of "imbibitional chilling" injury to germinating seeds.
"Imbibition" refers to the initial uptake of water by seed during the first 24 to 48 hours after being planted into moist soil. The resulting rehydration causes the seed to swell and the germination process to begin. Imbibition occurs naturally, with no physiological processes involved (e.g., dry wood will imbibe water). It also occurs whether soils are cold or warm and therein lies the potential for "imbibitional chilling" injury.
When the seed swells as it rehydrates, its internal cell membrane structure is damaged. When seeds (and soil) are warm, the membrane damage is quickly repaired by the physiological activity associated with germination and "life goes on" normally. When seeds (and soil) are cold, their cell membranes are less elastic, the cell membrane damage due to swelling is more severe, and the physiological repair of the damage is slowed or stopped. Left unrepaired, this damage to cell membranes and the subsequent leakage of cell contents can result in death of the seed.
Past research on the nature and causes of imbibitional chilling injury to seed does not clearly identify the environmental conditions "in the real world" that result in a high probability of the problem. The literature implies that soil temperatures simply lower than 50F are a key factor. It is not clear from past research whether the injury can occur with only a few hours of exposure to sub-50F soil temperatures or whether it requires lengthier exposure to cold temperatures. What is known is that this type of chilling injury is most likely to occur during the first 24 to 48 hours after planting seed into moist soil because that is when imbibition (and corresponding seed swelling) occurs.
Identifying and the diagnosing the problem in the field is often challenging for several reasons. First of all, germination and emergence of corn in cold soils will naturally be slow. The first visual indicator of germination (other than the seed swelling) is the appearance of the radicle root between 35 and 60 Growing Degree Days (GDD) after planting (Nielsen, 2019).
Tip: Calculating GDDs using soil temperatures is preferred over air temperatures for predicting corn development progress prior to about the 6-leaf growth stage (V6). The reason is that the seed & young seedling responds more directly to soil temperature as long as the main growing point of the corn plant (apical meristem) remains below ground (until about V5-V6).
When soil temperatures hover around 50F for days or longer after planting, accumulating 35 to 60 GDD may take 1 to 2 weeks. Initially, dead seed due to imbibitional chilling injury do not look much different than live seed taking their normal "sweet time" to germinate in cold soils. However, once 60 GDD or more have accumulated, then seed that seems to be "dormant" compared to others that exhibit radicle roots, coleoptiles, and lateral seminal roots may well be the result of imbibitional chilling injury. Sometimes, instead of immediate cessation of the germination process (i.e., "dormant" seed symptom), the radicle root and coleoptile emerge from the seed coat before ceasing further development (Fig. 2).
Another challenge in diagnosing imbibitional chilling injury as the cause of poor stands of corn is that eventually the dead seed or seed that germinated but simply ceased further development will naturally begin to decompose. Consequently, if you wait too long to investigate a problem field, you might be tempted to diagnose seed or seedling disease as the cause of the poor stand.
Daily, or hourly, soil temperature records coupled with knowledge of a field's planting date are useful for "pointing the finger" at imbibitional chilling injury. Because imbibition occurs within the first 24 to 48 hours after planting into moist soil, one can imagine that timing of planting relative to the onset of several days of cold soil temperatures influences the risk of imbibitional chilling injury. Anecdotal stories abound in the coffeeshops about fields planted 3 days ahead of a cold snap emerging just fine... fields planted 2 days ahead of the cold snap experiencing some emergence problems... fields planted 1 day ahead of the cold snap having more problems... and fields planted the day of the cold snap having major problems.
Here is the link to the full article. https://www.agry.purdue.edu/ext/corn/news/timeless/ImbibitionalChilling.html