Summer Heat and Forage Growth
We are in what is typically the hottest part of the summer and we need to consider how these temperatures affect our pasture and forage plants.
The two primary plant classifications are warm-season and cool-season and this is based on basic plant physiology and their specific photosynthetic pathway. Practically speaking, and as their names suggest, every plant species has a specific temperature range in which it maintains growth.
When it gets hot (90-plus degrees), cool-season plants such as bromegrass, orchardgrass, fescues, needlegrasses and wheatgrasses all struggle and will have a very slow growth rate, even if there is plenty of moisture. When it is very dry, these cool-season grasses may completely stop growth and have gone into a summer dormant state.
Warm-season grasses are just the opposite. Millet, sudangrass, sorghums and our native bluestems, gramas, switchgrass and other warm-season grasses thrive when the temperature is around 90 degrees. Their metabolism runs at peak efficiency when it is hot, so they grow rapidly while maintaining reasonable forage quality and good root growth. With drought conditions, also be aware of the potential for the seeded summer annual grasses to accumulate nitrates.
As you graze or hay, be aware of the stress weather is putting on your forage. When it’s too hot, allow plants a longer recovery period before the next grazing. And don’t expect high feed values or good animal gains when the nutritional goodies are burned right out of the plants.
Proper expectations and management adjustments can limit the stress from hot weather.
Storage Silage
Corn silage harvest may seem like a long way off, but preparation for a successful harvest begins now. Improper silage storage and fermentation can result in losses up to 20% prior to feeding. Plan your storage now to keep excessive storage losses from happening to you.
Preventing oxygen from entering your silage should be a top priority when considering silage storage. Bagged silage is a versatile option that allows the storage location to move year to year and comes with a build in oxygen barrier but can carry a high price tag and may not be appropriate for large harvest amounts. Placing the silage in a bunker is another that can increase oxygen exclusion, but make sure to check these structures for cracks and repair any that are found to maintain their integrity. If silage is a feedstuff on your operation, the reduction in losses that a permanent structure paired with covering the pile provides can offset the costs when spread out over several years.
Silage piles are the more traditional approach and can allow for greater volumes of silage to be stored in a smaller area without the cost and permanent nature of bunkers. Oxygen exclusion in piles that lack a permanent structure can be enhanced with some planning. Before harvesting, line the sides with bales and place oxygen-limiting plastic down the sides and for several feet under the bottom to seal the sides of the pile. At a minimum, placing plastic on top of the pile is an investment worth the time, labor and money. By covering the pile, we can reduce oxygen from moving into the pile from the top and reduce precipitation exposure.
Corn silage is a valuable feed resource and keeping oxygen out of your silage requires planning now. Pick an appropriate location for harvest and feed out success and store correctly to minimize feed losses.
Forage Options After Hail
Hail is a four-letter word that causes high anxiety. Since the average first fall killing frost in Nebraska usually occurs from Oct. 1-10, our growing season is now over halfway with only 70-80 days remaining. So, replanting severely hailed corn or soybeans fields are likely not good options, since even short season corn hybrids need at least 80-90 days of growing days, and the shortest season maturity group soybeans need at least 80 days of growing season for economic yields. Therefore, the best alternative options may be to move from a summer grain production mindset to possible forage options.
Assessing hail damage loss is a challenge when losses vary based on stand reduction, direct damage and leaf defoliation. For those with insured crops, check with your insurance company prior to replanting, grazing or converting your severely hailed acres to another crop. Next, review your herbicide labels for any restrictions regarding seeding new crops on hailed fields. Then, if forage production is still an option, consider planting warm-season annual forages in July or warm/cool-season forages in August.
Livestock producers may consider grazing hailed corn fields, where plants have been “mowed off” at the ear height or lower. Consider grazing the stalks first and then plant a cool-season forage this fall after grazing. Again, consider any chemical label grazing restrictions based on previous chemicals applied herbicides in the corn or soybean fields. In some cases, turnips or radishes can be drilled or broadcast into damaged cornstalks for fall grazing.
Regarding nitrates, manage the mid-season hailed corn fields similar to drought-stressed corn prior to ear development. Best practices include:
- Do not turn cattle into hailed cornstalks with an empty rumen;
- Have plenty of fresh water available;
- Allow cattle to openly graze the fields; and
- Provide supplement hay or energy.
Finally, avoid forcing the cattle to graze the hailed stalks below eight inches in height.
Another option might be “teff” (a drought-resistant warm-season annual that can be harvested 45-55 days after planting). Sudangrass (not the hybrid) has high grazing potential with low prussic acid grazing risk. Pearl millet is drought tolerant and does not produce prussic acid either but has lower yield potential than “cane” forage sorghums and sorghum-sudangrass hybrids.
More information and free forage videos are available on UNL CropWatch and BeefWatch.
