Surviving Hot Temperatures

About this time almost every year, we have to deal with high humidity and high temperatures. It is now officially summer, and it feels like it! After a cool, almost colder spring with plenty of moisture, the sun is shining and it is hot. Plants are starting to grow, but most fields are definitely behind schedule. Livestock also suffer during hot and humid periods of time.

For livestock, staying cool depends on first getting plenty of water. Check your watering systems to make sure they are working correctly. Keep water supplies in the shade. Cool water helps animals dissipate body heat. Make sure stock tanks are secure and full of water. Sometimes animals will try to get in the tank to cool off or knock it over. Make sure the water flow is adequate. Check automatic waterers and increase the flow if necessary. Dehydrated animals may need electrolytes; consult a veterinarian for the proper dosage. Misters and sprinklers also provide a way for animals to cool down.

In extreme heat, animals can get sunburn and often require shade. It helps if animal shelters or shade structures have cross ventilation to cool down animals. Check fans and cooling systems to make sure they are working correctly. If possible, feed animals in the evening or when it is cooler. Avoid feeding during the hottest time of day. For cattle, grain is a cooler feed than hay. Hay digestion creates heat and is better for winter feeding. Give animals more room to spread out if possible. Avoid moving or handling animals during the heat of day.

How can a crop farmer help crops during heat extremes? Crop roots are still shallow and not well developed yet. Early planted crops appear to be in better shape to survive higher temperatures and possibly drier soil conditions because they have more developed roots. First, try to terminate cover crops and weeds quickly to save moisture. Second, reduce or avoid tillage because each tillage pass dries out soil 0.5–1.0 acre-inch of water. Dry soil tends to blow and when it rains, the soil gets hard and turns to concrete. This drying causes crusting, reduced water infiltration, and poor root development.

For no-till and cover crop farms, surface residue is beneficial for reducing soil temperatures. A thermometer on bare soil could be 135°F when the air temperature is 90°F and one inch down the temperature can still be 100°F. Residue helps keep the soil cooler and reduces water evaporation. When the soil surface temperature gets that hot, many microbes that recycle nutrients to the plant die off. Rhizobia bacteria, which make nitrogen for soybeans, die off quickly when soils get too hot (above 140°F). Most plants are hurt as much by a lack of available nutrients as they are by a lack of water—with the two very closely tied together. Plants become stunted as growth is reduced due to a lack of nutrients. Most nutrients are made available by beneficial microbes, so if moisture is adequate, nutrients should be available.

Several nutrients are critical to surviving high temperatures in crops. Without adequate potassium (K), plants are less drought-resistant. Low K also promotes higher incidences of disease and insect pests. Adequate zinc (Zn) is critical to surviving hot temperatures. Zinc levels are commonly low on many soils and in plant tissue. Zinc helps plants reduce the incidence of disease-causing microbes by breaking down the cell wall of pathogens (bacteria) and preventing viruses from replicating.

A new element being researched is organic silicate (silicon), which strengthens the plant vascular system (xylem, phloem). Plants with high organic silicates are stronger and healthier (bigger, larger vascular system) and can resist many environmental stresses including hot and dry weather. Organic silicate also helps plants reduce frost injury in the spring or fall.

If a farmer is doing no-till with cover crops, should they leave the residue standing or roll it down? Getting the crop residue on the soil surface is beneficial by reducing soil temperature and conserving moisture. As residue breaks down, it releases nutrients to nearby plant roots. In rye, most of the beneficial allelopathic effects (natural herbicide) come from decaying stems and leaves, reducing weed pressure. Getting crops to canopy quickly is also beneficial to reducing soil temperatures and conserving moisture.

Finally, the wheat crop is turning yellow quickly and will probably be harvested early again this year. I would expect good to great wheat yields this year due to beneficial weather. With hot temperatures, give your pets and livestock plenty of cool water and some shade. Also, keep yourself, children, and elderly well hydrated and try to stay cool!