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Drought conditions challenge ag producers

South Dakota State University | Updated: 07/13/2012

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Extreme heat and varying degrees of soil moisture currently impact an expanding area of our country, says Jim Krantz, South Dakota State University Extension Cow/Calf Field Specialist.

"For many South Dakota crop and livestock producers, these conditions that prevailed last year in the southern plains have migrated northward, now threatening livelihoods earned from both sectors," Krantz said.

He adds that adapting to these conditions has challenged generations of farmers and ranchers and forced them to place renewed emphasis on their management skills in times of drought.

"As they do so, a systematic approach may provide the means to overcome or minimize the impact of Mother Nature," he said.

On the crop side, Krantz says that adequate moisture for most of the state provided almost ideal conditions for field preparation, planting and weed control. However, many areas are witnessing extremely dry conditions in the midst of a monster heat wave.

"Agronomic practices were part of a well-planned crop strategy that, until now, provided row crops and grains with the framework for rewarding yields. In drought-stricken areas, those yields now may be measured by tons of forage, not bushels of grain," Krantz said.

Avoid nitrate poisoning with these tips

If this scenario becomes a reality, there are some considerations Krantz says producers need to think about as they plan their forage options:

Well fertilized crops, under stress condition caused by drought, have higher nitrate levels than non-fertilized crops.
Plant parts closest to the ground contain the highest concentrations of nitrates. Most are in the lower third of the plant.

With this in mind, Krantz says strip grazing is not recommended.

"This practice forces the animals to eat all of the plants. Overgrazing is not recommended for the same reason, as cattle will be forced to consume plant parts with the greater levels of nitrates," he said.

If grazing is the preferred choice for utilization of these high nitrate crops, Krantz says livestock should never be allowed access if they are especially hungry.

"Hay or other forage should be provided to them prior to turn-out. Producers should only allow the livestock access for a portion of the day to begin with," he said. "This is recommended until the livestock become acclimated to the higher nitrate levels."

He adds that if the forages are harvested for silage, cutting heights should be adjusted higher, leaving the lower stalk unharvested.

Although the costs involved with mechanically harvesting high nitrate forages are significant, Krantz says there are livestock safety benefits to this approach.

"The ensiling process reduces nitrate levels making them much safer for consumption," he said. "However, it is not recommended to green chop these forages and let them heat overnight as this process favors the formation of nitrite which is even more toxic that nitrate."

Oats, corn and barley consistently have been documented as crops with the most potential to account for nitrate poisoning in livestock; however, Krantz says that annual forages such as sudangrass, sorghum-sudan hybrids and millets can be dangerous as well.

"Weather conditions may intensify the accumulation of nitrates in forages. Plants that survive an extended period of drought will experience increased levels of nitrates immediately following a rain as the parts of the plants begin to resume their growth. The nitrate levels will continue to increase for several days afterward," he said.

Quick nitrate testing is available at all SDSU Extension Regional Centers

Suspected crops may be brought to SDSU Extension Regional Centers for a preliminary test that only takes a few minutes. Although exact nitrate levels cannot be determined through this procedure, their presence can be determined. If and when nitrates are verified in the plant tissue, samples are then sent to a lab for further testing.

"If nitrates are not found, producers can be confident that the forage is safe for their livestock," Krantz said.

Water may be an additional source of nitrates for livestock whether consumption is from a dugout, dam or well. Krantz recommends producers obtain a livestock suitability analysis for water sources.

"This is especially important in areas where nitrate poisoning potential from crops is a concern," Krantz said.

Initial water tests for total dissolved solids can be accomplished at SDSU Extension Regional Centers. Depending on the levels recorded, further sampling at a lab may be required.

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