October 2021

Upcoming Events

October
7	Old World Bluestem Field Day
November
3 / 11 / 18 / 25 & / 26	Central Kansas Beef Summit / Office Closed / K - State Swine Day / Office Closed

Test to Prevent Nitrate and Prussic Acid Poisoning.
Many Kansas cattle operations rely on some type of harvested feed to use in the winter months and common among those sources is forage sorghum, sorghum-sudangrass and sudan. Forages in the sorghum family are prone to two different problems for feeding cattle, nitrate poisoning and prussic acid (hydrocyanic acid, HCN) poisoning. They are easy to get confused because both result in a lack of oxygen availability to the animal and are more likely to occur when the plant is stressed (fertility, hail, drought). Table 1. Key characteristics of nitrate and prussic acid poisoning.
In dry areas of the state, cattle may be removed from pasture early. Bringing hungry cattle into pens with weeds can be very dangerous as the nitrate concentration may be elevated throughout the plant and animal intake high. Manure in corrals can contribute to the elevation of nitrates in the weeds. Elevated nitrates may not result in death but could cause abortions.
Our current KSU forage fact sheet on prussic acid poisoning indicates that prussic acid potential dissipates as the forage dries. It goes on to say hay or silage that likely contained high cyanide concentrations at harvest should be analyzed before it is fed. We tend to forget this second statement and think that when the plant dries, all the cells are ruptured and any HCN is released. To confirm this, we measured dhurrin content in sorghum hay in a study last year. The dhurrin content was stable from 1 to 10 weeks of dry storage.

Item	Nitrate	Prussic Acid
Plant parts most affected	Base of Plant	Young or new growth
Types of plants	Many, especially sorghum family, pigweed (palmer amaranth, redroot, waterhemp), kochia, oat hay	Many (> 3,000 plant species), sorghums including Johnson grass, white clover, birdsfoot trefoil, Indiangrass, Cyndon spp. (Bermuda)
Grazing / problems	Consumption of lower plant, rarely a problem unless extremely high levels or forced to east the entire stem	Consumption of newest growth
Hay	Not impacted by drying	Not impacted by drying
Time of death	Several hours after consumption	Within minutes of consumption, treatment can rarely occur fast enough to save the animal
Blood/Oxygen	Chocolate brown colored blood, hemoglobin converted to methemoglobin and unable to carry oxygen	Blood bright cherry red, hemoglobin contains oxygen, but not available to cells

In the plant, dhurrin (the precursor to HCN in sorghum species) and the enzyme that converts it to cyanide, are stored in separate compartments within the cell. When the plant is eaten, the compartments are ruptured, and the cyanide formed and released. Measurement of dhurrin directly is used in some research studies. However, commercial labs do not typically measure dhurrin directly. Rather the procedure includes something to stimulate cyanide release. If hay is made from forages in the sorghum family or other susceptible species, testing for prussic acid in forage that has suffered from drought, hail or fertility issues is advised. Testing is cheap compared to the cost of losing even one animal.
Management recommendations common to both prussic acid and nitrates include:
Test first, don’t gamble. Keep in mind, different labs use different tests that have different scales.
Feed animals with a known safe feedstuff (s) before introduction to potentially problematic feeds. Don’t turn in hungry.
Ensiling will reduce concentrations of either by about half in well-made silage, but silage put up under less-than-optimal conditions could still contain very high levels. If extremely high before ensiling, a 50% reduction may not be enough to result in safe feed.
If testing before grazing, samples should reflect what the animals are expected to consume, generally leaves and upper portion of the plant. Sample a minimum of 15 sites across a given field. One method is to sample from each corner and the center by walking diagonal lines and sample plants every 50-100 steps or as appropriate for field size.
We expect levels of nitrates and prussic acid to be variable across a field, so more samples are better than less. A rule of thumb is to sample 10 to 20 % of the bales per field or cutting as a minimum. Be aware of areas of the field that exhibited more plant stress than others. If large enough areas, you may want to sample them separately. Your acreage size and feeding methods likely factor into this decision. Use a forage probe that cuts across all plant parts in a bale rather than a grab sample from individual bales or windrows. Most county extension offices can help with sampling procedures and equipment.
For more complete information on these problems see these publications Nitrate Toxicity and Prussic Acid Poisoning. If you have samples with high prussic acid concentrations, and are willing to share information on variety, growth, fertility, and harvest conditions, it will be helpful as we strive to better understand this issue. For more information contact Sandy Johnson, sandyj@ksu.edu.
By Sandy Johnson, Extension Beef Specialist, Colby
Insects in Central Kansas
This season has been peculiar for insects. I have witnessed armyworm and fall armyworm in populations that I hope never to see again. These worms arrived as moths that laid eggs, hatched into worms, pupated back to moths, and repeating the cycle resulting in greater numbers. The cycle can be repeated 2-3 times per season, and producers are left wondering if they will return once more, and where might that be? For that answer, we will probably need to wait and see. Weather will play a significant role, and that is difficult to predict. If we get a cold snap, it could drive the moths south or slow worm development. Not that I am rooting for winter, but I would enjoy the demise of these armyworms. In the meantime, keep watching alfalfa, particularly seedling alfalfa, covers and early seeded wheat, brome patches, and potentially your fescue yard. Sadly, they have not found a liking for pigweeds, or we might have a different opinion of them.
Other insect pests can be found, such as chinch bugs with large populations in fields much later than we usually see. Grasshoppers can be found near field edges and waterways. Large numbers of crickets are noticeable though they have no crop significance. Lastly, dectese stem borer or (soybean stem borer) is always here but in areas more significant this season. The larvae will tunnel down to the base of the stem late and chew at the base of the plant. That feeding will weaken the stem, so producers should be aware of potential lodging soybeans. If you have noticed fields with lots of stem borer, it would be best to prioritize it at harvest.
By Jay Wisbey, Crop Production Agent
Soil Testing Season is Nearing
As harvest is drawing to a close, it is a great time to start making plans for the crop ahead with a soil test. Rain is likely needed to make soils soften up enough to get a probe in the ground. If you are interested in mobile nutrients Nitrogen, Sulfur, and Chloride, you will want a 24-inch profile test to go with the 6” surface sample.
I am on the lookout for Soybeans Cyst Nematode again this year. If you know of small areas that yielded low or saw sudden death syndrome in soybeans (not related to drought), please call the office. Last season I was able to find a couple of small pockets of nematode activity, mostly related to fields with long soybean history and flooding.
Factors That Created Variable Yield Conditions
In my travels around the district talking to producers, I have heard a trend of how fall crops have turned out. The late summer weather or lack thereof has led to highly
variable yields across our district. Wide
variations are apparent from field to field but also within areas of the field.
Prior to August, many of our fall crops had almost an irrigated environment receiving enough rain that many fields had never lacked for moisture. Our plants grew fast and larger than we are accustomed to under “normal” Kansas stress.
The most noticeable thing I witnessed while harvesting plots is seed size. An average soybean size usually ranges from 2500 to 3000 seeds per pound. While harvesting plots, I saw seed so small that I was amazed the combine could catch it before it blew out the back.
Showing the excellent potential the soybean crop had. If our plot making 48.5-bushel per/ acre averaged approximately 4000 seeds per pound would have received enough timely rain to increase to 3000 seeds per pound, the resulting yield would have increased by 25% to 64.7 bushels per acre on seed size alone.
The consensus in talking to producers is that maturity and planting dates played a significant role in this year’s crop. That statement is not uncommon in our variable climate, though; the late-season drought magnified this to an extent. The soybean crop was running out of moisture in its critical growth stage. Every soil condition that can limit water uptake became apparent. Root-limiting conditions such as compaction on end rows or previous waterlogged soils in low areas are evident. Soil property conditions such as infiltration rates are seen on the slopes, such as the backs of terraces and hillsides. Soil texture as it relates to water holding capacity could be witnessed like lines on a soils map. Clay soils versus loamy soils or sandy soils showed up in yields. Areas that came up short of expectations displayed poor pod set, a significant abortion of seeds per pod, and smaller seed size.
Maybe we can learn from this experience as many years just one timely rain can hide problems. Are there things from a management perspective that we can do better? It is easy to look at the weather and say, “here is our problem.” That statement might be 100% true and correct. Or yet I wonder if we left or created a little more ground cover, would it have changed the outcome? Would it have conserved a little more of the July moisture? Maybe you found a compaction problem that needs attention. I tend to look for the takeaway from these farming experiences as they present themselves. Some years it is not as visual and apparent as farmers witnessed this harvest.
Jay Wisbey, Crop Production Agent
Soil Testing Season is Nearing
As harvest is drawing to a close, it is a great time to start making plans for the crop ahead with a soil test. Rain is likely needed to make soils soften up enough to get a probe in the ground. If you are interested in mobile nutrients Nitrogen, Sulfur, and Chloride, you will want a 24-inch profile test to go with the 6” surface sample.
I am on the lookout for Soybeans Cyst Nematode again this year. If you know of small areas that yielded low or saw sudden death syndrome in soybeans (not related to drought), please call the office. Last season I was able to find a couple of small pockets of nematode activity, mostly related to fields with long soybean history and flooding.
Factors That Created Variable Yield Conditions
In my travels around the district talking to producers, I have heard a trend of how fall crops have turned out. The late summer weather or lack thereof has led to highly
variable yields across our district. Wide
variations are apparent from field to field but also within areas of the field.
Prior to August, many of our fall crops had almost an irrigated environment receiving enough rain that many fields had never lacked for moisture. Our plants grew fast and larger than we are accustomed to under “normal” Kansas stress.
The most noticeable thing I witnessed while harvesting plots is seed size. An average soybean size usually ranges from 2500 to 3000 seeds per pound. While harvesting plots, I saw seed so small that I was amazed the combine could catch it before it blew out the back.
Showing the excellent potential the soybean crop had. If our plot making 48.5-bushel per/ acre averaged approximately 4000 seeds per pound would have received enough timely rain to increase to 3000 seeds per pound, the resulting yield would have increased by 25% to 64.7 bushels per acre on seed size alone.
The consensus in talking to producers is that maturity and planting dates played a significant role in this year’s crop. That statement is not uncommon in our variable climate, though; the late-season drought magnified this to an extent. The soybean crop was running out of moisture in its critical growth stage. Every soil condition that can limit water uptake became apparent. Root-limiting conditions such as compaction on end rows or previous waterlogged soils in low areas are evident. Soil property conditions such as infiltration rates are seen on the slopes, such as the backs of terraces and hillsides. Soil texture as it relates to water holding capacity could be witnessed like lines on a soils map. Clay soils versus loamy soils or sandy soils showed up in yields. Areas that came up short of expectations displayed poor pod set, a significant abortion of seeds per pod, and smaller seed size.
Maybe we can learn from this experience as many years just one timely rain can hide problems. Are there things from a management perspective that we can do better? It is easy to look at the weather and say, “here is our problem.” That statement might be 100% true and correct. Or yet I wonder if we left or created a little more ground cover, would it have changed the outcome? Would it have conserved a little more of the July moisture? Maybe you found a compaction problem that needs attention. I tend to look for the takeaway from these farming experiences as they present themselves. Some years it is not as visual and apparent as farmers witnessed this harvest.
Jay Wisbey, Crop Production Agent

The enclosed material is for your information. If we can be of further assistance, feel free to call or drop by the Extension Office.
Sincerely,

Jay Wisbey
District Extension Agent
Crop Production
jwisbey@ksu.edu
Salina Office
K-State Polytechnic
2218 Scanlan Ave.
Salina, KS 67401-8196
785-309-5850
Fax: 785-309-5851
Justine Henderson
District Extension Agent
Livestock Production
jwh04@ksu.edu
Minneapolis Office
307 N. Concord, Suite 190
Minneapolis, KS 67467
785-392-2147
Fax: 785-392-3605

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