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Crop watch

By Bob Streit - Columnist | Sep 28, 2020

This should be the week where statewide harvest begins in earnest. There were combines operating in both corn and beans last week depending on the maturity group of bean planted while there were also corn fields being harvested where the drought stressed the plants enough that moisture levels in the long dead fields were in the high teens. Not many good reports were coming from the combine operators south of Hwy 3 as summertime rains were scarce through the entire season. Rainfall amounts were more normal through most of July north of Hwy 3.

The grain markets have had a good run lately as many grain short countries have had their own weather problems this year and recognized the need to build their grain supplies while prices were relatively cheap. China has been the chief buyer during this period as flooding has been a huge issue. This period of wet weather continued as two more large typhoons moved inland to drop substantial amounts of rain on already soggy territory. Current weather and news reports are difficult to find, as communist countries don’t usually allow problems or stories from dissenters to get aired to the rest of the world.

As most producers move into harvest the thoughts will turn towards the 2021 crops and any lessons or observations from 2020 can be applied to our cropping programs. Sadly there were quite a few official or unofficial test plots and trials located on farms and in fields hit by the Aug 10th storm that were rendered useless and were destroyed.

Drought issues

The three to four day wet period of two weeks ago was very welcome as much needed rain fell over a wide area of the Midwest. The storm was a large counter clockwise front that kept sending bands of moisture across states that were under official drought status. The amounts received varied from 1 inch in northwest Iowa to 5-7 inches along the Illinois border. A sizeable portion of both crops were forced into early maturity and the rains did not contribute to grain fill. For the fields that still had 30 to 50% of green leaf tissue the moisture will contribute to higher yields.

Being too wet at the start of harvest has been a common event the last five or so years, as making deep ruts or getting combines, wagons and semis stuck were regular events. That won’t be happening this year. As crop moisture usage declines we realize that fall rain is meant to fill the deep profile for the 2021 crops. The 8 to 10-inch moisture deficit could affect next year’s production if it does not recharge to within 2-inches of being full. In previous falls Dr. Elwynn Taylor had fall soil moisture levels tracked at set locations and publicized. Ag personnel paid attention to those reports as a number of the 1990 to early 2000 years were dry. Yields were often limited if early season rains did not replenish the top 3-5 ft of profile moisture.

Dr. Taylor has also explained that the Chinese monks were great observers and recorders of the climate since biblical times. They recognized cycles and periods of excessively wet or dry conditions, so tried to keep adequate amounts of grain in storage to feed their people. What are they thinking now that we may have to adjust to or plan for?


Over this past season I have visited with a number of seasoned growers and ag professionals who have made observations as to what production practices or products they used that helped their crops and soils survive or thrive this season. The observations can be validated as harvest proceeds.

One group is reporting that the cornfields they were monitoring that maintained a 1.6 or higher K base saturation percentage stayed green longer and didn’t die early. They are also observing that if low K levels are yield limiting the best course of action is to apply 20 to 25 gals of a liquid K solution in season versus applying huge amounts of 0-0-60, lowering the cost more plus eliminate the over-application of Cl.

The observations with N have been mixed. The majority of growers are thanking their decision to side-dress or Y-drop early with supplemental nitrogen as the plants seemed better able to grow roots deeper and tolerate dry condition. Conversely other growers seem to see that excess N with low Ca created excessively lush growth and plants that did not survive the dry conditions.

The admonition to plant at least 2 to 2.5-inches deep was beneficial again. Planting shallower earlier led to corn plants that formed fewer roots less able to extract moisture from the soil.

The weed scientists in the Delta country warned us about Roundup resistant weeds and said there will be a year where there will be fields where growers were unable to control waterhemp with products that were formerly effective. Looking at a few fields overtaken by broadleaves, that year has arrived.

With the seed companies taking early orders in late summer, growers are forced to form opinions earlier than normal. After seeing the omnipresent Dicamba vaporization and drift problems in 2020, uncertainty over product availability plus tighter restrictions on Dicamba use and tank clean out, Enlist bean seed sales will likely increase next season. Conventional bean premiums are likely to be higher also.

Soil testing

This is when the advice being given will often center on timely soil sampling and making sure you stay with your 2, 3, or 4 year cycle of soil sampling to get absolute levels and to notice trends as to are you are building, maintaining or dropping nutrient levels. How should you approach sampling this fall when the soils are extremely dry? A soil geomorphologist like David Montgomery would explain that varying soil types contain different amounts of clay. Clays vary as to whether they are 1:1 or 2:1 in their oxygen to silica composition in their layering. K is held within those layers and is less available when the soil is very dry. The K may be there, but if it’s too dry the clays don’t release it. Other important minerals are made available thru microbial secretion. Under very dry conditions that activity is limited.

With dry conditions soil test results are likely to be lower than they would be in a normal moisture year. The best advice may be to stay with your normal soil sampling schedule, recognizing that if the test levels are lower than expected it could be a function of the dry soils. Watch your long terms trends.

Long term trends

With continued low ROI on growing commodity crops the focus in fertility seems to be on placing the proper amount of minerals in a stabilized and highly available form where the roots can access them early. That alters the priority from long term, expensive building of soil levels of all minerals to meeting immediate needs with real time applications. The conundrum this creates is it means being timely and specific with in-season applications. It sounds doable, but as operations increase in size, the demands on in-season application equipment increases to more than one machine and operator can handle, especially if good weather windows get narrower or capable operators become scarce.

Realize that front X-Ray defraction scanners could eventually be mounted on the front of a sprayer equipped with several direct injection pumps and tanks. The pumps and rear mounted booms would apply the minerals as determined by the scanner.

An update

Typically in mid to late August the still green corn crop can have a problem with Southern Rust. It differs from common rust in that the pustules are on the upper surface and increases in severity much quicker. In southern states it can kill a field in 8 to 10 days. I was able to test a new mineral product that was applied after the pustules appeared. It boosted the plant health enough that the disease disappearred. It worked perfectly on quite a few acres.

A plant disease note

I have mentioned before that growers who base their crop health program on simply making a July application of fungicide are missing a major step. They need to be managing their crop residue in the fall. This means enhancing corn residue degradation by applying a microbial mix which includes bugs, sugar and UAN. We like the Melt Down product for this task with its 29 microbe mix. Relying too much on hard chemistry allows faster selection of resistant pathogen biotypes, as seen in Brazil and on sugar beets.

Derecho damaged fields

There have been variations among insurance adjustors as far as what constitutes a non-harvestable corn field. There are fields around Madrid and Zearing through to Cedar Rarpids and Davenport that are 100% flat. There are also those where 30 to 50% of the areas within field are flat and the rest at a 45% angle. How does an operator decide when to raise or lower the head? Even with the best reel, maintaining a 1 mph harvest speed is going to be challenging. The bruised stalks will get weaker with each rain, as we have seen in the past ten days. The Maya head may be part of the answer, but not enough are available.

Good luck and be safe.

Bob Streit is an independent crop consultant and columnist for Farm News. He can be reached at (515) 709-0143 or www.CentralIowaAg.com.

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