Fieldwork finished

I believe that fall fieldwork is over for the time being. Our air temperatures got down to 9 degrees on November 12. There was some fieldwork on November 11. That fieldwork included fall ammonia application and tillage on corn stalk fields.

It seems that winter has arrived a little early. There has been snow in the air the past three days. The frost in the soil is down to about three inches.

Our growing season – for much of my area – was marked by some really heavy rainfall amounts in June. Much of that excess rainfall was received on June 14 to June 17. There are official rainfall amounts of 12 to 14 inches for the month of June. Emmetsburg, for example, was listed as 16.3 inches for the month of June.

The excess rainfall in June caused a lot of problems. One problem was the obvious loss of nitrogen from the soil profile. Farmers that were able to apply extra N in late June were rewarded for their efforts. However, that excess rainfall also reduced corn yield potential by reducing root growth and limiting leaf growth. It was very common to see corn plants at harvest that were only 4-5 foot tall in those poorly drained areas.

Our rainfall was moderate for July. There was also an area that developed some dry conditions. That dry area was in parts of Dickinson, Emmet, Kossuth and Winnebago counties.

Of course everybody wants to know what the yields are. It is also quite difficult to generalize. However, one generalization that can be made is that many farmers are disappointed in their final corn and soybean yields.

It is very common to hear a farmer say that yield levels ranged from 110 bu/a to 190 bu/a on corn. That same farmer will discuss 35 to 55 bu/a soybean yields. Also – there has been very little discussion on really high corn yields. There was some thought we would see some 220+ bu/a yields in some areas – but for the most part that did not happen.

Some of the factors that limited yields this year:

    - excess June moisture/poor drainage.
    - dry conditions in some areas late season.
    - widespread- but not real severe – Sudden Death Syndrome in soybean.
    - Goss’s wilt and Northern corn leaf blight in some corn hybrids.
    - frost on September 13 and 17.

Some factors that did not develop this year were:

    - very little damage from corn rootworm.
    - soybean aphids were present but not real severe.

We are also very thankful for good harvest weather. The outlook was pretty gloomy in early October. However, harvest weather turned around after that – and conditions were very favorable from October 5 to about November 11. Much of my area missed the widespread rain that occurred on October 13-14.

We also witnessed some good corn grain dry down – as corn grain moisture declined from the high 20s in early October to the upper teens by late October.

Good harvest weather

Our great fall weather continues for us in northwest and north central Iowa. We have had about two weeks of really good harvest weather.

I would say that most of the soybean harvest is complete. The soybean harvest started out really slow in early October. There were some farmers that had to quit harvesting soybeans because of excessive grain moisture. However, that changed in mid-October – as soybean grain moisture got down to the 10-11% moisture area.

Soybean yields are in the mid -50s for lots of people. Of course there are yields that far exceed that – but usually those are fields that may have been continuous corn for a few years. Often you do not get that complete story when you hear those really high soybean yields.

There have also been some fields in low to mid 40-bushel/acre area. Those yields have been in areas that received some of the 15+-inch rainfall in June. Some of those fields did not recover very well from that excessive rain in June and some of those same areas had some dry weather later in the season.

Corn harvest is about half complete in much of my area. Corn grain moisture is in the upper teens. There is some discussion in the country that farmers may delay harvest – to a certain degree – to take advantage of some of the field drying that is occurring. The weather forecast looks good – and farmers are willing to take a little risk on pre-harvest losses to save some drying costs.

It costs about $9.00 per acre to remove one point of moisture from 200 bushel/acre corn. That is based on 1.5% shrink and a commercial drying cost of $0.045 per point of moisture. You can use this info to assess the potential pre-harvest loss. It takes an ear of corn in 100 foot of a 30-inch row (250 square foot) to equal one bushel/acre loss.

Bean harvest nearly finished

Harvest is in full swing in my area. I would say that the soybean harvest will wrap up this week. We have had really good weather since October 14 – for soybean harvest and for corn grain drydown.

We missed the predicted widespread rainfall that affected most of the Midwest on Monday October 13. Only small amounts of rainfall were received – so most farmers were back in the field on October 14.

We have seen some good soybean yields. I think there will be a fair amount of whole field averages in the mid 50 bushel per acre area. We had a good rainfall in August and that is usually a good thing for soybean production.

Sudden Death Syndrome (SDS) was present in a lot of fields this past summer but was not real severe. So SDS was a minor factor that might have reduced soybean yields a small amount.

Farmers who have completed soybean harvest are hard at work on the corn harvest. We have had 38 Growing Degree Days (GDD) since October 14. That GDD figure is only slightly higher than normal for that time period – I thought it would have been higher than that. Growing Degree Days can be used to estimate corn field drydown. It usually takes about 25 GDDS to reduce grain moisture by one point. However, I think our good drying conditions last week – sunny, windy and low humidity – may have reduced grain moisture more than what the GDDs predict.

Farmers are reporting that grain moisture on corn that is currently being harvested at about 19- 20%. However, I also hear reports that there are fields that are still in the low to mid 20s for grain moisture.

So it still could be a long fall. However, everybody is really thankful for the recent good weather.

Corn drydown

Corn grain drydown in the field may be a big issue this fall. There are many factors that will affect rates of corn drydown. Some of those factors are obvious – like hybrid maturity, and the amount and duration of sun and wind activity. Also the amount of rainy days will affect the rate and amount of grain drydown – since little or no grain drying occurs during rainy conditions.

Grain drydown is like any other air drying activity – it requires heat to lower the relative humidity and air movement to assist the drying process. One way to estimate the drying power of the air is to use Growing Degree Days (GDDs). The use of GDDs to estimate corn drydown is not a perfect predictor, but it gives a general idea of the potential for field drydown.

Table 1 shows the expected GDDs for northern Iowa. Info on GDDs for 2009 is also listed, since the fall of 2009 was a challenging fall for field drying and harvest. One bright spot in the 2009 data shows one week in November that equaled the typical GDD accumulation for mid-October.

  Table 1.          
  dates normal       2009
    —GDDs base 50 NC Iowa—
  9/25-10/1 77       68
  9/30-10/8 75       24
  10/8-15 62       9
  10/15-22 47       26
  10/22-29 35       13
  10/29-11/5 24       18
  11/5-12 15       46
  11/12-29 11       8

Generally, it takes 30 GDDs to lower grain moisture in the field each point from 30% to 25%. Field drying corn from 25 to 20 percent requires about 45 GDDs per point of moisture. Sources of information on GDD requirements for rates of field drydown do not all agree. For example, some Ohio information shows that GDDs needed for one point of field moisture loss ranges from 22 to 29 GDDs/point.

Information from a field study by R.L. Nielsen from Purdue shows that rates of grain drydown can be 0.75 to 0.50 point/day in late September and early October. However, rates of field drydown usually slow considerably once mid-October occurs.

Much of the corn crop in northwest Iowa reached maturity on about October 1. Corn grain moisture is usually about 30% once corn reaches black layer maturity. Therefore, the potential for a lot of field drydown of this year’s corn crop is not real high. It will take some unusually warm late October weather to achieve high levels of field drydown.

Frost nips corn, beans

September has been an eventful month so far. We have had 5 rain events with 1.4 inches of rain in Spencer. The weather has been mostly cool and Growing Degree Days (GDDs) have been a little more than 50 below normal for September. It seems like it has been cooler and wetter than that- probably because most of that GDD deficit (44 of it) has occurred during the last week.

We had a frost event on September 13 and again on September 16. The outside air in the country smelled like a hay field on Saturday September 13. The frost seemed pretty minor at first – but by Sunday afternoon – it was apparent that there was some frost damage.

The frost damage varies quite a bit. Some fields have little damage and some cornfields appear to have most of their leaves frosted. Soybean fields are similar – but some soybean fields that were still green lost the top 6-8 inches of leaf tissue.

I do not think that the frost caused much frost damage in the grand scheme of things. Apparently others agree – since the media, the grain trade and my phone have been pretty quiet since the first frost.

We used to worry that frost damage to an immature corn crop would reduce the test weight and make the crop difficult to dry. However, recent experience indicates that frosted crops – if they are fairly well advanced – do not seem to have these problems.

That was the experience from the early frost in 1991. The early frost was blessing – of sorts – in 1991. Even though we had fairly immature crops and we had two nights of pretty good frost – the crop quit growing and started the dry down process at that time. And then – people will remember – we had a heck of a blizzard on Halloween that year.

Time to check for pests, SDS

We are wrapping up insecticide application on soybean aphids. The northern part of my area has treated a lot of acres for soybean aphids. The southern part has treated less.

There has been a trend the last several years where the aphids build up around the late R5 stage. The late R5 stage is where we tell people that treatment is no longer necessary. This is because research has shown there is not a large yield benefit from this late-season treatment.

However, some farmers have treated for aphids during this late time frame. That is because in the past we have seen aphid numbers build quickly in the late season when dry weather is a factor. This year, we have had some decent rainfall in August, so we expect the yield benefit from late-season treatment will be less.

We are seeing quite a few soybean fields getting to the R6 stage. The hot weather the week of August 18 helped with the development of the soybean crop.

Sudden Death Syndrome (SDS), shown in the pictures above, is fairly common in my area. I have observed fields in Emmet, Palo Alto, Clay and Buena Vista counties and have seen SDS in a lot of fields. This is the worst I have seen SDS in my area. However, it is not really severe in these fields – it is just there. And, it is nothing like it was in central Iowa in 2010.

Farmers are observing differences in SDS levels in soybean varieties, so we are encouraging farmers to study up on SDS resistant/tolerant varieties for next year and for two years from now. Also, since SDS and soybean cyst nematode (SCN) often occur together, farmers are encouraged to check their fields for SCN egg levels.

We have seen SCN egg levels creep up the last several years. Also there have been some SCN varieties that did not perform as well as they should where SCN is present. So, it might be worth it for farmers to check fields for SCN levels and check on seed varieties that perform better under SCN conditions.

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