Thank you to all who made the York County Fair go so smoothly! It’s always a joy to see the 4-H and FFA youth and families rewarded for the hard work they put into their projects!
Crop Update: I didn’t get out to the field much this week with fair but did spend a few
hours one afternoon. There are portions of the area I serve that have been blessed with rains and look really good. The main thing that I’m seeing a lot more of this week is aphids in corn fields. This can be common in fields where fungicide is applied as the fungicide kills a beneficial fungus that attacks aphids. Some aphid species are also attracted to moisture stressed crops. The heat has also pushed the crop along quickly. We have another yield forecasting article in this week’s CropWatch at http://cropwatch.unl.edu where we talk about the impact of the heat on yields. As of right now, based on comparing this year to 30 years of weather data, it’s appearing corn may reach maturity 1-3 weeks early. Irrigated yields are estimated to be near average and above to near average for non-irrigated corn (where drought is not a factor). These yield forecasts are based on simulations under ‘perfect conditions’ (with no nutrient loss, disease etc.) but they can give us an indication of what may happen if we continue with higher heat conditions.
Unfortunately, pockets in the area continue to miss rains. The drought monitor still is not
reflecting the drought in this part of the State; at this point, I’m unsure what else either Al Dutcher or I can do about this. One farmer reminded me drought occurred in the same area in 2006, 2012, and now 2018-six years apart each time. Driving the area, hardest drought-stressed crops really took a turn this past week with corn in hard dough to early dent with some kernel abortion and soybeans are beginning to abort pods and quit filling seeds. One question has been on weighing taking corn for silage or not. If you have at least an estimated 50 bu/ac grain in most of the field other than highly compacted areas, it may be more profitable to keep for grain (unless you’re looking for cattle feed). The following are some resources to consider further:
- July 2018 BeefWatch article on considerations for green chop/silage for cattle feed, include best management practices, etc.: https://go.unl.edu/e3y5
- July 2018 K-State article for considerations on taking corn for silage or grain: https://enewsletters.k-state.edu/beeftips/2018/07/02/considerations-for-use-of-drought-stressed-corn-for-cattle/
- All UNL Drought Resources: http://droughtresources.unl.edu
Dicamba: We’ve often mentioned the research showing a soybean plant producing a new node every 3.7 days upon reaching V1 stage. And, I’ve used that in the forensics assessment for determining a timing for off-target dicamba movement. One question I’ve had was “Do soybean plants continue to produce a new node every 3.7 days upon being affected by off-target dicamba?” My assumption in the forensic analysis I have used is that a new node continued to be produced every 3.7 days in spite of off-target dicamba. However, the only way to really test this would be to have the same soybean variety in both an Xtend and non-Xtend version. We will release a CropWatch article next week in which a situation like this occurred at the Eastern NE Research and Extension Center. Dr. Jim Specht counted nodes in both the non-Xtend variety with off-target dicamba and the Xtend variety that wasn’t affected. He found the same number of nodes in spite of the dicamba affected non-Xtend variety being shorter in height and having less canopy. So that in itself is good information for use in forensic assessments. However, he also found plants in which a higher off-target dicamba dose affected the top-most growing point. When that occurred, the number of nodes was affected.
Last year, a group of us released a dicamba survey during Soybean Management Field Days. Reminder those are upcoming this week (https://enre.unl.edu/soydays)! The survey helps us understand your perspectives about dicamba and this year we’ve added questions regarding using Xtend technology. Hopefully it will provide helpful information for all of us and the results will be shared via CropWatch and winter meetings. We’d encourage and be grateful for any soybean growers to participate at: https://www.surveymonkey.com/r/JWDCY3C.
South Central Ag Lab Field Day: Please hold August 29, 2018 for UNL’s South Central Ag Lab (SCAL) Field Day near Clay Center! Attendees can choose which sessions you would like to attend. Options include the latest SCAL research in the areas of Irrigation/Water Use; Nutrient Management; Weed, Disease, and Insect Management; Cover Crops; and Cropping Systems. CCA credits will be available and there’s no charge to attend. Will have more specifics for you next week but please hold the date for now!
Vine Crop Problems: The following resource explains options for diagnosing various problems with cucumbers, squash, and melons: https://hortnews.extension.iastate.edu/2011/8-24/cucurbitwilt.html.
Hoping these graphs change for us after this past weekend’s rain events! These readings were taken as of 5/17/18.
At the Lawrence location I’m just sharing last week’s graphs from 5/10/18. Soybean was planted into the corn stubble on 5/11/18 and the sensors were removed and re-installed with the readings needing time to adjust. The farmer said it was so dry he had to use a drill to re-install the moisture sensors. I have no idea what happened in the soybean stubble field but the readings this past week were crazy so decided to share new graphs on the Lawrence location next week.
The area of ‘abnormally dry’ or ‘moderate drought’ was reduced by 5% in Nebraska as of 5/8/18 compared to the previous week.
Today was interesting driving my route through the southern tier of counties I serve. Wearing overboots and walking instead of driving to the sensors was welcome at Byron and Superior where heavier rain events occurred this week. However, Lawrence and Bladen had largely missed the rains. The Clay Center location received 1″ the past two days, but other areas of Clay County received very little. The farmers who have allowed me to monitor pre-plant soil moisture thus far were interested in watching this throughout the growing season. Thus, sensors will remain in most of these fields. Where fields have been planted thus far (other than Clay Center), planters have planted around the sensors and seeds have been hand-planted between sensors.
Some rains helped with the top foot profile at some of these locations last week. One thing to keep in mind when viewing these graphs is we don’t always know what’s going on below the soil surface. One farmer had a good point regarding my “blips in the graphs” in my last blog post. I mentioned they could be due to a soil crack along the PVC pipe-which we do see occur and can be true. However, he also had a good point that it could be a worm hole, root channel, etc. that water may have followed for a brief time period, which could also be true, especially in these long-term no-till fields. As you look at the charts this week, it’s important to keep in mind that soil water also moves via gravity (termed ‘gravitational water’). Thus, sometimes why we can see changes in soil moisture in the successive drier layer with small amounts of precipitation.
Here is an update on beginning soil moisture status. The left charts are as of 4/19/18 with the right charts being the previous week. You can click on the images to enlarge them. The ‘weekend moisture’ event I refer to was the blizzard 4/14/18.
Bladen: The top foot is now slowly losing moisture one week later in spite of some weekend moisture. The second-fourth feet are all above 50% depletion.
Byron: Some weekend moisture may have allowed the top foot to remain steady. The second and third feet are both over 50% depletion bringing the total soil moisture in the 1-4′ depths closer to 50% depletion. There must have been a soil crack along my PVC pipe to allow for the moisture spike you see in 3 and 4 feet and not 1 and 2 foot depths.
Clay Center: This is still the wettest location in spite of the top foot slowly drying out this week. The second foot is still below field capacity with third and fourth feet and total soil moisture relatively unchanged. Must have had a soil crack along PVC pipe for third foot for the quick dip observed.
Lawrence Corn Stubble: Minimal change was observed at this location this past week. Essentially all feet remained the same in regards to soil moisture. A small crack along PVC pipe must have been present at 3 foot for short dip observed there.
Lawrence Soybean Stubble: This location (across road from corn stubble) showing dryer than last week. Top two feet now dryer than field capacity which increased the total (1-3′) soil moisture depletion.
Superior: Weekend moisture may have allowed the top foot to stay steady (as was also seen in Byron). However, the second, third, and fourth feet all lost moisture leaving the total soil moisture (1-4′) above 35% depleted at this location.
The current Drought Monitor shows 19% of Nebraska in the “abnormally dry” or “moderate drought” categories and in the shadow of large-scale drought in Kansas (97%) and Colorado (88%). Being curious about beginning soil moisture in non-irrigated situations, I installed Watermark soil moisture sensors in six non-irrigated, no-till locations in Webster, Nuckolls, Thayer, and Clay counties.
This quantitative information can be helpful as growers make planning and planting decisions. Granted, most planting decisions have already been made with inputs already purchased. Spring rains are also typically expected. However, information like this can help a grower be flexible in that planning should anticipated rains not be timely.
- The grower may choose to plant a more drought-tolerant crop like sorghum or a more drought-tolerant corn hybrid.
- A grower with livestock may choose to plant a feed/forage crop.
- A grower may choose to not terminate a growing cover crop such as rye, instead growing it for feed.
Soil moisture sensors were installed at 1-, 2-, 3-, and 4-foot depths in non-irrigated, no-till corn and soybean residue fields near Byron, Superior, Lawrence, Bladen, and Clay Center. The sensors were connected to Watermark dataloggers from the Irrometer company. Because the default soil temperature on the dataloggers is 70°F, a temperature sensor is also installed to ensure correct calibration of the soil moisture. This is because soil temperature during this time is dfferent (much lower) than 70°F.
Any farmer or crop consultant could do the same for his/her fields to determine the same information and wouldn’t need the datalogger. Taking weekly readings at the same time each week, or even daily at the same time, would also give one an idea of beginning soil moisture. It’s best to allow at least 48-72 hours for the sensors to equilibrate to the current soil moisture conditions. This process is essentially the same as when sensors are installed for irrigation scheduling. The difference is these are non-irrigated fields with no current crop growing. For additional information and videos on using watermark sensors, please see the Nebraska Agricultural Water Management Network website.
Nuckolls County is shown as in “moderate drought” on the Drought Monitor. At the Superior location, we were hoping to also install into actively growing rye and winter-killed forage to determine beginning soil moisture in those conditions. The rye is currently 6 inches tall in the tillering stage and the soil probe wouldn’t go in the ground beyond 6 inches, so no moisture sensors were installed. The soil probe would only go in 12 inches in the winter-killed forage consisting of sorghum-sudan and radishes; thus, soil moisture sensors weren’t installed in that field either.
Results so Far
During installation, the 3- and 4-foot depths at all locations (only 4-foot at Clay Center) seemed very dry. The soybean residue appeared drier than corn residue. Two sites are located near Lawrence, one in corn residue and one in soybean residue across the road from each other. That data shows differences in moisture between different residue types the most clearly. I was unable to install to the 4-foot depth at the Lawrence soybean residue location. At most other sites, a hammer was used to help install to 4 feet. However, given the difficulty in installing the 4-foot sensor, these graphs do not show them as dry or drier than the 3-foot at any location other than Bladen.
This could be due to several reasons:
- The soil textural properties at 4-foot depth could have more clay and higher soil bulk density in which the drier conditions would not be obvious or easily determined just by installation difficulty.
- There could be a compacted layer.
- The dryness or wetness of any given soil layer at any given time is a function of various factors including the farming history of the field, previous several years of root development in different layers, previous year’s precipitation amount and distribution during the season as well as during off-season, evaporation rate, and water uptake pattern of the crop from different soil layers as water update from different soil layers varies and also varies with time during the season.
- The 4-foot layer may not actually be drier than the 3-foot layer.
Because only a few days of data are shown thus far, it is difficult to make a determination at this time. Data will continue to be collected until each field is planted and the results will be posted weekly on my blog. Additional information regarding each location is in each figure caption.
A special thank you to each farmer cooperating with me on this effort and to Dr. Suat Irmak for providing additional equipment and advice on this effort.