Good Riddance to 2019… Maybe Not Just Yet.

The end of the calendar year for many agronomists and producers is denoted by the beginning of the winter meeting season and the conclusion of the growing season. Visiting among fellow agronomists and producers this time of year, a common topic is the sharing observations and lessons learned from the past year, and the 2019 growing season provided a lot of material for these conversations! Many are ready to put the challenges of 2019 behind and look forward to the 2020 growing season. While the delayed and wet spring planting of 2019 set the stage for many of the management challenges we faced during the 2019 growing season, the fall harvest of 2019 and the resulting management decisions have added to the legacy of 2019 that will impact producers for the coming years.

Years is correct, this is not a typo. So, from a soil perspective what will be some of the challenges moving forward?

First topic up for discussion, shallow compaction. Many fields during the wet spring of 2019 were tilled too wet during seed bed preparation. The conditions in much of the region were wet enough that any seed bed preparation, regardless of tillage tool used, created a shallow tillage layer. If these acres were harvested early and primary tillage was completed before the fall rain set in, this was alleviated to some degree. In many cases the quality of the soil structure was degraded, and a fall tillage pass will not completely correct this.

Correcting tillage layers by allowing the soil structure to improve will take time and less tillage, not more. There is a chance of the 2019 tillage layers impacting the rooting of the 2020 crop. Be watchful for tillage layers when scouting in 2020 by evaluating plant roots to identify fields that may be candidates to receive additional corrective actions like cover crops. If possible, limit the number of tillage passes in the spring of 2020 as to limit the potential for maintaining or making this issue worse.  If 2020 proves to be another wet spring, always remember doing no tillage is an option in some cases. A tillage layer can be created any time soil is lifted, shifted or moved.

Deep compaction will also be an issue. Many fields were harvested wet in the fall of 2018 leading to deep compaction. Much of this land did not see quality primary tillage in the fall of 2018 or in the spring of 2019, and wet soil conditions later in the fall of 2019 may also hindered correction of these issues. Much of the early harvested 2019 crop was done in dry soil conditions that keep the issue from getting worse. Many acres received primary tillage under these favorable conditions. However, there was a considerable amount of primary tillage that was completed later in the fall after the fall rains began.  This tillage may have removed the surface ruts and overall improved the appearance of the soil surface, but the deep compaction may still remain.

In 2020, place a focus on placing earlier maturing hybrids/varieties in those fields that were primarily tilled this fall in wet or less than ideal conditions. Focus on an early harvest of those fields with the greatest risk of deep compaction remaining from 2018 or 2019. This will increase the opportunity to complete the 2020 fall tillage in the best possible conditions.

The wet fall of 2018 prevented the collection of some soil samples, they were delayed until the spring of 2019. Some of these samples were not collected due to the wet spring of 2019 and then were delayed till the fall of 2019. Some of those remain uncollected yet in the fall of 2019.  Some producers took the opportunity to perform fall primary tillage immediately after harvest rather than wait for soil sampling or fertilizer application. Collecting soil samples after fall tillage is not wise. So, what are the options for soil sampling?

First off don’t make matters worse, any variances in the soil sample collection process can impact or vary soil test results. Repeatable and trackable soil test results over time require as much constancy among sampling events as possible. The following are ranked in the order of potential impact on sampling variation in soil test data.

1. Sample Depth – The sallower the sample, the higher the soil test values in most cases. Consistent depth is nearly impossible when sampling a tilled or muddy field.
2. Sample Location - For GPS guided sampling programs, collect sample in the same location as previous years.
3. Sampling shortly after fertilizer or manure application – Soil samples should be delayed for at least 2 to 4 months after fertilizer/manure application.
4. Crop yield – Increased crop yields lead to lower soil test levels.
5. Management of prevent plant acres – See previous article on this topic.
6. Previous Crop - Different crop residues release nutrients back to the soil at different rates, and different crops take up varying amounts of nutrients. For examples, fall soil sample nutrient values tend to be lower following a corn crop than following a soybean crop
7. Time of year – Spring soil samples tend to have a slightly higher soil test values than fall samples for some nutrients.
8. Soil moisture – Prolonged periods of dry weather can reduce soil test values. This is more common with summer than fall soil samples and more common in fall than spring samples.

If your soil sampling is out of normal sampling sequence here are some fertility management ideas to consider

1. If samples have been delayed since the fall of 2018 following soybeans in a corn-soybean rotation, rather than sample in the spring of 2020 ahead of the soybeans, wait until after the 2020 soybean harvest.
2. If your traditionally apply a 2-year fertilizer application, consider an annual fertilizer application. If the opportunity to sample arises you can adjust to new fertilizer recommendations.
3. If fall soil samples are delayed till the spring, consider a permanently switch so spring soil sampling.
4. Consider sampling a season or even a year in advance of fertilizer application. This is becoming popular in the industry for fall fertilizer applications so that the soil data is available to make fertilizer recommendations before harvest. The fertilizer can be ready for application the day of harvest, no waiting.

The fall of 2019 again forced some producers to make decisions that they did not wanted to make. Delayed planting lead to delayed crop maturity, leading to wetter harvest moisture, leading to slowed or delayed harvest, leading to … and the list goes on.  There were consequences to the action taken or the inaction of many decisions this past year.  In most cases it was not about making the “right” decision, but rather the least wrong decision. The decision that has the least costly long-term impact for the operation. Many of us may not want to accept the decisions we made managing the 2019 crop, but always remember you made the best decision you could with the information a you had at the time.  Many times, there was no “right” answer in 2019.