Assessing problems with a shovel

By Matt Hutcheson, Seed Consultants, Inc.

As we wrap up the 2024 growing season, it is a good time to reflect on problems we have experienced in the field and make plans to address them in 2025. In many cases when you observe a problem above ground, looking below the soil surface can shed light on the issue. An essential part of growing a productive crop is the soil’s ability to support it. Many factors impact the health of a soil and its ability to produce a successful crop.

One of the most important tools for assessing problems in the field is a shovel. Because of the drought and extremely dry soil conditions, assessing roots was more challenging late in the 2024 growing season. While it is easy to blame difficulty using a shovel this year on the dry soil conditions, I visited several fields prior to the drought where I had difficulty getting the shovel into the soil profile. In those fields I observed poor root development and roots that were restricted by layers of soil compaction. Additionally, our agronomic staff has observed poor root development due to compaction and smearing of the seed furrow at planting. I visited several fields with signs that field work was performed when soil conditions were too wet.

 Keep in mind compaction can cause significant yield loss. In a Penn State Extension Article titled: “Avoiding Soil Compaction” Sjoerd Willem Duiker states: “In a summary of the international soil compaction project, compaction due to axle loads of 10-12 tons reduced yields approximately 15% in the first year, decreasing to 3-5% 10 years after compaction.” Not only does a compaction event cause yield loss in the growing season it occurs, but also for several years following that event.

Growers can minimize the chances of soil compaction through management practices such as maintaining proper tire pressure, reducing tillage, using controlled traffic, etc. However, soil compaction is most likely to occur when soils are near or at their water holding capacity (field capacity). In years where planting is delayed, it can be tempting to perform field work when the soil moisture is “marginal” to finish planting in a timely manner. Keep in mind performing any fieldwork in wet conditions can cause significant and long-lasting yield loss and field work should not be performed when soils conditions are too wet.

Another critical soil issue that should be monitored is soil pH. Soil pH impacts the availability of key nutrients for the plant as well as microbial activity in the soil. While the ideal pH for each crop will differ, soil scientists generally recommend a range of 6.0 to 6.8 for mineral soils. In soils with low pH, the availability of nutrients such as nitrogen, phosphorus, and potassium will be reduced. Additionally, in soils with a pH below 6.0 soybean nodulation and nitrogen fixation are negatively impacted as well. In fields where symptoms of nutrient deficiencies are present, it is a good idea to determine what the soil pH is.

Finally, with regular large rainfall events, soil erosion is another problem that we need to continue to manage. It takes many years to build healthy, productive soils, and a large rain event can remove a significant amount of topsoil in a short amount of time. In the 2017 Farm Progress article “Economics of soil loss” Kurt Lawton states: “The average soil loss rate is 5.8 tons per acre per year…Over 10 years, 0.37-inch topsoil loss totals about $12,225 in lost yield and nutrients on 40 acres (given 5.8 tons per year average)…When no-till and cover crops are used, that cumulative erosion cost drops to $500 per decade, on that same 40 acres.” Soil erosion is costly, and it is important to take steps to minimize it. Management practices such as strip-till, no-till, and the use of cover crops will reduce soil loss and improve soil structure and health, all of which you can learn about with a shovel.

Many factors affect the soil’s ability to support a productive crop. As we look forward to the 2025 growing season, it is important to keep in mind how our management practices impact the soil and what we can do maintain healthy topsoil that can supply our crops with nutrients and water throughout the growing season.