“First and foremost, we are not agronomists. We are farmers that took an interest in the soil health of our farm.”
Liming and Soil Health
Written by Cole Carda, agronomist, Pinnacle Agriculture of Aberdeen, SD
When we talk about lime, we are referring to calcium carbonate. Calcium is not only a secondary nutrient required for plant growth, but also responsible for soil characteristics. Numerous soil characteristics intertwine with the calcium balances within our soils. Characteristics such as, per hydrogen (pH), water and oxygen infiltration, salt accumulation, soil hardness upon drying, and many more.
Why have lime applications become more common? Historically many soils had rich deposits of calcium due to the glacial till era. Up until the last few decades, soils deposits in root zones have begun to run out. For example, look at the soils that have been farmed for a longer period of time in the United States. These areas have been liming soils for many years already to maintain production goals. As crop production goals continue to increase, nutrient applications rates have increase greatly as well. Higher nitrogen fertilizer application rates are a major contributor to calcium leaching out of our soils. Nitrogen fertilizers, such as anhydrous ammonia, urea, ammonium sulfate, monoammonium phosphate (MAP), Diammonium phosphate (DAP), Urea-Ammonium Nitrate (UAN), and many others, create acidity within our soils and drives calcium deeper into the soil profile. Any plant growing out in a field or pasture creates acids to acquire nutrients from the soil, which also drives calcium out of the root zone. Aside from driving calcium deeper into the profile, plants are utilizing calcium as a nutrient for growth. Gradually year over year, calcium is lost within our soils and are rarely replacing what is being used up.
Calcium within your soil will be quantified on a basic soil sample, which will give you the parts per million (ppm) of calcium within your soil. Calcium must be looked at deeper than just a ppm reading, since the function of calcium within a soil relies heavily upon other nutrients within the soil. With this in mind, the base saturation percentages commonly on most soil tests will help in realizing a calcium balance issue. Base saturations within a soil test measures the amounts of cations (positively charged nutrients), which are present on our soil exchange sites. By looking at base saturation percentages of calcium compared to magnesium, potassium, hydrogen, and sodium, soil tests can begin to tell us where we should plan to start utilizing lime (calcium).
For example, if you have a clay loam soil type which seems to get very hard and tight once the soil starts to get dry, there is a high probability of soil balance issues. In looking at the base saturation percentages, soils that tend to turn very hard have a higher magnesium percentage and a lower calcium percentage. High magnesium percentages cause clay particles to disperse and not aggregate, which in dry field conditions lead to declined rates of air infiltration, water infiltration, and suppression of root development. Soils low in calcium suffer the most from these effects. The introduction of calcium will cause those same clay particles to aggregate and create soil stability, which increases air infiltration, water infiltration, and healthy root development. The most negatively impacted by high magnesium levels are air and water infiltration. Higher water infiltration will ensure stable moisture within the root zone, plus lower probability of surface water drown out areas. Air infiltration impacts root development and soil health by limiting oxygen within the root zone, which will greatly reduce soil microbial health. Unbalanced soils, which do not let oxygen into the root zone, will react just like drowned out areas within the field. Both unbalanced soils and drowned out areas kill a plant from lack of oxygen within the root zone. In legume crops, we rely upon rhizobia to fix nitrogen to feed the crop. If we do not have air flow into the soil to allow the rhizobia to fix nitrogen or have vigorous establishment, how can we expect legume crops to succeed? Areas such as these gradually grow over time due to less root growth which further compounds troubles within these areas, further decreasing productivity and soil health.
Too much of a good thing can be a problem as well. When looking at soils which will need amending, over application of lime in areas can create many issues as well. When amending soils, flat rate applications are never recommended since soils and soil types can fluctuate greatly across a field. Overapplication of lime can cause sandier soil to percolate water too quickly or potentially tie up other soil nutrients needed for plant growth. Develop variable rate management zones to maximize lime applications, without overapplication in areas that do not warrant soil amendments. In high lime application areas, I would recommend gradual applications over 2-5 years. Very high application rates in a single year can shock soil microbe life and cause calcium overload issues, such as reduced plant nutrient uptake and reduced soil particle nutrient exchange.
In conclusion, don’t be afraid to ask questions around lime applications and what it can bring to your operation. Look at both troubled soil areas as well as high producing areas via soil sampling and visual comparisons to see how lime could benefit you. As crop production continues to intensify and soils begin to become more unbalanced and calcium depleted, how much production loss potential can an acre sustain?
Why Applying Lime Became Important to Us
For the past 10 years or so, one of our neighbors has been spreading lime on his fields. He would try to explain the benefits to us, but when we would talk to our local co-op agronomy department, they didn’t feel there was a need for lime.
Four years ago, we decided to hire Robert Corzatt, Crop Consultant and Owner of Harvest Max (harvest-max.com) in Stronghurst, IL. We wanted him to give us an independent summary of our soil sample results. In their opinion, we needed lime! It was at this point, we started doing more research on our own. Some of this research we have linked to this website for you to review. REVIEW HERE.
We also did extensive research on different lime products. We settled on water treatment lime because it’s readily available at many municipalities and it can be applied at a mere fraction of the cost of commercial lime. You can find an analysis of this lime on a link in this website. You could also get a sample from the water treatment plant near you and send it to a lab of your choice.
Since we grid and zone sample our fields it was clear that not all the fields would need lime application. Therefore, we apply with variable rate technology, so we don’t apply lime on acres that don’t require it. Applying with variable rate application is more economical.
