Defining a Healthy Soil
“Soil health is defined as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans”. – NRCS.1
Four Characteristics of a Healthy Soil
Optimal Water Management
- A healthy soil will be able to hold sufficient water to support crop production, while being able to shed excess water quickly to avoid damage to the crops. Water is essential to all life. Plants and soil biology need water to survive and function. Yet too much water can limit normal air movement in the soil and reduce the growth of plants and soil biology.
Good Physical Structure
- A healthy soil physical structure is characterized by good soil aggregation, good aeration and lack of compaction. Adequate soil physical structure or tilth allows for good infiltration and storage of water, proper nutrient cycling, and provides a good habitat for soil biology.
Robust Soil Biology
- A healthy soil will have a robust and diverse biological community. Soil biology, such as, bacteria, fungi, earthworms, and many other living organisms, are an extremely important part of the soil ecosystem. They are responsible for breaking down organic matter, nutrient cycling and many also form important relationships with plant roots.
Sufficient Soil Fertility
- A healthy soil will be able to supply sufficient levels of nutrients to maintain healthy and productive crops. Plants require a variety of nutrients to grow and be healthy. In fact, many plant diseases can be attributed to a deficiency of a certain nutrient. Managing soil nutrition, making sure that there are sufficient nutrients for the crop when they are needed most, is essential to promote plant health and profitable crop production.
Guidelines for Managing for Healthy Soils
The following guidelines are general recommendations to put into practice to work towards having more healthy soils on your farm. The recommendations are grouped according to the four characteristics of healthy soil that are listed above.
Maintain Optimal Water Management
Remove Excess Water Quickly – Fix primary drainage issues as quickly as possible. If you delay on this, many of the other things you can do to promote soil and plant health will not work well, particularly in the wetter areas of the field. Maintain field ditches and canals, utilize crowning or land leveling appropriate to the field contours, and consider tile drainage.
Improve Internal Drainage and Water Holding Capacity – Utilize appropriate tillage, maintaining crop residues on the soil surface, and utilizing cover crops, will improve soil structure allowing more water to move down into the soil profile. This will have two primary affects. First, there will be less surface water that needs to be removed thus reducing strain on drainage systems and reducing crop injury from ponding water. Second, more plant available water will be stored in the soil profile to be used by the crop during drier periods.
Consider Advanced Systems such as Controlled Drainage Systems, Sub-Irrigation, and Irrigation – Crops need a consistent supply of water. Consider advanced systems that allow you to remove water, maintain water table at a certain level, and add water if needed.
Build & Maintain Good Soil Structure
Remove Compaction – Utilize appropriate tillage to break up compaction layers is the quickest way to solve the problem. Cover crops can, over time, break up compaction but it will be slow, and you will still have to deal with the problem for several years before it goes away.
Keep Compaction Out – Utilize cover crops to maintain plant growth all year, reduce traffic as much as possible, and avoid tillage when soil is wet. This will allow roots to grow deeply through the soil and help will reduce the likelihood that compaction layers will redevelop.
Reduce Tillage as Much as Possible – Tillage damages soil structure by fracturing soil aggregates and by destroying the web of fungal mycelium that help build those aggregates.
Maintain Crop Residues on the Soil Surface – When you must use tillage, use equipment that keeps as much crop residue on the soil surface as possible. This will protect the soil from compaction from heavy rain and will protect soil microbes from UV light and high soil temperatures.
Foster Soil Biology
Utilize Biological Inoculants and Bio-stimulants – Biological inoculants have the potential to provide a strong, profitable crop response quickly and immediately. Biological inoculants that include bacteria, fungi and a microbial food source are likely to have the greatest response.
Produce Healthy Plants All Year Long – Healthy plants produce sugars and carbohydrates that are exuded through the roots that supply soil microbes with an energy source so they can survive and grow. Having this microbial food source available will help build microbial communities and subsequently soil health will improve throughout the year.
Increase Diversity – Utilize longer, multi-year crop rotations, multi species cover crops, and pest resistant varieties can build soil health by breaking pest cycles, by building diverse microbial communities, and by providing different rooting structures.
Maintain Adequate & Balanced Soil Fertility
Soil Sample Regularly – One of the most important tools you need to use is regular soil sampling. This is how you know in detail the nutrient levels in your soils and how best to modify them for optimum crop growth. At IMPACT Agronomics, we utilize a management zone sampling approach based on soil type, drainage, crop and yield history.
For more information on our soil sampling programs please visit: https://impactagronomics.com/production-management-planning/
Utilize the 4Rs of Nutrient Management2
- Right Source – Utilize materials that provide necessary nutrients and do not damage soil microbial communities.2
- Right Rate – Use only what you need. Over application can cause problems such as too much vegetative growth and damage to soil microbial communities.2
- Right Timing – The best practice is to apply nutrients as close as possible to the time that the crop has the greatest need, which is generally reproductive stages of grain or fruit fill.2
- Right Placement – Choose the best placement for each nutrient concern, such as, 2×2 starter, in-furrow, banded, broadcast, etc. Also utilize variable rate technology to address spatial variability throughout the field.2
Utilize Plant Analysis to Fine Tune Fertility Strategies – Plant tissue analysis and plant sap analysis are essential tools to fine tune fertility programs and make adjustment and corrections during the growing season.
1 – Definition from NRCS Soil Health Website. Available: https://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/health/
2 – Adapted from the 4R Principles of Nutrient Stewardship. Available: https://nutrientstewardship.org/4rs/4r-principles/
For more information visit our website: https://impactagronomics.com/soil-health-monitoring/.