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Dairy Sense: What Is Soil Health?

Soil health affects soil fertility and production potential, which affects crop yields, quality, and production costs.

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Updated:

March 8, 2023

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July 2018

Production perspective

Animal health is typically the focus on dairy operations as it has a significant impact on growth and production. Considering the big picture view of a dairy, soil health should garner the same amount of attention. Poor soil health can have a ripple effect on soil fertility and production potential, which affects the quality and yield of crops raised as well as their unit cost. The challenge is “soil health" has become one of those buzz words used way too frequently. When asking people to define this term, there are a lot of differing responses. Some are very simple and precise, while others are more involved and complex. So what aspects determine if soil is healthy?

Penn State specialists Dr. Heather Karsten and Ron Hoover from the department of plant science provided a framework for describing soil health. Components include soil fertility, nitrogen (N) content, soil organic matter (OM), structure and porosity, compaction, and biological activity. Problems in one or more areas can result in less than optimal crop quality and quantity.

Soil testing for fertility nutrients is a relatively simple process, however it is done very infrequently on many farms. Most universities recommend testing each field at least once every three years. Like the concept of forage and feed analysis, which give guidance on how to feed the cows, soil tests help determine what is needed for fertilizer. Soil pH, phosphorus, potassium, and magnesium should be in the optimum test range for the crop to be grown in each field. Nitrogen is an important nutrient for optimizing crop yield and quality, but it is a very dynamic element. Soil N measured at any one time may not provide a good indicator of availability. Field history of organic N inputs from legume crops, livestock manure, and cover crops can be used to estimate its availability. There are various in-season sampling methods that can be used to estimate early season plant available N for corn.

Soil OM provides a good snapshot of soil health and is therefore often used as an indicator. However, this test is not always included in standard agronomic soil tests, but can be requested. Changes in soil OM are best monitored when the soil sample is consistently taken at the same time of year, typically every 3 to 5 years. The soil OM will vary with soil texture, climate, and cropping system, but by monitoring it over time, one can determine if management practices are maintaining or increasing OM. If soil OM is declining, reducing tillage frequency and intensity, integrating perennial crops and cover crops, and applying manure and compost are practices that have been demonstrated to improve OM.

Soil structure and porosity tend to increase with soil OM as they typically benefit from many similar cropping practices, particularly maintaining continuous plant cover with perennials and cover crops, as well as reducing tillage. Maintaining sufficient pore space helps with gas exchange, storing water, and resisting compaction. The latter can cause a lot of damage to soil structure with the result affecting crop performance. There are hand-held penetrometers that identify compacted zones in soils. Readings of 300 pounds per square inch are recognized as very compacted. Ideally, readings should be 200 pounds per square inch or less for optimal crop performance.

Soil biological activity is also associated with increases in soil OM and particularly with amendments of readily decomposable plant residues and manure and with plant residues that have a low carbon to N ratio (ex. legumes). Soil organisms such as earthworms, fungi, and bacteria promote many soil functions that improve soil structure and potentially reduce nutrient inputs as well as inputs to manage crop pests.

Maintaining and improving soil health is the first tier in optimizing feed quality and quantity. The next phases include management practices to control insects, weeds, and diseases, followed by harvesting at the proper stage of maturity. There are many facets to producing high quality forages and grains at yields needed to maintain ration consistency for the cows. It is no surprise that operating a dairy is an extremely complex and difficult endeavor. Attention to details in all areas is needed if farms are to remain sustainable during difficult market situations.

Action plan for improving crop quality and yields

Goal – Develop and monitor a cropping program that includes assessment of soil health, insects, weeds, diseases, and harvest management.

Step 1: Evaluate both the historic and current quality metrics for home-raised feeds and determine opportunities for improvements.
Step 2: Evaluate both historic and current yields on home-raised feeds and determine opportunities for improvements.
Step 3: Work with a crop consultant to develop a plan for soil testing and monitoring fields for insects, weeds, and diseases.
Step 4: Maintain records for each field including precipitation and temperature during critical periods of the planting and harvesting windows.
Step 5: Evaluate management practices during harvest and storage to avoid excessive feed losses or improper fermentation.
Step 6: Incorporate metrics on the cropping program into advisory team meetings on a regular basis.

Economic perspective

Monitoring must include an economic component to determine if a management strategy is working or not. For the lactating cows, income over feed costs is a good way to check that feed costs are in line for the level of milk production. Starting with July 2014's milk price, income over feed costs was calculated using average intake and production for the last six years from the Penn State dairy herd. The ration contained 63% forage consisting of corn silage, haylage, and hay. The concentrate portion included corn grain, candy meal, sugar, canola meal, roasted soybeans, Optigen, and a mineral vitamin mix. All market prices were used.

Also included are the feed costs for dry cows, springing heifers, pregnant heifers, and growing heifers. The rations reflect what has been fed to these animal groups at the Penn State dairy herd. All market prices were used.