Tracking Soil Health With Practical and Cost-effective Soil Testing

Farm operations implementing soil health practices can readily observe improvements to soil structure, water infiltration rates, and water-holding capacity. However, farms wishing to closely monitor changes to the physical, chemical, or biological characteristics of their soils as a result of soil health practices should ensure that soil testing remains simple, practical, and cost-effective. The first step in soil sampling is selecting a sampling methodology and sampling intervals.

After a sampling methodology and sampling intervals have been selected, soil tests should be chosen that can provide practical information on soil characteristics. Some basic tests like soil texture (% of sand, silt, and clay), pH, soil organic matter (SOM), and bulk density can be done using a lab analysis after samples have been collected. Soil health practices will not change soil texture, but they can help to bring pH closer to neutral, increase SOM, and lower bulk density. These basic tests are relatively low cost and can even be done on-farm with the bare minimum of soils lab equipment. Furthermore, soil samples for this set of tests can be collected at any time of year when the soil is not frozen.

In-situ tests, like water infiltration, can be challenging because they must undertaken at a time of year when soil conditions reflect growing season conditions and a series of water infiltration tests across a sampling grid or field zones can quickly add up in terms of time and labor. Other tests, such as respiration can give a good indication of soil biological activity. However, the labor necessary to conduct respiration tests makes them a questionable measure for large numbers of soil samples. Tests for N are of limited utility thanks to the dynamic state of plant-available nitrogen throughout the year and monitoring above ground cash crop biomass (using a methodology like N-Rich) would be a more effective way of monitoring N levels throughout the growing season. Tests for P can be effective, however testing methods must be chosen carefully based on specific soil chemical properties.

In summary, tracking soil health can be done in a cost-effective manner. But sampling methodologies as well as particular soil tests chosen must be simple, practical, easily repeatable, and have low overhead costs.

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