Soil Matters – Is Your Sample Yielding the Best Results?
Producers use soil sampling and testing to increase fertility for future crops or grow crops by measuring soil fertility levels. Soil testing can improve farming operations economically and environmentally. Implementing the nutrient stewardship practices of the 4R program: The Right Source, Rate, Time, and Place further supports the benefits of soil testing. Identifying the Right Source and Right Rate are most influenced by the results of your soil sample and through your nutrient recommendations.
How Do I Know Which Method of Soil Sampling Is Best for My Operation?
Producers can use results from soil tests to increase their financial returns through more effective use of nutrients applied. Traditionally, producers have collected their own samples by collecting various soil samples from an area of a field with consistent nutrient application and cropping history.
These samples were then sent to a soil lab as a composite sample and the analysis was returned to the producer. That analysis was then developed into a uniform nutrient application plan for the field used by the producer in the upcoming cropping season.
With advancements in technology, soil sampling and testing has improved applicable data for producers. The use of precision agriculture has changed the goal of soil sampling from developing an average of nutrient needs for a single field to developing nutrient plans for multiple areas within that field. This approach pinpoints where and what nutrients are needed instead of approaching the field with a blanket nutrient application.
Producers who are interested in advancing their soil testing practices may want to check with their custom fertilizer applicator and/or ag retailer to see what methods are best for their specific operation.
The optimal time for collecting soil samples is after the completion of harvest and prior to pre-planting activities such as spreading of litter/manure, fall application of nutrients, etc. It is also good to allow time for processing of the samples and developing the nutrient management plan.
How Do I Know Which Soil Tests to Request?
The following are some standard tests recommended by the University of Missouri’s Extension Soil and Plant Testing Laboratory. Because of the vast diversity in Missouri soil types and plant nutrition needs, producers would likely benefit from a consultation with their custom fertilizer applicator, ag retailer, and/or local University Extension office for specific soil test recommendations
Regular fertility tests
For a general analysis of a soil’s fertility, a regular soil test package should include
- pH
- Neutralizable acidity
- Phosphorus
- Potassium
- Calcium
- Magnesium
- Organic matter
- Cation exchange capacity
In certain cases additional tests may be necessary:
- Micronutrients
Zinc, iron, copper and manganese
Micronutrients may be desired in high pH soils - Sulfur
Sandy soils low in organic matter may have sulfur deficiency - Salt content (electrical conductivity)
Soils with salt problems should be tested for salt content (e.g. salt or fertilizer spills, heavy applications of manure, irrigating with alkaline water can lead to salt problems.)
These testing guidelines were repurposed from the University of Missouri Extension Soil and Plant Testing Laboratory.
Sources:
https://cropwatch.unl.edu/ssm/soilsampling
https://lgpress.clemson.edu/publication/precision-agriculture-based-soil-sampling-strategies/
https://extension.missouri.edu/programs/soil-and-plant-testing-laboratory/spl-soil-analysis
For producer case studies and more information about how nutrient stewardship can be implemented, visit www.4Rfarming.org.