Soil Sampling Strip-Tillage Practices

Traditional soil sampling has a few common goals when the puller meets the field.  Consistency, uniformity and repeatable locations, all play a large role in good sample data.  How are these standards still applicable to a situation where fields are purposely not uniform and consistent?  By implementing strip-tillage practices, a microclimate is formed in the strip. 

Strip-tillage is a broad term.  Its classification comes from manually creating a banded tillage strip instead of other forms of disruption.  It could also indicate with or without fertilizer.  In a conventional tillage system, the whole area is worked as uniformly as possible.  This could be for multiple reasons such as residue, pesticide and fertilizer incorporation, seedbed preparation or the constant losing battle against compaction.

On some farms the goal changes from uniformity to concentration.  These same growers are generally wanting to band fertilizers, minimize erosion, and build organic matter.  By creating a concentrated strip on tillage and fertilizer placement, the residue is left between the rows.  This keeps the benefits of no-till and maximizes fertilizer placement.  One of the tougher challenges to strip-tillage is keeping soil sample data consistent.

Soil sampling the same spot/area after the same crop every time creates a trend for soil tests.  From here, an accurate recommendation can be made for the best return on grower’s investments.  Banding fertilizer is not the only alteration strip-tillage creates.  The tillage aspect itself will change the soil’s physical, chemical, biological and water infiltration properties compared to the soil not being disturbed between the rows. 

One way to sample strip-tillage acres is to increase sample core volume.  Traditionally, a field is sampled 15 cores per sampling location.  This is then mixed in a non-reactive bucket and placed in a soil sample bag to the fill line.  For strip-tillage, five soil cores are sampled perpendicular to the rows.  One slightly off center of each the right and then left rows, and three between the rows.  This is then mixed for one composite core.  As one could tell, this is very inefficient but necessary to have the best soil data.  There are many types of strip-tillage practices and each may need different sampling methods.  For tillage only, sample as normal.  If the bands are moved each year, take more cores in the sampling area.

One way to be more efficient, and possibly even more accurate, is to separate the rows and in-between the rows separately.  This will show what the nutrient levels are in each environment.  Certain nutrients must stratify, like the surface in no-till, and then move to the soil between the rows.  Either way, the same amount of nutrients must be applied as it was with a blanket spread.  With crop removal rates, it may not be too much at once, but for build recommendations, a split application of fall then spring will have to be used on some soils, regions, type of fertilizer and crop being planted.