Evaluation of Planting Density on Soil Compaction.

EVALUATION OF PLANTING DENSITY ON SOIL COMPACTION

Steven Yergeau, Ph.D.

 

ABSTRACT

Compaction is a major problem impacting soil health in agriculture and horticulture, with compacted soils also hindering water infiltration through underlying soil, creating larger volumes of runoff and increasing flooding.  While many methods for mitigating compaction are available, one option that has not received much evaluation is the use of vegetation after soil compaction has occurred.  Plant roots growing through soils have the potential to create additional pore spaces to facilitate water infiltration and decrease compaction.  The objective of this study is to assess the impact increased planting density of vegetation has on compacted soils under unmowed conditions.  Three test beds with four different densities of switchgrass (Panicum virgatum; at 0, 9, 25, and 49 plants per square meter) were created and monitored for soil compaction and soil water content prior to planting and then on a monthly basis during the growing season (May – September).  Soil compaction was measured using a handheld static cone penetrometer and reported as the depth reached when soil resistance is 300 pounds per square inch.  Immediately after planting, compaction levels in all plots were not significantly different from each other, regardless of the presence or absence of vegetation, but did show an improvement on compaction when compared to the previous condition of mowed turf.  Results indicate that plots with vegetation had compaction levels that were significantly different than plots without vegetation at the end of the growing season.  A strong relationship between soil water content and compaction was observed during the study period.  Additional work covering additional growing seasons and additional research plots, and use other methods to measure compaction (i.e., ground penetrating radar) for a more accurate assessment of this mitigation strategy is being undertaken.