ARS | Publication request: SPATIAL VARIATION OF THE DEPTH OF ROOT-RESTRICTING LAYERS IN NORTHERN MISSISSIPPI

Submitted to: Intnl Conference On Geospatial Information In Agriculture And Forestry
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2000
Publication Date: N/A

Technical Abstract: The root-restricting layers present in most Southeastern soils prevent adequate root growth into the soil profile. Reduced root elongation contributes to temporal drought stress which annually limits yield potential in this region. Many farmers combat this layer of soil by annually subsoiling, usually to a depth of 25-40 cm. However, the depth of this root-restricting layer varies greatly from field to field and also within the field. Knowledge about the variation of the depth of this layer will help to determine if application of a uniform tillage depth is the most effective method of soil compaction amelioration. A tractor-mounted multiple-probe soil cone penetrometer was used to determine the depth and force to penetrate the root-restricting layer throughout a 1.56-ha soybean field. More than 70 locations were sampled in this field to determine the variation in the root-restricting layer. The multiple-probe penetrometer extended from a trafficked row middle across the row and into the adjacent untrafficked row middle. Knowing the orientation of the machine, the analysis of the root-impeding layer could include the effect of previous machinery traffic. The root-restricting layer was found to vary greatly from 0.2 m down to 0.7 m. Part of this variation was due to the effect of soil moisture, which was also measured at a 15-cm and a 30-cm depth. The average depth of the root-restricting layer was found to be 0.49 m in the non-trafficked row middle and 0.45 m in the trafficked row middle. The demonstrated variation in the root-restricting layer indicates that applying a uniform tillage depth to an entire field in this region could result in excessive expenditures of tillage energy.