Impact of Soil Compaction on Soil Physical, Hydraulic Properties and Yields
Soil compaction due to cultural operations is an acknowledged problem in the Northern Great Plains (NGP). Mollisols soils (mostly Typic Agriborolls), common to the region, are easily compacted at medium to high moisture contents. The most common causes of soil compaction or hardpans are tractors, harvesting equipment and implement wheels traveling over moist soils. Several researchers have found that approximately 80% of soil compaction from wheel traffic occurs on the first pass of a tire.
Soil compaction can reduce plant growth, reduce root penetration, reduce root size and distribution, restrict water and air movement in the soil, result in water and nutrient stresses and cause slow seedling emergence. Research has shown that compaction can reduce yields up to 50% in some areas depending upon the depth of compaction and its severity.
The impact of soil compaction on soil's physical condition is evident through the reduction of soil hydraulic properties such as infiltration rate and hydraulic conductivities. This can lead to excessive runoff and soil erosion, temporary perched water tables, deep wheel tracks and traction problems with self-propelled irrigation systems. Soil compaction also contributes to the lateral redistribution of applied water and chemicals from high to low lying areas within a field. Excessive water accumulations further reduce yields and/or crop quality by stresses due to excessive soil moisture (opposite problem) in the low areas. These water collection areas are believed to be the major locations where leaching of pollutants to the water table occurs. This is all compounded by spatial variability of soil texture, slope, pest infestations, various nutrients, crop growth patterns and rooting characteristics, furrow orientation and even center pivot wheel tracks.
The development of farming practices that minimize soil disturbance and compaction are essential for maintaining soil structure and eliminating the need for radical post-harvest soil treatments. Therefore, research is needed to develop best and sustainable agricultural management practices that prevent/reduce soil compaction, improve soil physical and hydraulic properties and improve the ecological and environmental sustainability of agronomic crop production in the NGP.
To meet these goals, we have established field experiments to quantify spatial and temporal distributions of soil compaction (penetration resistance) under various dryland and irrigated crop sequence, tillage and irrigation management systems, and to help assess their interaction on soil physical and hydraulic properties as well as the yield and quality of sugar beets, potatoes, and malt barley.