Fact: --there is a layer at the soil surface, even though it looks dry, that is at 100% humidity. This layer may be only 1-2micro's thick. This layer is maintained until the soil profile can no longer draw on it's reserves. How you manage this soil surface environment has a big impact on evaporation and the moisture available for the crop.
Fact: --residue modifies soil temperature. Soils are warmer through the winter and cooler during the summer with surface residue either standing or flat.
83% of rainfall over a two year wheat/fallow rotation is lost off the soil surface through evaporation. (see post of 9/19/2012)-- conclusion was to keep soils as cool as possible and air velocity across the soil surface as low as possible. This translates to, --maintain as much cover as possible over the soil, and keep the cover as tall as possible, for as long as possible, to maximize moisture available for crop production.
Our observations over 4 years indicates considerably fewer weed cultivars germinate and compete with the crop on ground that is not disturbed. The more residue, the less disturbance, including disturbance from tracks/wheels, the better.
THE LONG:
1-- Removing the straw row of a poor residue managing combine, is a major plus. It gives new life to older machines and increases capacity by 10-20%.
---There is much less material being processed. This has resulted in significant savings for us in combine repairs.
2--Potential increase in moisture available to the crop by:
---increasing snow catch (when we get it) over the standard cut or mowed height. This resists snow drifting, leaving more even snow (water) distribution over the field.
---Accompanied with solar energy which warms the stems, the snow melts and enters the soil at the base of the plants in a slow controlled manner.
---reduced weed competition when used as part of the ULD system. Fewer weeds, leaves more moisture for the crop. Less surface disturbance including wheel tracks, the fewer the weeds.
---reducing air velocity over soil surface. Studies are showing reduced evaporation from tall stubble. This means more moisture for the crop.
---reducing soil temperatures in the warm season. Several studies, including our own measurements with HOBO sensors show significant drop in summer surface temperatures compared to bare soil. Studies concur, that lower soil temperatures conserves moisture for the crop.
3--Modifies winter soil temperatures. Our HOBO sensors are showing that tall stubble insulates the soil, not only in the summer to reduced soil temperatures, but also insulates the soil from the cold winter temperatures.
4--The Shelbourne is a low maintenance header for us.
5--The Shelbourne, being a sealed unit, reduces harvest dust around the combine cab.
THE SHORT:
1--Is not useable for all the crops we grow.
---spring standup peas: grade reduction from cracked/skinned seed coats.
--mustard/canola: problematic if stems carry seed pods extending more than 24 inches along the plants vertical axis.
---crops with seeds forming around a central stem like sorghum.
2--Not all drills will successfully seed behind the stripper header. Type and density of residue needs to be considered.
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