<---- Pic on the left is an example of 2021 WW on ULD grnd. This area was seeded too shallow and got a late start.
This winter/spring I had a unique opportunity to run a lab test on two soils that have very different history. One soil has ~30 years of no-till, with the last eight years being ultra-low disturbance no-till. The other field, a couple hundreds yards away has a history of one hundred plus years of conventional tillage/cropping, with no no-till history. Both locations were fairly level with low erosion from weather, although a difference in tillage erosion would be apparent. The no-till field has a large amount (mat) of residue, and the tilled field has a small amount (a lot of open ground) of residue. I had high expectations of seeing a dramatic difference in OM, EC, BD, Respiration, and some differences of several macro and micro nutrients. WHAT A DISAPPOINTMENT!! Some numbers were the same, and some showed slight differences, but all in all, no revelations. This lab is not the general run of the mill type that we are all accustomed to. I have used this lab for a couple of years for different projects.
Physically there is a world of difference between these two fields. April 13th with no measurable rain since March 23rd the ULD grnd was soft to walk across, where the tilled field was hard under foot. Sinking a 1"diameter soil probe into the ULD field was easy, down the full 4 ft length of the probe, where the conventionally tilled field was very difficult down to ~18", where resistance eased up (maybe even softer than the ULD field in the lower 2'.
Why didn't the lab show differences as expected? Two things come to mind. 1)- In my mind this was such a no brainer that I was careless taking the samples. My process of taking an undefined slice of soil using a narrow trenching shovel was bad technique. A lot of possible error could result. 2)- This supports my comments on earlier posts about lab testing, and difficulty in trying to show value of no-tilling through our long recognized lab protocols.
I'm convinced that no-till deals primarily with the physical component of soil health, but secondary to other processes like biological diversity and nutrient recycling. Biological activity has to be helped with cover crops and possibly reintroducing microbiological species through well prepared compost and compost teas. No-till is significant in improving soil drainage, and it reduces destruction of soil organisms community life. No-till is the first step required for us (in the Palouse) in developing a healthy soil. With few exceptions, our environment will not support tillage and develop a healthy soil. Comparing infiltration rate, wet aggregate stability (SLAKE test), visual soil structure, and earthworm count is easy to do and shows dramatically what no-till brings to the table relating to soil health. Bulk density should be an easy comparison, but the penetrometer is effected by moisture content, soil type and other factors that vary from point to point. So, what do I conclude? As many of my earlier posts mention, a no-tillage farming system, is very effective in building soil structure over time. A no-tillage farming system, when coupled with high surface residue (soil armor) is very effective in controlling erosion from tillage, water, and wind. A no-tillage farming system is helpful in slowing evaporation when coupled with a protective mat (soil armor) on the ground, and even more effective if also coupled with standing stubble. Moisture is lost principally through evaporation, not crop production. Keeping soil surface temperature down, and a low wind velocity along the soil surface, saves moisture that can be used by the crop. Another benefit to a no-tillage system and heavy mat of residue is reduced competition from weed species, either broadleaf or grasses. We see it consistently year after year when comparing our neighboring fields with either conventional tillage or high disturbance no-till. Unfortunately, we still have to apply herbicides like everyone else.
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