Attempts to quantify the gain in OM have been elusive, and the subject is full of ambiguity, so this post will basically be antidotal. There are no records showings OM content on this property for cropping years prior to CRP. The top picture is of soil from the 25 year old CRP recently seeded to spring barley with the CrossSlot. The bottom pic is ≈ 100' away, across a property line seeded to spring barley. This soil has been one pass, DS for 20 plus years. The soil in the bottom pic is in poorer condition because it had less makeup soil available than that represented in the top pic during it's cultivated years. This spring we took a 4 foot sample and ran a series of tests for various nutrients and soil conditioning factors. The pics are fair representations of what I saw. The following stats are: Top pic -- pH of 5.8 and OM of 3.20. Bottom pic -- pH of 6.35 and OM of 3.12.
Commentary on top pic:--- This soil is heavy with worm castings. When turning the soil it breaks up into small clumps -- very friable. It has a sweet pungent aroma. It has a high moisture level (wet). High density of fine roots.
Commentary on the bottom pic:--- This soil is clumpier, showing more stickiness, less friability, and a lighter color. Good moisture, but not like the top pic. Not as sweet aroma as the top pic. Fewer roots. Note the pH is higher and OM is a little lower. The pH is probably higher because of more subsoil mixed into the top layer, also, giving it a lighter color. The OM is lower because, even though this area has been DS for 20 plus years, it has been in a three year rotation, and fallow is part of that rotation. Oregon State research shows that the fallow year lowers soil health more than the two DS crops can build up. We are lucky to have as good a number as we have. Both sets of numbers are in line with what I would expect. A couple of hundred feet away, a neighbor conventionally tills his field. I don't have any numbers from him but I would expect they are similar to the bottom pic -- maybe slightly less for both pH and OM. If the CRP had been managed like a crop, with added fertility, more biomass would have developed to feed more micro-biological communities. OM probably would have been some higher.
OM is difficult to build. (click OM on a label for accessing other posts on the subject.) The Oregon study was a real downer for me. It was the catalysis to upgrade our cropping system from high disturbance DS to ultra-low disturbance DS. At this point, we have the stripper header (attempt to reduce evaporation), the CrossSlot drill (attempt to reduce evaporation). Expanded crop rotation, and inter-seeding crops, and seeding cover crops will be next. The purpose is to build bio-mass, feed the micro-biological community, hold more water, recycle nutrients that have gone below our normal root zone, and start manufacturing nutrients (like N). The short version ---Build Soil Health for future production with less dependency on commercial inputs, and remove fallow from the rotation.
Commentary on top pic:--- This soil is heavy with worm castings. When turning the soil it breaks up into small clumps -- very friable. It has a sweet pungent aroma. It has a high moisture level (wet). High density of fine roots.
Commentary on the bottom pic:--- This soil is clumpier, showing more stickiness, less friability, and a lighter color. Good moisture, but not like the top pic. Not as sweet aroma as the top pic. Fewer roots. Note the pH is higher and OM is a little lower. The pH is probably higher because of more subsoil mixed into the top layer, also, giving it a lighter color. The OM is lower because, even though this area has been DS for 20 plus years, it has been in a three year rotation, and fallow is part of that rotation. Oregon State research shows that the fallow year lowers soil health more than the two DS crops can build up. We are lucky to have as good a number as we have. Both sets of numbers are in line with what I would expect. A couple of hundred feet away, a neighbor conventionally tills his field. I don't have any numbers from him but I would expect they are similar to the bottom pic -- maybe slightly less for both pH and OM. If the CRP had been managed like a crop, with added fertility, more biomass would have developed to feed more micro-biological communities. OM probably would have been some higher.
OM is difficult to build. (click OM on a label for accessing other posts on the subject.) The Oregon study was a real downer for me. It was the catalysis to upgrade our cropping system from high disturbance DS to ultra-low disturbance DS. At this point, we have the stripper header (attempt to reduce evaporation), the CrossSlot drill (attempt to reduce evaporation). Expanded crop rotation, and inter-seeding crops, and seeding cover crops will be next. The purpose is to build bio-mass, feed the micro-biological community, hold more water, recycle nutrients that have gone below our normal root zone, and start manufacturing nutrients (like N). The short version ---Build Soil Health for future production with less dependency on commercial inputs, and remove fallow from the rotation.
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