[Update 11/28/14] Cover crop potential in CRP: We are starting to take-out fields of CRP. Last year two fields went back into crop production. This coming summer we will take out 1-2 or 3 fields. I now, am scouting fields with a more critical eye. Instead of just looking for weed types with related location and density, I'm now looking at residue. Because we haven't regularly put money into these CRP stands (fertilizer and herbicides), the actual volume of surface residue is quite low. A lot of dirt showing! In part, this condition is due to worm activity. The vertical borers (night crawlers) pull a lot of material below the surface. The top portion of the soil profile in our CRP is all worm castings.
To help develop Bio-mass, and increase N in our CRP stands prior to takeout, my thinking is that we should inter-seed a mix of 1-3 legume cultivars for an N source, a tillage radish, possibly a canola or mustard to pull nutrients and moisture from deep in the profile. We should have considered inter-seeding these cultivars last spring. This would have given a full years worth of growth prior to takeout. Seeding this coming April and with planned takeout in May-July, the growth may not be sufficient to achieve desired results.
"Cover Crops" (CC) go by a number of names but all boil down to keeping something growing on the land as many days in the year as possible. This is a hot topic in many of the farm magazines. Nearly all of them are of mid western origin. For the last couple of years I have been reading about them and the potential they offer, but have always agreed with the critics that it will probably work in the midwest with all their summer moisture, but not in our climate. I'm not so sure now. The last Direct Seed/Oil Seed Conference in Kennewick did shed some light on how it may be possible to successfully introduce cover cropping into our cropping system. Statements like: "look for opportunity," "introduce species to accomplish a specific goal," " stands don't have to be heavy/thick," "cover crops don't need to be large," "cover crops gain you more moisture than you lose," "a cover crop takes only 1.5" of moisture," is helpful in opening up the thought process to at least consider them.
The question for me has always been how do you get your cash crop germinated with a cover crop taking your seed depth moisture? Well, consider: l)--look at breaking with tradition on seeding dates. We are already using that technique to some extent to assure a successful seeding of our fall wheat. 2)--Use 30-60 day weather forecasting to discover opportunities. We already give this consideration for fall seeding. If the fall looks dry we move our seeding date up. 3)-- Consider stopping the CC before it enters the critical moisture level for the cash crop to germinate. Cultivars vary in their high moisture use stage of growth, as well as the depth they tend to pull most of their moisture.
Interseeding another cultivar in an established crop is another avenue to consider in attempts to build soil health and biodiversity. Doing this is probably farther out of box than cover cropping. Cover cropping was done to some extent in the region prior to commercial fertilizer(≈1940). Sweet clover was a favorite cultivar to plow down. Interseeding a biodiverse crop into a spring barley crop prior to jointing may have potential if you use an Ultra-low disturbance drill, and choose a cultivar that emerges fast and grows slow and has it's high moisture use late in it's growth cycle. Hopefully one that could provide nitrogen for the following cash crop.
How do we remove fallow from our rotation?????? Well, we won't start any of this with big acreage. We do have a perfect test acreage of ≈67ac. It includes mostly shallow, diverse soils, with approximately 15" rainfall. I am adding "Links" as I find information that appears to be helpful about growing cover crops in our area. There are several studies in the Pullman, St. John, and Davenport, Wa. area on cover crops.
