Have you ever picked up a piece of plastic or tin that has been laying on the ground all winter only to find that the ground is a lot of wetter than the ground that was not covered? That is because the tin/plastic has insulated the ground and the moisture was unable to evaporate. Cover crops do the same when planted thick enough to shade the ground. I know what you are thinking, “planting a crop that uses moisture to conserve moisture does not make sense.” This statement is true, but it does not use as much moisture as one would think. In our own trials, in Rice County, we have seen moisture retention between a cover crop planted into standing wheat stubble and standing wheat stubble only differ by 5%. While the clean tilled ground is 10-15% below both the cover crop and standing wheat stubble. The cover crop is using moisture, however, it is far below what we had anticipated.
Phase two of the trial is to see if there are any nutrients being re-deposited from the 8-12” soil zone into the 1-8” zone. This is done with soil samples, the first of which were taken at planting on September 1st, the second will be taken in late November and another will be taken in February.
Phase three of this test is for the utilization of the cover crop as a grazing tool. Our intention is to weigh a set of cattle prior to them grazing the cover and when they are pulled off the cover weigh them again to calculate a rate of gain. Stay tuned…….