A Pennsylvania Extension educator has shown that intensive grazing on cropland low in organic matter can rebuild the soil quickly – in a matter of a few years in some cases. The cover crop and grazing practice also led to a “drastic increase in cation exchange capacity and water holding capacity of the soil,” according to the author, Sjoerd Duiker. (Read the article by clicking here).
Cation exchange capacity (CEC) refers to the soil’s capability to store and then provide certain nutrients, like calcium and magnesium, to crops grown on the soil. While soil types tend to dictate a CEC range, building soil organic matter greatly increases the capacity for cation exchange. That, in turn, determines the productivity of the soil and how much fertilizer you need to add.
Duiker said he sees potential for increased profitably by bringing grazing animals back on the croplands in the US. Crop and livestock experts he talked to advised combining nighttime-grazing and daytime stall feeding to allow for continued high milk production (75 lbs/day).
In terms of cover crop varieties used, Duiker mentioned annual ryegrass mixed with triticale for fall and spring forage and other crops like tillering corn, sudangrass, sorghum-sudangrass hybrids and forage soybeans, cowpeas, brassicas and sunnhemp for the rest of the year. He said that perennials are “tremendous soil builders and the annuals add benefits such as meeting forage needs during the summer slump when the weather is hot and dry as well as in late fall, and are a break crop between an old and new perennial pasture stands.”
If you want to build soil without investing much in a cover crop, consider annual ryegrass. A quick-growing, non-spreading bunch grass, annual ryegrass is a reliable, versatile performer almost anywhere, assuming adequate moisture and fertility. It does a fine job of holding soil, taking up excess N and outcompeting weeds.
