In a normal year, terraces may just be a headache for maneuvering planting and harvesting equipment, but in a wet year they can save a lot of soil, which makes sense if you think about how they were designed.
Cleveland County, N.C., for example, once had the nickname “County of Terraces.” Full of rolling hills and sandy, clay loams, the county had more than 6,000 miles of terraces by 1915. Now the nickname is largely forgotten, but most of the terraces remain.
By all accounts, 2013 was an extremely wet year, and the western piedmont of North Carolina hasn’t been hurting for rain (or snow) this winter. During the past year we’ve seen erosion problems on no-till tracts with plenty of residue—on tracts we’re farmers wouldn’t normally experience problems. On several of these tracts, terraces have been either rounded-off or completely removed.
If staked out by a county agent or soil conservationist, most terraces were sized and spaced to hold at least a 10-year storm without over-topping. Level terraces hold water like a small pond until the water infiltrates the soil, but most terraces in our county have some fall to them and divert water to a stabilized ditch or meadow strip.
The majority of terraces were installed in a time when farm equipment was smaller or “thrown up” by mule and plow. The earlier terraces had a narrow base, with a steeper ridge and channel. These narrow-based terraces were left in permanent sod, and cotton was planted in strips between them. Later terraces where broader based, more rounded, and capable of cultivation. All were intended to prevent water from picking up speed and soil.
The question many farmers face is “What to do with terraces designed in a bygone era?” Obviously, terraces were there for a reason, and if they’re removed altogether soil may start washing. We’ve also seen terraces with tops rounded-off that overtop and bust in a heavy rainstorm. If unnoticed, a busted terrace can lead to a gully quick.
Address the cause instead of the symptom
The answer to the terrace conundrum is sure to vary depending on the field. Staff from your local NRCS office and Soil and Water Conservations District can help brainstorm solutions to fit your equipment and fields. No-till has certainly reduced soil erosion, but this past year has proven it isn’t a cure all. And no-till is much more effective when planted on contour. If planted up and down the slope (which we see quite often), the coulters and disc openers create miniature channels for water to run downhill and pick up speed.
Perhaps one of the more promising solutions is to start addressing the cause instead of the symptom, or addressing soil infiltration instead of soil run-off. NRCS and Soil and Water Conservation Districts have cost-share programs available for farmers willing to try cover crop mixes to improve their soil’s infiltration rates and water-holding capacity. Cover crops can have multiple benefits.
For instance, in a three-way mixture of turnips, rye grain, and crimson clover, the turnips can bust up compacted soil layers, the rye can reduce weeds through natural allelopathic compounds, and the crimson clover can cut down on fertilizer costs by fixing nitrogen. The roots of cover crops improve pore space in the soil, allowing water to move downward. And the added organic matter acts as a sponge. Today some researchers are also turning to cover crops to fight back against herbicide-resistant weeds, especially pigweed.
For more info on the potential of cover crops, check out some of Ray Archuleta’s soil health videos. Ray is a conservation agronomist for the NRCS and is passionate about cover crops.
Both terraces and cover crops are nothing new, but they deserve a second look and shouldn’t be discarded from our soil conservation toolbox in the era of no-till. Like many things, if we toss them out, we just might realize how much we need them.