For small cropping: At what percentage slope should one consider terracing?

I have heard many people speak of terracing sloped land they want to grow crops on. Obviously how a patch of land is worked will greatly influence the "need" for terracing...

I have very gently sloped land. I don't know how sloped it is because I've never worried about it. If I had to guess maybe 1-2%? I use only hand tools and work on very small scales (aspiring to a whole one-half acre!), so I can't see any need for them today.

But who knows where life will carry me... I don't imagine I'll be where I'm at for 20 years... so I'm interested in hearing other perspectives. I'm reading about a long-established homesteader in my area whose cultivated land he says averages 6% slope and upwards of 16% slope at the worst. He was concerned about erosion so he did a lot of terracing. He does occasionally use machines like a 2-wheel tractor, but much of his work is all by hand. He also has a knack for overkill in certain endeavors...

I remember reading Edward Faulkner and him reporting that an agricultural researcher (or perhaps a soil scientist? It's been awhile...) reported an interesting observation from the Appalachian trail in areas where the winds and mountains collect, rather than disperse, the tree leaves; that litter is a major component of the soil. The report was that in torrential downpours, even on slopes of 45 degrees (100%!) there was zero runoff.

Granted that's anecdotal and it was on land that was NOT being touched by human activity. But I've got the crazy idea that if you have a huge amount of organic matter in the soil and if you have a generous mulch on top of that, then sloped areas carefully cropped and managed by hand are probably not as prone to erosion as we might think. Of course even if my crazy idea is on the right track there still must be an upper limit on slope. I haven't the foggiest what that might be and I haven't been able to find any data on it either.

Perhaps it's obvious by my asking that I haven't had the chance to take any permaculture design courses :)

Anyone have any thoughts they'd care to share?  

I WWOOF'ed on a farm that had a hilly area that they wanted to grow food on. Their terraces were very simple. Like you, their slope was pretty gentle. All they did was to establish no-till, no-dig lasagna beds that overtime became raised and stopped runoff/erosion. It wouldn't work on steeper grades, but it was a very low-energy solution there.

James Landreth wrote:I WWOOF'ed on a farm that had a hilly area that they wanted to grow food on. Their terraces were very simple. Like you, their slope was pretty gentle. All they did was to establish no-till, no-dig lasagna beds that overtime became raised and stopped runoff/erosion. It wouldn't work on steeper grades, but it was a very low-energy solution there.

Very interesting, thank you! My current raised beds do have lumber frames which will rot out in the not-too-distant future. I still don't have a final plan for when that happens. But a lasagna method could transition them into a natural mounded bed that would resemble terracing...

The slope of my fields averages around 2% to 3%. I don't feel any need or desire to terrace them.

Another area I manage has slopes of 6% to 9% up to 40%. I do a lot of terracing on that property.

Joseph Lofthouse wrote:
The slope of my fields averages around 2% to 3%. I don't feel any need or desire to terrace them.

Another area I manage has slopes of 6% to 9% up to 40%. I do a lot of terracing on that property.

That's a great sanity check, thank you!

On those lands more in the 6%-9% range, do use machinery on those areas? Or are they worked by hand/foot?

My ill-informed, gut-feeling is that anything around 10% slope or more might probably benefit from terracing regardless of the kind of cultivation employed on it...

In examining my neighbor's fields. It looks like 15% slope is about the limit of (machine based) agriculture in my valley. There are a few abandoned orchards that have slopes around 23%. I really feel like I'm living dangerously if I drive a tractor or truck on contour across a 20% slope.

Joseph Lofthouse wrote:In examining my neighbor's fields. It looks like 15% slope is about the limit of (machine based) agriculture in my valley. There are a few abandoned orchards that have slopes around 23%. I really feel like I'm living dangerously if I drive my tractor or truck on contour across a 20% slope.

I would imagine!!

Thank you again for the data points!