Need to slow water on slope, but also need to be able to use riding mower. Got any creative ideas?

I have a 2 acre property that is sloped north to south. The problem area I'm focused on right now is a rectangle roughly 70 by 100 feet, with the slope varying between roughly 10 to 30 degrees. (It's not a smooth slope; there are spots that are much steeper or flatter than average.)

I want to slow down the runoff and erosion when we get rain, both to stabilize this hill, and to decrease the flooding that happens at the bottom of the property. These are my constraints:
1. We get almost all of our rain during the winter and spring, then have a hot, dry summer and autumn.
2. The plants currently growing on this slope are mostly grasses (I believe some sort of rye and oat grasses), with some scattered small broadleaf species. These grasses MUST be kept very short throughout the growing season, in order to go into the summer season with minimal fuel in case of a fire.
3. If I continue to use my mower to keep the grasses short, I can't install swales. The ground needs to be as smooth as possible.
4. I currently cannot get livestock to graze the property, so it's not an option to replace the mower with grazing and therefore allow swales.
5. In theory I could install swales if I also did intense xeriscaping and covered them with thick landscape fabric and rocks/gravel to minimize growth of anything on the hill that I didn't plant myself, but that would be expensive and look barren and hideous. (It's just too large an area to put in enough plantings that it would look nice. It would be so barren.)
6. Controlling the grasses via mulching with wood chips in swales is not an option due to fire risk.

So... any creative ideas for me?

What kind of soil? What grows there?  Can you plant stuff that doesn't require much if any upkeep now or at least two weeks before frost?

Ever heard of Daikon radishes? They will drill deep roots and allow that winter water to get down in the ground. There are many other things you can plant with them. Fella named Gabe Brown does some good you tube vids about soil. Not specifically what you're after but I know they cross over from my own use! Those radish roots have been know to go over 25 feet deep. Plant them now and everything else you can think of or learn of overwinter. You don't even have to till the grass. Just scratch the ground and cover 1/2 to 1 inch. They are also great for eating and wildlife. I've had 22" radishes 2.5" across.. Fixed bad drainage issues here in heavy clay soil.

Some deep cross hill French drains might do the same but costly and not as likely to work.

What sort of slope can you mow with your mower? Maybe you can have more gentle/terraced swales and still mow them.

It sound like you have a Mediterranean climate, so you may find this thread of interest. I believe that by increasing the water content of the soil you can get a benefit in fire prevention too. Swales are just one way of going about that.
As regards grazing animals some are suggested here including borrowing grazing animals and using smaller animals like guinea pigs. Maybe others in the same situation will find it useful.

larry kidd wrote:What kind of soil? What grows there?  Can you plant stuff that doesn't require much if any upkeep now or at least two weeks before frost?

Ever heard of Daikon radishes? They will drill deep roots and allow that winter water to get down in the ground. There are many other things you can plant with them. Fella named Gabe Brown does some good you tube vids about soil. Not specifically what you're after but I know they cross over from my own use! Those radish roots have been know to go over 25 feet deep. Plant them now and everything else you can think of or learn of overwinter. You don't even have to till the grass. Just scratch the ground and cover 1/2 to 1 inch. They are also great for eating and wildlife. I've had 22" radishes 2.5" across.. Fixed bad drainage issues here in heavy clay soil.

Some deep cross hill French drains might do the same but costly and not as likely to work.

Whoops, forgot to say that it's very heavy, compact clay soil.
What currently grows is wild grasses (I think mostly rye and oat).
I can plant whatever I want there, but they need to be plants that I can mow later, due to the fire fuel issue.
Wow, 2 foot radishes! That's amazing. It sounds very promising and I will see if I can get some seeds ASAP. Thank you!

Nancy Reading wrote:What sort of slope can you mow with your mower? Maybe you can have more gentle/terraced swales and still mow them.

It sound like you have a Mediterranean climate, so you may find this thread of interest. I believe that by increasing the water content of the soil you can get a benefit in fire prevention too. Swales are just one way of going about that.
As regards grazing animals some are suggested here including borrowing grazing animals and using smaller animals like guinea pigs. Maybe others in the same situation will find it useful.

This is great "outside the box" thinking! I really appreciate it.
Unfortunately the bulk of this slope is already at the limit of what my mower can safely handle, so any pseudo-terracing would also create steeper spots that I wouldn't be able to get.
I was just starting to read that very thread on fire prevention! My time is limited and there's lots of great info, so it might take a while before I finish it. 😬

My suggestion would be to use swales that would still let you mow over them similar to traffic bumps that car drive over.

I would suggest using a string method to level those areas.

I also recommend planting winter rye on the swales as soon as possible to prevent further erosion.

Clay soil sounds good to me or doing this.

The good thing about winter rye is that if you temps cool off enough the winter rye will die letting other native grasses prevail.

I would not use landscape fabric or rocks as the fabric will deteriorate and the rocks will make mowing difficult.

Anne Miller wrote:My suggestion would be to use swales that would still let you mow over them similar to traffic bumps that car drive over.

I would suggest using a string method to level those areas.

I also recommend planting winter rye on the swales as soon as possible to prevent further erosion.

Clay soil sounds good to me or doing this.

The good thing about winter rye is that if you temps cool off enough the winter rye will die letting other native grasses prevail.

I would not use landscape fabric or rocks as the fabric will deteriorate and the rocks will make mowing difficult.

Thanks for your ideas, Anne. Unfortunately swales are really not an option. The slope is already at the limit of what my mower can safely handle, so introducing any uneven ground is not an option.
We already have rye and oat grasses all over the property - they start to grow as soon as the winter rains come. 🙂 And I'm sure they help, but I want to do anything else I can to help with the inevitable erosion and flooding of the lower areas.

If I may ask, why does it have to remain smooth? I feel as if that might play against your erosion control situation. I have a mild slope on my property and I have creatively placed a few logs along the slope to act as a silt/debris catch. While you have an existing wildfire concern, I wonder if you could replicate this with stone through making rock weirs?

Another thought is a different implement for maintaining the area. Would you be amenable to utilizing a weed wacker for this area? You can work around obstacles and still cover a fairly reasonable amount of ground once you get into the swing of it.

Timothy Norton wrote:If I may ask, why does it have to remain smooth? I feel as if that might play against your erosion control situation. I have a mild slope on my property and I have creatively placed a few logs along the slope to act as a silt/debris catch. While you have an existing wildfire concern, I wonder if you could replicate this with stone through making rock weirs?

Another thought is a different implement for maintaining the area. Would you be amenable to utilizing a weed wacker for this area? You can work around obstacles and still cover a fairly reasonable amount of ground once you get into the swing of it.

My riding mower cannot safely handle the slope if there are swales or obstacles like rocks or logs. The area is too big for a weed whacker.

I promise y'all, I have considered this thoroughly, and the restraints I wrote out in my first post are real and true. That's why I'm looking for alternative suggestions.

Juniper Zen wrote:

larry kidd wrote:What kind of soil? What grows there?  Can you plant stuff that doesn't require much if any upkeep now or at least two weeks before frost?

Ever heard of Daikon radishes? They will drill deep roots and allow that winter water to get down in the ground. There are many other things you can plant with them. Fella named Gabe Brown does some good you tube vids about soil. Not specifically what you're after but I know they cross over from my own use! Those radish roots have been know to go over 25 feet deep. Plant them now and everything else you can think of or learn of overwinter. You don't even have to till the grass. Just scratch the ground and cover 1/2 to 1 inch. They are also great for eating and wildlife. I've had 22" radishes 2.5" across.. Fixed bad drainage issues here in heavy clay soil.

Some deep cross hill French drains might do the same but costly and not as likely to work.

Whoops, forgot to say that it's very heavy, compact clay soil.
What currently grows is wild grasses (I think mostly rye and oat).
I can plant whatever I want there, but they need to be plants that I can mow later, due to the fire fuel issue.
Wow, 2 foot radishes! That's amazing. It sounds very promising and I will see if I can get some seeds ASAP. Thank you!

We also have heavy compact clay here. Not sure how cold it gets in 9B but another plant that helps break up heavy compact clay soil is buckwheat and it grows crazy fast like 6-8 weeks from seed to harvest if memory serves. Not that you'll want to harvest it. I'd let it keep reseeding if it were me. Sadly it doesn't tolerate frost or freezing at all! I've had the radishes overwinter here in zone 7a many times.

Seriously checkout Gabe Browns videos. You may be surprised at how much you learn. You also my reclaim a lot of water by combining all these plants locking it in the soil for summer cutting the fire risk way down!

How wide is the riding mower? Could you have very narrow trenches or single pits that it would pass over?

If all else fails perhaps you could use a spade, fork, or some sort of chisel plough. The idea being to make a swale-like tear in the soil that holds and soaks small amounts of water but the ground still looks flat.

Another thought is, dig a trench and fill it with wood chips, sawdust, sticks, etc. up to the brim, adding more to keep it level with the ground around it.

The same could be done with sand or gravel or charcoal if that is more accessible. If it’s sand, that could allow plants to grow on top of it, level with the remainder of the land.

Not sure about your physical abilities, but what about mowing with a scythe, rather than the riding mower, on this sloped parcel?

Another thought: could you make switchback terraces down this slope?  Level-ish where the mower runs, but with the slope of the terraces alternating back and forth across the fall line of the general slope.  Somebody (Ben Falk?) has done a version of this on a steep rocky slope  in the northeastern US, with very good results.  With your predominantly clay soil, retaining walls of rammed earth may be feasible (with or without an added stabilizer such as lime, Portland cement or wood ash).

Yet another idea:  can you do some dirt work to even out the slope, then contour plow with a chisel plow, middle buster or ripper?  Search for PA Yeomans for details, though true keyline plowing on such a small parcel probably isn't feasible.  This could be combined with the daikons already suggested.

Juniper Zen wrote:My riding mower cannot safely handle the slope if there are swales or obstacles like rocks or logs. The area is too big for a weed whacker.

I promise y'all, I have considered this thoroughly, and the restraints I wrote out in my first post are real and true. That's why I'm looking for alternative suggestions.

Which direction are you mowing downward or crosswise?  If crosswise logs could be moved if you just didn't want to avoid them.

In other words, mow across the slope or sideways,

larry kidd wrote:We also have heavy compact clay here. Not sure how cold it gets in 9B but another plant that helps break up heavy compact clay soil is buckwheat and it grows crazy fast like 6-8 weeks from seed to harvest if memory serves. Not that you'll want to harvest it. I'd let it keep reseeding if it were me. Sadly it doesn't tolerate frost or freezing at all! I've had the radishes overwinter here in zone 7a many times.

Seriously checkout Gabe Browns videos. You may be surprised at how much you learn. You also my reclaim a lot of water by combining all these plants locking it in the soil for summer cutting the fire risk way down!

We get a handful of nights that are barely below freezing, right in the middle of winter. The buckwheat may be a good option. Thank you. 🙂

Sadly I don't have time to watch long videos. I really need quick information at this point in my life. I do appreciate the suggestion, though.

M Ljin wrote:How wide is the riding mower? Could you have very narrow trenches or single pits that it would pass over?

If all else fails perhaps you could use a spade, fork, or some sort of chisel plough. The idea being to make a swale-like tear in the soil that holds and soaks small amounts of water but the ground still looks flat.

Another thought is, dig a trench and fill it with wood chips, sawdust, sticks, etc. up to the brim, adding more to keep it level with the ground around it.

The same could be done with sand or gravel or charcoal if that is more accessible. If it’s sand, that could allow plants to grow on top of it, level with the remainder of the land.

Ah, the idea of putting in trenches and then filling them is creative and might work! I would need to put soil back over the surface and tamp it down to keep it smooth and even - otherwise the mower might slip or pivot dangerously as wheels get caught - but I think that is doable. I could also get a broadfork to put in lots of drainage holes. Thank you for the ideas! 😃

Kevin Olson wrote:Not sure about your physical abilities, but what about mowing with a scythe, rather than the riding mower, on this sloped parcel?

Another thought: could you make switchback terraces down this slope?  Level-ish where the mower runs, but with the slope of the terraces alternating back and forth across the fall line of the general slope.  Somebody (Ben Falk?) has done a version of this on a steep rocky slope  in the northeastern US, with very good results.  With your predominantly clay soil, retaining walls of rammed earth may be feasible (with or without an added stabilizer such as lime, Portland cement or wood ash).

Yet another idea:  can you do some dirt work to even out the slope, then contour plow with a chisel plow, middle buster or ripper?  Search for PA Yeomans for details, though true keyline plowing on such a small parcel probably isn't feasible.  This could be combined with the daikons already suggested.

Hand tools are not an option due to time required + disability + too large an area, sadly.

Switchback terraces are potentially an option! I love the look of terraces, too. I have an a-frame level for finding contour. I would have to find a day free to spend time measuring and marking, to figure out whether the layout would work. Maybe I could combine a couple switchback terraces with the filled-in trenches suggested by M Ljin.

Rammed earth walls and keyline plowing aren't really feasible options for me. I would have to make the terraces with rocks and/or lumber. I do have a supply of rocks that are around 6-12" in diameter from lower on the property - just need to be dug up and transported.

Anne Miller wrote:Which direction are you mowing downward or crosswise?  If crosswise logs could be moved if you just didn't want to avoid them.

In other words, mow across the slope or sideways,

Right now I have to do both crosswise and downward, depending on the slope of the exact spot I'm at. Also my mower has a poor turning radius, so while I'm mostly going across, there are parts where it's going downward while turning around.

But I hadn't previously thought of laying things out in a switchback pattern, like Kevin suggested. I had been imagining putting in swales or terraces or whatever along the entire slope. If I could do that and also lay it out with my mower's width and turning radius in mind, I might have a solution.

I can't claim any originality for the idea of switchback terraces.  I think I first saw it in photos of a vineyard somewhere - maybe near Porto, Portugal?  I don't remember, now.  Ben Falk's version is mostly ponds, all down the slope, which isn't quite what I had in mind for your project.  Depending on the slope of the switchback terraces, it might be either prudent or necessary to add water bars or diversion trenches to slow or redirect the flow.  Maybe those could drain into small swales or ponds.

The wide turning radius of your mower could be trouble for my switchback terrace idea.  But, if you have a tractor with a shuttle shift (or don't mind driving backward very slowly) and can ride side-saddle, you might not even need true hairpin turns at the ends of the terraces, just flat spots somewhat longer than the mower where you can reverse direction and transition from one terrace to the next.  You might need the mower discharge chute to face down hill, unless you have a rear bagger.  Assuming you are using a suction-type finish mower deck.

For really steep slopes (30 to perhaps 45 degrees, or even steeper), there are several approaches used in, for example, the vineyards and high pastures of alpine Europe: winches to raise and lower tools, supplies and fruit; rack monorails (Doppelmayr is one brand); very wide track tractors (dual wheels on spacers), for improved stability on steep slopes; tracked tractors (rather than on wheels); and so on.

Thanks for your reply, Kevin. Very good things to consider and very cool stuff to look into, someday when I have extra time. 😉

There are perforated drain pipes that are medium 4" to large that could be buried at the level you would dig a swale down to, 8" to a foot?  Not sure how deep you want to catch water at. Pipe will divert it in whatever way you direct the pipe.  It's all underground so it wouldn't affect mowing.

It's a bit of a project, but it might well be worth it since they would last a very long time underground, would help with erosion, specifically direct water to a tank or pond or irrigation ditches where you don't mow.

The least expensive option, the coil of black pipe below, has this description from Home Depot.  (I have nothing to do with HD, other than they probably get a quarter of my income!  ha!)  I have this kind of drain pipe, and the only issue is that the gophers on the West Coast will eat through this, I don't know why.

4 in. x 100 ft. Singlewall Perforated Drain Pipe - The Home Depot
About This Product Advanced Drainage Systems, Inc. (ADS) 4 in. x 100 ft. Singlewall Perforated Drain Pipe provides superior strength while its high density polyethylene (HDPE) construction allows the corrugated pipe to be a flexible, light weight solution.

Juniper Zen wrote:I love the look of terraces, too. I have an a-frame level for finding contour.

You're welcome.  Happy to contribute some grist for the mill.

If you already have an A-frame style level constructed, so much the better.  For others who may not have one, another method of finding level (from which an off-contour slope can also be established), can be seen in this video:

Sort of a homemade dumpy or engineer's optical level.  A straight-up water level (hose level) would also work, but you'd be limited by the length of hose and (depending on how chilly it was) the liquid you could use to find level (RV antifreeze - the pink, non-toxic stuff - might be helpful, but I haven't tried it).

Eugenio has all sorts of Permie-adjacent and/or old-timey ways of doing things - from building construction and agriculture, to handicraft projects - documented on his channel.

Worth poking around to check out his offerings, in my opinion.

Cristo Balete wrote:There are perforated drain pipes that are medium 4" to large that could be buried at the level you would dig a swale down to, 8" to a foot?  Not sure how deep you want to catch water at. Pipe will divert it in whatever way you direct the pipe.  It's all underground so it wouldn't affect mowing.

It's a bit of a project, but it might well be worth it since they would last a very long time underground, would help with erosion, specifically direct water to a tank or pond or irrigation ditches where you don't mow.

The least expensive option, the coil of black pipe below, has this description from Home Depot.  (I have nothing to do with HD, other than they probably get a quarter of my income!  ha!)  I have this kind of drain pipe, and the only issue is that the gophers on the West Coast will eat through this, I don't know why.

4 in. x 100 ft. Singlewall Perforated Drain Pipe - The Home Depot
About This Product Advanced Drainage Systems, Inc. (ADS) 4 in. x 100 ft. Singlewall Perforated Drain Pipe provides superior strength while its high density polyethylene (HDPE) construction allows the corrugated pipe to be a flexible, light weight solution.

Thank you for the new idea! I do hope to put in a pond (someday) at the low point of the property, so this is something to keep in mind. 🙂