Deep hay mulching 3 years later

Three years ago I put together blog post What is deep hay mulching? It is a great way to save water and improve soil fertility. Recently someone on the Food Garden Group Facebook page wanted to know what those who used the method three years ago had learned. I decided to find out. Here is the result.

To find out what deep hay mulching is please read What is deep hay mulching?

Judy K in Lindisfarne

Judy began to experiment with deep hay mulching after attending a 2017 Food Garden Group workshop at the Botanical Gardens in which Marcus Ragus discussed and demonstrated deep hay mulching.

 

Now, three years later, Judy still does deep hay mulching, but not always with hay, because, living in Lindisfarne on the Eastern Shore of Hobart, she sometimes found it hard to find good weed-free hay.  She now sometimes uses pea straw or seagrass instead.

 

When the mulch layer has gone down to well below twenty centimetres it is time to add more mulch. Judy mixes compost with cow manure and pulverised sheep poo, and then puts a thin layer on the area where more mulch is needed.  She waters the compost mix with a soil bacteria mix (see below), and then adds the new layer of mulch on top of that.

Three years ago Judy would have soaked the hay or other mulch material in water for a while before using it as mulch, but she finds that this is not really needed, and therefore does not do this anymore.

 

Judy began to make her soil bacteria mix after watching YouTube video The Weedy Garden.  It is made with fermented rice water - fermented for a week (water retained after washing rice).  Whole milk is then added and fermented for another week.  Then molasses is added along with water to make the desired volume.  It is then once more left to ferment.  The result is diluted before adding it to the compost mix on her deep hay mulch beds.

 

So far Judy has used sea grass as part of the deep hay mulch process only on areas with greens and brassicas.  She reports that the greens and brassicas love it!  Judy does not soak the sea grass before adding it as a mulch.  It goes straight in as it comes off the beach.  Some is wet, some dry.

 

Judy now uses deep hay mulching for all vegetable beds, except ones where she sows. As an experiment she recently put a few rows of corn in a deep mulch bed. She is keen to find out how they will go.  Beds that she uses for seed sowing she does not deep-mulch.

Kate F in Cygnet

Kate began to use deep hay mulching in 2015.  Now, five years later, she said the following about her experiences:

 

I still use deep hay mulching, but maybe not as diligently! Its efficacy is clear, as the fertility of where I thoroughly applied the deep hay method for two years has improved enormously and, consequently, my dreadful twitch/couch problem has totally disappeared!

 

The method uses A LOT of hay. Keeping no less than 20cms cover all the time means careful, daily observation and immediate action when required. 

 

I fully intended to keep it going, but self-sown seedlings kept popping up and I didn't want to smother them, so I have let it slip a bit over spring. However, there is still about 10cms hay cover and the seedlings are happily popping up through it.  I have the twitch under control in that original area, but now it has surfaced in my Tasmanian-only plants area. These are now quite well-established small plants, so I am beginning to use deep hay mulch there, again to control the twitch.

 

I now do not use deep hay mulching in areas where I frequently change what I plant and also not on areas where I sow things. It is really fabulous for perennial vegetables and herbs etc, and also areas that have a grass problem or have low fertility.

This year I use silage instead of hay.  Hay often has a lot of grass and weed seeds.  Silage is fodder for cattle and sheep that farmers make by fermenting hay. You can see it as sauerkraut for livestock.  It has the benefits of hay, but the fermentation process kills all weed seeds. I was lucky enough to get some from an old farmer at Dover. 

 

Deep hay mulching certainly means you need to irrigate less because of the thick layer of mulch. A thick layer of hay is also excellent for building fertility. The plants are strong and healthy and more resilient. 

Lian T at Lauderdale

Lian began deep hay mulching after attending the aforementioned 2017 workshop. Now, three years later, she still uses the method. Here are her experiences:

Yes, I still use it. Down here at Lauderdale it’s a matter of doing whatever I can to keep moisture in the soil and stop it from drying out. It’s the best system I have found so far.

For the first couple of years I relied a bit too much on the hay, and didn’t add enough other material to the soil. This meant that there were beds that just didn’t work – the hay didn’t rot adequately, and the beds became too dry. So now I’m putting more focus on green manure in winter, plus getting my compost system working a bit more effectively. I think you need to combine other things with the deep mulch to make it work properly.

Deep hay mulching has definitely led to Lian using less water than she used to. When irrigation is needed, Lian uses mostly soaker hoses on top of the deep hay layer, plus occasionally overhead sprinklers.

Lian uses deep hay mulching for pretty much everything in her garden, with a few exceptions:

• Cucumbers seem to be far more prone to stem rot in a deep mulch, so I try to keep a small circle around them free from mulch. At least, that is my intention this year, having lost cucumber plants two years running. 
• Before sowing carrots, parsnips or beetroot I push the mulch layer away from the rows. When seedlings are big enough, I move the mulch layer back in place. I find that sowing late carrots, parsnips or beetroot is problematic because of a monstrous population of slaters, so I try to get them in fairly early.
• I have not grown garlic for years, so I don’t know how that would do in a deep mulch bed.
• When growing green manures I put only a very light sprinkling of hay over the top of the green manure seeds, so as not to leave the earth bare.

Lian uses whatever non-woody mulch-material she can get hold of, including seagrass. Last year she couldn’t get hay when she needed it, so she ended up using straw mixed with manure from a horse stable. That was a bit of a mistake – huge number of weeds!

I’m currently looking at something David Stephen suggests – sprinkling hay over the lawn before you mow it so you get a mix of grass and hay, and then sun drying it - aerating it twice a day - to get rid of the ammonia in the grass clippings, and using it as mulch.

There is nothing for which I don’t use deep hay mulching at all. Not at this stage! It’s definitely a learning process. It is the best system I have found so far for retaining soil moisture and building fertility!

Thank you!

Many thank to Judy, Kate and Lian for all the info you provided.

My conclusions:

1. Deep hay mulching is a great method for those who want to spend less time watering, want to save money by using less water, and want to create high soil fertility without buying and using a lot of fertilisers.
2. Deep hay mulching is not a set-and-forget method.  You have to monitor and replenish mulch levels on an ongoing basis.
3. Unless you have a regular no-cost source, you will need to buy a lot of hay or other suitable mulches to regularly add to the mulch layer.
4. Very worthwhile method that is best started on one or two raised beds or garden areas to gain experience.