Mulching experiment: update 2

This is my 2nd update since first starting my mulching experiment in mid-November 2011.

For bed 1 (standard cardboard and compost mulch), the cardboard and compost mulch has broken down much more since December. You can see that in December it was covering over all the edges of the raised bed, whereas now (2nd pic) it is sinking down the sides as it breaks down.

Bed 1: Mid-December 2011

Bed 1: Mid-January 2012

Because of the unusually warm weather throughout December and part of January, I did get a few odd annual weeds trying to grow on the top, which I promptly pulled out. Otherwise, just doing it's thing, no bother at all.

For the 2nd bed (based on the idea of 'three-layer grow through mulch', see first post for description of my changes), it's a bit different. I think you can tell that the veg remainders mulch is starting to breakdown more,  just. Not sure the photograph shows it that well, but I can assure you it has. So far had no annual weeds have popped up, unlike bed 1. However, the old chard remainders that I had dug up and thrown on top, are trying to grow!

Bed 2: Mid-December 2011

Bed 2: Mid-January 2012

You can see the new chard shoots at the top (from the middle going towards the right). Yes, I had thrown a little used compost (from containers) onto this mulch, in part to help hold it down in the high winds. But I literally threw the old chard root on top, in no way digging it it. But the bugger wants to grow anyway. It's not a lone wolf either, as at the other end of the bed (not in the photo) some other old chard roots have started to sprout.

I suppose I'll pick the young shoots and then maybe throw the rest of the root into my compost bin at home. I don't really want the chard to grow in this bed, as this is going to be the brassica bed this year. However, I'm very impressed with just how much the chard wants to grow.

Overall, the 2nd bed is mulching down much more slowly, which isn't surprising given both the unusually warm weather until the last week or so. The cardboard underneath is also drying out more and so taking more time to break down as well. It will be interesting to see if the recent cold weather helps break it down quicker.  Will report back mid-February.

Mulching experiment: update 1

A month after I first began the mulching experiment, here is the first update.

 Experiment 1: after 1 month

For bed 1 (standard cardboard and compost mulch), you can see that the cardboard is starting to break down a bit. No annual weeds have come up. This may not seem significant, but on my non-mulched beds, like those still with spinach and chard, some annual weeds have sprung up, even though I weeded them at the same time as setting up the mulching experiment. Usually I wouldn't need to weed so late, but we had such a warm autumn. I suspect now that it's finally turning into winter (light dash of snow on the ground this morning), the weeds shouldn't grow any more now until end of Winter/early Spring.

Bed 2: mid-November 2011

Bed 2: mid-December 2011

For bed 2, with the cardboard and non-composted plant material mulch, if you compare to the first photo from November, you can tell, only slightly (!), that the plant material is breaking down just a little. I think adding the extra compost to hold it down has helped, as has finally getting some cold weather. But not a lot of change really.

Let's see how it looks in January!

Mulching experiment

Green manure: Hungarian rye on the left, tares to the right. Will be dug in early Spring.

It's been the mulching time of year, well, more in Autumn, I'm just writing this up late! I decided to try experimenting with a couple of different mulching techniques on a couple of beds at the lottie which didn't have green manure in them, so they would not be bare over winter. The main reasons for mulching are:

1. Killing weeds by denying them light
2. To conserve water - reducing evaporation
3. To protect the soil from erosion or capping
4. To encourage biological activity
5. To add organic matter and nutrients to the soil

(from The Earth Care Manual, p.194)

The first bed I am doing my mulching experiment on had potatoes growing in it this year, and will be planted with courgettes, pumpkins & squashes and corn in 2012. My key aim for the mulching on this bed was to add organic matter and nutrients in preparation for plants that will need lots of food. A secondary aim was to kill weeds (annuals) by denying them light.

Having already tried to clear the bed of perennial weeds like couch grass when it was first dug, and again after I pulled up all the potatoes, I had hoped that I had got it all. Couch grass is very sneaky and the tiniest amount left behind will start a new plant. Clearly I haven't quite mastered the art of getting rid of perennial weeds as I still have couch grass appearing! So I therefore first did my best to dig out any perennial weeds, again.

Experiment 1: standard cardboard & compost mulch

I then covered the bed with cardboard, and then added in a couple inches of compost on top of the cardboard. The cardboard should help kill off any annual weeds. It will breakdown over winter, and the worms will take the compost down into the soil, doing the handy work of adding it's nutrients to the soil.

This is a fairly standard type of mulching, so I'm not doing anything new. I'm going to monitor this bed over winter and see how it breaks down. I will probably add another layer of mulch in early spring, as pumpkins etc are hungry feeders and I want to give them the best possible chance of yielding lots of yummy food.

The experiment part really comes in with comparing this standard way of mulching with another bed I mulched. This bed had broad beans on it this year, and I will be planting brassicas on it in 2012 (in fact there are already some over-winter cabbages in the bed). Again, these need lots of nitrogen nutrients.

For the 2nd bed, I'm using the idea of 'three-layer grow through mulch' (Earth Care Manual, p.195), but adapting it. The 'three-layer' mulch first has cardboard or newspaper placed on the bed. Then manure is added, and then holes made plants, i.e. potatoes, planted though a hole. The 3rd layer is a mulch of grass mowings, straw, generally loose material, which helps contain moisture. This system is really used for when you are immediately added young plants/seed potatoes, not leaving it over winter.

For my experiment* I have added a layer of cardboard (after again doing my best to get rid of the perennial weeds), but instead of adding manure, I have thrown on all the left-over bits of plants. This includes everything from the remains of corn, chard/spinach I had dug up prior to it going to seed, carrot tops, broad bean and pea roots, the remains of the asparagus plants after cutting them down in autumn, etc. I then threw on some compost to help hold it down. The lottie is very exposed to wind and as the plant material is a bit light, I needed something to hold it down so it didn't just blow away.

*This isn't my own bright idea. I know I've read or heard about this, or something similar to it, a few years ago but cannot find where, so I'm unable to give the credit for the idea. I'm just using what I remember and adapting it to what I think might work.

Experiment 2: Showing the cardboard layer, then plant material on top.

I could put all the plant material in the compost and break it down that way as usual, but I wanted to see how it might go if I just add the material straight onto a bed in autumn. My thoughts were that maybe the frosts and snow will help break the plant material and cardboard down a bit, and then when it starts warming up in early Spring, I'm hoping the worms will get to work and start taking some of the material down into the soil.

At the very least, this mulch will help kill annual weeds and stop the soil from being bare and at risk of winds blowing away some of the good top soil over winter. If it doesn't break down enough, I don't loose anything as I can just pull up the plant material and put it in the compost bin, then add some standard compost back onto the cardboard and bed.

In nature, trees loose their leaves and just fall to the ground. It doesn't get raked up and put on a compost pile and then once broken down added back to the soil. It is left to do it's own thing and nature gets to work and over time it breaks down and releases all it's nutrients back into the soil. So I'm trying this because I was curious to see how much the plant material would break down over winter, when just left there as is, kind of mimicking nature a little bit.

The photos above were from mid-November. I'll be taking photos once a month over the next couple of months and report back how it is going.