Steve Nicolini wrote:
So I am considering sheet mulching an area with four fruit trees standing in a line. We have a ton of hay on the way and I am wondering if the cardboard will keep the nutrient rich water from reaching the tree roots. The trees aren't in the best shape right now and my first concern is saving them.
Would it be better to just mulch really thick? Does the cardboard serve any purpose other than to kill the grass?
We have tried a variety of methods of mulching on our smallholding (extracts were published in Winter 2008 Permaculture Works, see my blog here for the full article
http://bellapermaculture.multiply.com/journal/item/30)
We assume that you are planting into an existing ecosystem, ie grassland, because this is a system it is a stable state. What you are trying to do is alter that to a different state i.e. a woodland. So you need to try to alter the feedback mechanisms that retain the characteristics of the grassland ie the make up of the soil, the relationships of all the individual elements that hold this in it's particular state. So, what we have found the quickest and easiest way to do this for trees in grassland is to use black plastic mulch not grass based materials (such as hay) which are part of the normal grass based cycle, perpetuating the grass based eco system.
We prefer the black plastic mulch over the cardboard mulching (for reasons see link above) when planting trees. Black Plastic sheet mulch for growing trees is really effective, much more so than cardboard mulch no matter how you do it.
Although there are still problems even with black plastic mulching on our site, we have found that short tailed voles ring bark saplings, they make nests and burrows under the plastic sheeting, but so far we have been fortunate. Each time the short tailed voles only damage a proportion of trees which do recover although they don't thrive as well. We learned to plastic mulch over the entire area and not to make 'collars' of mulch around our trees, because the 'collars', it seems, are perfect short tailed vole habitat. Under the collars they ring bark trees where you can not see the damage until the sapling is dead.
This no-dig, no-weed sustainable cardboard mulch method was developed in Australia in a woodland setting. A subtropical country with lots of sunlight, therefore less possibility of aggressive persistent agricultural weeds than we have throughout the UK. Black plastic mulch does photodegrade In our experience it photo-degrades when it is in the sunshine, it is does not photodegrade as quickly when shaded as the plant saplings grow through it. So we still have to cover it to prevent it disintegrating but only with a thin layer of material. It only takes six months to photo-degrade uncovered, but it will last years mulched over with organic materials. Black plastic mulch covers better than cardboard IF we ensure that we weight both edges of each 'run' down with heavy stones.
The other major advantage we have found with using black plastic mulch over straw/cardboard mulching for growing trees is that the fungal associates do appear to establish rapidly. We suspect that this is due to reduction in evaporation from the earth surface. We assume this would be advantageous in your situation. We found rapid growth of the trees resulting from using black plastic mulch.
'will keep the nutrient rich water from reaching the tree roots'.
We are not sure what you mean by this. What nutrient rich water? Trees don't necessarily directly gain their nutrition via their roots, they need a mediator ie arbuscular mycorrhizae
http://en.wikipedia.org/wiki/Arbuscular_mycorrhizae We argue that plastic sheet mulch is the quickest, most effective way to achieve rapid establishment. However, before all our fellow permies scream and rant at us, we see using plastic mulch as a relatively short term process; a means to an end. It is compatible with Permaculture techniques and ethics (use appropriate technology). In your situation, where you are only planting four trees, you could even recycle old plastic bags or black plastic films that have been used in farming. Transporting straw, cardboard, etc which has to be frequently replaced over the lifetime of the saplings has got significant negative impacts on the environment too. Use what you have, or what you can get very locally.