I wonder in places very hot and dry like in Texas and Arizona, I believe Mulching is very important before planting. DO you guys have any opinion to share? if you have data to share I welcome that. Please let me know or just share your opinion.
My comment on the article at http://www.puyallup.wsu.edu/~linda chalker-scott/FactSheets/Mulch fact sheet.pdf : The goal of this project is to determine whether mulching an unmanaged restoration site prior to plant installation is more beneficial to plant growth and survivorship than applying herbicide to the site. This is equivalent to asking if feeding a starved person is more beneficial than restricting his food even more. One of the many benefits of mulching is that organic mulching materials supply food for the soil organisms that, in turn, supply, or make available, food to plants. As the soil fertility increases vegetation becomes more abundant. The vegetation that dies after fulfilling its life cycle adds to organic soil content (roots), and adds to the layer of mulch on the top of the soil. And so the wheel pulling up soil fertility slowly starts turning. Poisoning of most what is left of the existing vegetation, and destroying microbial life dependent on the rhizosphere in the soil by applying herbicides prior to plant installation contributes to further impoverishment of the soil. It is wishful thinking to expect that the growth of plants installed after applying the poison can be superior to the growth on the soil that has been mulched instead. It is good that at least after so much research the good professor came to the (obvious otherwise) answer that mulching is better. Good job!
The main difference produced by mulching of new plantings is the shading and insulation of the soil. Mulching with cobbles can also be expected to improve results. The most complex and developed vegetation, the equatorial rainforest, often features a very shallow and ephemeral litter layer over terrible, heavily degraded soil. Specific effects of herbicides depends on which particular herbicides are used.
I'll speak up from an equatorial desert. I don't mulch, but grow edible xeric live cover instead (primarily Portulaca oloracea) - in my case, this is because my area is so windy that even small stones as mulch get blown off fairly quickly. However, there is definitely a value to ground covers, live or dead, in arid regions - shade and insulation are the factors (and I'll stop here, because the point has been made). I'll also second Ron's comment about rainforest and transitional forest soils - pretty much all plants there, even the largest trees, have extraordinarily shallow root systems and the soils are a thin layer (about 12-16 inches, in most areas) of leaf litter and decomposed veggie wastes over red or yellow clay. It's the main visible reason for the evolution of those massive buttress roots that rainforest trees are famous for - without them, the trees would topple.
