Related to orchards…a paper…
Some previous studies showed substantial benefits in tree growth, nutrition, yield, and soil conditions under orchard mulch systems and the advantages of mulches often are as- serted in popular gardening magazines. However, because most mulches are more expensive to establish and main- tain than herbicides, it is important to determine if the benefits of mulches compensate for their additional ex- penses. Our economic studies indicate that, for some fruit varieties, the in- creased crop value in mulched trees probably justifies the greater costs. Conversely, reduced fruit quality and lower packout crop values for trees in some herbicide systems may nullify the cost savings of these GMSs. The an- ticipated long-term benefits of in- creased soil fertility under mulches certainly are of some value, but were uncertain and inconsistent after 4 years in our field tests.”
As for my garden, recently planted and mulched with 1” of woodchips. I can attest to the water retention. My soil is beyond sandy and dries out exceedingly quickly in sun/wind. A few hours of sunlight make walking barefoot in the garden really painful… soil too hot to touch! With the chips, water stays in the sand/soil, even at the interface of soil/mulch, weeds are suppressed, and the soil remains a reasonable temperature.
My orchard rows have 4-6” of chips. Digging in, there is plenty of mycorrhiza, moisture, and weed suppression. Joy!
In my last expansion of the orchard, I tilled new land and had two rounds of cover crops. Both had buckwheat. Round one, growth of 6-12 inches in many places. Before tilling it in, I spread woodchips maybe 1-2” deep and replanted. The size and health of the second round of buckwheat was dramatic… 24”+ plants were the norm. I knew the risks of potential N lock, but it would be short term, at worst, and would add a lot of organic material to the soil beyond the first season or so. Now, the rows are mulched deeply, grafted trees are in, and I’m going to continue use spreading/tilling in chips in the alleys.