Agriculture Reference
In-Depth Information
er highly experienced with living mulches advised me that rodent problems
and the stunting of young trees during establishment were serious obstacles
for which we do not yet have all the answers.
During the first 3 years after planting, maintain a vegetation-free area at
least 4 to 9 square feet around each tree using weed barrier fabric squares,
mulching, spot treatment of weeds with thermal weeders or herbicides, hand
weeding, or a combination of these practices. Using blow-in mulch from a
vigorously growing alley crop such as alfalfa can be beneficial. If possible,
avoid in-row cultivation using tractor-mounted or other powered equipment
during the establishment years.
Once the trees are well established, consider testing in-row cover crops
to manage weeds and provide habitat for beneficial organisms. Protect the
trunks against rodent damage using hardware cloth screen cylinders ( figure
11.2 ) , and maintain an aggressive rodent control program. If you choose
to use living mulches, you might consider using slightly less dwarfing root-
stocks than you would employ if there were no vegetation under the trees.
Whattouse. Your choice of living mulch depends on your climate and avail-
able soil moisture. Alfalfa, grasses, or grass-clover mixes can make good al-
ley crops. In New Zealand trials, researchers tested red clover, rye grass, and
an herbal crop. Which crop was used made little difference, but its manage-
ment did. Blowing the mulch into the tree rows instead of leaving it in the
alleys increased the nitrogen, calcium, phosphorus, and potassium in the tree
row soil while substantially increasing soil organic matter.
For in-row living mulch cover crops, look for shallow-rooted herbaceous
perennials that are adapted to your area, establish quickly, and form dense
stands. Both legume and non-legume species can be used effectively.
Legumes can fix nitrogen within the tree rows, but they are especially at-
tractive to rodents. Annual clovers can be included with non-legume species
to provide early weed suppression while the non-legume covers establish.
Remember to inoculate legume seeds with Rhizobium to promote nitrogen-
fixing nodes on the roots. Some clovers require special inoculants. Some or-
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