224 
THE NATIONAL NURSERYMAN 
ORCHARD COVER CROPS 
Their Importance and Use in Orchard Management 
J. G. MOORE, Wisconsin 
The time at which cultivation shall cease and the cover 
crop be sown is very largely a matter of judgment. It 
depends almost entirely upon what soil moisture conditions 
are during the latter part of July, and what they are likely 
to be during the remainder of the season. One of the chief 
objects of the cover crop, says Mr.Moore in a recent bulletin 
of theWisconsin Experiment Station, is to assist in controll¬ 
ing the moisture content of the soil during late summer and 
early fall. If there are large amounts of moisture in the 
soil during this period, there is danger of new wood develop¬ 
ment continuing so long that it goes into winter only 
partially matured, 
and is very likely 
to winter kill.. On 
the other hand, re¬ 
ducing the quan¬ 
tity of moisture in 
the soil tends to 
hasten maturity, 
and avoid unfavor¬ 
able conditions. 
It will be seen 
then that in a sea¬ 
son in which there 
is heavy rainfall or 
probability of 
heavy rainfall dur¬ 
ing August and 
September, that a 
rapidly growing 
cover crop becomes 
an effective means of reducing the moisture content 
of the soil. In seasons of drought, the cover crop will 
make proportionately less growth and not prove 
injurious to the trees. In wet seasons the cover crop 
should be sown comparatively early; in dry seasons, 
rather later sowing is best. As a usual thing it is sown 
between July 15 and August i. In a season of drought 
during the early part of the season the probabilities of late 
growth are quite as great as when June and July have been 
rainy months. It is well, therefore, to have the seed in the 
ground ready to begin growth as soon as soil moisture 
conditions will permit. During the summer of 1910, the 
cover crop in the station orchard was sown about August i, 
but owing to continued drought, made practically no 
growth until after the first good rain which occurred on 
August 15. 
Another important funetion of the cover crop is to add 
vegetable matter to the soil. Without the cover crop the 
orchard soil would soon become depleted of its vegetable 
matter which would destroy its tilth and make the plant 
food much less readily available, unless considerable 
quantities of barnyard manure are applied. An ideal 
cover crop then should produce considerable vegetable 
matter. In order to do this the importance of having it 
ready to begin growth following a drouth in July or August 
is apparent. Rapid growing crops are usually preferable 
to slow growers although at times for special purposes the 
slow growing crop may be more advantageous. 
COVER CROPS AS PLANT FOOD SUPPLIERS 
Cover crops may be made to serve the purpose of in¬ 
creasing plant food in the soil. Not all crops used for 
covers are able to 
do this. Only le¬ 
guminous crops 
such as clover, 
peas, and vetch 
are capable of add¬ 
ing plant food, and 
these only nitro¬ 
gen. The legumi¬ 
nous eover crops, 
however, are a val¬ 
uable asset in keep¬ 
ing up the fertility 
of the orchard. If 
used too continu¬ 
ously it may prove 
detrimental, for 
excessive nitrogen 
tends to cause ex- 
cessive wood 
growth at the expense of fruit production. It also favors 
late growth, and in this way may result in consider¬ 
able winter top-killing. Because of these unfavorable 
conditions which are likely to arise, it is a good plan to 
practice rotation of cover crops using leguminous crops on 
average soils, not more than two out of three successive 
years. 
HARDY AND NON-HARDY COVER CROPS 
In addition to being divided into food-supplying and 
non-food-supplying, cover crops are also classified as 
hardy and non-hardy or tender crops. The hardy crops 
live over winter and make some growth in the spring, thus 
increasing the vegetable matter returned to the soil. They 
may or may not be efficient in holding the snow or prevent¬ 
ing deep freezing. Hairy vetch, although a hardy crop, is 
usually, less efficient in these respects than is oats, which is 
non-hardy, but which stands up well after frost. 
In the food-supplying, hardy group of cover crops are 
hairy vetch and crimson clover, the latter of which can only 
be considered half hardy in Wisconsin. Of the tender 
