Different crops have different nutrient requirements and
affect soil balance differently. Some, like corn and tomatoes,
are heavy feeders that quickly deplete soil nitrogen and
phosphorus. Thus, if you plant corn in the same spot year
after year, that plot of soil will run low on nitrogen and
phosphorus more quickly than other parts of your garden will.
By changing the location of corn each year, you'll be able to
renew the plot where it grew the preceding year, so your soil
won't get out of balance.
There are other crops that also use up
nitrogen rapidly. They tend to be the leafy and fruiting
crops, such as lettuce, cabbage, and tomatoes. In contrast,
root vegetables and herbs are light feeders. Peas, beans, and
other legumes add nitrogen to the soil but need lots of
The general rule of thumb for balancing out
soil nutrients is to avoid planting the same general category
of crop (root, legume, and leafy/fruiting) successively in the
same place. It's best to follow nitrogen-fixing legumes such
as peas or beans with nitrogen-loving leaf or fruiting crops
such as lettuce or tomatoes. Then, follow the heavy feeding
crops with light-feeding root crops.
Disease and pest
If you have a large home garden, you may want to plan your
crop rotation on the basis of plant families rather than on
nutrient needs. This can help in your overall program of
avoiding diseases and pests, because crops in the same
botanical family tend to suffer from the same pest and disease
problems. For example, Colorado potato beetles like to eat
potato plants, but they also enjoy feasting on tomato leaves
and eggplant foliage. Since these beetles over winter in the
soil, if you plant eggplant in a spot where you grew potatoes
the year before, you could be inviting a beetle problem for
your eggplants from the day they're planted. Likewise, several
serious bacterial and fungal diseases over winter in plant
debris in the soil.
Lengthy rotations are sometimes necessary
to control chronic soilborne problems. Bean anthracnose fungus
can persist in soil for up to three years, so a four-year
rotation is needed to keep the disease at bay. The same holds
true for such fungal diseases as Fusarium wilt and
Verticillium wilt. A few problems, such as club root, persist
in the soil for even longer, so rotation is less useful for
crop rotation plan
If you have a small garden, you may not be able to set up an
effective rotation by crop family. That's also true if you
grow only a few kinds of crops. In that case, stick to a basic
soil-balancing rotation. But if you have a large plot and grow
many different crops, you may enjoy the challenge of setting
up a rotation by crop family. Refer to the chart on the
previous page to learn which crops belong to the same family.
Keep in mind that cover crops can be included in a rotation
plan to discourage specific types of pests and to improve
soil. For example, beetle grubs thrive among most vegetables,
but not in soil planted in buckwheat or clover. A season of
either crop can greatly reduce grub populations and at the
same time will increase soil organic matter content.
Rotating Vegetable Families
Susceptibility to pests and diseases runs in plant families.
Leave at least two, and preferably three or more, years
between the times you plant members of the same crop family in
an area of your garden. When planning a rotation scheme, refer
to this rundown of the seven family groups most often planted
in vegetable gardens along with ideas for rotating them.
Rotate with legumes; avoid planting in soil with under
composed organic matter.
Carrots, parsnips, parsley, dill,
Moderate feeders. Precede with any other plant family;
condition soil with compost before planting. Follow with
legumes or heavy mulch.
Broccoli, Brussels sprouts, cabbage,
cauliflower, kale, kohlrabi, radishes, turnips:
High level of soil maintenance required for good root health.
Heavy feeders. Precede with legumes; follow by first
cultivating the soil to expose pests for predation, then
Cucumbers, gourds, melons, squash,
For improved pest control, precede with winter rye or wheat;
follow with legumes.
Beans, peas, clovers, vetches:
Beneficial to soil; few pest problems. Rotate alternately with
all other garden crops when possible.
Wheat, oats, rye, corn:
Plant before tomato- or squash-family crops to control weeds
and improve soil's ability to handle water.
Eggplant, peppers, potatoes,
Heavy feeders with many fungal enemies. Precede with cereal
grain or grass; follow with legumes.
Crop rotation is a method of organic pest-control which
reduces the build-up of soil borne disease. Members of any given family should not be grown in the same
spot for more than one year. Vegetables from different groups can share a plot if they
require the same conditions. Perennial varieties and those from the miscellaneous group
need not feature in a rotation plan