Yard and Garden
April 4, 2015
Q. Last year I grew
tomatoes for the first time on this property. I want to grow them again
this year, but I was told that I should not grow them in the same space.
Is this true? Why? I really do not have another location available
this year.
KDAZ radio
call-in
A. Crop rotation, moving plants to different
locations in the garden is a good idea. The reason for not growing the
same plant, tomato or other crop, in the same location year after year is to
reduce the accumulation of disease organisms in the soil at that site and to
allow better nutrient utilization.
If the same crop or related crops that
are subject to the same diseases are grown year after year in the same
location, the disease organisms may build up to levels that cause crop
failure. Changing to crops that do not harbor the same disease organisms
helps reduce this problem. Addition of well-made compost also helps
reduce the incidence of disease accumulation in the soil. Tomatoes,
potatoes, chiles, egg plants, and some other plants in the Solanaceae plant
family should not follow each other in a garden. Beans (Fabaceae family),
corn (Poaceae family), squash (Cucurbitaceae family), and certain other plants
are better choices for following tomatoes. The tomatoes should be rotated
to different areas and not returned to any previous location for about 4 years
if possible.
There are disease organisms that can
infect several of the plants listed as good for following tomatoes in the
garden. Properly made compost added to the garden soil will help reduce the
chances of these organisms accumulating by putting beneficial organisms in the
soil to compete with the disease organism for niches in the soil
environment. If diseases do develop over time, it may be possible
to reduce the problem by solarizing the soil. Solarization is the solar
heating of the soil to a pasteurization temperature (160 degrees) by covering
the moistened soil with clear plastic. The edges of the plastic should be
sealed to the ground by covering with soil, rocks, or boards. Sunlight
passing through the plastic warms the soil. The plastic with a layer of
condensed moisture on its underside hold the heat in by the greenhouse
effect. In the New Mexico environment, the temperature of the soil will
rise fairly rapidly, especially in the summer. A soil thermometer, or longer
stemmed compost thermometer, can be used to determine the depth to which
pasteurization temperatures penetrate the soil. Sticky tape can be used
to seal the hole after checking the soil.
Having said all that, since you have
only grown tomatoes in that location once before, if it is not possible to move
them to another location this year the chances of a disease developing are not
great. You should plan for crop rotation in the future.
Another reason for rotating crops is
that by changing crops to those that use different proportions of nutrients
from the soil, you can help maintain soil fertility and allow recovery from the
depletion of nutrients by each crop. Addition of compost also helps with
this. Soil testing periodically to determine the nutrient status of the
soil and to identify nutrients that should be applied as supplements to the
soil is also a good idea. Applying fertilizers to replace nutrients
without knowledge of the nutrient status of the soil may not result in good
crop production. Your local NMSU County Extension Service office can help
you find a soil testing laboratory and help you understand the test results
that you receive from the laboratory.
Send your gardening questions to Yard and Garden, Attn: Dr.
Curtis Smith, NMSU Agricultural Science Center, 1036 Miller Rd. SW, Los Lunas,
NM 87031. You may also send to cwsmith@nmsu.edu or leave a message at https://www.facebook.com/NMSUExtExpStnPubs. Curtis W. Smith, Ph.D.,
is an Extension Horticulture Specialist, retired from New Mexico State
University’s Cooperative Extension Service. NMSU and the U.S. Department
of Agriculture cooperating.
