Agriculture Reference
In-Depth Information
mainly depends upon the exposure time of the soil and soil temperature
that is to be maintained.
Soil solarization is not universally effective
against all weeds and may require additional weed management ap-
proaches.
12.9
SOIL NUTRIENTS AVAILABILITY
Solarization initiates changes in soil physical-chemical features that im-
prove plant growth and development. Solarization speeds up SOM break-
down, resulting in the release of soluble nutrients such as nitrogen (NO 3 ,
NH4 + ), calcium (Ca ++ ), magnesium (Mg ++ ), potassium (K + ), and fulvic acid
making them more available to plants (Chen et al., 2000). The concentra-
tions of ammonium- and nitrate- nitrogen are consistently increased across
a range of soil types after solarization. This has also increased availability
of plant nutrients due to the relative increase in populations of rhizosphere
favorable bacteria ( Bacillus spp.) which contribute to the marked increase
in growth, development and yield of fruit crop plants grown in solarized
soil. The increased availability of mineral nutrients following soil solar-
ization are particularly those tied up in the organic soil fraction primarily
as a result of the death of the soil microbiota. Extractable P, K, and Ca,
Mg sometimes have been found in greater amounts after soil solarization.
The solarization mode of action liberates vapor, liquid N compounds and
hence, increases the concentration of reduced N (NH 4 -N) which then ni-
trify (convert to NO 3 -N) after termination of the solarization to provide
NO 3 for increased crop growth response.
12.10
SOIL ORGANIC AMENDMENTS
Solarization can be combined with organic amendments, such as com-
posts, crop residues, green manures, and animal manures to increase the
pesticidal effect of the combined treatments (Chellemi et al., 1997). The
incorporation of these organic materials act to reduce soil borne pests by
altering the composition of the resident microbiota and/or of the soil phys-
ical environment. Soil organic amendments protect soil microbial biomass
and enzymatic activities from the detrimental effect of heating. Organic
green manures, crop residues, and animal waste amendments such as ma-
nures (especially chicken manure) also help in the increase of the soil so-
 
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