Agriculture Reference
In-Depth Information
component. Solar heating decreased pathogenic and ectomycorrhizal in-
oculum potential and increased soil nitrate has been reported (Salerno et
al., 2000). Plant pathogenic fungi weakened by high soil temperatures are
more susceptible to these antagonists. Nitrogen fixing
Rhizobium
bacteria
are also sensitive to high soil temperatures, but the reduction in nodulation
of the roots of legumes such as peas or beans in solarized soils is also re-
ported temporarily. However, in another study, Nair et al. (1990) reported
an increase of root nodulation, colonization by arbuscular mycorrhizal
fungi and yield of legumes.
12.11.1 SOIL MOISTURE CONSERVATION
Soil moisture conservation is essential to achieve higher yields from rain-
fed agri-horticultural crops. Soil moisture is often the most unreliable and
scarce resource, so the challenge is to enhance water availability for crop
production. There are several ways to enhance soil moisture retention in-
cluding, conservation tillage, mulching and compost use and restricting
deep drainage. Mulch is defined as any material that is spread over soil
acting as a protective cover. Mulch or compost is used to retain water
and reduce moisture loss to the atmosphere. Advantages of mulching are
the reduction of soil evaporation, suppression of weeds, insulation of the
soil against extreme heat and cold, prevention of soil compaction, and
control of wind and soil erosion. Mulch has a high C:N ratio (sawdust,
wood chips) and may cause nitrogen deficiency on plants. Bacteria that
break these materials down use nitrogen, thus depriving plants of this vital
element. The best solution is to compost these materials until they start to
break down. Non-chemical weed control that maintains soil quality has
been identified a priority need by organic orchardists. Mulching systems,
including cover crops and living mulches, offer the potential for adequate
weed control along with benefits for water conservation and soil fertility
12.11.2 MOISTURE CONSERVATION MULCH MATERIALS
Mulching is an excellent horticultural technique that is beneficial to all
fruit crop plants and particularly useful during dry periods. There are two
main types of mulch practices used: organic and inorganic. Organic mulch-
es are dried or composted plant materials that decompose over time when
