Agriculture Reference
In-Depth Information
production expenses, and 7) other unfavorable effect on the ecosystem (Wong
et al., 1999; Tu et al., 2006).
As previously mentioned, different agricultural practices such as excess
use of chemical fertilization and agricultural machinery have increased the
production of greenhouse gases. Enhanced production of greenhouse gases are
not considered favorite because they can adversely affect the environment
resulting in the process of global warming (Franzluebbers, 2005; Robertson et
al., 2000). Use of organic farming can alleviate such adverse effects by
substantially decreasing the use of chemical fertilization and agricultural
machinery in the field. Furthermore, because of the repeated use of chemicals
to inhibit pathogen activities in soil, they have become resistant to such
chemicals (Montesinos, 2007).
The quality of crop plants has also decreased because of the excess use of
chemicals. Under conventional farming the expenses of crop production may
also increase, although usually the higher amounts of yield production may
cover such expenses (Liebhardt et al., 1989; MacRae et al., 1993). In addition,
contrary to the conventional farming method, organic farming can have
favorite effects on the ecosystem. However, during the transitioning period
from conventional to organic farming limited nutrient availability as well as
weed and pathogen dominance can adversely affect crop production. Hence, it
is important to find ways, which improve soil productivity when producing
organic crops. It is suggested that the transitioning process be performed
gradually and not at once (Tu et al., 2006). In other words, when transitioning
from conventional to organic farming, the applied treatments must include
both chemical and organic sources, with a more emphasis on organic
treatments. It is necessary that soil conditions become appropriate for organic
plantation, while agriculturally sustainable.
To provide necessary nutrients for plant growth under organic farming,
usually different sources of organic material including farmyard manure,
compost, legumes, other crop residues and limited amounts of chemical
fertilization are used. AM fungi and N fixing rhizobium are also useful sources
of P and N in organic farming under different conditions including tripartite
symbiosis (Greenland, 2000).
In addition to the changes taking place in nutrient availability during the
transitioning process, soil microbial diversity and biomass also are subjected
to alteration. Organic farming can favorably increase soil microbial diversity
and biomass. During the initial period there is a pick in soil microbes' diversity
and population, which is due to the more suitable conditions for the activity of
soil microbes. However, during this period, crop yield decreases as soil
