Agriculture Reference
In-Depth Information
1.4
Organic Farming: Feed the Soil to Feed the Plant
Intensive cropping systems resulted in decline of SOM and lead to loss of soil fer-
tility. Large inputs of chemically synthesized fertilizers were used to sustain crop
production year after year. Conventional agriculture, by land use intensification, de-
creased soil microbial activity and microbial functional diversity (Shen et al.
2008
).
Furthermore, the application of N-fertilizers with rates higher than crops need has
altered the abundance and the diversity of soil microbial communities (Enwall et al.
2005
; Chu et al.
2007
). The negative consequences of the increased use of chemical
fertilizers resulted in the implementation of governmental environmental policies
that underline the role and importance of SOM in crop production (Rosenani et al.
2003
). Organic farming is considered an alternative farming system that overcomes
the environmental, economic, and ethical consequences of the industrialized high
external inputs agriculture. The philosophy of organic farming is to feed/fertilize
the soil rather than the plant. Synthetic fertilizers directly feed the plant and not
the soil, which contradicts the principles of organic farming. Moreover fertilizers
in mineral forms are not permitted in organic agriculture due to high solubility in
water and potential risk of environmental pollution. Accordingly, only organic fer-
tilizers can be used, which involves an active soil microflora that should be able to
mineralize organic forms of nutrients into plant accessible forms, which is a prior-
ity in organic farming (Fließbach and Mäder
2000
). However, the integration of
bacteria with traditional inorganic fertilizers in the field may prove to be effective
means to increase the solubility of inorganic phosphorous ions and other nutrients to
plants (Kumar et al.
2009
). Bacteria take systemic and simultaneous account of en-
vironmental aspects, quality of the produce and profitability of agriculture (Maene
2000
). Substitution of chemicals with bacterial fertilizers and biopesticides, espe-
cially blending of chemical fertilizers with chemical adaptive bacteria is a promis-
ing approach to obtain sustainable fertility of the soil and plant growth (Kumar
et al.
2011
). However, bacteria in the form of biofertilizers with synthetic chemical
fertilizers enhance significance crop yield in comparison to individual application
of synthetic chemical fertilizer. Sustainable management of natural resources and
progressive enhancement of soil quality, biodiversity and productivity are some of
the steps to achieve the evergreen revolution (Keshvan and Swaminathan
2006
).
Compost application—a core practice in organic farming—is used by farmers to
preserve soil fertility for a long-term. Compost contains small portions of plant nu-
trients in inorganic forms that do not require mineralization to be solubilized in the
soil-water solution. This fraction has a direct effect; its nutrients are easily available
for plant absorption, while the organic forms of plant nutrient in compost provide
the slow release effect for nutrients through the growing season, given that environ-
mental and soil conditions are suitable for the gradual release of plant nutrients. It
is important to consider a match between nutrient release from compost and plant
demand for nutrients; mismatch might result in nutrient leaching (mainly nitrate
in humid areas), toxicity or nutrient deficiency. Nevertheless, sole compost is not
enough to cover the whole nutrients requirements on a short-term period to satisfy