Agriculture Reference
In-Depth Information
these organic residues into the inputs for growing crops (Gaur 1984 ). Organic ma-
nures are bulky in nature that supply the plant nutrients in small quantities hence,
termed as bulky manures, e.g., farmyard manures, rural and town composts, night
soil, green manures etc. Whereas those containing higher percentage of major plant
nutrients like nitrogen, phosphorus and potassium are termed as concentrated or-
ganic manures, e.g., oil cakes, blood and meat meals, fish meals, guano and poultry
manures etc. It is recognized that the bulky organic manures plays a significant role
in increasing the crop yield via supply of the both macro as well as micro-nutrients
to the plants and in improving the physical, chemical and biological properties of
the soil which greatly constitutes to its fertility and water holding capacity. It ame-
liorates the soil structure i.e., sandy soils become compact while clayey soil be-
comes more open. The crumb structure of soil is due to humus.
The process and application of organic manures or composts in the agricultural
fields is a traditional approach of composting. Generally the mature crop residues
like wheat straw, rice straw, sugarcane bagasse, saw-dust etc. are used for which the
production of compost, have high C/N ratio and contain highly resistant lignified
tissues that are difficult to degrade. Thus, breakdown or microbial conversion of
these complex organic materials require long time and the final product in form of
compost is bulky with low in major plant nutrients.
12.2
Recycling of Organic Materials for the Maintenance
of Soil Fertility
The process of recycling for maintenance of the soil fertility is as old as agricul-
ture itself. When early nomad shepherd settled down as farmers, they realized the
significance of compost. Organic residues of plant and animal origin have been con-
sidered as a source of immense practical value for enhancement of crop productivity
both directly and indirectly. While indirect enhancement of plant growth enhance-
ment of plants may occur due to immobilizing nutrient availability and plant growth
promoting activity of diverse microorganisms associated with rhizosphere. Which
facilitate direct growth promotion with production of growth promoting hormone
and solubilizing essential nutrient for plant availability (Maheshwari et al. 2013 ).
Such microorganisms promote plant growth provisioning bio-control activity
against several fungal pathogens (Kumar et al. 2012 ).These microorganisms called
as PGPR's utilize several organic compounds as their sole source of carbon supply
and have influence in composting. Organic residues including green manures, ani-
mal and municipal waste serves as effective source for mobilization of nutrient for
improving plant growth and enhancement of soil fertility. In fact, tropical and sub-
tropical soils in India are generally deficient in organic matter and plant nutrients
because of their rapid loss of these components in the biodegradation processes.
To make up these losses, extensive utilization of organic residues in agriculture
through various processes such as green manuring, green leaf manuring, mulching
and composting had attracted the attention of many workers (Mandal et al. 2003 ;
Elfstrand et al. 2007 ; Möller and Stinner 2009 ).
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