Digestate as Fertilizer

Significance of digestate in developing countries
feeding operations of all sizes, and the same is being
followed in India. The plan was developed to assist
animal feeding operations in meeting nutrient levels
and water quality goals and regulations. Furthermore,
Indian water emission limits require the submission of
an action plan or management programme that outlines
nutrient land application rules as well as measures to
meet permitting requirements related to any industrial
effluent discharge.
Digestate production
In India, mineral fertilizers, in particular, are becoming
increasingly expensive due to energy-intensive production
and are responsible for a significant proportion of
GHG emissions and water pollution from agriculture.
Furthermore, with a depleting level of organic carbon
in the soil, there is a great need to reduce the amount of
mineral fertilizers and improve management of organic
wastes.
Cattle shed
A few examples and studies in India have cited the
positive benefits of using digestate rather than manure
on the crop yield of sugar cane, bananas, mango etc.,
although there is no comparative data on mineral fertilizer.
Digestate must be integrated into the fertilization
plan of farms in the same way as mineral fertilizers and
applied at accurate rates, with equipment that ensures
uniform applications throughout the whole fertilized
area. Furthermore, the CNMP encourages the implementation
of biogas plants, because use of digestate
provides farmers with greater flexibility with regard to
time and area of fertilizer application. A wide range of
technologies are available to create novel digestate
products - such as concentrated nutrient streams with
the needed enrichment to produce standardised fertilizer
products. However, operational experience of
these technologies in India is currently limited and very
often application of digestate in the vicinity is likely to
remain the most economical option.
Arable land just before sowing and applied with digestate
Facts & figures:
Small-scale (1-6m³/day): Approx.
4.6 million plants mainly used for
household cooking
Off-grid biogas plant (< 250KW
elec. eq): Approx. 260 plants with
cumulative capacity of 5.5MW
Vermi-composting of digested
slurry from digestor
Large-scale biogas plant (> 250KW
elec. eq): Approx. 150 plants with
cumulative capacity of 225MW
elec. eq.
Further Information: Indian Biogas Association www.biogas-india.com
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