ORGANIC AMENDMENTS IN
PLANT DISEASE MANAGEMENT
Dr. J. Kumar
Dr. Roopali Sharma
SOIL AMENDMENT SOURCES
IS IT A FERTILIZER OR A SOIL
COCONUT COIR AND HUMANURE
ALLELOPATHIC EXTRACTS IN RELATION
TO PLANT ECOLOGY
ALSO TO BE CONSIDERED……..
• Continued depletion of plant nutrients and organic
matter in the soil and diseases, are major problems
affecting sustainable crop production. The use of
organic amendments and water-retaining products, if
economically viable, may contribute to overcome these
• Organic growing medium amendments usually are
derived from nature, that occur naturally (residues, peat
moss from peat bogs), or are the by-products of
chips, bark, bagasse, rice hulls) or waste disposal plants
(compost, processed sewage sludge, biosolids).
properties, either directly or by activating living
organisms in the soil.
All soils require the supply of organic matter as
carrier of utilizable energy and nutrients for the soil
organisms, as well as for:
improvement of soil structure and porosity
increase in water-holding capacity of soils
improvement of aeration
reducing soil temperature fluctuations
storage of nutrients in exchangeable form
provision of nutrients
SOIL AMENDMENT SOURCES
• On-Farm Sources. include bedding, compost,
crop residue, manure, contaminated runoff, silage
juice, spoiled feed, wash water, spent soilless
media, and spent nutrient solution.
• Off-Farm Sources. These are usually purchased
and include chemical fertilizers, chemical
conditioners such as lime, soilless media
constituents such as perlite, manure from other
farms, compost, woodwaste, and non-agricultural
wastes such as municipal biosolids.
Is it a Fertilizer or a Soil
Fertilizers. provide sufficient nutrients in a balance
suitable for crop use.
• Fertilizers counteract imbalances in the soil and replace
nutrients removed by crop harvest.
• e.g., composts, fish wastes, food processing wastes,
spent nutrient media, pulp and paper residues, crop
• have a carbon to nitrogen ratio of less than 30 to 1.
• Liming products are not considered as fertilizers.
Soil Conditioners. any material(s) that contain
limited amounts of nutrients, but are managed
primarily for their beneficial impact on the
biological, physical or chemical nature of the soil.
• They can also be used as a plant growth medium.
e.g., bone meal, peat, compost, coir, manure,
straw, vermiculite, sulfur, lime, blood meal,
compost tea and sphagnum moss.
• typically have high levels of organic matter and have
a carbon to nitrogen ratio greater than 30 to 1.
Table 1.1 Management of Soil Amendments Based on
Less than 20:1
Manage as a fertilizer
Between 20:1 and 30:1
Material has properties of a
fertilizer and a soil conditioner
Greater than 30:1
Manage as a soil conditioner
Liquid extract or a dissolved solution but not simply
a suspension of compost. It is made by steeping
compost in water for 3–7 days.
Practiced to suppress foliar fungal diseases by
competition, suppression, antibiosis on the leaf
potassium, sodium, chlorides and sulfates.
The extract is applied as a spray to non-edible
plant parts such as seedlings, or as a soil-drench
(root dip), or as a surface spray to reduce
incidence of harmful phytopathogenic fungi in the
Based on incorporating soil amendment release
chemical substances, known as isothiocyanates
(ITC's), able to suppress soil-borne pests and
diseases, plus a soil heater to enhance biological
activities. Plants from Cruciferae family (cabbage,
radish, cauliflower etc.) release large amount of these
toxic to soil-borne pests and diseases substances - in
Low cost alternative to peat moss.
Excellent growing medium due to
its spongy structure and
Has ability to absorb H2O and
retains 8 to 10 times its own dry
Highly resistant to bacteria, fungal
growth and does not get
hydrophobic like peat moss.
Improve the flow of moisture.
Can also act as mulch.
Human excrement (feces and urine) that
is recycled via composting for agricultural
or other purposes.
Combination of feces and urine with
paper & additional carbon material(such
A compost toilet collects human
excrement which is then added to a hot
compost heap together with sawdust and
straw or other carbon rich materials,
where pathogens are destroyed.
This aids in preventing soil degradation.
Human fecal matter and urine have high
percentages of nitrogen, phosphorus,
potassium, carbon, and calcium.
Derived from Kaolin clay, a natural
mineral, forms a barrier film that acts as
a broad spectrum crop protectant. It
works to control insect pests and
disease, protect against sunburn and
heat stress. Applied as a water-based
slurry before pests arrive.
Few More Examples of organic amendments.
D.E. is the fossilized shells of tiny waterdwelling organisms called diatoms, with
microscopically fine, sharp edges which break
the outer protective layer of the insect and
desiccate them. Applied as a dust or mixed into
a slurry for foliar spraying. Barrier to crawling
pests and soft bodied insects, used in the
garden and as a stored grain additive. Can be
used as a dust on manure for fly control and for
intestinal parasite control.
Soymeal, poultry manure
Horse, swine manure
significantly reduce the incidence of
Verticillium wilt, common scab of potato, and
plant parasitic nematode populations
ALLELOPATHIC EXTRACTS IN
RELATION TO PLANT
The Glucoside (DIBOA, DIMBOA, saponins) which are
present in wheat, rice, maize can have many aspects:
Influence the growth of weed
Involve in detoxification of pesticides,
Increase the resistance of insects, fungi and
bacteria, in cereals,
Are mutagenic agents
Check soil-borne diseases e.g., common
root rot of cereals (Cochliobolus sativus )
increase the rate at which soil
microfloral And microfaunal
Soils with high levels of o.m.
have been shown to prevent
spores of C. sativus from
Can influence pathogen growth,
sporulation, and survival through
the release of fungicidal and
fungistatic compounds during the
process of residue break down,
pathogens to feed on.
ALSO TO BE CONSIDERED…..
Neem (Azadirachta indica) has been widely
studied for its antibiotic and nematicidal
properties, and has been used as plant
extracts, oil cakes, or whole plant materials
performance of other organic amendments
when used in combination.
Decomposition products from cruciferous
plants have shown good activity against
nematodes and other plant pathogens. Their
most effective applications may be under
plastic in biofumigation or biosolarization.
Suppression of nematodes by marigold
(Tagetes spp.) and Crotalaria spp. including
sunn hemp (Crotalaria juncea) have been much
studied). Tannins and phenolic compounds
released from some plant residues may be toxic
Adding amendments to soil may alter many
factors that affect nematodes directly, including
soil structure, particle aggregation, pH, salinity,
and levels of carbon dioxide, oxygen, and other
Adding cover crop residues stimulated fungi that
parasitized plant-parasitic nematodes
Amendments can improve nutrient and water
availability which benefit plant health and yield.
Straw and chitin generally reduce clubroot
symptoms in organic brassica crops. Seedlings in
both straw and chitin amended soil tends to have
Blood meal and fishmeal eliminated the incidence
of verticillium wilt of tomato in pot trials.