4. In one teaspoon of soil there are…
Bacteria 100 million to 1 billion
Fungi 6-9 ft fungal strands put end to end
Protozoa Several thousand flagellates & amoeba
One to several hundred ciliates
Nematodes 10 to 20 bacterial feeders and a few fungal feeders
Arthropods Up to 100
Earthworms 5 or more
Introduction
5. Definitions
Soil: An ecological system consisting of
inorganic minerals, decomposing organic
matter, living organisms and growing plants
Soil: A farmer's "Silent Partner“
6. SOIL HEALTH:
• Soil health is a capacity of the soil to function as a vital living
system to sustains biological productivity maintain
environmental quality and promote plant, animal, and human
health.
• “A healthy soil should be capable of supporting life processes
such as plant anchorage and nutrient supply, retain optimal
water and soil properties, support soil food webs, recycle
nutrients, maintain microbial diversity, remediate pollutants,
sequester heavy metals, and contribute to disease suppression”
(Wang and Hooks, 2010).
9. CHARACTERISTICS OF HEALTHY SOILS
Sufficient supply of nutrients.
High biological diversity
Ability to maintain the integrity of nutrient cycling and energy flow
Suppression of multiple pests and pathogens
Ability to improve plant health
Maintenance of water and air quality
Good soil tilth
Good internal drainage
Low populations of parasites
High populations of plant-health promoting Organisms
Low weed pressure
No toxic chemicals that harm plants
Wang and Hooks (2010)
12. Soil health management practices
Manage organic matter
Minimize disturbances
Diversify soil biota
Maintain soil cover
Crop rotation
Cover crops and green manures
Organic amendments
Conservation tillage
13. Soil health and disease management
Crop rotation
Soil moisture,
pH, temp
Nutrient
management
Organic
amendments
Cover crops
and green
manures
Beneficial
organisms
Conservation
tillage
14. Soil moistutre
Pathak and Srivastava (2001) reported that, with increasing
soil moisture and decreasing soil temperature, decreases the
incidence of Rhizoctonia bataticola in sunflower
Soil Moisture Increase
Phytophthora spp.
Rhizoctonia spp.
Pythium spp.
Soil Moisture Decrease
Fusarium spp.
Verticillium spp.
Armillaria spp.
15. Soil pH
• It affects nutrient availability and microbial
activity.
• Most plants and microorganisms prefer a pH
range of 6-7.
• Raising the soil pH to 6.5–7 by using nitrate
nitrogen in place of Ammonical nitrogen will
decrease the development of Fusarium wilt
16. Potato scab is more severe in soils with pH levels above 5.2.
Below 5.2 the disease is generally suppressed.
Club root of crucifers can be reduced by raising pH(alkaline)
Fusarium wilt disease (i.e. the more acidic the soil, the more
severe the disease).
Takeall of wheat disease- Gaeumannomyces graminis, is
favored by alkaline pH.
17. Soil pH have a strong effect on infective juveniles
survival.
Survival and pathogenicity nematodes declined slightly
as the soil pH decreased from pH 8 to pH 4.
Acidic soil with pH levels below 4.0 may limit the
nematodes host-finding
(Kung et al., 1990)
18. SOIL TEMPERATURE
Warm, moist soils with high levels of carbon to nitrogen will
have higher levels of microbial activity and a relatively higher
level of suppression
Most of the soil organisms function best at an optimum soil
temperature of 25 to 35⁰C
Soil temperature can greatly affect the activity of locomotion,
infection and reproduction of nematodes
High temperature can manage- Verticillium spp.
Decreasing soil temperature, decreases the incidence of
Rhizoctonia bataticola
20. How does compost suppress
disease?
Improves soil physical and chemical properties
Improve soil structure and fertility
Enhanced activities of antagonistic microbes
Increased competition against pathogens for resources that
cause fungistasis
Release of fungitoxic compounds during organic matter
decomposition
Induction of systemic resistance in the host plants
27. CONSERVATION TILLAGE
• Reduced tillage systems accumulate OM and
increase the rate at which soil microfloral and
microfaunal decomposition progresses
• Soils with high levels of OM have been shown
to prevent common root rot of cereals
(Cochliobolus spp)
28. NUTRIENTs
Plants suffering a nutrient stress will be more
susceptible to diseases, while adequate crop nutrition
makes plants more tolerant or resistant to disease.
The nutrient status of the soil and the use of particular
fertilizers and amendments can have significant
impacts on the pathogen’s environment.
Calcium, play a major role in the ability of the plant to
develop stronger cell walls and tissues.
29. How can mineral nutrition prevent plant disease?
Mineral nutrition can affect two primary
resistance mechanisms:
A) Formation of
mechanical
barrier (eg.
Thickness of cell
wall )
B ) Synthesis of natural
defence compounds
(eg: phytoalexins ,
antioxidants and
flavanoids)
30. Nutrient Suppressing
Disease
Crops
Calcium 1)Clubroot
2)Fusarial wilt
3)Damping off
1) Crucifiers
2) Tomato, Watermelon and
cotton.
3) Peanut, Soybean, Pepper,
Tomato, onion, Bean and
Wheat.
Nitrate Fusarium wilt Tomato, Celery and Carnation.
Sulfur Scab Potato
Potassium Verticillium wilt Cotton
Phosphate Fusarium wilt Cotton and Muskmelon
Copper (cu) G. graminis var
tritici
Erysiphe spp.
Alternaria spp.
Take all of wheat ,
Powdery mildew of wheat
Sunflower
(Kausadikar et al ., 2006)
NUTRIENTs in management of plant diseases
35. EFFICACY OF SOIL HEALTH MANAGEMENT PRACTICES FOR PLANT
DISEASE MANAGEMENT
Positive effects
Not sufficient to complete control
20 to 80 per cent reduces soil borne diseases
Foliar pathogens diseases
Examples
Rust and mildews
36. Cont...
• Rhizobacteria: Induced Resistance to foliar and
soil borne disease
• Compost amendments induce resistance through
activation of plant defense response
• Examples: Botrytis Rot, Anthracnose, Angular
Leaf spot.
• Additional control measures for foliar pathogens.
38. Objective: To know the effect of cropping sequences
on Root Knot Nematode population
39.
40.
41. OBJECTIVE: The role of microbial activity in the effect
of soil moisture and temperature on disease severity
42. Dry root weight of wheat seedlings with (a) and without (b)
inoculation with R. solani AG-8, at different soil temperature and
moisture levels.
43. Objective: To determine the effect of PMR amendments
on soil borne and foliar diseases of cucumber and snap
bean grown on a sandy soil
44.
45.
46. Objective: To evaluate the efficacy of Brassica cover
crops used as soil amendments for managing
Phytophthora blight of squash
47. Reduction in Phytophthora blight on squash plants by soil amendments with
shoots (A) or roots (B) of cover crops under greenhouse conditions. Plant
tissues were used to amend infested soils at 1 or 2.5% (plant/soil, w/w).
51. CONCLUSION
Management practices that promote soil health by improving
soil physical, chemical, and biological properties, resulting in
improved nutrition, enhanced yield and disease suppression
Contribute to building active, diverse and potentially disease-
suppressive microbial communities and can provide the base
of a sustainable disease management program
Biodiversity is important to make management strategies
reliable
Use of soil health management practices can substantially
reduce soil borne disease problems, but cannot completely
eliminate them, may take time to develop, and should be used
in conjunction with other approaches to achieve sustainable
disease management