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1. ENV 107:
Introduction to Environmental Science
Lectures 15
Sustainable Agriculture
Instructor: Raisa Bashar (RBr)
1

2. Agriculture
• Agriculture refers to the production of goods (food, fiber,
etc.) through the growing of plants, animals and other life
forms. It is the art and science of farming.
• People obtain food from cultivated plants and
domesticated animals.
• Historically, humans have depended on three systems for
their food supply:
– (1) croplands (mostly for producing grains, which provide about 76%
of the world's food),
– (2) rangelands (for producing meat mostly from grazing livestock,
which supply about 17% of the world's food), and
– (3) oceanic fisheries (which supply about 7% of the world's food).

3. 3
Characteristics of Bangladesh Agriculture
 Cropping intensity 179%
 Irrigated land 56%
 Surface water:21% groundwater:79%
 Land-man ratio: .06 ha
 Mainly subsistence farming
 Inadequate agro-processing
 Non-mechanized farming
 Fragmented land/plots
 Dependence largely on nature

4. 4
Some Challenges
 Rapid shrinkage of agricultural land @1% per year
 Population growth @1.48% per year
 Climate change and variations
 Rapid urbanization growth @12% per year
 Agricultural research and education (manpower shortage,
updating course curriculum)
 Technology generation (needs expertise, time and money)
 Technology dissemination (needs expertise, time, logistics
support)
 Alternate livelihoods/rehabilitation program
 Inadequate value addition/food processing

5. 5
Challenges continued…
 Climate change adaptation & mitigation
 Developing stress tolerant varieties
 Transferring updated information and technologies to
the field
 Attaining irrigation efficiency
 Regaining soil fertility and natural ingredients
 Research-extension-farmer-market linkage
 Shortage of Agricultural labor at peak seasons

6. What is Sustainable Agriculture?
“Sustainable agriculture means an integrated system of
plant and animal production practices having a site-specific
application that over the long term will:
 Satisfy human food and fiber needs.
 Enhance environmental quality and the natural resource
base upon which the agricultural economy depends.
 Make the most efficient use of nonrenewable resources
and on-farm resources and integrate, where
appropriate, natural biological cycles and controls.
 Sustain the economic viability of farm operations.
 Enhance the quality of life for farmers and society as a
whole.”

7. Differences between the Contemporary and
Sustainable Types of Agriculture
Contemporary Agriculture Sustainable Agriculture
1. System
simplification/monoculture
2. Specialized agriculture
(economically vulnerable)
3. Soil is considered just as a
medium
4. Feed the plant directly, not the
soil
5. Linear flow of nutrients or
energy
1. System of production diverse
not restricted by monoculture of
crops
2. Recycling of nutrient pool for
crop
3. Feed and nurture the soil, not
the crop
4. Holistic approach to farm
productivity

8. Positive aspects of Sustainable Agriculture
• Affordability by any farmer
• No sophisticated/imported and special technology is necessary
• Environmental conservation and protection
• Healthy atmosphere/healthy food
• Prevent/avoid ecological degradation
• Increasing stability and status of soil fertility
• Security more through higher levels of disease and pest resistance
• Recycling of nutrients
• Substance of soil fertility through organic recycling
• Diversity
• Inter dependency
• Efficient use of natural resources
• Self sustaining

9. Elements of Sustainable Agriculture
A) Soil Conservation: Soil conservation methods including contour
cultivating, contour bunding, graded bunding, vegetative barriers, cover
cropping, reduced tillage etc. which help to prevent loss of soil due to wind
and water erosion.
B) Crop diversity: Increased crop or Bio-diversity on farm can help reduce
risks from extremes in weather, marketing conditions, and pest disease
incidences. The increased diversity of crop and other plants such as trees,
shrubs and pastures also can contribute to soil conservation habitat
protection and increased populations of beneficial insects.
C) Nutrient management: Integrated management of essential nutrients
can improve and sustain soil fertility and protect environment. Increased
use of on farm low cost inputs such as organic manures, composts, green
manures and crop residues not only reduces cost of production but also
rejuvenates soil health.

10. Elements of Sustainable Agriculture
D) Integrated Pest Management (IPM): It is a sustainable approach to
manage pests by aptly integrating the available plant protection
methods like cultural, physical, mechanical biological and chemical
methods, which optimizes the production costs besides maintaining
environmental balance.
E) Water quality & water conservation: Practices like zero tillage, deep
ploughing, and mulching and micro irrigation techniques and mulching
can help to optimize the water consumption or requirement besides
conserving and augmenting the soil moisture on long term basis. It also
helpful in protecting the quality of drinking water and surface water.
F) Agro forestry: A combination of Silvi-pastoral, Agri-Silvi-Pastoral, Agri-
Horticulture, Horti -Silvi Pastoral, Alley cropping, Ley farming etc that
can help conserve soil and water and profitability. Also leads to supply
of fuel wood, horticultural products and achieve balanced nutrition to
rural people.

11. Elements of Sustainable Agriculture
G) Marketing: Improved marketing facilities can ensure remunerative
and sustainable returns to farmers. Direct marketing of produce can
exclude intermediaries and ensures higher returns and malpractices.

12. Arable land Management
• Vegetative cover: Vegetative cover refers to as trees,
perennial bunchgrasses and grasslands, legumes,
and shrubs
• Strip cropping mulching
• Ridges/furrows
• Water ways with vegetative cover and gully
plugging [Gully (drain) control is very essential to prevent its extension
and further destruction of cultivated lands and grasslands. The sloping sides are
planted with grass and trees. Suitable temporary and permanent structures
such as check dams, overflow dams, drop structures are also provided]

13. Land/Soil Degradation through different Processes
Soil Degradation
Physical
Compacting
& crusting
Desertification
Erosion &
Depletion
Water
Erosion
Wind
Erosion
Chemical
Fertility
imbalance
Acidification
Biological
Decline in Organic
matter
Reduction in Macro
& Micro fauna
Salinization &
Alkalization
Toxicant
accumulation
Elemental

14. Integrated Nutrient Management (INM)
The basic concept underlying Integrated Nutrient Management system
is the maintenance of soil fertility, sustaining agricultural productivity
and improving farmers’ profitability through judicious and efficient use
of fertilizers, organic manures and bio-fertilizers to the extent
possible.
According to Steen, a renowned scientist
a. Integrated Nutrient Management implies the minimum supply of
nutrients from any source which is, at the same time, sufficient to
meet the requirement of the crop and maintain soil fertility,
b. Integrated Nutrient Management implies the efficient use of
plant nutrients which is achieved by following research based site
specific recommendations and adopting ‘Best agricultural
practices’ and Integrated Nutrient Management recognizes the
existence of natural soil processes which make certain loses
unavoidable”

15. Integrated Nutrient Management - Some basic
considerations
• Soil fertility and soil productivity
• Nutrient availability in soil
• Physical, physicochemical and chemical constraints for crop
production
• Crop response to externally added nutrients through mineral
fertilizers or organic manures or bio-fertilizers
• Nutrient-yield relations
• Nutrient uptake ratios and their significance
• Nutrient interactions in plant
• Water availability and irrigation facility
• Weather and environmental factors affecting productivity
• Management practices

16. Plant Nutrients
Sixteen chemical elements are known to be important to a plant's
growth and survival. The sixteen chemical elements are divided into
two main groups: non-mineral and mineral.
Non-Mineral Nutrients are hydrogen (H), oxygen (O), & carbon (C).
Mineral nutrients:
The macronutrients are nitrogen (N), phosphorus (P), potassium (K),
calcium (Ca), magnesium (Mg), and sulfur (S). Plants use these mineral
nutrients in large amounts for their growth and survival.
The micronutrients are boron (B), copper (Cu), iron (Fe), chloride (Cl),
manganese (Mn), molybdenum (Mo) and zinc (Zn). Plants use these minral
nutrients in less amounts.

17. Different Sources of Nutrients for Integrated Nutrient
Management
The following are the major Sources of Nutrients
1. Chemical fertilizers
2. Organic Manures or Compost: Cow dung, Animal dung, Kitchen
waste ect. used for composting.
3. Bio-fertilizers: The preparation containing specialized live
microorganisms for seed treatment or soil application with objective
of increasing the number of such microorganisms and accelerates the
microbial process of converting unavailable form of plant nutrients to
available form.
4. Green Manures: Green manures are applied to the field without
composting. Eg. legume crop
5. Vermi-Compost: Vermi-composting is gaining popularity during
recent years because it is environmental friendly and economic.

18. What is IPM?
Integrated Pest Management (IPM) is a system
that, in the context of prevailing environment and
population dynamics of the pest species, utilizes all
appropriate techniques and methods in as
compatible a manner as possible and maintains
pest populations at levels below Economic
Threshold Level (ETL)
-FAO, 1967

19. Components of Integrated Pest Management
IPM
Ecology of Pest
Host Plant Resistance
Pest Surveillance and monitoring
ETL ( Economic Threshold Level)
Legal Method
Behavioural methods
Pheromone
Allelochemical
Physical methods of pest control
Mechanical methods
Cultural methods
Chemical methods
Genetic/Biotechnological methods
Biological methods
Botanicals
Predators
Parasitoids
Pathogens
Virus
Fungi
Bacteria
Protozoa

20. IPM Components
Biological control: the control of a pest by the introduction of a
natural enemy or predator. Biological control is a method of
controlling pests such as insects, mites, weeds and plant diseases
using other organisms. It relies on predation, parasitism, herbivory,
or other natural mechanisms, but typically also involves an active
human management role.
Integrated pest suppression: An approach to compatible
utilization of all available forms of pest suppression, including
mechanical, biological, chemical, and natural control, in a
systematic fashion, with the primary goal of safe, effective, and
economical pest population reduction. It may be directed at a
single important pest species by combining a variety of measures
against the species, or at a complex of pests, integrating the
individual protective measures applied against each, so as not to
interfere one with the other.

21. Physical method of pest control
The following are some examples of the use of physical methods of
insect control
• Use of activated clay at 1% or vegetable oil at 1% has been found to
effectively control damage by Callosobruchus chinensis in stored
pulses.
• Solar heat treatment of sorghum seeds for 60 seconds using solar
drier kills rice weevil and red flour beetle without affecting
germination of seeds.

22. Mechanical method of Pest Control
 Hand picking of caterpillars
 Hooking of rhinoceros beetle adult with iron hook
 Sieving and winnowing for stored product insect control
 Shaking plants- to remove caseworm in rice and June beetles from
neem trees

23. Use of botanicals in pest management
Grainge and Ahmed (1988) listed about 2400 plant species with
pesticidal properties (insecticide, acaricide, nematicide, fungicide etc.
which are distributed in 189 plant families).
 Neem oil at 2% and neem seed kernel extract (NSKE) at 5% with
liquid soap 0.05% have been proven effective against major pests
of rice, sucking pests of cotton and vegetable.
 Neem cake applied at 250 kg/ha at last ploughing before sowing
has been found effective against cotton stem weevil and soil
insects of many other crops.

25. Advantages of IPM
We often hear the question “what are the advantages of IPM?”. Think
of this:
• More regular crop quality and quantity
• Healthier plants
• Reduced contamination of the environment
• Reduced use of pesticides
• Reduced input costs
• Better use of natural resources
• Reduced contamination of the crop with chemical residues
• Reduced risk of farmers from contamination with chemicals

26. Irrigation Water Management
Irrigation can also be defined as the supply of water to crops by artificial
means, designed to permit farming in arid regions and to offset drought
in semiarid and semi humid regions.
• To add water to the soil for supplying the moisture essential for plant
growth
• To provide protection to crops against short duration droughts
• To cool the soil and atmosphere, thereby making more favorable
environment for plant growth
• To wash out or dilute salts in the soil
• To reduce the hazards of soil piping, and
• To soften tillage pans

27. Water Management to Reduce Water
Requirement
Developing improved varieties, improving agronomic management -
introducing optimum combinations of improved technologies or
management practices such as pest control and nutrient management
can raise crop yields and output per unit of transpiration. Changing the
crop planting date, reducing water use for land preparation, changing
rice-planting practices, reducing water use in the crop growth period,
making more effective use of rainfall, water distribution strategies and
water recycling and conjunctive use improves the irrigation water
productivity. General strategies for increasing water productivity are
rehabilitation and modernization, and irrigation management transfer
(IMT).

28. Different method of Irrigation
The four methods of irrigation are:
1. Surface
2. Sprinkler
3. Drip/trickle
4. Subsurface