305 lect 19organic ecosystem and their concepts.ppt

organic ecosystem and their concepts

1. LECTURE NO.19
Organic ecosystem and their concepts –
Soil and water management- soil organic matter and
humus- Their physical, chemical and biological
properties.

2. Soil Organic Matter and Humus
•Physical Properties
•Structure
•Soil Texture Improvement
•Water Retention
•Chemical Properties
•Nutrient Supply
•Cation Exchange Capacity (CEC)
•Soil pH Buffering
•Biological Properties
•Microbial Activity
•Enzyme Production
•Microbial Habitat
•Decomposition

3. The core element in organic crop husbandry is the
management of a site-specific and market-oriented
crop rotation.
Alternating a wide range of crops over time and
space can facilitate efficient use of the soil resource
of a farm by cultivating crops of varying profiles in
nutrient demand and supply, growth habit and
phytosanitary characteristics.

4. Biodiversity, buffer and contamination control 
Maintaining and enhancing biodiversity is considered central to
developing a sustainable organic system.
 Organic farming depends upon stabilizing agroecosystems,
maintaining ecological balances, developing biological processes
to their optimum and linking agricultural activities with the
conservation of biodiversity.
Increased biodiversity improves and buffers ecological services
such as pollination, pest control, maintenance of soil fertility, thus
strengthening farming systems and practices.
some organic certification organizations have incorporated
biodiversity requirements into their standards.
The Swiss organic standards, for example, require farmers to use
7% of their land as semi-natural habitats.

5. a.Genetic diversity
 
The adoption of high yielding, uniform breeds and varieties
has led to a considerable reduction in the number of species and
in the number of varieties/breeds within species
There are many schemes and projects worldwide working to
conserve seed banks and indigenous varieties, many of which
are linked to organic agriculture projects.
Variety choice in organic farming is an essential factor of
successful production.
Conventional plant breeding aims at optimizing yields under
high inputs.

6.  As the diversity of organic farming systems and conditions is
large and results in a larger genotype-environment–
management (G X E X M ) interaction than in conventional
agriculture,
the organic farmer is more interested in varieties that have the
ability to adapt to variable conditions and perform well with
stable yields in different years at the specific site.
 In many countries, there are variety trials under organic
conditions, but not for every crop and every year.
Some are conducted by farmer groups, others by commercial
seed companies.

7. A possible future threat to genetic diversity and biodiversity in
general, could be release of genetically engineered or
modified organisms (GMOs) into the environment.
 In organic agriculture, genetic engineering is banned.
The International Federation of Organic Agriculture
Movements (IFOAM, 2002) is opposed to genetic
engineering in agriculture, in view of the unprecedented
danger, it represents for the entire biosphere and the particular
economic and environmental risks it poses for organic
producers.

8. The reasons mentioned by IFOAM can be clustered into 3 groups:
1.Risks for human health and the environment:

Release of irreversible compounds that have never
before existed in nature and which cannot be
recalled.

It also causes Pollution of off-farm organisms and
pose unacceptable threats to human health.

10. In organic farming, as the input level is low, varieties
that have high nutrient uptake efficiency is essential as much
as the ability to interact with other soil organisms, such as
bacteria and fungi, enhancing plant mineral nutrition.
3. GM technology is incompatible with principles of
sustainable agriculture.

12. C. Habitat and biodiversity-
Management of an appropriate habitat for sustenance of different
life forms is an essential component of organic farming.
This can be achieved by ensuring crop diversity and by maintaining
a wide variety of trees and bushes as per climatic suitability.
 These trees and bushes will not only ensure the nutrients from air
and deep soil layers to surface layer, but also attract the birds and
predators, friendly insects and also provide the food and shelter.
There may be some loss of productivity due to shading effect ,but
that loss can be compensated with reduced pest problems and
natural biological pest control system.

13. In the plains, for a 10- acre farm,
plant at least five to six neem trees (Azadirachta indica),
one to two tamarind (Tamarindus indica),
two gular(Indian Fig tree - Ficus glomerata),
eight to ten ber (Zizyphus Sp) bushes,
one to two aonla (Emblica officinalis),
one to two drumstick (Moringa oliefera ) and
10– 15 wild bushes.

14. Alley cropping or hedgerow intercropping
It is an agroforestry practice in which perennial, preferably
leguminous trees are grown simultaneously with an arable crop.
The trees, managed as hedgerows, are grown in wide rows and
the crop is planted in the 'alley' between the tree rows.
During the cropping phase the trees are pruned and used as
green manure or mulch to improve the organic matter status of
the soil and to provide nutrients, particularly nitrogen, to the crop.
The hedgerows are allowed to grow freely to shade the inter-
rows when there are no crops.
 Alley cropping retains the basic restorative attributes of the
bush fallow through nutrient recycling, fertility regeneration and
weed suppression and combines these with arable cropping
They also provide an important habitat for wildlife.

15. Shelter belts/zones
are planted across the direction of wind.
The protection offered by the shelterbelts is dependent
on the height of central tree row in the shelterbelts.
Generally, shelterbelts give protection from desiccating
winds to the extent of 5 to 10 times their height on
windward side and up to 30 times on leeward side.
Due to reduction in wind speed, evaporation losses are
reduced and more water is available for plants.

17. In serious droughts, the foliage from shelter belts (such as
poplar and willow species) can be harvested and used to feed
stock.
Use of appropriate tree species may encourage bees, especially
in early spring, and predators or parasites of crop pests.
Shelter belts also provide habitats for birds, and native trees
may attract native birds.
The leaves and vegetative matter within and dropped by
vegetation intercept raindrops and prevent the pounding of soil
and dislodgment of soil particles.
 The litter dropped by vegetation increases the organic matter
within soils increasing the ability of soils to absorb and hold
water and to reduce run-off.
The roots of plants bind and hold the soil.

18. Selection of crops and cropping systems
 
The central role of crop rotations in organic farming is highlighted
by the important focus on rotations in many organics certification
standards.
Crop rotation is the term used to [indicate] that crops are grown
over time in a very specific order.
After a number of years (length of the crop rotation), the cycle will
be repeated.
The crops grown in one year on the available area of a farm make
up the cropping plan.
If the crop rotation is consistent and unchanged, the cropping plan
is the same every year.

20. Non monetary crop production management
a) Seed/ Planting material Treatment
 
In organic management, protection measures are used only in the
case of problematic situations.
Use of disease free seed stock and resistant varieties is the best
option.
 There is no standard formulation or treatment methodology,
available as on today, but farmers use different methods.

21. Few of such innovative seed treating formulations are

Hot water treatment at 53
0
C for 20-30 min.

Cow urine or cow urine-termite mound soil paste

Beejamrut or Asafoetida 250gm in one lit. of water for 10
kg seed

Turmeric rhizome powder mixed with cow urine or
Panchgavya extract or Dashparni extract

Trichoderma viride (4gm/kg seed) or Pseudomonas
fluorescens (10gm/kg seed)

Biofertilizers (Rhizobium/ Azotobacter +PSB)

22. b. Planting densities
 
Weed management itself is important in determining crop
densities and planting configurations.
Wider rows are advantageous for weeding to allow access for
tillage and hand- weeding implements, particularly under heavier
weed loads.
However, higher crop densities along the row achieved through
closer transplant distances for seedling-grown crops or higher
sowing rates for seed-grown crops are used to maximize resource
capture and competition against weeds.

23. c.Timing of operations 
scheduling of farming activities is an important cultural
strategy used by organic growers to manage resources efficiently
and improve their effectiveness.
The main factors for which timing can be manipulated include
sowing, tillage, applying inputs and harvesting.
Farmers' decisions about timing may be influenced by
agronomic considerations such as crop phenology, the quantity
and growth stage of weed seedlings, environmental factors such
as climate and soil condition,

24. Nitrate leaching can be an undesirable impact of organic crop
production.
Losses of mobile N of 100 kg ha
-1
or more have been reported
posing a serious economic and ecological problem, especially if
continuous leakages within the rotation cannot be avoided.
 However, careful timing of farming operations such as
fertiliser applications and green manure management to match
availability with demand can be achieved.
Conventional 'best practice' is designed to minimize nitrate
leaching by improving the N use efficiency of crops, as well
as protecting soil N from leaching during higher rainfall.

25. d. Mulches
Mulches can be used economically in many organic
horticultural crops including annual herbs and vegetables as well
as perennial vine and tree crops.
In addition to suppressing weeds, organic mulches have other
benefits such as conserving soil and moisture,
reducing soil temperature fluctuations,
adding organic matter and nutrients to the soil and
preventing soil from splashing onto crop leaves.
 Materials used as organic mulches include
compost and manures,
crop residues (ash, grass, hay, in situ residues, starch, straw),

tree products (bark, sawdust and woodchips),
fibre products (fabric, jute, coconut fibre, wool), and
paper products (pellets, sheets, rolls, chopped, shredded).

26. Synthetic mulches are allowed for limited use in organic
production (IFOAM, 2002) and offer many of the benefits of
organic mulches ,
but are considered less sustainable owing to the non-renewable
source materials, energy required in manufacture, single usage
limitation and long-term disposal requirements.
Woven plastic material, such as weed matting, is permitted and
restricted for short-term use only

27. e. Weeds as indicators
 specific weeds to specific soil conditions and that refer to the
possibility of weeds being 'indicators' of soil status.
The presence of a given weed therefore suggests that the land
has too much or too little of a certain soil feature (e.g. drainage,
pH, copper levels) that may be modified by the farm manager.
Tilman et al. (1999) investigated the relationship between
dandelion (Taraxacum officinale) abundance and High soil K.
Crab grass – overall low nutrients specifically calcium
Purslane – rich fertile and high in Phosphorus
Thistle – dry heavy, acidic and iron deficit soils

28. Soil physical problems and reclamation
 
a) Soil Crust & Low Permeability
Rain impact on exposed soil is probably the main
method of crust formation.
A lack of ground cover (e.g. stubble retention) to protect
the soil surface can result in soil crusts forming following
a rainfall event.

30. b. Soil compaction & soil hardening
Operation of heavy vehicles (e.g. harvesters, construction
machines) on agricultural land can cause soil compaction
resulting in low porosity (n) or high bulk density (ρb) &
which causes mechanical impedance to plant root growth,
poor aeration, and restrictions to water infiltration.
While hardening occurs due to intensive cultivation, soil
aggregate structure is damaged due to long term use of
chemical fertilizer.
 

31. Organic farming as a remedy

Soil compaction and hardening of soil reduce by
conservation tillage which doesn’t involve repeated use
of heavy vehicles.

Organic manure can improve soil structure, release soil
nutrients, increase the activity of soil organic matter,
expedite disintegration of humus which helps prevent
soil compaction/hardening and activate soil
microorganisms in the soil.

Beneficial microbes, earthworms and other small
animals naturally reproduce, promoting the gradual
softening of soil structure and the activation of soil
bacteria.

32. c. Low water retention

Clay type, organic content and soil structure influence soil water
retention.

The soil’s ability to retain water is strongly related to particle
size; so clays generally retain more water.

Conversely, sands provide easier passage or transmission of
water through the profile.
Remedial measures

Sphagnum peat is an excellent soil amendment, especially for
sandy soils, which will retain more water after sphagnum peat
application.

Sphagnum peat is generally acidic (i.e., low pH) and can help
Gardeners grow plants that require a more acidic soil

34. d. Intensive Tillage:
Tillage adds oxygen to soil, which leads in the
microbial population and results in Quick
decomposition of Soil Organic Matter
in addition, tillage breaks up soil aggregates,
exposing more organic matter to microbial
decomposition

35. Remedial measures in organic farming
Reducing tillage is important from the viewpoint of
environmental-farming for a number of reasons.
 The cover of crop residue helps prevent soil erosion by water
and air, thus conserving valuable top soil.
 Soil structure improves because heavy machinery (which
causes soil compaction) is not used and soil tilth is not tampered
with artificially.
 With earthworms not being routinely disturbed by deep
tillage, their numbers increase bringing with them the
accompanying benefits of better soil aeration and improved soil
fertility.
 Microbial activity in soil also increases for the same reason.
 Another important environmental effect of reduced tillage is the
reduction in use of fossil fuels on the farm.

36. Water management and Organic farming
Capturing and retaining rainfall is an effective tool for reducing
dependency on off-site water resources.
Land management approaches such as creating levees, berms,
swales and ditches all effectively capture water for local recharge.
Creating catchment areas greatly reduces the dependency on
water pumped from other areas.
Collection ponds capture water during large rainstorms, which
reduce erosion and nutrient leaching from the soil.
Additionally, they provide habitat, which increases biodiversity
and protects native plants and animals.

39. Rainwater harvesting systems not only supply farmers with
irrigation resources, but can be effective tools for providing
water to livestock.
Capturing rainwater off roof tops of houses, barns or other
surfaces can provide drinking supplies for cattle during dry
seasons.
In arid lands the careful use of water is as much a part of
organic growing as is any other technique.
Organic farming systems help to maintain water quality by
reducing the amount of chemicals used in agriculture and by
reducing eutrophication.

40. Role of Organic Systems in improving Water use efficiency
Humus is one of the most important components of organic
matter.
It stores from 20 to 30 times its weight in water so that rain
and irrigation water is not lost through leaching or evaporation.
 It is stored in the soil for later use by
the plants.
Research shows that organic systems use water more efficiently
due to better soil structure and higher levels of humus.
‘Soil water held in the crop root zone was measured and
shown to be consistently higher by a statistically significant
margin in the organic plots than the conventional plots, due to the
higher organic matter content in the organic treated soils.’

41. Integrated Farming system (IFS):
Farming system refers to raising of crops, forest and fruit trees,
animals including fisheries, piggery, duck farming, sericulture,
mushrooms on a given unit of land to increase the productivity
and profitability to upgrade natural resource base and to achieve
overall improvement in the environment.
These systems also need to be socially acceptable,
economically viable and eco-friendly.
The increased productivity from the various enterprises can
only come from the better understanding of the nature and extent
of the interactions among various enterprises and natural
resources.

42. Integrated farming system models vary widely in each
agro-climatic zone with very high location specific
natural resource availability like rainfall and other
climatic factors, soil types and market demand.
IFS models are classified into a. Wetland b. Irrigated
dry and c. Dryland.