|
Organic
Cultivation
By H.M. Behl
According
to David Pimental of Corneall University, USA, 67 million birds are killed
annually in the USA from direct impact of pesticides. Pesticides pose dangers
to the biodiversity; health and well being of humans, animals and plant life;
and are detrimental to soil micro-flora, microfauna and soil health.
Developing nations like India have to procure these pesticides by paying
precious foreign exchange. However, there are unknown dangers in this chemical
recipe. Is this chemical cocktail indeed a necessary evil? Perhaps not.
In a natural
ecosystem, there has to be a harmony between food, forests, human population
and grazing population (in biological language, we say producers and
consumers). Increase in the number of consumers beyond the carrying capacity of
the land and need to export more for financial gains, motivates the communities
to produce more. Increased and unmanaged production results in poor
productivity per unit area, imbalance in the soil-water-microbes system,
degradation of soil sites and irrational land use systems.
Green
revolution vs. Sustainable green revolution
Improved
varieties, and methods of cultivation, can increase productivity, however,
chemical fertilizers and chemical pesticides changed the agriculture scenario
in the world. Varieties that respond to chemical fertilizer inputs were
selected for higher productivity. Irresponsible methods of cultivation and
increased use of quick release chemical fertilizers, over irrigation rendered
the soil unfit (not necessarily deficient in total nutrients but deficient in
available nutrients) for cultivation. A higher input of fertilizers was
practiced. However, there is a limit to application of fertilizers that soil
can transmit to the crops or the crops can accept. Thus so-called "Green
Revolution" was not a "Sustainable Green Revolution". The quick release
fertilizers don't involve the microbes and don't follow the natural system of
uptake. Such an uptake is a luxury intake. The so-called 'degraded soil sites'
are actually man made. Decrease in production and productivity are thus our own
creation.
Unhealthy
Crops
Intensive
cultivation, degraded soil sites, selection of varieties that are dependent
upon quick release fertilizers and unmanaged high input agriculture or
horticulture invites an array of diseases. Insect pests, fungal-and viral
infections further decrease productivity and result upon chemical fertilizers
and pesticides. The farmer is no more able to take his decisions and is
dependent upon chemical fertilizers and pesticides.
Chemical
pesticides are toxic, non renewable, non degradable, lethal and stay in the
environment for many years. Many of these can stay in the body for several
years and cause serious diseases. These chemicals kill the entire spectrum of
microbes including the friendly ones. Chemical pesticides are a 'slow release
nuclear' bombs' that have far reaching lethal effects than we can apprehend.
Higher
application of chemical fertilizers results in higher imports, higher costs of
production, transportation and overheads. It results in erosion of local
resources and poverty. The technology meant for increasing food production
becomes, in the long run, a cause for poverty, ecological imbalance,
unsustained development and disharmony between man and his environment.
Organic
Cultivation
There are
several aspects of Organic Cultivation. A planned Organic Cultivation will
involve site specific and crop specific decisions. The manager has to plan
Organic Cultivation at a specific site taking into consideration local
resources, status of the environment, community involvement including demands
from the cultivation project. However, two of these aspects, fertilizers and
pesticides are very crucial.
Organic
Pesticides
Supporters
of chemical pesticides claim that there is no option but to use these lethal
pesticides. It is surprising that though we are aware of several phytoactive
metabolites from the scientific body of knowledge as well as from the knowledge
available in Vedic literature, yet the society has patronized chemical
pesticides. Commercial gains, quick success, impatience and ignorance has led
to wide spread use of toxic chemical fertilizers. The losses to living
organisms, microbes, environment and crops are ignored for the apparent
commercial gains.
Search for
environmentally safe pesticides received an impetus in early 1960s following
the publication of 'Silent Spring' by Rachel Carson in 1962. Out of 1000s of
plants with bioactive properties, neem tree
(Azadirachta
indica
A.
Juss), the Nimba, as is known in Sanskrit language, provides pesticidal options
that are par excellence. The chemicals present in neem are safe, biodegradable
and are environment friendly. Vedic literature particularly Atharva Veda,
Ghryhasutra , Sutragrantha and Puranas provide a wealth of information on neem.
Brihat Samhita, the Hindu treatise associates neem plantation with
constellations. Long before synthetic chemicals and commercial insecticides and
fertilizers were available, neem derivatives were used in Indian villages to
protect and nourish crops. Today through scientific researches we know that
neem extracts can influence nearly 400 species of insects.
Neem plants,
as do all other plants, contain several thousands of chemicals. Of special
interest are hundred of terpenoids that are unique to neem and some related
members of this family. Of its biological constituents, the most active and
well-studied compound is
Azadirachtin.
However in most traditional preparations of neem as pesticide or medicine, a
mixture of neem chemicals are present and provide the active principles.
Neem is
quite effective against armyworm, one of the most devastating pests of food
crops in the western hemisphere. Azadirachtin in extremely low concentrations-a
mere 10 mg per hectare-inhibits the pests. Neem extract is useful against
leaf-miner, a serious pest in parts of North America. Neem seed extract has
been approved by the US environmental protection agency for use on leaf miners.
Neem is extremely useful as an anti-feedent and ovi-positional repellent for
protection of crops like tobacco, groundnut, cotton and sweet potato from the
damages caused by tobacco caterpillar or tobacco cutworm, a serious polyphagous
pest of several crops.
Neem is also
effective against fruit flies. Spraying neem can control med fly, one of the
most damaging horticulture pests. Whereas conventional pesticides will kill
fruit flies as well as thrips and internal parasites, neem products on the
other hand leave the friendly organisms unaffected. De-oiled neem cake (the
residual remaining after the oil has been pressed out of the seeds) and neem
oil are quite effective against rice pests. Five applications of a 25%
oil emulsion sprayed with an ultra low-volume applicator can protect rice crops
against brown plant hoppers. Neem products greatly reduce the tungo virus
transmission efficiency of green leathopper in rice. One of the traditional
uses of neem in Asia has been for controlling pests of stored products. Farmers
usually mix neem leaves with grain before keeping it in storage for several
months. Neem leaves, oil or extracts act as repellent against several insects
such as weevils, flour beetles, bean-seed beetles and potato moths. Treatment
of jute sack by neem oil or azadirachtin-rich-products prevents the penetration
of pests like weevils and flour beetles. Neem oil destroys bean- seed beetles (bruchids)
- variety of insects mostly attacking legumes -at the egg-stage itself.
Organic
Fertilizers
Organic
fertilizers include application of agriculture waste, composting using
earthworms, farmyard manure etc. However, microbes play a vital role in
facilitating uptake of nutrients in a crop. Rhizobia among several of these
mocrobes are quite popular for leguminous crops. Rhizobia and blue green algae
fix atmospheric nitrogen and reduce dependency upon artificial application of
chemical fertilizers. Mycorrhizae, the fungal organisms, facilitate P uptake.
Pseudomonas
and several other bacteria facilitate nutrient uptake and form a very friendly
network around the roots. Symbiotic organisms form a harmonious environment in
the soil. There have been several researches worldwide to show that these are
very friendly organisms. These organisms are usually available in the
soils, more abundantly in the tropical climates. The local crop manager has to
identify these microbes, select and multiply in sufficient quantities for
applications. It empowers the local community to use its own resources in terms
of biodiversity resources and rights, saves on application of high cost
fertilizers, renders the soil healthy and avoids interference with the
environment. The crop productivity can be optimized in the given environment.
Indian
farmers have traditionally used de-oiled neem cake as a fertilizer in their
fields. The dual activity of Neem cake as fertilizer and pest repellent has
made it a favoured fertilizer. When neem cake is ploughed into the soil it also
protects plant roots from nematodes and white ants. Farmers in southern parts
of India puddle neem leaves into flooded rice fields before the rice seedlings
are transplanted.
Neem cake
has been successfully used for organic cultivation of bananas. It protects
banana rhizome from infections and also serves as a ferfilizer. Unbelievable,
but no pesticides are then required. For cash crops such as turmeric,
sugarcane, banana and cardamom, 200 kg per hectare of Neem cake is
applied. For black peper and betel vine 250 g per plant is applied. Neem
cake is also extensively used for citrus trees, jasmine, roses and vegetable
crops as organic manure. 100 kg of Neem seed cake will provide nearly 3.6 kg to
N, 0.8 kg of P, 1.7 kg of K, 0.77 kg of Ca and 0.75 kg of Mg. Cases where urea
application is unavoidable, coating of urea with neem extract prevent
denitrification and increases urea efficacy.
Organic
cultivation is an integrated crop management. Selection of elites among local
cultivars or land races, producing hardy seedlings, applications of
bio-fertilizers, microbial management, application of vermi-compost, practicing
bio-pesticides, intercropping of 'protective' or symbiotic grasses, herbs or
weeds are all components of Organic Cultivation.
Government
of India, as also many other countries, provide accreditation as labeling for
household and other consumer products, which meet the set environmental
criteria. The ECOMARK logo is an earthen pot.
Organic
cultivation is a beginning. In fact, we are re-discovering it since this was
the form of cultivation from Vedic times to recent India. Indian agriculture of
the past 5000 years was not Petro-chemical based agriculture rather an
organic agriculture. Let us revert to Vedic Organic Cultivation; it may be
agriculture, horticulture, silviculture or kitchen gardening.
Dr. H.M. Behl is Deputy Director & Head, Biomass Biology Division at the
National Botanical Research Institue, Lucknow & Executive Editor of EnviroNews
|
