Crop Plant Agriculture vis-ã-vis
Environment
S.K.T. Nasar
The is a magazine article to create
awareness about environment; hence, details of technical aspects are avoided.
Published in Jeebaner Paribesh - Environment of Life; 2nd Year, 9th Issue, 15 April 2014, pp 15-19
Agriculture
Sustains Life and Livelihood of Billions
Many perceive Agriculture as too muddy for respectability which,
in fact, it is not. Agriculture includes all operations from sowing seeds to
harvesting and making agricultural products available for use as food, feed,
aesthetics and industrial raw materials. Agriculture encompasses almost all
spheres of human life.
The enormity of agriculture as a sub-system of biology, society,
economy and environment emanates from data that more than seven billion people
globally, 1.27 billion in India, are eating food and using agricultural
products. Demand for contaminant-free food-cum-nutrition is rising as never
before. Requirements for agricultural products for services and as industrial
raw materials are growing exponentially.
Agricultural production is prone to environmental conditions.
Spells of drought or flash floods cause devastations that make the landless
farmers to the members of the United Nations Organisation to sit up in alarm.
Earth quakes, Tsunamis and typhoons spell disasters not only for local
communities but trigger international ripples in prices and in transborder
businesses.
Agriculture contributes to making or marring the environment.
Agriculture and environment maintain a two-way traffic.
Sunlight
Energy and Agriculture
The fundamental tenet of capturing and utilising sunlight energy
through agriculture has not changed over millennia. Nor is it likely to alter
in the foreseeable future. Agriculture in India as elsewhere has modified from
subsistence- to surplus- to commercial agriculture giving way to
internationalisation of farming systems. This sunlight energy captured by all
green cells including those of crop plants passes through food webs on to other
organisms that lack the mechanism of capturing sunlight energy. Solar energy
ultimately reaches the human species from different sources from crop products
to edible animals - their meat, milk and egg.
Agro-ecosystems like natural ecosystems recycle all substances
created by life processes and from dead organisms. The process is bio-geo-chemical recycling.
Breakdown of the recycling processes has far reaching consequences for the
environment.
Glocal
(i.e. global plus
local) Concerns
No wonder then that Agriculture is glocal business and trade at
global to local levels. Policy concerning self-sufficiency in agriculture and
its sustainability besides equitable accessibility to food, and profit-making
to satisfy human needs and, of course, greed are bothering all stake holders.
Agricultural operations transcend national, environmental, geographical and
generational boundaries.
Location specificity and seasonality of agricultural commodities
are determined by the environment. Sustainable agriculture needs to adjust to
climate change and unprecedented environmental fluctuations. That is a
formidable challenge.
Massive intensive and extensive agricultural operations to
assure the escalating needs of exponentially growing human population indeed
modify the environment in diverse ways.
Agriculture and environment are inseparable components affecting
each other.
Facets
of agriculture
Agriculture has been defined as ‘the systematic and controlled use of living organisms and the
environment’. It includes cultivation of terrestrial and aquatic plants,
animals and fish. Major operational schemes of agriculture are related to
where, when and how of cultivation methods, choice of the right varieties and
essential practices to be followed. Inputs like seeds, implements, irrigation
water, energy in the form of fuel and electricity, fertilisers and devices for
pest protection have to be made available to grower-farmers. These are non-farm operations. Non-farm
agricultural activities have a direct bearing on the environment and vice versa.
On-Farm
Plant Crop Production in Relation to Environment
A quick look at the production technology and package of
practice for plant crops highlights the two-way relationship between
agriculture and environment.
Vital agricultural operations of plant crop are land preparation,
sowing of desired seeds, providing irrigation water, adding fertilisers, taking
pest control measures, and finally harvesting products. Timeliness of each
operation is crucial.
Manoeuvres are different for the production of human food and
livestock feed, plantation crop, flower, fibre, wood-fuel, biofuel, medicines, and
industrial raw material. Molecular farming for specific molecules is in high
demand. Agriculture uses, in addition to plant species, organisms such as
microbes, animals, fish, insects with similar goals of production and services.
Agricultural procedures may combine the benefits of different organisms for
specific production targets. These operations depend on local climatic
conditions and on the environment at large.
Photosynthesis
is fundamental to all life and the essence of agriculture
Agricultural production is dependent entirely on photosynthesis,
the natural phenomenon in which living green cells capture energy from sunlight
and convert it to chemical energy. Leaves of crop plants appear green due to
the presence chlorophyll contained in special compartments within cells, the
chloroplasts. Crop plant agriculture is the only managed system that brings in
energy from extraterrestrial source, the Sun.
During photosynthesis, sunlight energy, the photon, is first
captured by the chloroplast/chlorophyll which then, through a series of complex
biochemical processes, combines carbon dioxide (CO2) and water (H2O)
to produce carbohydrate such as sugars and starch which are ultimately
converted into protein, fat etc. However, all organisms must respire to sustain
life. The biochemical process of respiration breaks down photosynthetic
products but then, in balance, the accumulation of biomass i.e. biological mass
is the outcome. Photosynthetic products during the prehistoric past formed
fossil fuel that are presently contributing to the production of food, feed and
other products that humans utilise.
The photosynthetic CO2 comes from the atmosphere
while H2O, nutrients and minerals are mined from the soil by plant
roots.
Agriculture contributes greatly to reducing CO2 load
of the atmosphere and to raising O2 levels thus assisting the
maintenance of environmental equilibrium.
Ecosystem
and agro-ecosystem
Different kinds of organisms co-exist in nature. Living
organisms form the biological or biotic factor of an ecological system called
ecosystem. Air, water, soil, weather, and non-living matter together make the
non-biological or abiotic component of an ecosystem. Agro-ecosystem is a
managed ecosystem as opposed to unmanaged natural ecosystem such as a forest
ecosystem.
Human societies began shifting from hunting edible animals or
fish and gathering edible forest products such as cereals, fruits and fuel wood
to domesticating animals and sowing seeds of plants for food and services more
than twelve thousand years ago. This process gradually gave rise to organised
agriculture and by about eleven thousand or more years ago societies were
established as food producers.
Natural forest lands had to be cleared irreversibly for
organised agriculture, human settlements, plantations, pastures for livestock,
mining etc. It was from this time on that naturally occurring landscape
continued to be converted into managed farm lands. This phenomenon impacted
glocal environment. Yet, agricultural fields continue to be significantly
influenced by the environment at local levels depending upon climate and
topography. While climate determines the energy from sunlight and CO2,
the supply of water is determined by local geography, rainfall pattern
and soil type.
Ploughing
of Farmland
Agricultural practices include tillage by ploughing to primarily
loosen up the soil for aeration and smothering of weeds to achieve good
germination of crop seeds, easy penetration of roots and desired plant growth.
For the cultivation of wet or lowland rice (Oryza
sativa), the ploughed land is puddled to retain water in the crop field. On
the other hand, water must not be retained in the field for upland or dry
cultivation of wheat (Triticum vulgare)
for example.
Soil operations are confined mostly to the uppermost layer. The top
soil is the most fertile soil rich in micro-organisms, nematodes and mites,
earthworms, organic matter and crop nutrients. The top soil shows high
biological activity.
The soil contains large quantities of essential nutrients for
crop plants. Living soil organisms
convert crop nutrients to forms in which these are utilised by the plants. Soil
moisture supplies water to the crop.
Ploughed soil is removed from cultivated fields with the outflow
of excess water or is blown away from dry and dusty crop land with high velocity
wind. Erosion moves soil into water bodies adding enormous amount of sediments.
Sedimentation over decades causes choking of dams and irrigation canals. Soil
erosion depletes fertility in farmland. Soil organisms including seeds of
noxious weed are spread out to large areas. Ecosystem equilibrium is thus
disturbed every cropping season. Emission of Green House Gas (GHG) is another
international concern to which wetlands and wet agriculture is a contributor.
Quenching
Crop Thirst – A Necessary Evil?
Crop plants need water at different stages of growth.
Irrigation is resorted to where rain is scanty or when rain water is
unavailable as required.
Irrigation water is sourced from open water bodies, for
instance rivers, streams, lakes and ponds, or from groundwater aquifers by tube
wells. Excessive withdrawal of ground water for irrigation besides for
municipal and industrial supplies causes subsidence of the groundwater table.
Intensification of agriculture has caused depletion of
groundwater leaving the soil dry with crusts of unwanted salts. Desertification
or salinisation of once fertile arable land is not very uncommon in some areas.
Desertification, salinisation, alkalisation and acidification of soils impact
the environment in several ways.
Many aquifers contain iron, arsenic and selenium.
Groundwater contaminants are spread by irrigation and absorbed by farmland,
water bodies and crops. Agricultural products are contaminated to unacceptable
levels. The case of arsenic contamination is well known. Chemical contaminants reach humans and
livestock via the ecosystem food web. Health hazards and diminished saleability
of commodities are rampant in vast geographical areas.
Periurban farm fields are largely sewage-irrigated with
urban effluents overloaded with chromium (Cr), cadmium (Cd), arsenic (As), lead
(Pb), copper (Cu), zinc (Zn), and antibiotic-resistant bacteria and fungi.
These toxic chemicals and disease-causing biological
entities infused into agricultural products adversely affect the well being of consumers.
Dams and labyrinthine canals have been constructed to
provide irrigation to crop plants at huge public costs. The total area of
agricultural land in India is about 8.32 million hectares out of which about 2.67904
million hectares are under irrigation. Dams are evidenced to create
environmental and social problems. Silting of canals and choking of dams lead
not only to huge costs for restoration but cause floods and disasters on large
scales.
Channelling of river water for agriculture and industries
is already creating inter-state and inter-nation conflicts. Water war is likely
to follow Oil war at international levels.
Protecting crop
plants from pests
Crop plants are vulnerable to pest attacks. Destructive
pests may include species and strains of virus, bacterium, fungus, nematode,
mite and insect either singly or in combination. Rodents and birds also destroy standing
crops. Large quantities of pesticides are employed to ward off or kill pests to
save pre- and post-harvest losses in production.
Weeds are another group of common agricultural pests.
Herbicides and weedicides are applied to control infestation of weed plants
that compete with crop plants for water, nutrient and also harbour other pests.
All pesticides are toxic to life forms. These chemicals
not only kill unwanted target pests but also non-target crop-friendly organisms
such as pollinators (honey bees, butterflies), root zone-dwelling bacteria and
fungi.
Many pesticides are retained in agricultural products
consumed by humans and livestock. There is a build up of pesticides in the
agricultural soil carried to water bodies through run off movements. Over time,
pesticides also leach into aquifers. Finally, pesticides are consumed by
people. We pay to eat poison!
Feeding the Food
Producing Crop Plants!
Fertilisation is the timely supply of nutrition to hungry
crop plants to produce food. Some chemical elements vital to crop survival and
growth are the main ingredients in fertilisers. Atmospheric air supplies hydrogen
(H), oxygen (O), and carbon (C) as non-mineral nutrients. Mineral nutrients
comprising macronutrients and micronutrients come from the soil and are absorbed
through roots. Among these, nitrogen (N), phosphorus (P), and potassium (K) are
primary nutrients, whereas calcium (Ca), magnesium (Mg), silicon (Si) and sulphur
(S) are secondary macronutrients. In addition, boron (B), copper (Cu), iron (Fe),
chlorine (Cl), manganese (Mn), molybdenum (Mo) and zinc (Zn) are micronutrients
needed only in small quantities.
For crops under nature farming or organic farming, the
nutrition is made available by the soil through recycling of organic matter or
by converting soil nutrients into forms suited for uptake by plants.
Modern intensive and extensive farming entails the use of
factory manufactured fertilisers. If not applied appropriately, excess N and P
can have negative environmental consequences. Surplus N from synthetic
fertilisers as highly soluble nitrate can lead to groundwater nitrate
contamination. Nitrate with P contaminates areas causing eutrophication i.e.
over dominance of a single species turning the area ultimately into dead zones.
The major inputs of heavy metals such as lead (Pb),
cadmium (Cd), arsenic (As), selenium (Se) and mercury (Hg) into agricultural
systems also derive from fertilisers, organic wastes and industrial effluents.
These accumulate in downstream reservoirs contaminating water creating a toxic
web.
Genetically Modified Organisms (GMOs) in Agriculture and Environment
GMOs in Indian agriculture are
fiercely debated. Scientists and public are arguing. The Parliament is
considering the issue. The National Biodiversity Authority (NBA) and Karnataka
Biodiversity Board (KBB) have ordered prosecution under Biodiversity Act 2002 of
senior representatives of the University of Agricultural Sciences, Dharwar, M/s
Mahyco/Monsanto and M/s Sathguru. The
High Court of Karnataka dismissed on 11th October 2013 petitions that sought
quashing of criminal prosecution. Higher courts are weighing options. The
hullabaloo is all about Bt brinjal.
The Genetic Engineering Appraisal (formerly Approval) Committee (GEAC), created under the Environment
Protection Act 1986 in the Union Ministry of Environment and Forests, is eager
to order release of Bt brinjal for large scale cultivation. Curiously,
Bangladesh has allowed commercial cultivation of Bt brinjal giving a talking
point to proponents of Bt brinjal in India.
Bt brinjal is a brinjal (Solanum melongena; baigan, begun) variety created by inserting a gene
which is an engineered stretch of DNA segments from bacteria and virus. The crystal
protein gene, Cry1Ac, is extracted
from a soil bacterium Bacillus
thuringiensis and inserted into the genome, the complete genetic makeup of
cultivated brinjal varieties. The process is known as transgenesis. The
transgenic brinjal plants show resistance against specific insect pests, namely
Brinjal Fruit and Shoot Borer, Leucinodes
orbonalis, and Fruit Borer, Helicoverpa
armigera.
Bt cotton, the first non-edible transgenic crop, is being
cultivated in India for some years with the claim that Bt reduces heavy
pesticide use. However, long term results need to be scrutinised.
Insect resistant crop varieties have been created through
conventional plant breeding techniques for over a century. In most cases the
resistance breaks down chiefly due to the fact that the species of insect pests
alter their genetic makeup over time. Preliminary data indicate that insects
mutate to breakdown resistance of GM crops.
GM crops such as herbicide resistant Canola, a Canadian
oilseed crop, result in genetic contamination of native plant species through unintended
natural hybridisation. Feral communities of canola have been reported recently.
Feral species are the species cropped in agricultural fields but escape to
establish in natural ecosystems.
Non-target insects such as pollinators and natural
enemies of other pests are also killed by Bt-toxin produced by GM crops. The Bt gene composed of DNA is also known to
move to other native organisms. These processes are likely to lead to genetic
contaminations of cropped and wild plant species with far reaching
consequences.
Future is Tricky
but not Bleak, Provided........
The future of agriculture will come with unprecedented
challenges. Sustainability with higher production in consonance with the
environment can be achieved, provided we act diligently no later than now. Agriculture
must conserve ecological balance and retain natural resources sustainable and
provide biologically and chemically clean food-cum-nutrition, feed and other
products. Technology supported by science is available to minimise
contamination in, and by agriculture.
Climate change has emerged as a formidable challenge.
Weaponising the weather is likely to aggravate problems for future agriculture.
Water wars along with energy wars have begun to be felt across the globe. National policy to combat such challenges must
be in place before it is too late.
Agriculture is a multi-level multi-factorial system that
requires new approaches for data gathering and statistical analyses and for
multi-level multipronged actions. The debates on chemical agriculture versus
organic and restorative agriculture must end and well thought out actions must
begin. Development of new generation pest control mechanisms including
biotechnology approaches already in use should be strengthened, augmented and
advanced. Application of nanotechnology to agriculture is immediately called
for to meet the requirements of future agriculture.
Advancements in new biology are required to be used in
agriculture. Recent knowledge on panspermia, extracellular DNA, 4-stranded DNA,
genomics, proteomics and biotechnology must be applied on a much bigger scale
to face challenges ahead. Public funded and freely accessible GM crops that
pass bias-free and scientific risk assessments are needed now as also for
future agriculture. Nanotechnology applied to agriculture has begun to show
promising results. New methods of agriculture should sustain environment and
natural resources.
Situation specific agricultural mechanisation based on
zero/renewable energy technology is another essential for a successful agricultural
future. GMOs are a gift to agriculture but it has to be applied with utmost
caution with special reference to monopolisation of technology, environmental
costs and ecosystem disturbances besides genetic health of both target and
non-target organisms. Rural and urban water harvesting systems need to be
enlarged.
Agriculture cannot afford to go in conflict with the
environment. Only environment friendly agriculture will save humanity.