Crop Plant Agriculture vis-ã-vis Environment

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.