eChapters

Introduction

Climate change and climatic variability are expected to reduce agricultural productivity and threaten food security of the world, particularly in developing countries. Producing enough food for the increasing population in a background of decreasing resources and a changing climate scenario, is a challenging task. Agriculture, forestry and land use change account for about 30% of greenhouse gases (GHGs) emissions. Therefore, mitigation of GHGs emission while enhancing production is another challenge in agriculture.
 
Conservation agriculture (CA), with the three core inter-linked principles of minimizing mechanical soil disturbance, enhancing organic matter cover on soil and diversification of crops, is a viable option for sustainable agriculture with an effective solution to climate change adaptation and mitigation. The principles can be integrated and applied into most of the rainfed and irrigated production systems including horticulture, agro-forestry, organic farming, rotational farming and integrated crop-livestock systems to strengthen ecological sustainability. Worldwide about 105 Mha land is under CA and the area is increasing. However countries like USA, Brazil, Argentina, Canada and Australia occupy about 90% of the area under CA. The CA, which is advocated as an alternative to the conventional production system for improving productivity and sustainability, is now adopted by many countries and agencies as a lead model for sustainable agricultural intensification.

Introduction

Cycling of plant material is required for any production system for biological activity, humus formation and thereby formation of a dark colored top soil. Incorporation of biomass results in production and proliferation of soil biota. But under annual crops compared to forest, production is much less, the biomass is largely removed, the soil is tilled several times each year. Consequently, less food and moisture are available for earthworms, insects, micro-flora and fauna; and their habitats are repeatedly disturbed or destroyed. Therefore, the primary need of our agricultural activities is to feed soil organisms (bacteria, fungi, earthworms etc.) and to regulate their living conditions while protecting them from chemical and mechanical impacts.

Introduction

Agriculture is the most important sector in India accounting for 13.7 per cent of the country’s GDP and employs more than 60 per cent of the labour force. Our country has recorded the highest food grain production of 257 million tonnes during 2012-13, under favourable weather conditions those prevailed throughout the year. The mission of increasing food grain production, though realized to a commendable extent at present, but under risk due to climatic aberrations and reduced availability of land, water, nutrients along with poor and continuous degradation of the resources to cope up with the demands of increasing population. Although the country had attained self sufficiency in food grain production through intensification of agriculture with high–yielding varieties, fertilizer application and chemical pest control during the green revolution, productivity is still low and is stagnating.

The Global Environmental Issues

 
Expansion of the scale of human activity in recent years has put so much strain on the natural environment of this planet that in some cases nature can no longer recover. The nature’s ability though recovers damage or harmful effects in one part of the world do not stop in the very area and keeps going beyond national borders and become environmental problems on a global scale, but in a limited manner.

Energy, food production and various other natural resources are the limiting factors on this earth. The result of this bitter truth has been published in a book titled ‘The Limits to Growth’ in 1972. If the enormously growing population and the industrial process is not checked, then the earth’s civilization may come to an end within next hundred years.

By considering the space travel, we can very well understand about the Ecosystem. When we go away from the biosphere, it will be appropriate to develop unlimited environment through the energy accumulated from the sunlight in space. For the space travel for some days to moon and back to earth, we need not establish the entire ecological system as greater quantity of O₂ and food stuffs can be stored and CO₂ and other unwanted materials can be fixed for establishing space colonies, we have to build a special space ship with important abiotic components which can be recycled for use again and again. The vital processes of production, consumption and decomposition can be established and balanced through biotic components. In other words we are creating a complete mini human ecological machine. Before we established this system, we should be quite familiar about the space problems and its implications.

HUMAN POPULATION GROWTH

The evolution of man took place about one million years ago in response to changes in the physical environment. We learnt gradually to adapt different modes of life to varying environments and migrated different parts of the world. Human activities have had their impact on the environment, which was depending on the number of people living in  the area and  their level  of economic development. Per capita consumption of food, energy and other resources in developed countries is larger and its impact on the environment is much greater than equal number of persons living in developing countries in Africa or Asia. Therefore, the distribution of population needs to be examined in detail.

Continental drift is the theory that continents move slowly about the earth’s surface, changing their positions relative to one another and to the poles of the earth. It includes the idea that former continents may have broken apart and that the fragments have recombined in different patterns (Fig. 15.1). Some authorities have considered that this happened only once, beginning within the past 200 million years; others believe that it has long been a continuous process, so that all existing continents are mosaics. Those who accept the theory believe that the rates of motion have been only a few inches a year. Earlier, it was considered that the continents moved like ships through a slightly plastic ocean floor. Today some consider that the continents are frozen into the earth’s surface like rafts in ice, and that the motions are the result of growth of the sea floor along certain midocean ridges and reabsorption of the sea floor elsewhere beneath deep ocean trenches and young mountains. The continents are carried passively about embedded in moving plates of the surface. Some authorities  now  agree  that  there  is  a  deformable  layer,  called  the asthenosphere, at depths of from about 50 to 400 kilometers within the earth. It is white hot, and slightly viscous, and many believe that the surface can break into plates which slide over it.

The phenomenon we call tsunami is a series of large waves of extremely long wavelength and period usually generated by a violent, impulsive undersea disturbance or activity near the coast or in the ocean. A tsunami is a very long-wavelength wave of water that is generated by sudden displacement of the seafloor or disruption of any body of standing water.  Tsunami are sometimes called “seismic sea waves”, although, as we will see, they can be generated by mechanisms other than earthquakes.  Tsunami have also been called “tidal waves”, but this term should not be used because they are not in any way related to the tides of the Earth.  Because tsunami occur suddenly, often without warning, they are extremely dangerous to coastal communities.

It is a well known fact that natural disasters strikes countries, both developed and developing, causing enormous destruction and creating human sufferings and producing negative impacts on national economies. Due to diverse geo-climatic conditions prevalent in different parts of the globe, different types of natural disasters like floods, droughts, earthquakes, cyclones, landslides, volcanoes, etc. strikes according to the vulnerability of the area. India is considered as the world’s most disaster prone country. It has witnessed devastating natural disasters in recent past like droughts, floods, cyclones, earthquakes, landslides, etc. 

Pesticides are used to control plant growth (herbicides), insects (insecticides), worms  (vermicides), bacteria (bacteriocides), fungi (fungicides), and other organisms. Almost without exception, pesticides are used to benefit humans by the control of unwanted species of plants (e.g. weeds in a lawn), disease-causing bacteria (e.g., Pneumococcus, the causative agent of pneumonia), disease-carrying insects (e.g. malarial or yellow fever mosquitoes) or in controlling destruction of agricultural products by disease-causing organisms (e.g., corn-borers, the virus of anthurium blight). Although they are by and large mostly beneficial, pesticides used both properly and improperly are also “resources out of place”, that is pollutants, that are subject to normal ecological processes.

For the hundreds of thousands of years that we lived on earth,there were few rapid changes in the atmosphere. It is only in recent times, particularly since the Industrial Revolution, that our activities on earth began to modify our environment in a significant manner.  Industrial pollution has affected the water we drink, the air we breathe, and in general,the biosphere itself.Now noise has joined the bandwagon of pollutants.

Noise certainly comes within the scope of definition of a pollutant that “..... any undesirable change in the physical, chemical or biological characteristics of our air, land and water that may or will harmfully affect human life or that of any other desirable species or industrial process, living conditions or cultural assets, or that may or will waste or deteriorate our raw material resources.”

Soil pollution happens when we destroy the thin layer of healthy and productive soil, which covers the earth’s surface. Most of the world’s food is produced using this resource and if we don’t protect it the world’s farmers will be unable to grow enough food to support the worlds people.
 
Healthy soil depends on bacteria, fungi, and small animals (such as worms) to break down wastes in the soil and release its nutrients which help plants grow. The over use of fertilizers and pesticides can limit the ability of soil organisms to process wastes, which in turn makes the soil less productive or in the worst case scenario useless or even poisonous. 

Water is indispensable for our life. About 2/3 of earth is covered with water. No organism can survive without water. So keeping water free from any pollutant is very important. Water is said to be  “polluted” when it is hanged in its quality and composition directly or indirectly by man’s activity so that it becomes less suitable for drinking, domestic, agricultural or any other purpose. Polluted water transmits a large number of diseases in man. They are cholera, typhoid, dysentery, jaundice and other bacterial or viral diseases.  Water becomes polluted by the presence or addition on inorganic or organic substances or biological agents. Soil erosion, leaching of minerals from rocks, decaying of organic matter are natural sources of water pollution. There has been an alarming increase in the degradation of water quality in the recent past in the large cities and industrial areas.

Water pollution can be studied under the following heads—  (i) medium in which it occurs (surface water, ground water); (ii) habitat (lakes, estuaries and open seas); and (iii) type of pollutants (bacterial, metallic, thermal and radioactive).

The ozone layer is a region in the Earth’s stratosphere where a certain amount of incoming solar radiation is absorbed. Over the last twenty years or so a series of man-made threats to it have been reported and each has been treated  with more gravity than the last. Now a-days such threats feature  regularly on the agendas of international conferences.

Ozone, Positive and Negative : Ozone, or trimolecular oxygen (O3) can be advantageous or exert harmful influence on human health, as well as that of other organisms. It is all depends on whether it is present in the troposphere or stratosphere (Fig. 8.1). In the stratosphere, ozone is a beneficial serving as a shield in screening out most of the damaging portions of ultraviolet radiation which have wavelengths between 290 and 320 nanometers. In the troposphere, ozone is a negative as it appears as a component of smog with a number of deleterious effects, as will be discussed below.

El Nino is the name given to the occasional development of warm ocean surface waters along the coast of Ecuador and Peru. When this warming occurs the usual upwelling of cold, nutrient rich deep ocean water is significantly reduced. El Nino normally occurs around Christmas and lasts usually for a few weeks to a few months. Sometimes an extremely warm event can develop that lasts for much longer time periods. In the 1990s, strong El Ninos developed in 1991 and lasted until 1995, and from fall 1997 to spring 1998.

The ‘greenhouse effect’ earns its name from the rough similarity between the way it works and the way the glass of a greenhouse works. Glass too, is transparent to short-wave radiation but opaque to long-wave radiation, so the greenhouse traps heat.
Carbon dioxide plays a critical role in controlling the Earth’s climate because as an aerosol it absorbs and reflects or scatters incoming radiation on the one hand and absorbs and reradiates outgoing infrared radiation on the other. This latter phenomenon results in what is popularly called the Greenhouse Effect, an analogy to what happens in a greenhouse.

Air is one of the most important constituents of man’s environment. It is calculated that a roan breathes about 22,000 times a day inhaling about 16 kg of air by weight. Air is present everywhere and its entrance from one place to another cannot be checked. Clean and pure air is very essential for the health and survival of man.

Any living organism in its natural habitat is called a wildlife. It may be plant animal or a microbe. The significance of wild life lies in setting up the balance of population in nature by maintaining food chains and food webs. It acts as the gene banks in relation to breeding of plants and animals for introduction of desirable characters such as high yield of economic product and resistance to diseases. The scientists are performing studies to screen and select useful genes in economically important organisms.

Conservation has always been one of the most important applications of ecology.Unfortunately, the term “conservation” suggest “hoarding”, as if the idea were simply to ration static supplies so that there would be some left for the future. In the eye of the general public the “conservationist” is too often presumed to be an antisocial person who is against any kind of “development”. What the real conservationist is  against  is unplanned  development  that breaks  ecological  as  well as human laws. The true aim of conservation, is two fold–
    
(1)     To ensure the  preservation of a  quality  environment that considers esthetic and recreational as well as product needs; and  
    
(2)     To ensure as continuous yield of useful plants, animals and materials by establishing a balanced cycle of harvest and renewal.

“Natural” means an ecosystem not influenced by man and resources means that reserve stock of supply which living things can take from nature for sustenance of life. In reference to man, natural resources can be defined as those natural reserve stocks of supply which man utilizes for his sustenance and welfare. The reservoirs of natural resources are the sun,  the  atmosphere,  the  lithosphere  and the  hydrosphere.  Natural resources include energy, air, water, soil, minerals, plants and animals. The nature of resource depends upon many factors such as scientific and technological development of the society, profession of that particular society, and culture.