343N. Tuteja and S. Singh Gill (eds.), Plant Acclimation to Environmental Stress,DOI 10.1007/978-1-4614-5001-6_13, Springer Science+Business Media New York 2013
The domestication of plants started over 10,000 years ago and led to the birth of agriculture. Since then, the main emphasis has been on increasing productivity, sometimes compromising on long-term sustainability. During initial years, the farming community observed that if the same crop was cultivated over years on the same soil, there was gradual decline in productivity. Thus, without any scienti c knowledge, the farmers realized that there was need to leave the soil fellow for a while so that it regains its vigour, a process which was later called shifting/jhum cultivation. Even today, in some regions of the North east India, the practice is still prevalent. Unfortunately, due to population pressures, the land is no more available in abundance which has led to shortening of Jhum cycles, thus resulting in insuf cient time for soil to rejuvenate fully. Further, the process is not ef cient as burning bio-mass to clear the land is a wasteful process. Other methods adopted for restoring soil fertility are the cereal-legume rotation and crop-livestock integrated farming. Legumes are known to x atmospheric nitrogen and thus improve the nutrient status of the soil. Similarly, animal waste adds to the organic nutrient status and improves texture of the soil. The practice of ploughing back all agricultural residues into the soil is also being adopted to improve the physical structure and the organic matter status of the soil. Thus, a sustainable system of soil maintenance and enhancement was developed through experience and experiments ever since the agriculture started.
During early years of agriculture, crop health management was a serious chal-lenge as not many agrochemcials were discovered. However, the farmers were quite successful in keeping pest control under control through maintenance of rich
V. Dhawan (*) The Energy and Resources Institute (TERI) , Habitat Place, Lodhi Road , New Delhi 110 003 , India e-mail: email@example.com
Chapter 13 Sustainable Agriculture Practices for Food and Nutritional Security
344 V. Dhawan
agrobiodiversity, planting of varieties resistant to major insects, use of botanical pesticides and intercropping and planting of different crops at any given time to spread the risk.
2 Green Revolution and Sustainable Agriculture
Unfortunately over the years, the traditional practices of conservation and sustainable use gradually gave way to high-input agriculture leading to monoculture, widespread planting of few selected varieties, unsustainable usage of water and excessive use of fertilizers and pest-control chemicals. Inspite of the fact that legumes and millets can be grown in dif cult production environments (such as drought-prone areas), their cultivation has reduced drastically mainly due to lower yields and poor price realiza-tion. Green revolution marked the beginning of expansion of production through productivity improvement, became a blessing in terms of saving land and forests, but it led to overexploitation of land and water, and excessive use of chemical pes-ticides and mineral fertilizers resulting in environmental pollution. Prof. MS Swaminathan, known as Father of Green Revolution in India for introducing and developing high-yielding varieties of wheat in India, recognized the probable nega-tive impacts of the technology. During his address in Indian Science Congress held in Varanasi in January 1968, he cautioned the world that exploitive agriculture offers great dangers if carried out with only an immediate pro t or production motive. The emerging exploitative farming community in India should become aware of this. Intensive cultivation of land without conservation of soil fertility and soil structure would lead, ultimately, to the springing up of deserts. Irrigation without arrangements for drainage would result in soils getting alkaline or saline. Indiscriminate use of pesticides, fungicides and herbicides could cause adverse changes in biological bal-ance as well as lead to an increase in the incidence of cancer and other diseases, through the toxic residues present in the grains or other edible parts. Unscienti c tapping of underground water will lead to the rapid exhaustion of this wonderful capital resource left to us through ages of natural farming. The rapid replacement of numerous locally adapted varieties with one or two high yielding strains in large contiguous areas would result in the spread of serious diseases capable of wiping out entire crops, as happened prior to the Irish potato famine of 1854 and the Bengal rice famine in 1942. Therefore, the initiation of exploitative agriculture without a proper understanding of the various consequences of every one of the changes introduced into traditional agriculture, and without rst building up a proper scienti c and training base on sustain it, may only lead us, in the long run, into an era of agricultural rather than one of agricultural prosperity (Swaminathan 2010 ) .
The Green Revolution of late 1960s transformed the agriculture in most parts of the world. The technological package of improved seeds of cereals, chemical fertilizers, irrigation and other pest-control measures transformed agriculture lead-ing to rapid-productivity gains and widespread acceptability of the technology among the farmers (Timsina and Connor 2001 ; Gupta et al. 2003 ; Gupta and Seth
34513 Sustainable Agriculture Practices for Food
2007 ) . The bene ts of green revolution were not just restricted to food security, but changed the entire social fabric of rural communities and became the main driver of economic growth in rural areas. The associated services, such as sale of seed and other farm inputs, lead to entrepreneurship development. Also, with surplus income, farmers started investing in education and products that were earlier restricted to elite class, thus boosting the rural economy.
Unfortunately, in India the productivity gains since the beginning of this century have more or less stagnated (Duxbury 2001 ; Kataki et al. 2001 ; Kumar et al. 2002 ; Ladha et al. 2003a, b ; Prasad 2005 ; Dhawan 2008 ) leading to concerns over national food security and lagging economic growth in the rural areas. An analysis of green revolution has further raised concerns about its sustainability as it has led to wide-spread salinity in many areas, overexploitation of ground water resulting in receding water tables, and ground water pollution with fertilizers and pesticides and even heavy metals such as arsenic in ground water. Dogra ( 1986 ) estimated that nearly 4.5 million ha of irrigated land was affected by salination and another 6 million ha due to water logging. These concerns, sometimes overstated, demand technological interventions to conserve resources, reduce production cost and improve productivity while sustain-ing environmental quality (Hobbs and Gupta 2003 ; Gupta and Sayre 2007 ; Gupta and Seth 2007 ; Erenstein and Laxmi 2008 ) , leading to evergreen revolution. Also, the conventional agricultural practices must be revisited and evaluated in the light of R&D in other related elds for meeting the objective of long-term sustainability.
3 Future Challenges
Today agriculture in many parts of the world is challenged by the changing pattern of temperature and precipitation (climate change) and growing scarcity of water. The rivers are fully exploited, and at least during part of the year, there is more or less a crisis situation. The massive expansion of canals and tubewells has further led to serious overdrawing of groundwater. The virtual ow of water as grains or other agricultural produce must be studied, especially for crops such as rice, and adequate policies be formulated keeping in long-term vision. Water-ef cient varieties of the crops that are grown over large acreage must be developed and promoted. Temperature extremes and change in the pattern of temperature regimes are also affecting the grain yield for major crops, drawing the attention of agricultural scien-tists to develop either early-maturing varieties or those which can tolerate wide range of temperatures.
Inspite of progress made in chemicals for controlling pests, plant diseases still remain to be the major problem. For many crops (for example, cabbage in India), inspite of impressive pest control measures being developed through R & D, the percent losses today are greater than what they were at the time of independence in 1947. In most cases, pest develops resistance to a particular chemical, resulting in continuous search for developing new formulation. The problem is further com-pounded by high cropping intensities, mono-cropping and high fertilizer use which
346 V. Dhawan
creates dense lush green canopies in which pests can thrive well. The large-scale plantation of similar varieties leads to similar susceptibility causing pest problems. Initially, control was based on prophylactic chemical applications, driven by calen-dar rather than pests and diseases. This approach disrupted the natural pest predator balance and led to resurgence of pest problems that required even higher doses of pesticide applications for proper control. The excessive use of pesticides has led to environmental problems and has even affected health of the farm workers. Some of the pesticides are even carcinogenic and the leachate, which gets into the ground water has serious health implications to the entire community.
4 Organic Farming
Organic farming has been advocated in many parts of the world but most often the alternative farming approaches fail to match high productivity levels achieved by farming methods of green revolution (Pretty et al. 2007 ) . The green manure production is also gradually losing ground as the land needed to grow the crop is not available readily (Hazell and Wood 2008 ) .
Organic farming has enormous potential to improve yields of small and marginal farmers, who either cannot afford to invest in fertilizers/chemicals or are in remote areas with limited access to markets. The biofertilizers/biopesticides can also replace part of the chemical requirements, thus restoring soil health. For example, in most wheat-growing areas of India, upto 40% chemical fertilizers can be replaced through application of mycorrhizal biofertilizer (Mder et al . 2011 ) . Organic culti-vation is also practiced for high-value crops for the elite customers and certi ed organic produce are being sold at premium price.
While bene ts of organic cultivation have been documented and practiced for a long time, it has not become popular. More research interventions are required so as to develop reliable commercial products with adequate shelf life. Subsidies on syn-thetic chemicals further act as a disincentive for biofertilizers and biopesticides. Certi cation of inputs (e.g. biopesticides and biofertilizers) giving details of active ingredients and product (certi ed organic vegetables/fruit/grains) is essential so as to develop customers con dence, be it at the producer level (farmer) or at the consumer level (public) to commercialize this technology further.
5 Technologies for Ef fi cient Resource Utilization
Other efforts to improve sustainability involve precise matching of nutrients, switching to slow-release fertilizers and use of drip irrigation. At present, these are largely adopted for high-value horticultural species, but the success achieved de nitely calls for policy interventions such as providing subsidies. While subsidies are available on electricity cost for drawing water for agricultural practices, they
34713 Sustainable Agriculture Practices for Food
may be extended to put drip irrigation facilities leading to ef cient water utilization.
In recent years, fortunately the environmental concerns have attracted attention, leading to enhanced research efforts towards developing sustainable technologies and farming practices. Apart from technological innovations, one must relook at the old technologies and supplement them with newer tools. Many of the technologies have failed in the past as they were labour intensive and thus were not viable. However, with invention of newer tools, it has now become practical to adopt them at wider scale. Some of the old technologies that are proving to be extremely promising are as follows.
5.1 Zero-Tillage Planting of Wheat and Rice
Zero tillage typically saves energy, helps in preventing soil and land degradation (such as decline of soil organic matter, soil structural breakdown and soil erosion) and leads to more ef cient use of water and other inputs. The interest in zero tillage originated due to the time con icts between rice harvesting and wheat planting (Harrington et al . 1993 ) . Wheat is grown in cool dry winter (November-April in Northern India) while rice is grown during the warm monsoon season (MayNovember in Northern India). The technology involves tractor-drawn seed drill with 611 inverted T lines to seed wheat directly into unploughed elds with a single pass of the tractor. This specialized agriculture machinery was not originally available, thus demanding a lot of manpower which was actually not feasible. The technology was introduced in India by CIMMYT in 1989 and, thereafter, in 1991 a rst proto-type of Indian Zero tillage was developed in GB Pant University of Agriculture and Technology in Pant Nagar in the State of Uttarakhand. A collaborative program for further development and commercialization of zero-tillage drills by small-scale farm machinery manufacturers was initiated by the national agricultural research system in collaboration with CIMMYT and subsequently with the Rice-Wheat Consortium of the Indo-Gangetic Plains, leading to the adaptation of the technology by large number of farmers.
It is interesting to note that introduction of genetically modi ed (GM) herbicide (glyphosate tolerant) soybean in 1996 in Argentina was specially adopted for use with zero-tillage technologies that facilitated the wheat-soybean double cropping scheme (Trigo et al. 2010 ) . This has been the major technological event in the agricultural history of the country. The zero-tillage systems expanded from about 3 million ha in 19901991 to more than 22 million hectares in 20072008 in Argentina, thus demonstrating acceptability of the technology and its gelling with the most advanced transgenic seed technology. Zero tillage has positive effect on environment although further research is needed for putting values to the environmental impacts (Akhtar 2006 ; Sarwar and Goheer 2007 ; Erenstein and Laxmi 2008 ; Hobbs and Govaerts 2009 ; Pat...