Authors: S. R. Assumi, T. Angami, H. Rymbai
By the year 2050, the world population is projected to reach 9.3 billion (Cohen, 2003). By that time, 84% of the world's population will be in those countries that currently make up the 'developing' world. Despite several decades of remarkable agricultural progress, the world still faces a massive food security challenge. Today, even though enough food is produced in aggregate to feed everyone, and with world prices falling in recent years, some 700-800 million people still do not have access to sufficient food (Pinstrup-Andersen and Cohen, 1999). Most commentators, therefore, agree that food production will have to increase, and this will have to come from existing agricultural land. Many predictions are gloomy, indicating that the gap between demand and production will grow, judging likelihood of success on the basis of past performance of 'modern' agricultural development (FAO, 2009). But solving these problems is not simply a matter of developing new agricultural technologies.
Sustainability in agriculture is resource conserving, environmentally non-degrading, technically appropriate, economically and socially acceptable approach. Sustainable agriculture has become a popular code word for an environmentally sound, productive, economically viable and socially desirable agriculture (Schaller, 1993). Different expressions have come to be used to imply greater sustainability in some agricultural systems over prevailing ones which includes biodynamic, community based, eco-agriculture, ecological, environmentally sensitive, extensive, farm fresh, free range, low input, organic, permaculture, sustainable and wise use (Cox et al., 2004).
Sustainable agriculture integrates three main goals i) environmental health, ii) economic profitability and iii) social and economic equity. The key principles for sustainability are to i) integrate biological and ecological processes such as nutrient cycling, nitrogen fixation, soil regeneration, allelopathy, competition, predation and parasitism into food production processes, ii) minimize the use of those non-renewable inputs that cause harm to the environment or to the health of farmers and consumers, iii) make productive use of the knowledge and skills of farmers, thus improving their self-reliance and substituting human capital for costly external inputs, and iv) make productive use of people's collective capacities to work together to solve common agricultural and natural resource problems, such as for pest, watershed, irrigation, forest and credit management. Though, offers entirely new opportunities, by emphasizing the productive values of natural, social and human capital, all assess that world either has in abundance or that can be regenerated at relatively low financial cost. Sustainable agriculture is a way of farming that can be carried out for generations to come, this long-term approach to agriculture rests on a biological paradigm that is best described as ecological and sustainability is framed by an emerging community-centered and problem-solving perspective (Lyson, 2002).
Resource Conserving Technologies:
Agricultural systems or agro-ecosystems are amended ecosystems that have a variety of different properties (Table 1). Converting an agro-ecosystem to a more sustainable design is complex and generally requires a landscape or bioregional approach to restoration or management. It is a bounded system designed to produce food and fiber, yet it is also part of a wider landscape at which scale a number of ecosystem functions are important. For sustainability, interactions need to be developed between agro-ecosystems and whole landscapes of other farms and non-farmed or wild habitats (e.g. wetlands, woods, riverine habitats), as well as social systems of food procurement and mosaic landscapes with a variety of farmed and non-farmed habitats (Swift et al., 2004).
Table 1: Properties of natural ecosystems compared with modern and sustainable agro-ecosystems.
|Property||Natural ecosystem||Modern agro-ecosystem||Sustainable agro-ecosystem|
|Productivity||Medium||High||Medium (possibly high)|
|Natural population regulation||High||Low||Medium-high|
|Dependence on external inputs||Low||High||Medium|
|Human displacement of ecological processes||Low||High||Low-medium|
(Adapted from Gliessman, 2005).
There are several types of resource-conserving technologies and practices that can be used to improve the stocks and use of natural capital in and around agro-ecosystems. Many of these individual technologies are multifunctional and this implies that their adoption should mean favourable changes in several components of the farming system at the same time. These are:
a. Integrated pest management - which uses ecosystem resilience and diversity for pest, disease, weed control and seeks only to use pesticides when other options are ineffective (Bale et al., 2008).
b. Integrated nutrient management - which seeks both to balance the need to fix nitrogen within farm systems with the need to import inorganic and organic sources of nutrients and to reduce nutrient losses through erosion control (Moss, 2008).
c. Conservation tillage - which reduces the amount of tillage, sometimes to zero, so that soil can be conserved and available moisture used more efficiently (Holland, 2004).
d. Agroforestry - which incorporates multifunctional trees into agricultural systems and collective management of nearby forest resources (Leakey et al., 2005).
e. Aquaculture - which incorporates fish, shrimps and other aquatic resources into farm systems, such as into irrigated rice fields and fish ponds, and so leads to increases in protein production (Bunting, 2007).
f. Water harvesting in dryland areas - which means formerly abandoned and degraded lands can be cultivated and additional crops can be grown on small patches of irrigated land owing to better rain water retention and improving water productivity of crops (Morison et al., 2008).
g. Livestock integration into farming systems - such as dairy cattle, pigs, poultry, including using zero-grazing cut and carry systems (Wilkens, 2008).
Any future increase in agronomic/food production will have to occur through vertical increase in production per unit area, time and input (e.g. nutrients, water, energy) of the resources already committed to agriculture. It is in this context that developing and identification of some innovative methods of soil management are crucial to feeding the world population of 7 billion. These methods/technologies must minimize losses by delivering nutrients and water directly to the plant roots during the most critical stages of crop growth. Degraded and desertified soil must be reclaimed through enhancement of the soil organic matter (SOM) pool, creation of a positive elemental budget with balanced supply of all essential nutrients, effective control of soil erosion by water and wind, restoration of soil structure and tilth through bioturbation, and enhancement of activity and species diversity of soil fauna and flora. Soil management techniques are chosen to ensure liberal use of crop residues, animal dung and other biosolids, minimal disturbance of soil surface to provide a continuous cover of a plant canopy or residue mulch, judicious use of sub-soil fertigation techniques to maintain adequate level of nutrient and water supply required for optimal growth, an adequate level of microbial activity in the rhizosphere for organic matter turnover and elemental cycling and use of complex cropping/farming systems which strengthen nutrient cycling and enhance use efficiency of input. Identification, development and validation of such innovations must be based on modern technologies such as GIS, remote sensing, genetic manipulation of crops and rhizosphere organisms, soil-specific management and slow/time release formulations of fertilizers (Lal, 2008; Lichtfouse, 2009).
Conservation agriculture (CA) is defined as minimal soil disturbance (no-till) and permanent soil cover (mulch) combined with crop rotations. It is a recent agricultural management system that is gaining popularity in many parts of the world. CA maintains a permanent or semi-permanent organic soil cover and this can be a growing crop or dead mulch which functions to protect the soil physically from sun, rain, wind and to feed soil biota. The soil micro-organisms and soil fauna take over the tillage function and soil nutrient balancing as contrast to mechanical tillage which disturbs this process. Therefore, zero or minimum tillage, direct seeding and varied crop rotations are important elements of CA (FAO, 2014).
a. Permanent or semi-permanent organic soil cover - reduces soil water losses by evaporation and also helps moderate soil temperature. This promotes biological activity and enhances nitrogen mineralization, especially in the surface layers through their effects on soil physical, chemical and biological functions as well as water and soil quality (Hatfield and Pruegar, 1996).
b. Minimum soil disturbance, combined with permanent soil cover - has shown to result in a build-up of organic carbon in the surface layers, minimizes SOM losses and is a promising strategy to maintain or even increase soil carbon and nitrogen stocks (Bayer et al., 2000).
c. Rotations - increases the microbial diversity, therefore reduces the risk of pests and disease outbreaks from pathogenic organisms, since the biological diversity helps keep pathogenic organisms in check (Howard, 1996).
Precision agriculture encompasses a range of management practices that attempt to achieve optimal crop, livestock or forestry output by using information to adjust inputs to expected soil, weather and environmental conditions (National Research Council, 1997). It is simply a more disaggregated version of the kinds of best management practices already recommended at the field scale (Ogg, 1995). Furthermore, precisely matching fertilizer and pesticide inputs to the capabilities and needs of the crop for small areas and precise scheduling of the crop inputs limits the amounts of these materials that can escape to the environment. Some evidence suggests precision agriculture can reduce the amount of chemicals applied and the levels of residual nitrogen (Kitchen et al., 1995). Information technologies used in precision agriculture cover the three aspects of production i) data collection or information input, ii) analysis or processing of the precision information and iii) recommendations or application of the information.
Biological and biotechnical methods for agricultural crop production and waste utilization could be potentially employed for attaining sustainable approach in agriculture. The various methods are i) biological fertilizers, a potential stem nodulating green manure and economic impact of Azolla biofertilizer for rice crop, soil conditioners and green manure, ii) utilization of agricultural wastes, microbial decomposition of viscose factory wastes, industrial waste water treatment by algae, mushroom production and utilization of mushroom spent waste, composting of coir pith byPleurotus, towards zero waste in the Malaysian oil palm industry, iii) biochemical compounds from neem and their effects on insects, nematocidal potential of plants, production and application of fungal cellulases, bio-degradation of organochlorine pesticides and other organic halogen compounds, iv) immobilized N-fixing Cyanobacteria in polyurethane foam for ammonia production, ammonia production by immobilized Cyanobacteria for rice production, land application with by-product gypsum, a salt-tolerant green alga ( Dunaliella ) for the production of beta-carotene, Azolla as a potential livestock feed and v) N fixation in forestry and agro-forestry systems (Kannaiyan, 1999).
Sustainable horticultural production system requires an integrated consideration of inputs (germplasm, water, fertilizer, pesticides and growth regulators), as well as potential consequences of these inputs to man and his environment (salinization, contamination of water supplies, loss of soil structure and fertility). This can be achieved by appropriate planning and building on the general Best Practice Management approach increasingly employed by modern horticultural enterprises to achieve a holistic approach to farming system. The issues and impacts that need addressing for a sustainable horticultural system are to:
a. Protect and enhance existing native vegetation for greater biodiversity and security of the rural environment at large.
b. Manage the use of scarce water resources to ensure greatest efficiency, productivity and protection of surrounding catchments and waterways from salt, soil, fertilizers and chemicals carried in run-off water.
c. Manage healthy soils through protection from degradation, loss by erosion, organic matter depletion, unbalanced and inappropriate fertilizer usage.
d. Manage the impact of pest and diseases while minimizing the usage of chemicals and maximizing profitability over short and long term.
Hence, new opportunities for strengthening the horticulture sector will emerge, not necessarily from increased land area for production but from the development of horticultural marketing, plant breeding, agronomic management techniques and horticultural supply chain (Newley and Treverrow, 2006).
It is defined as the sum of experiences and knowledge of a given ethnic group that forms the basis for decision-making in the face of familiar and unfamiliar problems and challenges. Indigenous knowledge can play a key role in the design of sustainable agricultural systems, increasing the likelihood that rural populations will accept, develop and maintain innovations and interventions. They have names for different kinds of plants, ways to diagnose and treat human and animal diseases and methods to crop fertile and infertile soils. This knowledge has accrued over many centuries and is a critical and substantial aspect of the culture and technology of any society. Yet it has often been overlooked by Western scientific research and development (Warren, 1988).
Crop production in the next decade will have to produce more food from less land by making more efficient use of natural resources and with minimal impact on the environment. This will be a tall order for agricultural scientists, extension personnel and farmers, as ecologically sound farm management practices rely on low levels of inputs, indigenous knowledge and appropriate technologies. Among the available technologies the challenge is to decide suitable, affordable and competitive technology. Against massive environmental degradation, the challenge is to ensure people's right to food security by guaranteeing that present and future generations have equal access to the capital, human and natural resources. Global food demand is growing rapidly and the current global trajectory of agricultural expansion has serious long term implications for the environment. The environmental impacts will depend on the trajectory along which global agriculture develops. A trajectory that adapts and transfers technologies to under yielding nations, enhance their soil fertility, employing more efficient nutrient use worldwide and minimizing land clearing will provide a promising path to more environmentally sustainable agriculture.
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About Author / Additional Info:
Scientist at ICAR Research Complex for NEH Region, Umiam, Meghalaya