The term pest management was first used by Bartlet, and later on elaborated by Stern, as a concept of integrating the use of biological and other methods of controlling pests. This was later broadened to include the coordinated use of all biological, cultural, and artificial practices.
In integrated pest control (IPC), pesticide is used only when the size of pest population warrants less damage to the natural enemy complex and the environment, with ultimate economic benefit accrued by the farmer.
Integrated Pest Management Components
1. Agronomic and cultural: There exist a number of physical and mechanical methods of pest control, which are non-chemical in nature and farmers traditionally, have more confidence in these methods. Some of these could be modified, thereby leading to more effective and economic methods of pest control.
2. Biological: Biological control encompasses a wide spectrum of use of biological organisms and biologically based products including pheromones, resistant plant varieties, and autodial techniques such as sterile insects. It also includes such cultural practices as crop rotation, mixed and multiple cropping with varying plant densities and genetic heterogeneity.
3. Semio-chemicals: Modern pest management switched over to the use of naturally occurring chemicals, some made by insects themselves and used to control their behaviour. These are the semio-chemicals: the broad term for insect attractants and other behaviour-modifying chemicals widely adopted as key components of IPM.
4. Genetic Engineering: Pest resistance represents the ability of a specific crop variety to produce a larger crop of acceptable quality compared to ordinary varieties, given the same level of insect (pathogen) population.
The inheritance of resistance to specific pests is controlled by a single gene, monogenic (specific) or more than one, polygenic. It is difficult to determine how long a newly developed resistant variety will remain resistant. Hence constant vigilance on resistance functioning is recommended.
5. Bio-engineered Crop Plants: In terms of integrated management of pests, the most important breakthrough has been the use of genetically engineered crops to confer resistance via the inclusion of genes expressing Bt toxins, cowpea trypsin inhibitor or secondary plant metabolites. Transgenic crops with enhanced resistance may be used within the IPM programmers’.
6. Herbicide use for Weed Control: Crop plants suffer severe competition from weeds for three important inputs: solar energy, water and nutrients. About 250 species, or 0.1 per cent of the world’s flora, are known to be sufficiently troublesome as weeds in crops. Of these, 70 per cent are found in 12 families, 40 per cent alone being members of Graminae and Compositae. Interestingly. 12 crops of five families provide 75 per cent of the world food, and the same five families provide many of the worst weeds. Weeds act as reservoirs of disease organisms and as alternative hosts for insect pest.
7. Biotechnology: This is a generic term that includes many techniques to provide a wave of new products for pest management. However, the main hope for IPM is largely based on the use of genetic engineering techniques, or more precisely the recombinant DNA technologies.
It is ironical that IPM will benefit from a technology that is largely under the same control of multinationals that produce pesticides and that generate products having negative environmental impacts similar to those of pesticides.
However, this industry should focus on using genetic manipulation and other techniques to increase the virulence and host a range of biopesticides, instead of designing them as mere complements to natural strengths. Biotechnology, relative to other technologies, needs careful assessment.
The possibilities of a more lasting progress in ecologically sound pest management and sustainable agriculture will result from agro-ecological research focussed on redesigning the structure and operation of agricultural ecosystems.
IPM embodies an ecological approach to the pest problem with the sole objective of reducing or eliminating use of chemical pesticides. The gains are reduction in costs of production, more economic access of food to the poor, and conservation of the resilience and integrity of the ecosystem.
Water logging, Salinity of Indira Gandhi Canal Project in Western Rajasthan: Case Study
Water logging and salinisation of the land occur when the sub-soil water table invades the root zone of the crop and comes up to within 1.5 metre of the surface.
As a result, the soil which needs adequate aeration for its health-beings to lose its fertility and ultimately becomes totally unproductive it has been estimated that approximately 12 mh have been affected by water logging and salinity so far in the country.
Major and medium irrigation projects, during their useful life, as side effects, produced water logging and salinity in certain low-lying pockets. This problem has been discussed on several forums but still a serious effort to reduce it has yet to take place in the country.
The Indira Gandhi Canal project has been constructed in the northwestern part of the state of Rajasthan, covering a part of the Thar Desert. The construction of this canal in such an inhospitable and hazardous area has been a challenging task.
The word ‘Barren land’, takes a new meaning when one travels through the western most districts of Bikaner and Jaisalmer of Western Rajasthan. In these districts even the shrubs find themselves difficult to survive against the relentless movement of fine desert sand, gradually burying everything in its path.
The Indira Gandhi Canal command area however, covers approximately four percent of the arid zones of India and nearly one-twelfth part of the Rajasthan state. With the completion of the main canal, it will lay over 649 kms. And to flow through mainly four districts of W. Rajasthan, i.e., Ganganagar, Bikaner, Jaisalmer and Barmer. The canal is oriented approximately parallel to the India and Pakistan border at an average distance of 40 kms.
Water logging and salinity is a major problem, developed due to the presence of hardpan at a shorter distance below the surface. The authorities were aware of the existence of large areas with hardpan of gypsum along the route but they lined the canal to minimise seepage. However, only to cut the costs, the distributaries and watercourses were not lined.
The existence of the hardpan especially in Stage II was not known. Hydrological and geological surveys are under way and suggest that the previous findings, which put the critical area at around 27 per cent of the command area, were under estimated. Two decades ago, this area was also studied by Food and Agriculture Organisation (FAO) to assess the impact of canal irrigation.
They recommended the development of pasturelands on the basis of topography and the traditional occupation of the people. But the advice of the FAO and others were not taken into consideration.
The cumulative effect of all these, have led to a gradual rise of the water table, even in areas where there is no hardpan close to the surface. As a result, vast area along the canal has become waterlogged.
Several families have become homeless and landless and more settlements and agricultural lands will be affected in future if the suitable measures are not adopted.
The official estimate is that 34 per cent of irrigated areas in stage I, is affected by either water logging or salinity, chiefly in Ganganagar and Bikaner districts command. According to Bithu out of 7,000 sq. kms area 7.3 per cent is waterlogged in Stage I.
In the Ganganagar district, due to the rise in the water table, 15.39 per cent of the canal command area is likely to be affected by water logging and salinity over a period of 38 years.
In 1981-82 to 1988-89, the average rate of water use for irrigated area was around 1,500 mm against the designed value of 723 mm. measured in terms of water released at the head of the feeder canal. Between 1976-1988, total average annual inflow in the head reaches of stage I due to Ghaggar floods was 715 million cubic metres (0.58 MAF), which in turn increased the ground water level.
65 percent area in the Rajasthan desert has highly mineralized groundwater with dissolved soil content, i.e., over 3,200 ppm. Similarly at shallow depth, the sub-surface salt rich formation may also contribute in the mineralization of ground water.
The large acreage of fertile land in Jalore, Jodhpur, Barmer, Ganganagar and Bikaner districts have been degraded or turned into wasteland, only because of the use of the highly mineralised groundwater.
The soil working and water infiltration has been difficult in parts of Barmer and Bikaner districts because of irrigation with groundwater, exploited from granatic formation which has higher content of residual sodium carbonate.
Salt is generated due to physico-chemical reaction of the weathering process in the reservoir and geomorphological settings like igneous, volcanic and metamorphic formation. Salt content in the reservoir also increases by seepage and evaporation.
Irrigation from saline water causes the salinity/alkalinity problem, resulting in the depletion of agricultural productivity. Large acreage of agricultural land has turned saline and unproductive due to the irrigation from Sardarsamand and Hemawas reservoirs.
In the culturally command area (CCA) of the Sardarsamand reservoir, 9.600 ha of land has been affected due to excess irrigation by saline water, which has 358 to 23,000 ppm total soluble salts.
Similarly, Jaswant Sagar reservoir has turned 6,170 ha cultivated land into wasteland by means of saline water irrigation having 280 to 868 ppm total soluble salt.