Geographic Information System

Recently, use of GIS in agriculture has increased because of misuse of resources like land, water, etc. GIS is the principal technology used to integrate spatial data coming from various sources in a computer. GIS techniques deal with the management of spatial information of soil properties, cropping systems, pest infestations and weather conditions. This is primarily an intermediate step because it combines the data collected at different times based on sampling regimes, to develop the subsequent decision technologies such as process models, expert systems, etc. The manipulation of spatial information had begun in the 1960s, but has grown rapidly with the development of computer-aided techniques. In the new millennium, GIS-aided techniques are indeed needed for sustainable food production and resource utilization, without further depletion of the environment. GIS technology will help the farmers and scientists in decision making, as precise information on field will be readily available. GIS techniques make weed control, pest control and fertilizer application site-specific, precise and effective; it would also be very useful for drought monitoring, yield estimation, pest infestation monitoring and forecasting. GIS coupled with GPS, microcomputers, RS and sensors is used for soil mapping, crop stress, yield mapping, estimation of soil organic matter and available nutrients. In combination these technologies have brought out rapid changes in data collection, storing, processing, analysis and developing models for input parameters.

Manual mapping during field operations 

Measurements may also be taken during field operations by the farmers. The most common measurements during field operation are yield recording and soil properties during tillage. Manual measurement has also been done for soil sample, pest infestation and other crop problems. These measurements are performed at a specific time and usually provide the most accurate and useful information. Whatever may be the mapping technique followed, the crucial element always seems to be the measurement of the quantity to be mapped. Accurate and reliable sensors are needed for the conversion of physical and biological quantities into electronic value. Mapping also requires an accurate locator to establish the geographical location of the quantities measured, for which differential GPS (DGPS) is very useful in PF.

          Control strategies

The documented spatial variability in maps is used to control the variability of soils, crops or pests through field operations. The common response to soil variability within fields is the control of fertilizer application in a spatially variable manner. In the same way, soil moisture map is used to control irrigation. The crop yield and pest infestation maps are also used to control the application of irrigation, fertilizer and patch spray of pesticides. Field operations in a spatially variable manner will need the following equipments :

·          A control computer to co-ordinate field operations based on the maps on computer memory;

·          A locator to determine the current location of the equipment;

·         An actuator to receive the command from the control computer.

            Opinion

The important aspect for these equipments is the dynamic response; otherwise the action will be performed after it was desired. The instruments SOILECTION and FALCON, developed by AgChem, USA are used for application of fertilizer and pesticides in a spatially variable manner, according to digital maps. Combine-mounted crop yield monitor is one of the most popular instruments for PF, with a large number being used in North America. Yield monitors are also currently available for corn, soybeans, wheat, potatoes and peanuts. Variable-rate technology (VRT) is another instrument, which uses the variability information and applies the inputs according to the requirement of the site, which includes fertilizer, pesticides and micronutrient application, liming, seed rate, irrigation and drainage. VRT and yield monitors are an essential component of PF, which has mostly relied on the integration of GIS and GPS technologies, plus the implementation of VRT farm equipment. The success of PF depends mainly on the communication links and it enables a continuous electronic conversation among the workers, to interpret the information for better decision making.

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