Global Positioning System (GPS) in Precision Agriculture

Global Positioning System (GPS) in Precision Agriculture

U.K. Shanwad, V.C. Patil, G. S. Dasog, C.P. Mansur and K. C. Shashidhar
Department of Agronomy, University of Agricultural Sciences
Dharwad - 580 005. Karnataka, India
shanwad@rediffmail.com

The growing food demands due to ever-rising human populations forced world farmers to adopt resource-intensive and unsustainable practices that increased both economic and environmental costs. Developing countries farming systems, therefore, present both obstacles and opportunities for adoption of precision agriculture. Tailoring soil and crop management to match varying conditions (soil texture, moisture, nutrient status and pest distribution) within a field is not entirely new to farmers. The growers traditionally noted yield variability in space, time and changed farm practices depending on site conditions to optimize soil resources and external inputs. This was possible because most developing countries farms were relatively small and farmers were familiar with spatial and temporal variation. However, the precision farming in terms of using technologies such as Global Positioning Systems (GPS), Geographic Information Systems (GIS) remote sensing, yield monitors, guidance systems for variable rate application to manage within-field variation is still in its infancy in almost all developing countries including India (Srinivasan, 1999). Precision agriculture is an integrated crop management system that attempts to match the kind and amount of inputs with the actual crop needs for small areas within a farm field. Precision agriculture is often referred to as GPS (Global Positioning System)- based agriculture, variable-rate farming, prescription farming, site-specific farming etc.

The need for Global Positioning System (GPS)
Global positioning system has revolutionized positioning concept, though it started primarily as a navigation system. Today, the Global Positioning System (GPS) has become an international utility. In addition to its ease of use and worldwide all-weather operation, GPS owes its popularity to the dependable high accuracy with which position, time and direction can be determined. (Ajai, 2002). As a tool of precision Agriculture, Global Positioning System satellites broadcast signals that allow GPS receivers to calculate their position. This information is provided in real time, meaning that continuous position information is provided while in motion. Having precise location information at any time allows crop, soil and water measurements to be mapped. GPS receivers, either carry to the field or mounted on implements allow users to return to specific locations to sample or treat those areas.

GPS role in Precision Agriculture
Precision Agriculture is doing the right thing, at the right place, at the right time. Knowing the right thing to do may involve all kinds of high tech equipments and fancy statistics or other analysis. Doing the right thing however starts with good managers and good operators doing a good job of using common tools such as planters, fertilizer applicators, harvesters and whatever else might be needed. (Colvin and Kerkman, 1999).

In this context, GPS becomes part and parcel of precision agriculture. For analysis and processing of remote Sensed images requires ground truth information, collected in the field, at a variety of sites and often at various times throughout the crop production season. Conventionally this data has been manually recorded on field sheets, air photos or paper maps and considerable time and effort is required to convert it to digital format for use in remote sensing or GIS. For image analysis the ground data must be digitized in order to create a mask for training the software to recognize different conditions and classify the remote sensing imagery. We have developed an interactive, portable system to record field data directly into a digital database consisting of yield, soil, road, water and contour maps overlain on air photos or remote sensing imagery. A GPS receiver is linked to a note book computer displaying appropriate, pre loaded information layers, and a software package then combines incoming GPS signals with the displayed data to allow the user to see where they are with respect to the map components. The various layers of information can be easily edited and modified in the field and new data can be added as point or polygon layers and attribute tables. (Mc Govern et al., 1999).

The system also allows the user to save GPS data to view and track field activity at a later date. Data recorded in the field, such as the location of weed patches, field boundaries and crop condition noted can be moved easily to other GIS. Spreadsheet and image processing systems to enhance datasets and improve analysis. The image classification process in particular can be improved with the accurate and easily accessible ground-truth data.

Precision Farming at a Glance-Steps Involved

Strategy Formulation and Impact of Precision Farming

System Elements of Precision Farming

Yield Monitoring and Mapping: The most common use of GPS in agriculture is for yield mapping and variable rate fertilizer/pesticide applicator for yield mapping harvester travel speed and flow rate of material are measured. The yield is calculated as

Yield/area = (Flow rate) / (Harvester travel speed) x (effective harvesting width)

Grain yield monitors continuously measure and record the flow of grain in the clean grain elevator of a combine. When linked with a GPS receiver, yield monitors can provide data necessary for yield maps. Yield measurements are essential for making sound management decision.

The yield maps are used to determine the cause of crop/soil variability. This in turn helps to make decision regarding space and time variable management practices. The variable rate applicators execute these management decisions. The variable rate applicator has basically three components:

Control computer
Locator and
Actuator

The control computer coordinates the field operation. It has a map of desired activity as a function of geographic location. It receives the equipment’s current location from the locator, which has a GPS in it, and decides what to do based upon the map in its memory or data storage. It then issues the command to the actuator, which does the input application (Ravi and Jagadeesha, 2002).

Precision Agriculture: Indian Scenario
Precision Agriculture has been mostly confined to developed countries. Reasons of limitations of its implementation in developing countries like India are: a) Small holdings b) Heterogeneity of cropping systems and market imperfections c) Lack of technical expertise knowledge and technology d) High cost. In India major problem is the small field size. More than 58 percent of operational holdings in the country have size less than 1ha. Only in the states of Punjab, Rajasthan, Haryana and Gujarat more than 20 per cent of agricultural lands have operational holding size of more than 4 ha. There is a scope of implementing precision Agriculture for crops like, rice and wheat especially in the states of Punjab and Haryana. Commercial as well as Horticultural crops shows a wider scope for precision Agriculture.

Adoption of precision agriculture needs combined efforts on behalf as scientists, farmers and government. The following strategies may help in the successful adoption of precision agriculture in the country.

Creation of multidisciplinary teams involving agricultural scientists in various fields, engineers, manufacturers and economists to study the overall scope of precision agriculture.
Formation of farmer’s co-operatives since many of the precision agriculture tools are costly (GIS, GPS, RS, etc.).
Government legislation restraining farmer using indiscriminate farm inputs and thereby causing ecological/environmental imbalance would induce the farmer to go for alternative approach.
Pilot study should be conducted on farmer’s field to show the results of precision agriculture implementation.

Future prospects of precision agriculture and GPS in India:
Advances in GIS, GPS and Remote Sensing technologies are changing the way we will look at precision farming. The success of precision farming will be measured by the type of information that is provided to the farmer, how quickly the farmers were convinced. Competition for the farmers business should help in making the success a reality.

The study on precision agriculture has been initiated in many research institutions. For Instance space Application. Center (ISRO), Ahmedabad has started experiment in the Central Potato Research Station farm at Jalandhar, Punjab to study the role of remote sensing, GIS and GPS in mapping the variability. M.S. Swaminathan foundation, Chennai, in collaboration with NABARD, has adopted a village in Dindugal district of Tamilnadu for variable rate input application. IARI, New Delhi has drawn up plans to do precision agriculture experiments in the institute’s farm. Project Directorate for Cropping Systems Research (PDCSR), Modipuram, and Meerut (UP) has initiated a project on precision agriculture in collaboration with Central Institute of Agriculture Engineering (CIAE), Bhopal.

The use of GPS in Agriculture is limited but it is fair to expect wide spread use of GPS in future. Recently a GPS-based crop duster (precision GPS Helicopter), which can spray an area as small as 4 X 4 mtr. is attracting great attention. Some progressive farmers are now beginning to use GPS for recording observations. Such as weed growth, unusual plant stress, colouring and growth conditions, which can then be mapped with a GIS programmes. In the years to come, GPS system role in precision agriculture may help the Indian farmers to harvest the fruits of frontier technologies without compromising the quality of land and produce.

References

Ancha Srinivasan, 1999, Precision farming in Asia: Progress and prospects. Precision Agriculture- Proceedings of the 4th international conference. PP. 623-640.
Ravi, N. and Jagadeesha, C.J., 2002, Precision Agriculture, Training course on Remote Sensing and GIS Applications in Agriculture, May 27th –7th June, 2002, RRSSC- Bangalore, pp: 225-228.
Ajai, 2002, GPS and its applications, Training course on Remote Sensing and GIS Applications in Agriculture, May 27th –7th June, 2002, RRSSC- Bangalore, pp: 89-99.
Colvin, T.S. and Kerkman, E. W., 1999, Precision Agriculture Requires precise tuning. Precision Agriculture- Proceedings of the 4th international conference. PP. 1083-1088.
Mark, A. Mc Govern, T. Hirose, B.K. Hopp and T. E. Huffman, 1999, Agriculture Ground Truthing GPS, GIS, system. Precision Agriculture- Proceedings of the 4th international conference. PP. 975-978.