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Precision farming in Indian context - Role of Remote Sensing
S. S. Ray*, S. Panigrahy and J. S. Parihar
Space Applications Centre, ISRO, Ahmedabad-380 015
Precision farming is one of the most scientific and modern approaches to sustainable agriculture that has gained momentum in 21st century. Consider this situation: 'A farmer goes to his field with his GPS (Global Positioning System) guided tractor. The GPS senses the exact location of the tractor within the field. It sends the signal to a computer on the tractor, which has a GIS, storing the soil nutrient requirement map in it. The GIS, in consultation with a Decision Support System, decides what is the exact requirement of the fertilizer for that location and then commands a variable rate fertilizer applicator, attached with the tractor, to apply the exact dose at that precise location. And all this is done within a second, before the tractor moves further.' Sounds like an excerpt from a scientific fiction. But this is what precision farming (PF) means to the large growers of the US or European countries. Hence, the first thing that comes to mind is that, this system is not for developing countries, especially India, where the farmers are poor, farming is mostly subsistent and the land holding size is small. But, this is far from the truth as this approach has a large potential for improving the agricultural production in developing world. This article is an attempt to explain the possibility of adopting PF in India and the role of satellite based remote sensing in facilitating that.
2. Precision Farming and its Objective
Precision farming aims to improve crop performance and environmental quality. It is defined as the application of technologies and principles to manage spatial and temporal variability associated with all aspects of agricultural production (Pierce and Nowak, 1999). In other words, precision farming is the matching of resource application and agronomic practices with soil attributes and crop requirements as they vary across a field.
Thus, the concepts of precision farming include:
A host of terms have been used to describe the concept of precision farming. Generally all these terms are combinations of two phrases. The first phrase is 'Spatially variable', 'GPS based', 'Prescription', 'Site-specific' or 'Precision', whereas the second phrase can be 'Farming', 'Agriculture' or 'Crop production'.
- Variations occur in crop or soil properties within a field.
- These variations are noted, and often mapped.
- Management actions are taken as a consequence of the spatial variability within the field.
Though, the 20th century agriculture had been characterized by the increase in land and labour productivity, the use of external inputs, an increase in efficiency and efficacy of external inputs, it has also been associated with the stimulation of uniformity in agricultural production areas and the negative side-effects of agriculture. The PF techniques, by appreciating the variability within the field and adopting management practices to cater the variability, are serving the dual purpose of enhancing productivity and reducing ecological degradation. The real value from precision farming is that the farmer can perform more timely tillage, adjust seeding rates, fertilizer application according to soil conditions, plan more crop protection programs with more precision, and know the yield variation within a field. These benefits can enhance the overall cost effectiveness of crop production, however the grower must be willing to make adjustments in his management styles to make it work.
3. Developments which prompted PF
Many technological developments, which occurred in 20th century contributed to the development of the concept of precision farming. These technological developments are as follows.
3.1 Global Navigation Satellite System
The Global Navigation Satellite Systems (GNSS), such as the NAVSTAR GPS of the USA and the GLONASS of the former Soviet Union have been helpful in pinpointing the precise location. In the post- S/A (selective availability) the positional (horizontal) accuracy of the GPS can be of the order of 20 m, where as that for GPS operating in Differential mode is around 1 m.
3.2 GPS-Guided agricultural machinery
This is the major development, which brought the concept of precision farming. There are basically two categories of agricultural positioning system The first category is for monitoring or sensing pertinent soil and crop parameters, such as soil moisture content, nutrient availability weed location or yield mapping. The second category, where in-field position is required, is for control of precision application machinery (variable rate applicators) where actual position of the field vehicle must be related to a digital field map of the relevant parameter. For monitoring/mapping operations only the position in real time is required, where as for precision application, position in real time along with forward prediction of positioning is required.