What is Remote Sensing and how it is applicable in agriculture?

What is remote sensing?

The term remote sensing was introduced in the late 1950s in the United States Office of Naval Research. In 1962, Parker defined remote sensing as covering the collection of data about objects which are not in contact with the collecting device. It can also be defined as the measurement of information of some property of an object or phenomenon, by a recording device, i.e., not in intimate contact with the phenomenon. So, it is a multidisciplinary activity that deals with inventory, monitoring, and assessment of natural resources by observations from a remote platform.

THE REMOTE SENSING OF AGRICULTURAL AREAS 

There are some remote sensing agricultural areas which include-

i) International government institutions: EEC - Empowered Export Committee, ESA - European Space Agency, ASEAN - Association of Southeast Asian Nations, etc.

ii)National agencies of US: USAID- United States Agency for International Development, ODA - Official Development Assistance

iii) International agencies: FAO, WORLD BANK, IFAD- International Fund For Agricultural Development

iv) Indian Institute of Remote Sensing ( IIRS,  in Dehradun)

TYPES OF SENSING

1) Active Sensing: When sensing device directs electromagnetic radiation at an object and detects the amount of that energy that reflects. For example, radar, radio wave emissions, and laser imaging radar.

2) Passive sensing: When the sensing device detects electromagnetic radiation originating from another source, primarily from the daylight.

INTRODUCTION

It should be noted that the UN Committee on the peaceful uses of outer space ( COPUOS) in several publications that differentiate in remote sensing between the collection of data in the outer space ( that is, Satellite remote sensing) and inner space ( that is, airborne remote sensing).

Remote sensing detects differentiate between the reflected or emitted radiation from various areas on the land surfaces over different wavelength ranges. It can be performed from various platforms(aircraft) and data are recorded either in photographic form or in digital form.

Data should be in digital form for computer processing so that air photographs must be converted to a digital format before image analysis and sophisticated data processing. Most of the satellites and airborne scanner imagery is recorded in digital form. In digital form, remotely sensed data provides a natural input to GIS ( Geographic Information System) where they can be put into layers along with spatial data.

COMPONENTS OF REMOTE SENSING 

1) Signals from source or sunlight

2) Sensors on a platform

3) Sensing ( Signal reception, storage, processing, information extraction)&( active sensing and passive sensing).

TYPES OF REMOTE SENSING

1) AIRBORNE REMOTE SENSING:

Aerial photographs are helpful in interpretation and map soils but it should be done carefully to avoid errors. Photographs are an essential tool for soil scientists, remote sensing techniques give information about soils. Remote sensing techniques often use multispectral images taken from satellites. Black and white aerial photography was recognized for separating the stands of conifers and broad-leaved species in the cool temperature of forests. In the 1960s, color photography started competing in forestry operationally with black and white photography. Natural colored photographs received great importance in forest studies. Its importance was useful for disease detection and identification of tree species growing in temperate zones.  Aerial photography is used for soil surveys and its scale depends on the height of aircraft flying above the ground and focal length of the camera.

Photoscale= flying height / focal length

Aerial photos are used to locate the changes occurring in land surface patterns that may be related to different soil properties. It is also used for interpretation of soil boundaries and planning fieldwork, for field navigation and plotting.

2) SATELLITE REMOTE SENSING:

Satellite data is being applied more and more in forestry, particularly in multitemporal and multi-stage surveys of forest resources. Photographs taken from space satellites and new methods of recording pictures are developed. Then new techniques and photography are known as " Remote Sensing ". Remote sensing involves obtaining pictures and electromagnetic records of the Earth's surface from a distance and the treatment and processing if the picture data.

STAGES OF REMOTE SENSING 

1) source of electromagnetic energy

2) transmission of energy from the source to the surface of the earth 

3) interaction between energy and earth surface 

4) transmission of emitted or reflected energy to5) detection of energy by the sensor converting into output or image.

6) recording sensor output

7) data processing for the generation of the database.

8) collection of ground truth and  collateral information

9) data processing and interpretation

APPLICATION OF REMOTE SENSING IN AGRICULTURE

- Identification of crops

- Identification of stressed plants

- detection, diagnosis, control of plant diseases

- Estimating crop yield 

- yield maps

- plant breeding research

- soil analysis

- soil mapping 

- land cover mapping 

- reflectance modeling

- crop science

- vegetation science

- agro climatology, agroecology

CONCLUSION

Remote sensing is used for o for survey sources like agriculture, forestry, minerals, water, etc. Agricultural applications if remote sensing is characterized by several phenological, land management, and economic features, which combinedly ensure that remote sensing plays a significant role in monitoring agricultural paths. Its main concern is to increase agricultural productivity. It helps in crop production forecasting and monitoring of surface water bodies. It is used in flood mapping and damage assessment, land use or cover mapping, mapping of wastelands, soil mapping, groundwater exploration.

Remote sensing can be applied in marine resources and coastal, mineral resources studies. It is applied successfully in phytoplankton estimation. It is helpful in the identification of rocks and other geological studies. So, effective management and planning are required in agriculture and can be carried out easily through space-based remote sensing.