Greenhouse Technology:
Definition:
It is a controlled environment (protected) cultivation. It has been evaluated to create favourable micro-climate in which crop production can be made possible throughout the year /part of the year as required.
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ADVERTISEMENTS:
i. It can be called as “food factories”
ii It includes many of the followings:
(i) Bench/Beds.
(ii) Misters/pogger.
ADVERTISEMENTS:
(iii) Drainage.
(iv) Light (Fluorescent/PAR lamps).
(v) Heating & cooling system.
(vi) Irrigation systems.
ADVERTISEMENTS:
(vii) Co, enrichment.
(viii) Controlled system.
Benefits:
(i) Raising crop anywhere, anytime, any crop.
(ii) Yield is maximum.
(iii) High Quality product (Exports).
(iv) Raising of seedlings.
(v) Crop productivity several times higher than open conditions.
(vi) Income generation for small farmers (Export).
(vii) Utilisation of wetland.
Types:
i. Thatch house; Making dark area. (Structures)
ii. Shade nets; for filtration of sun light (entire nets).
Example:
i. Vegetable; cauliflower, cabbage, tomato chillies, brinjal, cucumber.
ii. Flowers; Rose, orchids, chrysanthemum.
iii. Fruits; Strawberry.
Disadvantages:
1. High labour requirement
2. Higher cost of production
3. Initial capital investment is high.
Remote sensing:
Measurement or acquisition of information of some property of an object/phenomenon, by a recording device that is not in physical or inmate contact with the object/phenomenon under study. Principle
Based on the reflected radiation energy from different areas on the land surface over a range of wavelength, the objects are distinguished.
Types of Sensors:
Active:
Sensing device directs/creates EMR. Passive: Using other energy/natural energy sources (Sun).
Types of sensing
(l) Airborne remote sensing:
i. It is the method of remotesensing in which cameras or other devices fixed in an aircraft flying at fixes altitude are used to take photograhs of any sources on earth.
Types of aerial photographs:
(i) Infrared aerial photograph
(ii) Black & white aerial photography
a. Particularly for mapping boundaries of water sources.
(iii) Colour aerial photography
a. Disease detection.
b. Identification of tree species in temperature zones.
Space/Satellite Remote Sensing:
It is the method of remote sensing in which cameras, sensors and other devices attached to a satellite, orbitting round the earth take photographs of earth and its resources.
Stages of Remote Sensing:
(i) Origin of EMR.
(ii) Emission of energy from source to surface.
(iii) Interaction between energy in earth surface.
(iv) Transmission of reflected energy to the sensor.
(v) Detection of energy & converting into photographic image/electrical.
(vi) Recording the sensor.
(vii) Data processing.
(viii) Collection of special information.
(ix) Data processing & interpretation.
Basic concern:
(i) Radiation from sun and other terrestrial Sources.
EMR spans a large spectrum of length from 10-10 m (a-ray) to 106 m (long radiowaves).
In remote sensing useful regions are
(a) Visible (0-4 -0-7 µm)
(b) Infrared (0-7 – 3-0 µm)
(c) Thermal infrared (3-5 µm)
(d) Microwave regions (0-3 – 300 cm)
The sun is important source of EMR used in conventional optical remote sensing.
(ii) Effects of atmosphare
Electromagnetic radiation is scttered and absorbed by gases and particulate matters while passing through atmosphere.
Signatures concept:
Any set of observable charateristic which is directly or indirectly related to the identification of an object and or its condition.
1. Spectral:
Change in reflectance/emittance of objects as a function of wavelength. Ex. Forest.
2. Spatial:
Arrangement of terrain features such as shape, size, texture of objects. Ex. Mountain
3. Temporal:
Change of reflectivity/emissibility with time. Eg. Crop growth.
4. Polarisation:
Changes in polarisation of radiation reflected or emitted by an object.
Analysis & generated data:
1. Visual analysis
Eg: Colour, texture, shape size etc.
2. Digital image processing techniques Computer analyse the shapes signature so as to associate each pixel with a particular feature of imaging.
Application of RS in Agriculture in INDIA:
1. Crop production forecasting.
2. Land use
3. Mapping of waste lands
4. Soil mapping
5. Drought monitoring & its assessment
6. Monitoring of surface water bodies
7. Ground water exploration
8. Flood supply & damage assessment.
Cloud Seeding/Artificial Rainfall:
Cloud Seeding:
Cloud seeding is one of the tools to mitigate the affects of drought. It is defined as, “A process in which the precipitation is encouraged by injecting artificial condensation nuclei through aircrafts or suitable mechanism to induce rain from turbulent cloud”.
The rain drops are about a million times heavier than cloud drops. So, rain develops only if the cloud droplets grow by some mechanism. These mechanisms are different for acid and warm clouds.
Seeding of Cold Clouds:
This can be achieved by two ways.
1. Dry Ice Seeding
a. Dry ice (solid carbon-dioxide) has certain specific features. It remains as it is at 80 °C and evaporates, but, does not melt.
b. Dry ice is heavy and falls rapidly from top of cloud and has no persistent effects.
Steps involved are:
1. Aircraft flies across the top of a cloud and 0.5-1.0 cm size dry ice pellets are released in a steady stream.
2. While falling through the cloud a sheet of ice crystals is formed.
3. From these ice crystals rain occurs.
This method is not economical as 250 kg of dry ice is required for seeding one cloud. To carry the heavy dry ice over the top of clouds special aircrafts are required, which is an expensive process.
2. Silver Iodide Seeding
Steps involved are:
1. Minute crystals of silver iodide produced in the form of smoke acts as efficient ice-forming nuclei at temperatures below -5°C.
2. When these nuclei are produced from a flame on the ground generators, these particles are fine enough to diffuse with air currents.
3. Silver iodide is the most effective nucleating substance because; its atomic arrangement is similar to that of ice.
4. The time taken for silver iodide smoke released from ground generator to reach the super cooled clouds was often some hours, during which it would drift a long way and decay under the sun light.
5. So, the appropriate procedure for seeding cold clouds would be to release silver iodide smoke into super cooled cloud from an aircraft.
In seeding cold clouds silver iodide technique is more useful than dry ice technique, because
(a) Very much less of silver iodide is required per cloud.
(b) There is no necessity to fly to the top of the cloud, if area to be covered is large.
Seeding of Warm Clouds
1. Water Drop Technique:
1. Coalescence process is mainly responsible for growth of rain drops in warm cloud.
2. The basic assumption is that the presence of comparatively large water droplets is necessary to initiate the coalescence process.
3. So, water droplets or large hygroscopic nuclei are introduced in the cloud.
4. Water drops of 25 mm are sprayed from air craft at the rate of 30 gallons per minute and rain occurs within a few hours.
2. Common Salt Technique:
1. Common salt is a suitable seeding material for seeding warm clouds.
2. It is used either in the form of 10 per cent solution or solid.
3. A mixture of salt and soap avoid practical process.
Mangrove Forests of India:
Bordering the Indian ocean and its vicinity, mangrove vegetation is found in the Sunderbans in the estuary of the Ganges, Brahmputra system, the Andaman Islands and the Irrawady delta. Small remnants of mangroves are also found in the estuaries of the Mahanadi, the Godavari and the Krishna on the east coast. The west coast mangroves can be divided into two forms – the open scrubby mangroves of the Kutch and Saurashtra coasts and the close forests extending from the mouth of the Narmada and Tapti southwards in the Karnataka and Kerala states.
(a) The coast line of Saurashtra and Kutch (Gujarat):
On sea coast Avicennia officinalis associated with Aegiceras mayus, Pandanus tectorius\ on salt marshes along the coast Bruguiera gymnorhiza together with Aeluropus villosus grass; in salt marshes and tidal creeks Rhizophora mucronata and R. conjugata are common.
(b) The coast line of Maharastra from the mouth of the Narmada southwards:
Coastal sea water and semi-fluid mud area has Avicennia officinalis, Acanthus ilicifolius, Rhizophoramucronata. Salt marshes of tidal creeks have Rhizophora mucronata, R. conjugata, Sonneratia apetala, S. acida, Excoecaria agallocha, Lumnitzera racemosa etc.
(c) The coast line of the Karnataka, Kerala and Tamilnadu:
The mangrove forests have been divided into three zones. The coastal sea water and semi-fluid mud zone contain Rhizophoramucronata, R. conugata, Kandelia rheedii, Bruguiera gymnorhiza, B. caryophylloides, Acanthus ilicifolius etc. Only the West coasts of Karnataka and Kerala contain Ceriops candolleana and Bruguiera eriopetala.
Salt marsh zone along the coast is dominated by Lumnitzera racemosa, Excoecaria agallocha and Arthrocnemum indicum. East coast of Tamil Nadu is more rich having species of Avicennia, Salicornia, Scyphiphora etc. In the salt marshes of tidal creeks Aegiceras majus and Herritiera littoralis occur dominantly in addion to Sonneratia apetala, Avicennia officinalis (in west coast of Karnataka and Kerala only). Towards the interior dry marsh lands of east coast of Tamil Nadu only, Suaeda Mudiflora, S. maritima, S. Monoica occur.
Weather forecasting:
Within the year 2025 the world population would exceed 850 crores, but the production of Agricultural commodities remains uncertain. Agriculture has to meet this challenge, by increasing production in a sustainable way. Agriculture is still a gamble in a country like India as they lie near the equator.
The weather and climate near equator always remain dynamic and unstable. Hence the prediction of weather in these areas is highly difficult and not stable. Hence any strategy to increase agricultural production should take explicit amount of the complimentary of agrometeorology and development.
Already the area available under cultivation is getting reduced day by day due to urbanisation & other factors. Hardly there are lands to bring into cultivation. In this situation, increasing the production per unit area per unit time is essential for which the use of weather factors play a major role in our country. In India, crops on 67 percent of the 14.2 crores of arable land depends on rain. Therefore 44% of the food comes from dryland and 40% of the Indian population depend on the dryland agriculture. Dryland cultivation is mainly dependent on the prevailing weather parameters. 40% of food grains, 80% of maize, 95% of pearl millet and sorghum, 95% of pulses, 75% of oil seeds are grown in dryland areas.
The following aspects of weather concepts are essential to decide the sustainability of production and productivity in our country.
(i) The date of onset and termination of rainy season and variability.
(ii) The distribution of rainfall.
(iii) Micro climate of the cropped area to decide the occurrence of pest and diseases etc., i.e., air, temperature, relative humidity, dew fall, soil temperature wind speed of the cropped area.
By weather forecasting, decision can be taken in advance in agricultural operations and thus planning can be done.
There are three types of weather forecasting:
Among all these types of weather forecast, medium range weather forecast is given much importance as their applicability can be materialised easily, as their validity and accuracy is satisfactory. In case of short range forecast, the validity is for only one or two days which is a small period, for the farmers to collect the recommendation and then to follow. In case of long range weather forecast the accuracy is not as good as medium range weather forecast.