Water harvesting structure in dryland | Evapotranspiration and its units | what is mulches and types of mulches | what is antitranspirants and their types | methods to reduce evaporation | what is mulching in agriculture and horticulture | types of mulching in agriculture amd horticulture

EVAPOTRASPIRATION

Evapotranspiration

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Evapotranspiration is the sum of the evaporation and transpiration of plants from the land and ocean surface to the atmosphere.

● Evaporation explains the movement of water in the air from a source such as the interception of the soil canopy and water bodies.

● Sweat explains the movement of water within a plant and the consequent loss of water in the form of vapor through the stomata of its leaves.

● It is an important part of the water cycle.

■ an element such as a tree that contributes to evapotranspiration can be called an evaptranspirator.

UNIT

□ The evapotranspiration rate is normally expressed in millimeters per unit of time. Rate expresses the amount of water lost from the surface of a crop in units of water depth.

The unit of time can be an hour, a day, a month or even a full growth period and a year

Related links:-

Problems of crop production in dryland

Irrigation system used in greenhouse

Microsystem of irrigation

Water use efficiency

Methods for reducing evaporation.

● There are three principles for controlling evaporation under field conditions.

1. Reduce the turbulent transfer of water vapor into the atmosphere by growing plants, erecting windbreaks, straw mulch, etc.

2. Reduction of capillary conductivity through the rapid absorption of the surface layers of the soil.

3. Reduce capillary flow and soil movement retention capacity.

● Mulch is any covering material applied to the soil surface to reduce evaporative losses. This material can be grown and held in place or any material grown and modified prior to placement for any material or product process and transported prior to placement.

For evaporation control, mostly mulches are used.

MULCHES

mulches

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Type of mulch

a. Soil mulch and powder mulch: -

• Much of the soil consists of a thin layer of loose topsoil which can be created by frequent soil theft with surface tillage tools such as knife harrows, etc. of the movement of the soil by capillary action.

• The soil also prevents deep cracks in the soil by reducing the direct action of the atmosphere and therefore also evaporation.

• Repeated intercropping performed in the Rabi crop even in the absence of weeds helps to reduce evaporation losses.

• Of the different types of mulch, while topsoil is the cheapest.

B. Straw and stubble mulch: -

• Straw and other crop residues, such as stubble, peanut sales, cotton, etc. They can be used as mulch on the soil surface to conserve moisture. Straw mulch reduces both the amount of energy absorbed by the soil and its movement on the ground, thus reducing evaporation. However, the capacity for adequate crop residues is a problem for use as a mulch.

C. Plastic covers

• Plastic mulches are as effective as mulches in controlling evaporation, as cost is not a limiting factor.

• The plastic covers can be white or black. It absorbs solar radiation and improves the soil temperature to accelerate the germination of winter crops such as wheat, barley, etc.

• White plastic mulches will reflect incident radiation and reduce evaporation of moisture from the soil.

HORTICULTURAL CROPS LINKS:-

Cinnamon (Daalchinni)

D. Chemical coverage: -

• Chemicals such as hexadeconol, a long alcohol, when mixed with a 5mm soil surface, can reduce evaporation by approximately 40%.

• The top layer of treated soil dries faster than that of untreated soil creating a diffusion layer upon evaporation.

E. Vertical padding: -

• This is a technique in which trenches 40 cm wide and 50 cm deep are dug at intervals of 2 to 4 along the slope and the field with organic or stable debris up to a height of 10 cm above the ground. Runoff is controlled, collected in shallow trenches and redistributed to the adjacent soil layer and infiltration increases into the black soil.

F. Live padding: -

• It is the term used to describe the soil surface coverage through the canopy of the plant in the associated system.

• Example sorghum + cowpea sorghum forage + sword bean

G. Gravel mulch: -

• Where are small pebbles like stones placed on the ground surface?

• This mulch will be successful in growing fruit trees on land.

• The pebbles placed in the arboreal basin not only reduce evaporation but also facilitate the infiltration of rainwater into the basin.

ANTITRANSPIRANT

● Any material applied to the clear surface of the plant to reduce water loss is called an antiperspirant.

Antiperspirants are also known as sweat suppressants. Foundation antiperspirants reduce sweat loss by up to 30-40%.

● There are four types of antiperspirants: -

A. Type of stomatal closure: -

Transpiration occurs mainly through the stomata on the surface of the leaves. Some fungicides such as PMA (phenylmercuric acetate) and herbicides such as low concentration atrazine act as antiperspirants by closing stomata.

PMA is known to inhibit photosynthesis of the mesophyll. Although success has been reported from greenhouse studies, its efficacy under field conditions is limited.

B. Type of film formation: -

The plastic and waxy material that forms a thin film on the surface of the leaves to delay the escape of water due to the formation of a physical barrier. The success of these chemicals is limited as they also reduce photosynthesis.

• The desirable characteristics of the film-forming type of antiperspirant are that it must form a thin layer, it must be more resistant to the passage of water vapor than carbon dioxide and the film must maintain continuity and must not break.

• These film-forming antiperspirants can be either thin-film or thick-film.

Type of thin film former: - hexadecanol.

Type of thick film formation: - polyethylene S 60 mobileaf

C. Leaf reflector type: -

It is a white material that forms a layer on the leaves and increases the reflectance of the leaves.

By reflecting the radiation, they reduce the temperature of the sheet and the pressure gradient of the vapor from the sheet to the atmosphere, thereby reducing transpiration.

About 5% of spray kaolin reduces the plate temperature by 3-4 degrees Celsius and reduces perspiration by 22-28%.

Celite and hydrated lime are also used as a reflective type of antiperspirant.

D. Type of growth retardant: -

This chemical growth of radium buds and increased root growth allow the plant to reduce the transparent surface and resist the drought condition. They increase the root / shoot ratio.

Example:-

Trimethylammonium chloride, phosphone D, maleic hydrazide (MH)

● The antiperspirant generally reduces photosynthesis, so its use is limited to saving the crop from dying in case of severe water stress.

● If the crop survives, it can use the rain received later.

● Antiperspirants are also useful for reducing the transplanting of nursery plants. have a practical use in nurseries and horticultural crops.

● Waxy material is used to reduce shrinkage of fruit after harvest.

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