Determination of maximum water holding capacity of soil .pptx

It all about how to determine maximum water holding capacity of soil by laboratory method with calculation of the different types of soil s Water holding capacity

1. DETERMINATION OF MAXIMUM WATER HOLDING CAPACITY OF SOIL Presenting to: Presentation by: Dr D.M.Patel Professor and head of agronomy department C.P.College of agriculture Prakash Dodiya Sem:First Roll no:05 AGRON 504 PRINCIPLE AND PRACTICES OF WATER MANAGEMENT

2. Introduction 02 It is also called "maximum moisture retentive capacity" of soil What is maximum water holding capacity ? Maximum water holding capacity is the amount of moisture absorbed (I.e., Macro and micro pore space is completely filled with water) per unit weight of dry soil, when placed in under saturated condition .It is expressed in terms of percentage.

3. The moisture retains is governed by inherent characteristics of soil Texture Type and amount of clay minerals Particle size distribution Organic matter content capillary and non- capillary porosity 03 Such as...

4. Principle: When a thin layer of soil is allowed to absorbed water from a free water surface total pore space gets completely fill with water gradually. the amount of water retained in the soil helps in calculating maximum water holding capacity of soil. 04

5. 04 Apparatus/material Brass cup with cap Filter paper Balance Petri dish Spatula Balance Petri dish Spatula

6. Procedure: Weigh an empty brass cup with cap and filter paper Fill up the dry soil in brass cup with gentle taping after removing the cap Tap the brass cup and level the soil with a help of spatula Remove the outer soil with the help of brush and place the cap on brass cup weigh the brass cup with soil and cap Place the brass cup in a petri dish containing water (Brass cup should submerged in water up to 1/4th depth) 05

7. 06 Conti..... Allow the brass cup with soil in water for one and half hour till the soil become completely saturated with water I.e , soil surface become shining After complete saturation , take up the brass cup , wipe off the outer surface of cup with blotting paper and weight Subtract the moisture absorbed by the filter to correct the results and calculate maximum water holding capacity of the given soil.

8. Observation: Weight of empty brass cup(W1) =________ gm Weight of brass cup + soil (W2) = ________ gm Weight of brass cup + soil + water (W3) =________ gm Weight of water absorbed by filter paper (W4) =_______gm

9. Calculation: Weight of dry soil = W2 – W1 =________ gm Weight of water absorbed by soil = (W3 – W2) – W4 =_______ gm Maximum water holding capacity (%) = moisture held by soil X 100 weight of dry soil = ( W3 – W2) – W4 X 100 W2 – W1 = _____________%

10. Example: Observation : 1. Weight of empty brass cup (W1 ) = 109.446 g. 2. Weight of brass cup + soil ( W2 ) = 169.86 g. 3. Weight of brass cup + soil + water ( W3 ) = 189.09 g. 4. Weight of water absorbed by filter paper ( W4 ) = 0.5 g. Calculation : Weight of oven dry soil = W2 - W1 = 169.86 – 109.446 g. = 60.414 g. Weight of actual water absorbed by soil = ( W3 – W2 ) –W4 = ( 189.09 – 169.86 ) – 0.5 g. = 19.23– 0.5 g. = 18.73 g.

11. Maximum water holding capacity : MWHC ( % ) = ( W3 – W2 ) - W4 X 100 W2 - W1 = ( 189.86 – 169.86 ) – 0.5 X 100 169.86 – 109.446 = 18.73 X 100 60.414 = 0.31 X 100 = 31.002 %

12. Prakashsinh Rajput Thank You!