Water availability in different soils pptx

This ppt briefs about water availability in different soils and factors affecting this availability

1. Water Availability in different soils Presented By Rajat Kumar (F-2024-55-M) To Nitin Sharma ( Assistant Professor)

2. WATER AVAILABILITY It is the capacity of soil to hold water that is available for the plant use. The available water is the difference between field capacity which is the maximum amount of water soil can hold and wilting point where the plant can no longer extract water from the soil. The water availability is the total amount of water available for the plants at field capacity soils with different textures and level of aggregation have different water availability.

3. AVAILABLE WATER CONTENT Saturation – The soil can be compared to a water reservoir for the plants when the soil is saturated ,the reservoir is full .However some water drains rapidly below the root zone before the plant can use it.

4. Field Capacity – When this water drained away the soil is at field capacity the plants roots draw water from what remains in the reservoir.

5. Permanent wilting point – When the soil reaches permanent wilting point , the remaining water is no longer available to the plant so this reaches to the permanent wilting point.

6. SANDY SOILS Any soil is based upon its texture ,structure and minerals the sandy soils contain primary minerals which are those materials that are similar to the parent material from which they formed they are often round and irregular in shape. As we know that sandy soils have low water holding capacity and poor structure which means they can’t hold as much water as other soils. Texture Inches of water storage per foot of soil depth Coarse sand 0.25 - 0.75 Fine sand 0.75 – 1.00 Loamy sand 1.10 – 1.20

7. LOAMY SOILS The loamy soils have a volumetric water content of about 11% at the wilting point , which is when plant can,t extract enough water the loam soils absorb water at a rate of ¼ to 2 inches per hour . The loam soils have about 20% of their water available to plants which is about three times more than sandy soils but less than clay soils. The loam soils release about 4/5 of their available water before it becomes difficult to extract . Texture Inches of water storage per foot of soil depth Sandy loam 1.25 - 1.40 Fine sandy loam 1.50 – 2.00 Silt loam 2.00 – 2.50

8. SILTY SOILS Silt soils have moderate water holding capacity and can retain moisture longer than sandy soils. Silt loam soils can hold about 2.4 inches of water the silt loam soils have 20% available water by volume . This is because silt soils have medium sized particles , which provide a larger surface area for water to be held. Texture Inches of water storage per foot of soil depth silt loam 2.00 - 2.50 silt clay loam 1.80 – 2.00 Silty clay 1.50 – 1.70

9. CLAYEY SOILS The clayey soils are formed of secondary minerals that are the result of weathering of the primary minerals ,leading to the formation of plate like particles known as clay which has large surface area. Clayey soils absorbs water slowly that is less than ¼ inches per hour and can retain water more than any soils but this does not mean all of water available to plants Texture Inches of water storage per foot of soil depth Clay 1.20 - 1.50 Silty clay 1.50 – 1.70 Silty clay loam 1.80 – 2.00

10. FACTORS AFFECTING WATER AVAILABILITY Soil Texture – The texture of soil is based upon the percentage of sand silt and clay found in that soil it is generally believed that increasing the clay content in soil profile is associated increase in water holding capacity , however it does not mean more water available for plant use. In the uniform coarse textured soil ( e.g Deep sand ,sandy earth) low amount of clay and silts results in poor soil aggregation and free draining profile . Soil structure – The soil aggregates create pores which store water for plants to access a poor or non- existent soil structure with high clay content will have reduce volume of soil pores. coarse textured soils will generally have larger pore sizes and littlr soil structure resulting in rapid water drainage.

11. THANK YOU