Soil-Water Relationship

-Introduction

-Basic Layout

-Additional Layout Options

-Soil-Water Relationship

-Product Selection Guide

-Spacing Between Dripperlines

-Length of Dripperlines

-Other Components

-Slopes

-Simplified Design

-Subsurface Systems

-System Monitoring

-Application Rates

-System Flow Rates

-How to Specify

-Technical Data

-Performance Specs

Most soils are mixtures of sand, silt and clay. The ideal soil is loam, which contains equal proportions of sand, silt and clay. Sandy soils also contain sand, silt and clay, but predominantly comprise sand. Likewise, clay soils are also a mixture of these three elements but clay is the largest component.

Hence, the watering requirements are different for the various soil types. It is important to design the irrigation system so that the optimum emitter discharge rate and appropriate spacing are selected.

When applied slowly from a drip emitter, water moves through the soil in two directions.

    (a) Gravitational forces which draws the water downwards 
    (b) Capillary forces which draws the water upwards and outwards.

In clay soils, the capillary forces will be more dominant than in sandy soils. In sandy soils, the opposite is true. Hence, the soil type will have a major impact on the way water moves through the soil.

Typically, the wetting pattern in a sandy soil will be fairly narrow but deep, while in a clay soil, the water will spread laterally but shallower.

As we are trying to create overlapping wetting patterns below the surface at the root zones, the water emission points must be closer for sandy soils and further apart for clay soils.

Another important factor to consider when designing the system is the soil infiltration rate. This is the rate that the soil can accept the water and is a function of the soil type. Any water application rate in excess of the infiltration rate may result in puddling, run-off and erosion.