The soil type influences the movement of water and consequently the entire operation of a drip irrigation system.

Different soil types have different physical properties. To classify the different soil types, we have to consider the size of the particles (which affects the capillarity) that compose the soil, subdividing them into: clayey soils, sandy soils and medium soil.

When the size of particles decreases, the capillary forces increase. A greater capillary force allows a greater movement of water through the soil in all directions. A smaller capillary force limits the movement to gravity alone, as in heavily sandy soils.

Clay soils

Clay-based soil has small, flat, compact particles with large ratios between exposed surface area and volume. These soils are often difficult to prepare for sowing as they are slippery when wet and hard when dry, making the timing of field operations crucial to avoid damaging the soil structure and to achieve adequate soil porosity for sowing. In these soils water is absorbed and moves slowly, but once they are wet, they retain significant amounts of moisture. This means that water applied quickly to the clayey soil tends to flow to the surface rather than penetrate the soil. Therefore, when irrigating clay soil, the water must be applied slowly over a long period of time, just as it may not be necessary to irrigate the field for several days.

Clay soils have a greater capillarity (laterally and upwards) than sandy soils. For these soils, with smaller particles, the emitters/drippers need to be spaced further apart because the capillary force will attract the water further away before gravity brings it downwards.

Sandy soil

Sandy soil, on the other hand, have relatively large particles with a reduced surface/volume ratio. They are generally easier to prepare for sowing and can be worked even after significant rainfalls. Water is absorbed quickly and it moves by gravity, but it is retained very weakly and in very small quantity. Therefore, irrigation on sandy soil must be applied quickly and for short periods. Irrigation time on sandy soil should be shorter, otherwise water moves beyond the root zone, becoming unavailable to the plant and contributing to soil leaching. For efficient water use under certain weather conditions, sandy terrain may need daily irrigation for short periods of time.

Rapid water release on sandy soil will contribute to a wider wetting area, providing more soil volume for root exploitation.

In case of soil with large particles, water will start moving downwards almost immediately. The emitters must be positioned closer together to spread the water before it disperses under the root zone due to gravity.

Drip irrigation solutions

Soil type can vary considerably within the same field. Drip irrigation systems can be divided into zones to take this variation into account. Each irrigated zone can be divided according to the predominant soil type. The emitter flow rate can also be selected to suit different soil types: high emitters flow rate used on sandy soil and low flow rate on clay soil. Emitter spacing can also be modified basing on soil type: longer spacing on clay soil and shorter spacing on sandy soil. Growers using drip irrigation systems should take advantage of these options to maximize water use while minimizing environmental impact.

Paying attention to the soil type and the way it should be irrigated will make water usage more efficient and environmentally friendly. With our tool you can find out which will be the best tape suitable for your soil.