The effect of spray head sprinklers with different deflector plates on irrigation uniformity, runoff and sediment yield in a Mediterranean soil

Low-pressure centre-pivot systems are usually equipped with spray head sprinklers that can have different types of deflector plates and thus produce different drop sizes causing different effects on the infiltration process. Field tests using low-pressure (140 kPa) spray head sprinklers with smooth and medium groove deflector plates and maximum water applications rates between 99 and 125 mm/h were carried out in a Mediterranean soil. These tests made it possible to study the effect of the deflector plate on irrigation uniformity, runoff and sediment yield. Medium groove deflectors produce lower irrigation uniformity, but apply water with larger water droplets which are less affected by wind and can lead to less evaporation and wind drift losses. However, these droplets have higher impact energy over the soil surface, increasing surface sealing and crust formation, which reduce infiltration and increase runoff. Higher runoff amounts and soil particles detachment produced by grooved deflectors also lead to more sediment yield and soil erosion.