Influence of droplet kinetic energy flux density from fixed spray-plate sprinklers on soil infiltration, runoff and sediment yield

Droplet kinetic energy flux density (DEf) has often been used in evaluating the influence of water droplet impact on soil surface. The D3000 series sprinklers, which are the most popular fixed spray-plate sprinklers (FSPS) used in centre-pivot sprinkler irrigation systems in China were investigated. The influence of DEf generated from the D3000 series sprinklers fitted with medium concave spray-plates on soil surface runoff, bulk density of soil surface crust, sediment yield, and infiltration depth prior to runoff of a sandy loam soil was investigated in indoor experiments. The tested DEf values produced by the sprinkler ranged from 0.27 to 1.76 W m−2, which was above some of the values in earlier reported studies. The results show that the runoff rate, bulk density of soil surface crust, and sediment yield were generally directly proportional to DEf values; while the initiation of runoff, infiltration rate, and infiltration depth prior to the runoff were inversely proportional to DEf. Thus DEf appears to be a suitable indicator in evaluating the effect of droplet impact on soil water infiltration, runoff and sediment yield. The overall DEf from the sprinkler overlap could potentially be minimised by proper selection of sprinkler type, spacing and height above soil surface, nozzle size and pressure, combined with the appropriate centre-pivot lateral length and rotation speed.

► Droplet kinetic energy flux density (DEf) influences soil characteristics.
► Increasing DEf increases runoff rate, sediment yield and soil bulk density.
► Increasing DEf decreases infiltration rate and infiltrated depth prior to runoff.
► High DEf produced by D3000 series sprinklers could accelerate soil surface crust.
► DEf is a suitable indicator in evaluating the effect of droplet impact on soil.