Detachment of Soil Aggregates by Simulated Rainfall

Abstract

Abstract Sharpsburg silty clay loam was separated into 11 aggregate fractions with the following diameters: 9,250–4,760µ, 4,760–3,360µ, + … +, 297–210µ, and <210µ. Krilium solution was added to half of each aggregate fraction to make the aggregates more water‐stable. The aggregate fractions were packed into splash‐cups and exposed to simulated rainfall intensities from 2 to 12 cm/hr. Raindrops were 5.1 mm in diameter and fell 11.33 m onto the surface of soil materials. Splash of soil particles and aggregates was caught, oven‐dried, and weighed. The amount of detachment of aggregates was linearly related to the rainfall intensity. Detachment of non‐treated aggregates exposed to rainfall increased from 76 mg of particles per cm 3 of water to a maximum amount of 172 mg/cm 3 as the aggregate diameters decreased from 9,250–4,760µ to 2,360–1,680µ. Then, the amount of detachment decreased with decreasing diameter to aggregate to 78 mg/cm 3 for aggregates < 210µ diameter. The addition of Krilium to aggregates reduced the amount of detachment of aggregates >420µ in diameter exposed to simulated rainfall. The amount of splash increased with decreasing diameter of Krilium treated aggregates until 297–210µ diameter was reached (138 mg/cm 3 ), then it decreased (101 mg/cm 3 ) for aggregates < 210µ diameter.