Effects of Beef Cattle Manure on Water‐stability of Soil Aggregates

Abstract

AbstractA field experiment was established to determine the effect of applying varying large amounts of manure on (i) the size distribution of water‐stable aggregates and (ii) their resistance to dispersion during prolonged periods of shaking in water. It was hypothesized that the formation of highly water‐stable aggregates as a result of organic matter amendments to the soil took a relatively long period of time to occur.Beef cattle manure was applied at rates of 0, 180, and 360 metric tons/ha for 3 consecutive years to a Sharpsburg silty clay loam soil in eastern Nebraska. One year after the third manure application, soil samples were collected from the 0 to 10 cm depth of soil and air dried. Aggregates of 4,760–9,440 µm in diameter were wetted under vacuum and then shaken in water for 2, 20, and 200 min. The size distribution of aggregates in water was measured using pipette, elutriators, and sieves.Increased rates of manure application increased the percentage of water‐stable aggregates >295 µm in diameter and decreased the percentage in size groups 18.5–295 µm and <18.5 µm in diameter after 2‐ and 20‐min shaking periods. Distribution of aggregates present after 200 minutes of shaking was not affected by levels of manure application to the field plots.