Earthworms as a Factor in the Reduction of Soil Crusting1
- Eileen J. Kladivko,
- Alec D. Mackay and
- Joe M. Bradford2
Surface soil crusting after heavy rainfall is a problem on many cultivated soils. The objective of this study was to investigate the effect of earthworms (Lumbricus rubellus) on the aggregate stability and infiltration rate of a soil and then assess the susceptibility of this soil to surface crusting. The effect of 0, 15 (250 m−2), or 30 (500 m−2) earthworms pot−1 on a Raub silt loam (Aquic Argiudolls) to which no, soybean [Glycine max (L.) Merr.] or corn (Zea mays L.) residue had been added was studied in 16-L pots over a 54-d period in the greenhouse. Earthworms increased both mean weight diameters (MWD) and water-stable aggregates > 2mm when determined on initially moist soil. In the absence of earthworms, steady-state infiltration rates on the Raub soil were 22 µm s−1 (8 cm h−1). Addition of 15 and 30 earthworms pot−1 to soil containing crop residues, increased infiltration rates to 181 and 328 µm s−1 (65 and 118 cm h−1), respectively. The susceptibility of the undisturbed soil in the 16-L pots and of sieved, repacked soil to surface crusting under simulated rainfall was evaluated by measuring corn seedling emergence. Ten days after planting and simulated rainfall (6.25 cm h−1), 85 to 100% of corn seedlings had emerged in the undisturbed soil in which earthworms were active, whereas in the absence of earthworms only 50 to 52% of seedlings had emerged. When the sieved soil that had received residues and earthworms was exposed to simulated rainfall, 40 to 73% of seedlings had emerged at 10 d, and by 16 d 80 to 88% had emerged. This compares with only 38% emergence in soil to which neither residue nor earthworms was added. Through their feeding, casting, and burrowing activity, earthworms are an important factor in the reduction of surface crusting.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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