Plant remediation of soil beneath an abandoned animal waste lagoon

In the 21st century, remediation of the soil beneath animal waste lagoons will become an important issue, as they are closed due to environmental regulations. Methods to remediate abandoned lagoons to prevent environmental degradation have not been developed. One remediation method might be to grow plants in the contaminated soil. They would stabilize the soil and prevent erosion. No work has been published to see if plants will grow in abandoned animal waste lagoon soil with its high level of ammonium N. Thus, the first objective of this experiment was to determine under greenhouse conditions if barley (Hordeum vulgare L. ‘Weskan’), the most salt tolerant of commercially important crops, would grow in the lagoon soil. A second objective was to determine if plant residues [oat (Avena sativa L.) straw and maize (corn) (Zea mays L.) cobs] added to the lagoon soil would tie up N, because of their high C:N ratio. The lagoon soil came from the bottom of a closed swine lagoon. The high concentration of ammonium N in the swine-lagoon soil (1349 mg kg−1) did not inhibit barley emergence and growth. The lagoon soil with no residues sustained barley growth. Plants grown in soil amended with oat straw grew as well as plants grown in the soil with no residues, but barley grown in lagoon soil with corn cobs grew poorly for two reasons. First, the corn cobs provided an inadequate seedbed and emergence was low. Second, water moved through preferential paths in the soil with corn cobs and was not retained in the pot for plant growth. More N remained in the lagoon soil with both types of residues than in the soil without residues. The results showed that the physical characteristics caused by the residue were of most importance in permitting sustained barley growth in swine-lagoon soil.