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Core Ideas After 3 yr, soybean yield was higher from multispecies than from single‐ and double‐species cover cropping. Multispecies cover cropping had higher soil water and inorganic N content than less‐diverse treatments. Soil organic C was unaffected by cover crop species diversity. Several years of cover cropping are needed to achieve ecosystem benefits. Multispecies cover cropping has become popular in recent years because of the multiple ecosystem benefits compared with single‐ or double‐ species cover cropping. However, scientific studies on the effects of multispecies cover cropping—especially in the southern United States—are limited. A field study was initiated in 2013 at the University of Tennessee's Research and Education Center in Milan, TN, to assess the agronomic and soil responses from single‐, double‐, and multispecies cover cropping in corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] systems. After 3 yr, we found that a multispecies mixture of legumes, grasses, and Brassica spp. significantly increased soybean yield, gravimetric soil water content, and soil inorganic nitrogen as compared to the less‐diverse treatments and a no‐cover control. However, after 3 yr, cover cropping did not increase soil organic carbon. Although multispecies cover cropping exhibited a positive effect on yield and some soil properties after 3 yr, we plan to continue collecting multiple years of data from this field trial.

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Concentrated animal feeding operations typically store livestock waste in clay-lined ponds. Although these ponds are regulated to include a liner with a small hydraulic conductivity to limit leaching, previous studies have traced surface and groundwater contamination from such regulated animal waste ponds. This research examined the transport of 17b-estradiol (E2) and its primary metabolite, estrone (E1), through soil liners using field-and laboratory-based studies. Additionally, a potential engineering solution to limit hormone transport-applying biochar to new pond liners to act as a retardant-was studied. Soil cores 80 cm in length were collected beneath a mature dairy waste pond and analyzed for moisture content and hormone concentrations. Unsaturated conditions and E2 concentrations of 4 to 250 ng g -1 were detected beneath the waste pond. In the laboratory portion of the study, hand-packed columns of sand or clay were subjected to infiltration by a 2.3-m head of dairy waste. A subset of the hand-packed sand columns was amended with powdered biochar to test its ability to retard E2 and E1. For 3 mo, column leachate was analyzed for hormone concentrations, and at the conclusion of the study E2 and E1 concentrations in the soil were measured. In the 44 d after sealing, the clay, sand, sand with a thin layer of biochar, and sand mixed with a biochar amendment leached a total of 0.54, 1.3, 0.09, and 0.45 mg of E2, respectively. The biochar amendments to the hand-packed columns considerably minimized E2 in the leachate.

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