|ASHWORTH, AMANDA - Orise Fellow|
|ALLEN, FRED - University Of Tennessee|
|TYLER, DONALD - University Of Tennessee|
Submitted to: Pedobiologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/2017
Publication Date: 1/7/2017
Citation: Ashworth, A.J., Allen, F.L., Tyler, D.D., Pote, D.H., Shipitalo, M.J. 2017. Earthworm populations are affected from long-term crop sequences and bio-covers under no-tillage. Pedobiologia. 60:27-33.
Interpretive Summary: Earthworms play an important role in improving soil quality, and their abundance in a given soil can serve as a critical indicator of soil biological health. Because soil health must be maintained for highly-productive agricultural systems to be sustainable, a research team inventoried earthworm populations in two soils where six no-till cropping sequences and three different bio-covers had been used for twelve years. They found that earthworm populations under corn and soybean rotations were more than twice those under cotton rotations; and earthworms under poultry litter applications were more than twice as numerous as under wheat and hairy vetch cover crops. This study is of interest to scientists, extension personnel, and agricultural producers because it indicates soil health may be more sustainable when growing no-till corn and soybeans under nutrient-rich bio-covers such as poultry litter.
Technical Abstract: Earthworms are crucial for improving soil biophysical properties in cropping systems. Consequently, effects of cropping rotation and bio-covers were assessed on earthworm populations under no-tillage sites. Main effects of 6 different cropping sequences [corn (Zea mays), cotton (Gossypium hirsutum), and soybean (Glycine max)] were rotated in four-year phases for 12 years at two field sites in Tennessee, USA in a randomized complete block design with three split-block bio-cover treatments of hairy vetch (Vicia villosa), wheat (Triticum aestivum), poultry litter, and a fallow control. Earthworms were collected to a 15-cm depth, hand sorted, and identified spring of 2013 and 2015 as one of three species (i.e., Diplocardia caroliniana, Lumbricus rubellus, or Amyntha spp). Population richness and relative abundance were affected by bio-covers and cropping sequences for both years at one site, but only by bio-covers at the other location (P<0.05). Under continuous cotton, overall earthworm populations were reduced 55-68%, and D. caroliniana decreased as much as 88% (P<0.05). Conversely, sequences with soybean and corn had greater populations of D. caroliniana (P<0.05), which did not differ when in rotations, indicating favorable food sources in the rhizosphere of these crops. Poultry litter supported 2.2 times as many D. caroliniana and L. rubellus across locations and years, compared to cover crops and the fallow control (P<0.05). Consequently, earthworm populations were greatest under nutrient rich bio-covers (poultry litter) and high residue producing, less pesticide-intensive cropping sequences (soybean and corn compared to cotton), suggesting a more dynamic soil ecology under these cropping systems.