Above and belowground litter decomposition of cover crops grazed at different intensities |
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| Authors: | Erick R. S. Santos José C. B. Dubeux Jr. Cheryl Mackowiak Lynn E. Sollenberger Gustavo D. Farias Bruno G. C. Homem David M. Jaramillo Luana Q. S. D. Zagato Luana M. Dantas Queiroz David L. Wright Nicolas DiLorenzo Martin Ruiz-Moreno |
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| Affiliation: | 1. Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada;2. North Florida Research and Education Center, University of Florida, Marianna, Florida, USA;3. North Florida Research and Education Center, University of Florida, Quincy, Florida, USA;4. Agronomy Department, University of Florida, Gainesville, Florida, USA;5. Department of Forage Plants and Agrometeorology, Integrated Crop-Livestock System Research Group (GPSIPA), Federal University of Rio Grande do Sul, Porto Alegre, Brazil;6. Department of Animal Sciences, Federal University of Lavras, Lavras, Brazil;7. United States Department of Agriculture (USDA)–Agricultural Research Service, U.S. Dairy Forage Research Center, Marshfield, Wisconsin, USA;8. Aberdeen Research and Extension Center, University of Idaho, Moscow, Idaho, USA |
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| Abstract: | Grazing cover crops may increase land-use efficiency while promoting sustainability. We investigated how grazing intensity affects cover crop litter quantity, quality, decomposition, and cotton (Gossypium hirsutum L.) N uptake. Cover crops were a mixture of rye (Secale cereale L.) and oat (Avena sativa L.) managed as follows: no grazing +34 kg N ha−1 (NG34), no grazing +90 kg N ha−1 (NG90), heavy grazing (HG), moderate grazing (MG), and light grazing (LG). Grazed treatments received 90 kg N ha−1. After cover crop termination, above- and belowground litter was collected and incubated in situ for 0, 4, 8, 16, 32, 64, and 128 days, with cotton plants sampled on the same days to estimate N recovery and synchrony between N release from litter and uptake by cotton. By Day 128, only 13% of initial NG34 aboveground biomass had disappeared, whereas 42% of HG disappeared. Nitrogen retained in aboveground litter of HG was less than NG90 (27 vs. 60 kg N ha−1), and aboveground final N stock (at Day 128) of HG was less than NG90 and LG (16, 47, and 41 kg N ha−1, respectively). Belowground litter contributed 98 kg N ha−1 versus 46 for aboveground. Belowground N disappearance from litter bags was greater from NG90 than NG34 (39 vs. 21 kg N ha−1). Cotton N uptake by Day 128 was similar across treatments (191 kg N ha−1). Grazing cover crops impact aboveground litter quantity, quality, and decomposition rates, and belowground litter plays an important role on the N cycling. |
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| Keywords: | forages grazing management nitrogen nutrient cycling roots |
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