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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| Institution: | 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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