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Nitrogen Fertilization and Proportion of Legume Affect Litter Decomposition and Nutrient Return in Grass Pastures
Author(s) -
Kohmann Marta M.,
Sollenberger Lynn E.,
Dubeux Jose C. B.,
Silveira Maria L.,
Moreno Leonardo S. B.,
Silva Liliane S.,
Aryal Parmeshwor
Publication year - 2018
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci2018.01.0028
Subject(s) - monoculture , legume , biology , litter , agronomy , paspalum notatum , nutrient , zoology , plant litter , biomass (ecology) , nitrogen , ecology , chemistry , organic chemistry
Warm‐climate grasslands are often N limited. Legume litter decomposition can contribute significantly to N input in grazing systems, but its contribution depends on litter deposition, decomposition, and chemical composition. We evaluated these responses for 2 yr in unfertilized (BG) and fertilized (BGN; 50 kg N ha −1 ) bahiagrass ( Paspalum notatum Flügge) monocultures and in mixed swards of bahiagrass plus the legume rhizoma peanut ( Arachis glabrata Benth.). Legume–grass mixture litter had greater initial N concentration (26 g N kg −1 organic matter [OM]) and lower C/N ratio (22) than BG and BGN, which did not differ from each other (18 g N kg −1 OM, C/N ratio of 31). Litter biomass relative decay rate was greater for mixtures than for bahiagrass monocultures. As a result, less biomass and N remained at the end of incubation in mixtures (62 and 76%, respectively) than in monocultures (69 and 80%, respectively). Litter deposition rate was similar across treatments, but faster decomposition and greater N concentration for legume–grass mixtures resulted in larger litter N release than in monocultures (44 and 26 kg ha −1 , respectively). At the end of incubation, remaining litter biomass and remaining N decreased with increasing litter legume proportion, whereas litter N concentration and litter decay rate increased. Results indicate that legume–grass mixtures are an alternative to N fertilizer for increasing N cycling through plant litter in grasslands, and although litter deposition rates were similar across treatments, increasing legume proportion in mixtures is likely to be associated with greater litter N release.