Nitrogen fertilization and genotype jointly drive bermudagrass ( Cynodon spp.) productivity but are not associated with differences in SOC

Nitrogen fertilization and genotype jointly drive bermudagrass ( Cynodon spp.) productivity but are not associated with differences in SOC

Pastureland contributes a large share of the global soil C stock, much of which derives from root systems. Management practices like fertilization and the introduction of improved forages have clear benefits to aboveground forage production, but their impacts on belowground biomass (BGB) and hence s...

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Bibliographic Details
Published in:Agrosystems, geosciences & environment Vol. 6; no. 3
Main Authors: Rusch, Hannah L., Mendoza Mahomar, Augusto Cesar, Lopez, Yolanda, Andrade, Mario Henrique Murad Leite, Maltais‐Landry, Gabriel, Rios, Esteban F., Wilson, Chris H.
Format: Journal Article
Language:English
Published: Hoboken John Wiley & Sons, Inc 01-09-2023
Wiley
Subjects:
Biomass
Compound fertilizers
Cultivars
Cynodon
Ecosystem services
Fertilization
Fertilizers
Forage
Genotype & phenotype
Genotypes
Germplasm
Harvest
Nitrogen
Organic matter
Organic soils
Pasture
Pastures
Plant introductions
Plot (Narrative)
Potassium
Soil organic matter
Soils
Tradeoffs
Florida
United States > US
Georgia
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Summary:Pastureland contributes a large share of the global soil C stock, much of which derives from root systems. Management practices like fertilization and the introduction of improved forages have clear benefits to aboveground forage production, but their impacts on belowground biomass (BGB) and hence soil C are less clear, especially in relatively understudied subtropical pastures. If fertilization and improved cultivars increase BGB, C sequestration may benefit. However, long‐term soil C stocks, and their associated ecosystem services, may be compromised if these practices sacrifice roots in favor of shoot production. We studied the aboveground and belowground biomass of nine bermudagrass ( Cynodon spp.) genotypes in response to four escalating NPK fertilization rates and compared the soil C and N stocks among them. As expected, increasing fertilization improved forage accumulation (FA) although gains from additional N diminished at higher fertilization rates. A positive relationship between fertilization and BGB emerged but varied among genotypes. The latter identified potential tradeoffs between aboveground and belowground allocation in newly released and commercial forage varieties, which may affect pasture persistence and contributions to soil organic matter over time. Overall, we found subtle differences in soil organic C/soil organic N stocks among NPK fertilization rates and genotypes, with the strongest signal emerging from C isotopic analysis. Our results suggest that fertilization at the recommended rate and improved genotype selection minimized negative tradeoffs between aboveground and belowground biomass and did not elicit differences in SOC in the top 15 cm but likely contributed to ecosystem disservices as it relates to N losses. The rate of forage accumulation diminished with increasing fertilization and varied by genotype. Belowground biomass varied strongly with genotype and increased with increasing fertilization. The recommended fertilization rate reduced tradeoffs between aboveground and belowground biomass.
ISSN:2639-6696
2639-6696
DOI:10.1002/agg2.20412