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Aggregate Carbon Pools after 13 Years of Integrated Crop‐Livestock Management in Semiarid Soils
Author(s) -
Fultz Lisa M.,
Moore-Kucera Jennifer,
Zobeck Ted M.,
Acosta-Martínez Veronica,
Allen Vivien G.
Publication year - 2013
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2012.0423
Subject(s) - silt , soil carbon , soil water , agronomy , environmental science , irrigation , perennial plant , organic matter , soil organic matter , tillage , chemistry , soil science , biology , paleontology , organic chemistry
Integrated crop‐livestock (ICL) systems that utilize perennial or high‐residue no‐till annual forages may build soil organic matter and, thus, enhance aggregate stability, water retention, nutrient cycling, and C storage. We examined long‐term effects of ICL management on soil organic C (SOC) pools compared with continuous cotton [CTN; ( Gossypium hirsutum L.)] at the system and individual vegetation levels, both using limited irrigation (65 and 77% replacement of evapotranspiration, respectively). Soil samples collected in 1997 (baseline) and 2010 were fractionated into four water stable aggregate‐size classes: macroaggregate (>250 μm), microaggregate (53–250 μm), and silt + clay (<53 μm), and three intra‐aggregate size classes: particulate organic matter (>250 μm), microaggregates (53–250 μm), and silt + clay (<53 μm). Reduced tillage and increased vegetation inputs under WW‐B. Dahl Old World bluestem [ Bothriochloa bladhii (Retz) S.T. Blake; bluestem], a component of the ICL, resulted in increased mean weight diameter (1.5 mm in bluestem vs. 0.40 mm in CTN) and higher proportions of macroaggregates (59%) than under CTN. A continued increase in SOC was measured in the ICL following 13 yr with 22% more SOC relative to CTN. The results from the detailed soil aggregate C fractionation revealed that an ICL under limited irrigation enhanced SOC stored in protected, recalcitrant aggregate pools (intra‐aggregate microaggregate SOC of 8.2 and 5.4 mg g ‐1 macroaggregate in the ICL and CTN, respectively). These benefits impart important ecosystem services such as potential C sequestration and reduced erosion potential, which are especially important in these semiarid soils.