02845naa a2200241 a 450000100080000000500110000800800410001902400400006010000160010024501570011626000090027350001630028252019120044565300080235765300080236565300150237365300250238865300270241365300190244070000180245970000190247777301070249610628382022-03-15       2022    bl uuuu     u00u1 u    #d7 a10.1016/j.geoderma.2022.1158042DOI1 aNÚÑEZ, A.  aIrrigation effects on the formation of soil organic matter from aboveground plant litter inputs in semiarid agricultural systems.h[electronic resource]  c2022  aArticle history: Received 28 October 2021/ Revised 25 February 2022/ Accepted 25 February 2022/ Available online 7 March 2022 /Version of Record 7 March 2022.  aABSTRACT: In semiarid agricultural systems, irrigation may increase soil organic matter (SOM) due to higher biomass  production. However, aboveground production tends to increase more than belowground biomass, and in no-till  systems SOM responses to irrigation would strongly depend on the fate of crop residues left on the soil surface.  Litter decomposition and SOM formation can also be affected by irrigation due to changes in water dynamics, but  little is known about the impacts of irrigation on the pathways of SOM formation. We used dual 13C and 15N  labeled maize litter to quantify the effect of irrigation on the contribution of aboveground crop residues to SOM  formation in semiarid, no-till agricultural systems. We incubated the litter in a continuous maize cropping system  with two treatments, dryland and irrigated, and measured litter decomposition and its contribution to different  SOM pools. Irrigation had a larger effect on litter C and N losses than on the formation of new SOM. After 13  months the C and N losses from the litter layer were 24% higher under irrigation, but there were no treatment  differences in the litter-derived C and N recovered in SOM. Most of the litter-derived organic matter (OM) was  found in the mineral associated OM pool (MAOM), but irrigation did not affect the amount of litter-derived OM  found as MAOM or as particulate organic matter. Irrigation increased the amount of litter-derived OM found in  macroaggregates, and this observation was more related to a higher aggregation than to aggregate enrichment in  the irrigated treatment. Our results suggest that a smaller proportion of aboveground crop residues will form  SOM in irrigated systems compared to dryland conditions and may help to partially explain why irrigation has a  stronger relative effect on crop productivity and C inputs than on SOC stocks in semiarid agricultural systems.  a13C  a15N  aAggregates  aLitter decomposition  aPhysical fractionation  aTable isotopes1 aCOTRUFO, M.F.1 aSCHIPANSKI, M.  tGeoderma, 2022, Volume 416, Article number 115804. doi: https://doi.org/10.1016/j.geoderma.2022.115804