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Title: Perennial grain on a Midwest Alfisol shows no sign of early soil carbon gain
Abstract Perennial grain crops are expected to sequester soil carbon (C) and improve soil health due to their large and extensive root systems. To examine the rate of initial soil C accumulation in a perennial grain crop, we compared soil under perennial intermediate wheatgrass (IWG) with that under annual winter wheat 4 years after the crops were first planted. In addition, we tested the effect of three nitrogen (N) sources on C pools: Low available N (Low N (Organic N); 90 kg N ha −1 poultry litter), moderately available N (Mid N; 90 kg N ha −1 urea) and high available N (High N; 135 kg N ha −1 urea). We measured aboveground C (grain + straw), and coarse and fine root C to a depth of 1 m. Particulate organic matter (POM-C), fractionated by size, was used to indicate labile and more stabilized soil C pools. At harvest, IWG had 1.9 times more straw C and up to 15 times more root C compared with wheat. There were no differences in the size of the large (6 mm–250 µm) or medium (250–53 µm) POM-C fractions between wheat and IWG ( P > 0.05) in surface horizons (0–10 cm). Large more » POM-C under IWG ranged from 3.6 ± 0.3 to 4.0 ± 0.7 g C kg soil −1 across the three N rates, similar to wheat under which large POM-C ranged from 3.6 ± 1.4 to 4.7 ± 0.7 g C kg soil −1 . Averaged across N level, medium POM-C was 11.1 ± 0.8 and 11.3 ± 0.7 g C kg soil −1 for IWG and wheat, respectively. Despite IWG's greater above and belowground biomass (to 70 cm), POM-C fractions in IWG and wheat were similar. Post-hoc power analysis revealed that in order to detect differences in the labile C pool at 0–10 cm with an acceptable power (~80%) a 15% difference would be required between wheat and IWG. This demonstrates that on sandy soils with low cation exchange capacity, perennial IWG will need to be in place for longer than 4 years in order to detect an accumulated soil C difference > 15%. « less
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Award ID(s):
1637653 1027253
Publication Date:
Journal Name:
Renewable Agriculture and Food Systems
Page Range or eLocation-ID:
1 to 13
Sponsoring Org:
National Science Foundation
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