Soil organic carbon dynamics in semi-arid irrigated cropping systems

Bierer, A.M. and Leytem, A.B. and Dungan, R.S. and Moore, Amber and Bjorneberg, D.L. (2021) Soil organic carbon dynamics in semi-arid irrigated cropping systems. Agronomy. 11(484):1-30. 15 March 2021. Available: https://doi.org/10.3390/agronomy11030484

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Abstract

The insufficient characterization of soil organic carbon (SOC) dynamics in semi-arid climates contributes uncertainty to SOC sequestration estimates. The opportunity exists to improve estimates of SOC dynamics in irrigated semi-arid croplands by studying research locations in south-central Idaho. This study intended to estimate changes in SOC (0-30 cm depth) due to variations in manure management, tillage regime, adoption of winter cover, and crop rotation. Empirical data from three research locations was also used to drive denitrification decomposition (DNDC) models in a “default” and calibrated capacity as well as forecast SOC levels until 2050 under “high” and “low” emissions future climate scenarios. Empirical data indicates: (i) increasing C input results in more rapid increases in SOC; (ii) no effect (P = 0.51) of winter triticale on SOC after 3 years; (iii) SOC accumulation (0.6 ± 0.5 Mg ha-1 yr-1) under a dairy forage rotation of corn-barley-alfalfax3 and no change (P = 0.905) in a commercial rotation of wheat-potato-barley-sugarbeet; (iv) manure applied annually at rate 1X is not significantly different (P = 0.75) from biennial application at rate 2X; and (v) no significant effect of manure application timing (P = 0.41, fall vs spring). The DNDC model simulated empirical SOC and biomass C measurements adequately in a default capacity, yet specific issues were encountered. The calibration improved model fit however simulation of soil water contents and actual evapotranspiration remained unacceptable. By 2050, model forecasting suggested: (i) SOC stock was ~ 1 % different between future emissions scenarios; (ii) triticale cover resulted in SOC accrual (0.5 – 0.27 Mg ha-1 yr-1); (iii) when manure is applied, conventional tillage regimes are favored; and (iv) manure applied treatments accrue SOC fitting a quadratic relationship (all R2 > 0.85 and all P < 0.0001), yet extending the simulation to 2100 indicated no equilibrium was realized. It is possible that under very large C inputs that C sequestration is inaccurately favored by DNDC which may influence “NetZero” C initiatives. Our findings improve upon knowledge of SOC dynamics in semi-arid irrigated cropping systems and could aid DNDC model development endeavors.

Item Type:	Article
NWISRL Publication Number:	1700
Subjects:	Manure Soil > Chemistry Soil > Soil quality Soil
Depositing User:	Users 6 not found.
Date Deposited:	16 Mar 2021 14:00
Last Modified:	16 Mar 2021 14:00
Item ID:	1738
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/1738