Location: Agricultural Systems ResearchTitle: Residue and soil carbon sequestration in relation to crop yield as affected by irrigation, tillage, cropping system and nitrogen fertilization
Submitted to: World Congress of Soil Science
Publication Type: Abstract Only
Publication Acceptance Date: 2/15/2014
Publication Date: N/A
Technical Abstract: Information on management practices is needed to increase surface residue and soil C sequestration to obtain farm C credit. The effects of irrigation, tillage, cropping system, and N fertilization were evaluated on the amount of crop biomass (stems and leaves) returned to the soil, surface residue C, and soil organic C (SOC) at the 0-85 cm depth in a sandy loam soil from 2005 to 2011 in western North Dakota, USA. Treatments were two irrigation practices (irrigated vs. non-irrigated) as the main plot and six cropping systems (Conservation Reserve Program [CRP], conventional till malt barley with N fertilizer [CTBN], conventional till malt barley without N fertilizer [CTBO], no-till malt barley-pea with N fertilizer [NTB-P], no-till malt barley with N fertilizer [NTBN], and no-till malt barley without N fertilizer [NTBO] as the split plot arranged in a randomized complete block with three replications. Crop biomass varied with treatments and years and was greater in the irrigated CTBN, NTB-P, and NTBN than other treatments. Soil surface residue amount and C content were greater in CRP and NTBN than other cropping systems, regardless of irrigation. The SOC at 0-5 cm was greater in irrigated CRP than other treatments, except non-irrigated CRP, NTBN, and NTBO. At 0-85 cm, SOC was greater in non-irrigated NTBN than other treatments, except irrigated CRP and non-irrigated CRP, CTBN, CTBO, and NTBO. At 0-50 cm, SOC declined by 500 kg C ha-1 yr-1 in the irrigated treatment and 40 kg C ha-1 yr-1 in the non-irrigated treatment from 2005 to 2011. Similarly, at 0-20 cm, SOC declined by 20 to 630 kg C ha-1 yr-1 in all cropping systems, except in CRP and NTB-P where SOC increased from 220 to 1080 kg C ha-1 yr-1. No-till increased SOC by 8.5 % at 0-5 cm but decreased by 9.2% at 5-10 cm compared to conventional till. Perennial grasses increased SOC at 0-85 cm by 7% compared to annual crops. The SOC at multiple depths was related to annualized crop grain yield (R2 = 0.26 to 0.45, P = 0.05, n = 10). Irrigation led to a decline in SOC compared to non-irrigation and tillage redistributed SOC in the surface soil layers. While perennial grasses increased SOC probably by increasing root biomass compared to annual crops, regardless of irrigation, NTB-P increased SOC from 2005 to 2011 compared to decreases in other annual cropping systems. As a result, no-till barley-pea with N fertilization can be used to increase C sequestration in the surface layer and annual crop grain yields compared to other cropping systems, regardless of irrigation, in the northern Great Plains, USA.