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Soil Carbon and Crop Yields Affected by Irrigation, Tillage, Cropping System, and Nitrogen Fertilization

Sainju, Upendra M., Stevens, William B., Caesar-TonThat, Thecan
Soil Science Society of America journal 2014 v.78 no.3 pp. 936
Conservation Reserve Program, Hordeum vulgare, Pisum sativum, agricultural land, barley, biomass, carbon, carbon sequestration, conventional tillage, crop residue management, crop residues, crop rotation, fertilizer application, grain yield, irrigated farming, irrigation, leaves, magnesium, malt, malting barley, nitrogen fertilizers, no-tillage, peas, sandy loam soils, soil organic carbon, stems, North Dakota
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 lands converted from grassland to cropland in western North Dakota, USA. Treatments were two irrigation practices (irrigated vs. non-irrigated) 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]). Crop biomass varied with treatments and years and was greater in 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 practices. The SOC at 0-5 cm was greater in irrigated CRP, but at 0-85 cm was greater in non-irrigated NTBN than other treatments, except irrigated and non-irrigated CRP and non-irrigated NTBO. At 0-50 cm, SOC decreased by 0.05 to 0.17 Mg C ha-1 yr-1 in irrigated and non-irrigated treatments from 2005 to 2011. At 0-20 cm, SOC increased by 0.22 to 1.80 Mg C ha-1 yr-1 in NTB-P and CRP, but decreased by 0.02 to 0.63 Mg C ha-1 yr-1 in other cropping systems. Surface residue C and SOC at 0-10 cm were related in linear and curvilinear fashions to annualized crop grain yield (R2 = 0.45-0.77, P = 0.12, n = 10). Perennial cropping systems, such as CRP, increased soil C storage compared to annual cropping systems, regardless of irrigation practices. Because of increased C sequestration rate and favorable crop yields compared to other cropping systems, no-till malt barley-pea rotation with adequate N fertilization may be used as a management option to increase C storage in surface residue and sandy loam soil (0-20 cm) and sustain yields in annual cropping systems, regardless of irrigation practices, in the northern Great Plains, USA.