Title: Crop diversity effects on near-surface soil condition under dryland agriculture Authors
Submitted to: Applied and Environmental Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 14, 2014
Publication Date: July 22, 2014
Citation: Liebig, M.A., Archer, D.W., Tanaka, D.L. 2014. Crop diversity effects on near-surface soil condition under dryland agriculture. Applied and Environmental Soil Science. Vol. 2014, Article ID 703460, 7 pages. DOI:http://dx.doi.org/10.1155/2014/703460. Interpretive Summary: The northern Great Plains of North America has recently undergone an unprecedented transition in agricultural land use involving conversion of grassland to annual crops coupled with increased prevalence of monoculture cropping. Such trends underscore the value of understanding crop rotation effects on soil properties that infer the status of critical soil functions. Given this context, we sought to quantify effects of crop rotation on a suite of soil properties within four long-term cropping systems in south-central North Dakota. Cropping system treatments included small grain – fallow and three continuously cropped rotations (three year, five year, and dynamic). Soil acidification was greater in the three year rotation compared to the small grain – fallow and dynamic rotations. The five year and dynamic rotations possessed greater soil organic carbon and total nitrogen compared to the three year rotation and small grain – fallow. Among the four long-term cropping systems evaluated in this study, only the five year and dynamic rotations increased soil organic carbon over time. Collectively, our results suggest crop rotations characterized by longer rotation cycles and greater crop diversity minimize soil acidification and increase soil organic carbon. These rotation-induced outcomes serve to foster the maintenance and/or improvement of soil ecosystem services that affect agricultural sustainability.
Technical Abstract: Unprecedented changes in agricultural land use throughout the northern Great Plains of North American has highlighted the need for understanding the role of crop diversity to affect ecosystem services derived from soil. This study sought to determine the effect of four long-term no-till cropping systems differing in rotation length and crop diversity on soil properties. Cropping system treatments included small grain – fallow (SG-F) and three continuously cropped rotations (3yr, 5yr, and Dynamic) located on the Area IV Soil Conservation District Cooperative Research Farm in south-central North Dakota, USA. Near-surface (0 to 10 cm) physical, chemical, and biological soil properties were evaluated in each cropping system, as well as in nearby grazed pasture. Soil pH was lower in the 3yr rotation (5.17) compared to the Dynamic (5.51) and SG-F (5.55) rotations (P<0.05), though cropped treatments were 0.67 to 1.05 pH units more acidic compared to grazed pasture. Among cropping system treatments, 5yr and Dynamic rotations possessed significantly greater soil organic C (SOC) and total N (Mean = 26.3 Mg C/ha, 2.5 Mg N/ha) compared to the 3YR (22.7 Mg C/ha, 2.2 Mg N/ha) and SG-F (19.9 Mg C/ha, 2.0 Mg N/ha) rotations (P<0.05). Comparison of SOC measured in this study to baseline values measured at the research site prior to treatment establishment revealed only the 5yr and Dynamic rotations increased SOC over time. Outcomes from this study suggest a diverse portfolio of crops is necessary to minimize soil acidification and increase SOC.