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ARS Home » Plains Area » Brookings, South Dakota » Integrated Cropping Systems Research » Research » Publications at this Location » Publication #320231
Title: A diversified no-till crop rotation reduces nitrous oxide emissions, increases soybean yields, and promotes soil C accrual

Author
item Lehman, R - Michael
item Osborne, Shannon

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2016
Publication Date: 2/28/2017
Citation: Lehman, R.M., Osborne, S.L. 2017. A diversified no-till crop rotation reduces nitrous oxide emissions, increases soybean yields, and promotes soil C accrual. Soil Science Society of America Journal. 81:76-83.

Interpretive Summary: Increasing diversity within row crop production systems by increasing the complexity of crop rotation can produce multiple benefits and maintain economic competiveness. Crop rotation has documented advantages such as improved water use; increased soil nutrient content, plant availability and uptake; reduced pest, pathogen, and weed pressures; and increased soil organic matter. These beneficial effects often decrease input costs and increase current and future crop yields. The effects of crop rotational diversity on greenhouse gas (GHG) emissions and global warming potential (GWP) have not been thoroughly documented. We compared two no-till crop rotations with differing complexity (a two-yr corn-soybean rotation and a four-yr corn-field peas-winter wheat-soybean rotation) with respect to their GHG emissions and GWP over a period of four years. Mean annual N2O fluxes were 23% lower for the four-yr rotation compared to the two-yr rotation. Both rotations accumulated soil organic carbon (SOC) in the top 30 cm over the 12-year period following establishment of no-till, but SOC gains for the two-yr rotation were confined to the shallowest soil depths. No-till management enabled both rotations to sequester sufficient SOC to offset any production of GWP by GHG emissions and inputs. There was no significant difference in yields between corn grown in a two-yr or four yr rotation. However, the yield of soybean in the four-yr rotation was 22% greater than soybean within the two-yr rotation. We concluded that diversified rotations may decrease nitrous oxide emissions, increase and/or accelerate carbon sequestration, distribute soil carbon gains deeper in the soil profile, and boost yields of some crops (i.e., soybean). These data enable predictive modeling of future global climates and contribute to the development of best management practices for regional agriculture.

Technical Abstract: We evaluated the impact of crop rotational diversity on greenhouse gas (GHG) emissions, global warming potential (GWP), and crop yields. Under no-till, rain-fed conditions, a two-yr (corn (Zea mays L.)-soybean (Glycine max (L.) Merr.)) rotation and a four-yr (corn-field peas (Pisum sativum L.)-winter wheat (Triticum aestivum L.)-soybean) rotation were established in a randomized, complete block design on upper Midwest U.S. Mollisol soils. Soil surface GHG emissions were measured with static flux chambers and GWP calculated using changes in soil organic carbon (0-30 cm) and published values for other inputs (e.g., fertilizer, fuel). Results were reported for a four-year period concluding 12 years after these no-till rotations were established. Mean annual N2O fluxes were 23% lower for the four-yr rotation compared to the two-yr rotation. There was no difference in annual CH4 fluxes between the two rotations. Over this four-yr period, both rotations sequestered SOC in the top 30 cm; however, gains in SOC within the two-yr rotation were confined to the top 15 cm. The net total GWP including fuel and fertilizer was -1.72 Mg CO2-eq ha-1yr-1 for the two-year rotation and -2.43 Mg CO2-eq ha-1yr-1 for the four-year rotation. There was no significant difference in yields between corn grown in a two-yr or four yr rotation. Corn yields averaged about 6.75 Mg ha-1 across both treatments. However, the yield of soybean in the four-yr rotation (2.87 Mg ha-1) was 22% greater than soybean within the two-yr rotation (2.35 Mg ha-1). We conclude that after 12 yr, no-till management enabled both rotations to sequester sufficient SOC to offset any production of GWP by GHG emissions and inputs. We also found that diversified rotations may decrease nitrous oxide emissions, increase and/or accelerate carbon sequestration, distribute soil carbon gains deeper in the soil profile, and boost yields of some crops (i.e., soybean).