Microbial activity responses to water stress in agricultural soils from simple and complex crop rotations

Authors: SCHNECKER, JOERG - University Of Vienna; MEEDER, D - University Of New Hampshire; CALDERON, FRANCISCO - Oregon State University; Cavigelli, Michel; Lehman, R - Michael; GRANDY, A - University Of New Hampshire

Submitted to: Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2021
Publication Date: 8/26/2021
Citation: Schnecker, J., Meeder, D.B., Calderon, F., Cavigelli, M.A., Lehman, R.M., Grandy, A.S. 2021. Microbial activity responses to water stress in agricultural soils from simple and complex crop rotations. Soil. 7:547-561. https://doi.org/10.5194/soil-7-547-2021.
DOI: https://doi.org/10.5194/soil-7-547-2021

Interpretive Summary: Increasing climatic pressures such as drought and flooding represent challenges to sustainable production from agricultural systems. The resilience of biological soil processes to extremes in soil water content will influence biogeochemical cycles of carbon and nitrogen and the overall productivity of arable lands. Soil biological responses to water stress will interact with soil-climatic conditions and crop management practices. Our objective was to evaluate the resilience of soil biological properties to drought or flooding across multiple soil-climatic regions. In addition, we tested whether crop rotation management influences the response of soil biological properties to water stresses. We measured soil heterotrophic respiration during single and repeated stress cycles in soils from four different sites along a precipitation gradient (Colorado, MAP 421 mm; South Dakota, MAP 580 mm; Michigan, MAP 893 mm; Maryland, MAP 1192 mm). Each site had two crop rotational complexity treatments. We found soil heterotrophic respiration was responsive to both drought or flooding at each site but did not distinguish between crop management practices and was not directly related to site climatic conditions. However, a combination of multiple soil properties was able to detect the effect of crop rotation on responses to water stresses at the driest (Colorado) and wettest of these sites (Maryland). Drought generally caused more severe changes in respiration rates and potential enzyme activities than flooding. All soils returned to pre-stress levels for most measured parameters as soon as the stress was removed, suggesting that the investigated soils were highly resilient to the applied stresses. The lack of sustained responses following the removal of the stressors may be because they are well in the range of natural in situ soil water fluctuations at the investigated sites. Without inclusion of plants in our experiment, we found that soil biological properties in the investigated agricultural soils were resistant to drought and flooding, during single or repeated stress pulses, which should assist with sustained crop productivity. The influence of crop rotational treatments on soil resilience to water stress was not apparent with any single soil property but could be determined by combining multiple soil properties suggesting the value of this approach in measuring soil resilience.

Technical Abstract: Increasing climatic pressures such as drought and flooding challenge agricultural systems and their management globally. How agricultural soils respond to soil water extremes will influence biogeochemical cycles of carbon and nitrogen in these systems. We investigated the response of soils from long term agricultural field sites under varying crop rotational complexity to either drought or flooding stress. Focusing on these contrasting stressors separately, we investigated soil heterotrophic respiration during single and repeated stress cycles in soils from four different sites along a precipitation gradient (Colorado, MAP 421 mm; South Dakota, MAP 580 mm; Michigan, MAP 893 mm; Maryland, MAP 1192 mm); each site had two crop rotational complexity treatments. At the driest (Colorado) and wettest of these sites (Maryland) we also analyzed microbial biomass, six potential enzyme activities and N2O production, during and after individual and repeated stress cycles. In general, we found site specific responses to soil water extremes, irrespective of crop rotational complexity and precipitation history. Drought usually caused more severe changes in respiration rates and potential enzyme activities than flooding. All soils returned to control levels for most measured parameters as soon as soils returned to control water levels following drought or flood stress, suggesting that the investigated soils were highly resilient to the applied stresses. The lack of sustained responses following the removal of the stressors may be because they are well in the range of natural in situ soil water fluctuations at the investigated sites. Without inclusion of plants in our experiment, we found that irrespective of crop rotation complexity, soil and microbial properties in the investigated agricultural soils were more resistant to flooding but highly resilient to drought and flooding, during single or repeated stress pulses.