How soil carbon fractions relate to soil properties and crop yields in dryland cropping systems?

Authors: Sainju, Upendra; LIPTZIN, DANIEL - Soil Health Institute; Stevens, William - Bart

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2022
Publication Date: 3/1/2022
Citation: Sainju, U.M., Liptzin, D., Stevens, W.B. 2022. How soil carbon fractions relate to soil properties and crop yields in dryland cropping systems? Soil Science Society of America Journal. 86(3):795-809. https://doi.org/10.1002/saj2.20399.
DOI: https://doi.org/10.1002/saj2.20399

Interpretive Summary: Crop producers are increasingly viewing their soil resource as more than just a medium in which crop plants grow. Instead, they are beginning to realize that the soil is a living ecosystem composed of beneficial organisms that require careful management in order to thrive. Farmers need reliable ways to measure the health of the soil ecosystem as it responds to changes in management practices. Soil labile carbon fractions that change rapidly within a growing season have been proposed as promising soil health indicators, but it is unclear how well the size of these fractions correlate to other soil properties and long-term crop yields in semi-arid dryland cropping systems. ARS researchers in Sidney, MT in collaboration with the Soil Health Institute evaluated relationships among soil carbon fractions and 62 soil properties as well as with mean crop yields in two long term (14 and 36 years) dryland cropping systems experiments in eastern Montana. They reported that potential carbon mineralization, which is an indicator of soil microbial activity, was better related to soil properties and crop yields than other soil carbon fractions. Results from the study show that potential carbon mineralization is a promising indicator of soil health in dryland cropping systems in the semiarid climatic region of the northern Great Plains. This potential indicator may provide crop producers with a valuable tool for assessing the impacts of management practices on the soil ecosystem.

Technical Abstract: Soil labile C fractions have been proposed as promising soil health indicators, but they have not been related to extensive soil properties and crop yields. We evaluated the relationships among soil labile and nonlabile C fractions, 62 soil physical, chemical, biological, and biochemical properties and mean crop yields in two long-term (14 and 36 years old) sites under dryland farming in the northern Great Plains, USA. Soil C fractions were soil organic C (SOC), soil inorganic C (SIC), water-extractable C (WEC), KMnO4-extractable C (POXC), potential C mineralization (PCM), and microbially active C (MAC). Treatments were till- and no-till spring wheat (Triticum aestiveum L.)/barley (Hordeum vulgaris L.), pea (Pisum sativum L.), and fallow rotations with and without N fertilization. Carbon fractions were greater in no-till continuous cropping than till crop-fallow at both sites. The SOC was correlated to 21-30 out of 62 soil physical, chemical, biological, and biochemical properties (10-13 weakly, 4-10 strongly, and 4-10 very strongly related). The PCM was correlated to 22-31 out of 62 soil properties (8-14 weakly, 9-10 strongly, and 5-7 very strongly related). Other C fractions were related less to soil properties. All C fractions, except SIC, were also related to mean crop yields across years. Although SOC related well to C fractions and crop yields compared to other C fractions, PCM may be used as a promising soil health indicator because of its greater sensitivity to management practices and better relationship to soil properties and crop yields than other labile C fractions.