GLOBAL CHANGE AND BELOWGROUND PROCESSES IN AGRICULTURAL SYSTEMS
Location: National Soil Dynamics Laboratory
Title: Effects of Atmospheric CO2 Enrichment on Crop Nutrient Dynamics under No-till Conditions
Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 2007
Publication Date: April 1, 2008
Citation: Prior, S.A., Runion, G.B., Rogers Jr, H.H., Torbert III, H.A. 2008. Effects of Atmospheric CO2 Enrichment on Crop Nutrient Dynamics under No-till Conditions. Journal of Plant Nutrition. 31(4):758-773.
Interpretive Summary: The increasing level of CO2 in the atmosphere may increase farm productivity, but, how CO2 will affect crop nutrient characteristics in the field has not been well studied. Plant nutrients of soybean and sorghum crops grown in the field under elevated CO2 were evaluated. Nutrient levels were generally higher for soybean compared to sorghum. High CO2 often increase crop nutrient levels primarily in soybean. Responses were less variable in grain compared to non-yield residues. More notable differences in macronutrients (N, P, K, Ca, Mg) were found, while differences in micronutrients (Cu, Fe, Mn, and Zn) were highly variable. The consistent CO2-induced increases in grain nutrient levels favors reliable predictions of cropping system nutrient outputs, but, predictions of crop nutrient inputs (non-yield residues) to the soil are less robust. Again, this is more true in regards to micronutrient dynamics in CO2-enriched cropping systems. Our results may assist in predicting future fertilizer expenditures and assessing environmental impact from nutrient management practices.
Increasing atmospheric CO2 concentration could increase crop productivity and alter crop nutrient dynamics. This study was conducted (3 yrs) with two crops ([Glycine max (L.) Merr.] and grain sorghum [Sorghum bicolor (L.) Moench.]) grown under two CO2 levels (ambient and twice ambient) using open top field chambers on a Blanton loamy sand under no-tillage. Macronutrient and micronutrient concentrations and contents were determined for grain, stover, and roots. Although elevated CO2 tended to reduce nutrient concentrations, high CO2 had consistently increased nutrient content especially in grain tissue; this response pattern was more notable with macronutrients. The CO2 effect was observed primarily in soybean. The consistent CO2-induced increases in grain macronutrient contents favors reliable predictions of system outputs, however, predictions of crop nutrient inputs (i.e., stover and root contents) to the soil are less robust due to observed variability. Again, this is particularly true in regards to micronutrient dynamics in CO2-enriched cropping systems.