|Hu, Shuijin -|
|Cheng, Lei -|
|Zhu, Jianguo -|
Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 30, 2009
Publication Date: August 5, 2009
Citation: Hu, S., Cheng, L., Zhu, J., Booker, F.L., Burkey, K.O. 2009. Assessing the integrative impact of climate change factors on soil cation nutrients. Soil Science Society of America Annual Meeting Nov 2009. Technical Abstract: Nutrient availability for plants is a major determinant of ecosystem productivity and critically affects plant responses to the increasing carbon dioxide in the atmosphere and the potential of ecosystem C sequestration. Crop yields are predicted to increase under future carbon dioxide scenarios assuming that N availability can be maintained through fertilization. However, this prediction essentially ignores limitations caused by other nutrients, particularly essential cation nutrients that are often deficient in many agroecosystems. Crop harvest constantly removes nutrients from agroecosystems, and because of their short life cycle, crop plants have to largely rely on labile nutrient pools (e.g., exchangeable cations). Increasing evidence has shown that climate change components (e.g., elevated carbon dioxide, ozone and reactive N inputs) can significantly alter rhizosphere processes by modifying root and microbial growth. The resulting changes in rhizosphere physiochemical environments may affect the valence state, displacement, and/or bioavailability of nutrient cations. However, the magnitude, directions and long-term implications of climate change effects on soil cations largely remain un-explored and the underlying mechanisms have not carefully been examined. We examined how climate change factors (elevated carbon dioxide and ozone) affect soil cation dynamics and availability for plants in rice paddies in China, and soybean and wheat fields in USA. While free air carbon dioxide enrichment (FACE) was used to manipulate carbon dioxide concentration in the rice-wheat systems, an open-top facility was used to control carbon dioxide and ozone in a soybean-wheat system. Elevated carbon dioxide in general increased Ca and Mg, but reduced K in solutions both in rice paddies and dryland soils. Corresponding to carbon dioxide -stimulation of Ca, Mg and K availability in soil solutions, plant biomass K, Ca and Mg increased. Carbon dioxide-enhancement of cations in soil solutions positively correlated with root activities, indicating a major role of biological processes in carbon dioxide-stimulation of cation release from soil. These results suggest that over the long term, atmospheric carbon dioxide-enrichment may facilitate Ca and Mg losses from soil. The underlying mechanisms governing the carbon dioxide-enhancement of soil Ca and Mg, and potential impacts on soil fertility will be discussed.