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United States Department of Agriculture

Agricultural Research Service

Bruce A. Kimball



Plant Physiology & Genetics Research Unit

USDA-ARS, Arid-Land Agricultural Research Center


Bruce A. Kimball

Soil Scientist

Arid-Land Agricultural Research Center

21881 North Cardon Lane

Maricopa, Arizona 85239


520-316-6330 (FAX)



Ph.D. Soil Physics, Cornell University, 1970

M.S. Soil Physics, Iowa State University, 1965

B.S. Soil Physics, University of Minnesota, 1963


Research Interests:

Have studied the movement of soil heat and soil gases and have developed several new analysis and measurement methods.  However, most of professional career have studied the effect of CO2 on plant growth and water relations. At the beginning, focused on exploitation of CO2 enrichment to increase agricultural productivity in closed greenhouses for arid regions. But for the last two decades, have determined the effects of the increasing atmospheric CO2 concentration and climate change on yield and water use of outdoor field crops. Have assembled and analyzed the published literature on this topic, as well as the likely effects of global change on water resources. Have led or co-led large cooperative multi-variate experiments using open-top chambers (OTC) and free-air CO2 enrichment (FACE) to expose field-grown crops to elevated CO2, including sour orange, cotton, wheat, and sorghum. Besides management role, was responsible for the measurement of canopy microclimate, energy balance, and evapotranspiration.


Most recently, have been trying to establish the feasibility of ecosystem warming experiments, especially with infrared heaters in order to study the effects of global warming, along with elevated CO2, on open-field plots. A hexagonal array of such heaters produces very uniform warming over 3-m-diameter plots. Interest in this arrays is high and collaborative experiments are underway at Haibei, Qinghai, China and at Cheyenne, Wyoming, USA. And in March, 2007 we launched a "Hot Serial Cereal" experiment here at Maricopa, AZ; wherein arrays of infrared heaters are suspended over open-field plots of wheat that is being planted every six weeks for a 2-year period.


Key Publications


Kimball, B.A., K. Kobayashi, and M. Bindi.  2002.  Responses of agricultural crops to free-air CO2 enrichment.   Advances in Agronomy 77:293-368.

Kimball, B.A. 2005. Theory and performance of an infrared heater for ecosystem warming. Global Change Biology 11:2041-2056.

Kimball, B.A., M.M. Conley, S. Wang, X. Lin, C. Luo, J. Morgan, and D. Smith. 2008. Infrared heater arrays for warming ecosystem field plots. Global Change Biology 14:309-320.


Hot Serial Cereal Expt


During March, 2007, we initiated a “Hot Serial Cereal” experiment at Maricopa, AZ. The “cereal” comes from using wheat, the “serial” comes from our planting the wheat serially every six weeks over a 2-yr time period, and finally, the “hot” comes from our deploying arrays of infrared heaters over 3-m-diameter plots of the wheat on three of the planting dates (1Mar, 1Sep, and 1 Dec). These treatments will expose the wheat to a huge range of high temperatures from natural seasonal changes (wheat is not a summer crop here) and from the infrared heating. The heaters control the wheat canopy temperatures to be 1.5 degrees C (2.7 degrees F) above a reference plot during daytime and 3.0 C (5.4 F) at night to simulate the amount of global warming expected toward the end of this century.


Besides obtaining useful agronomic information about the optimal planting time for wheat in our area, we are also obtaining valuable data to text the temperature response aspects of processes in wheat growth models. Such models will be used to predict the future productivity and water requirements of wheat in the U.S. and around the world.


Scientists involved include Bruce A. Kimball (Soil Scientist), Jeffrey W. White (Plant Physiologist), and Gerard W. Wall (Plant Physiologist) from the U.S. Arid-Land Agricultural Research Center, Maricopa, AZ, and Michael J. Ottman (Extension Agronomist) from the Plant Sciences Department, University of Arizona, Tucson, AZ. Technical assistance comes from Matt Conley, Laura Olivieri, Zahra Troeh, and Charlie Blackshear.


The next page shows an overall view of the wheat plots planted in March, 2007, and the page after that shows an array of infrared heaters deployed over a 3-m-diameter plot of the wheat.




Hot Serial Cereal picture

Infrared Heater Array

Last Modified: 5/7/2008