http://www.springerlink.com/content/n073641q14661246/

Published in “Plant and Soil”, Springer Netherlands

ISSN     0032-079X (Print) 1573-5036 (Online)

Wednesday, March 10, 2010

Julie Major1, Marco Rondon2, 3, Diego Molina2, 4, Susan J. Riha5 and Johannes Lehmann1

(1)        Department of Crop and Soil Sciences, Cornell University, Ithaca, NY 14853, USA

(2)        Centro Internacional de Agricultura Tropical (CIAT), A.A. 6713 Cali, Colombia

(3)        Present address: International Development Research Centre, Ottawa, ON, K1G 3H9, Canada

(4)        Present address: Centro de Investigaciones en Palma de Aceite, cra 42 # 33-07, Villavicencio, Colombia

(5)        Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY 14853, USA

Abstract

The application of biochar (biomass-derived black carbon) to soil has been shown to improve crop yields, but the reasons for this are often not clearly demonstrated. Here, we studied the effect of a single application of 0, 8 and 20 t ha−1 of biochar to a Colombian savanna Oxisol for 4 years (2003–2006), under a maize-soybean rotation. Soil sampling to 30 cm was carried out after maize harvest in all years but 2005, maize tissue samples were collected and crop biomass was measured at harvest. Maize grain yield did not significantly increase in the first year, but increases in the 20 t ha−1 plots over the control were 28, 30 and 140% for 2004, 2005 and 2006, respectively. The availability of nutrients such as Ca and Mg was greater with biochar, and crop tissue analyses showed that Ca and Mg were limiting in this system. Soil pH increased, and exchangeable acidity** showed a decreasing trend with biochar application. We attribute the greater crop yield and nutrient uptake primarily to the 77–320% greater available Ca and Mg in soil where biochar was applied.

The online version of this article (doi: http://dx.doi.org/10.1007/s11104-010-0327-0) contains supplementary material, which is available to authorized users.

**For a definition of “Exchangeable Acidity” see:

http://www.springerlink.com/content/q57u45884n7n5331/fulltext.pdf?page=1

“Exchangeable acidity… can be regarded as a deterioration of the exchange surfaces. …the surface exchangeable cations decrease and gradually aluminium dominates the negative charges, the pH of the soil drops towards 4.0…

Acid rains that accompany fossil fuel emissions, and repeated application of acidifying fertilizers during crop cycles can accelerate soil deterioration.”