2012 Annual Report 1a.Objectives (from AD-416): ARS is interested in determining chemical properties in tropical soils and in the assessment of elemental composition of tropical plants. 1b.Approach (from AD-416): Plant (cacao, cover crops) and soil samples of tropical crops will be collected from field studies carried out in Peru and Brazil and will be transported to the U.S. under APHIS soil and plant import permits. Soil chemical (pH, C, N, macro and micro nutrients: N, P, K, Ca, Mg, Na, Zn, Cu, Fe, B, Mn, etc.) and biological properties (microbial biomass- of C, -N, -P) and plant mineral compositions (C, N, Ca, Mg, K, P, Na, S, Al, Zn, Cu, B, Fe, Mn, etc.) will be determined at the University of Florida, Indian River Research and Education Center (IRREC), Fort Pierce, Florida. Soil and plant (cacao, cover crops) samples will be collected from experiments conducted at SPCL facilities at Beltsville, MD. These soil and plant will be analyzed for macro and micronutrients (N, C, Ca, Mg, K, P, Na, Al, Zn, Cu, B, Fe, Mn, etc.) at the University of Florida, IRREC, Fort Pierce, FL. 3.Progress Report: This agreement provides funds for plant and soil elemental analysis of samples from cacao and cover crops field studies in Bahia, Brazil; Tarapoto, Peru and growth chamber and greenhouse experiments conducted at Beltsville, Maryland. During this period, macro (N, P, K, Ca, Mg, Al,) and micro (Al, B, Co, Cu, Fe, Mo, Zn, Ni, Mn) nutrient concentrations were analyzed in nine cover crops subjected to three light levels and three cacao genotypes grown at three levels of K.