/AnMtgsAbsts2009.54584 Soil Carbon and Phosphorous Fractions in Field Crop Rotations of the Argentine Pampas.

Wednesday, November 4, 2009
Convention Center, Exhibit Hall BC, Second Floor

Ignacio Ciampitti, Intl. Plant Nutrition Inst., Latin America Southern Cone Program, Acassuso, Argentina, Fernando Garcia, Latin America Southern Cone, Intl. Plant Nutrition Inst., Acassuso Buenos Aires, Argentina, Gerardo Rubio, Univ. of Buenos Aires, 1417 Buenos Aires, Argentina and Liliana Picone, Agronomy, INTA-Facultad Ciencias Agrarias Univ. Nacional Mar del Plata, Balcarce, Argentina
Poster Presentation
  • Ciampitti ASA 2009.ppt (3.3 MB)
  • Abstract:
    In temperate cropping systems, a better understanding of soil carbon and phosphorus pools transformations in a medium-term is required. Two cropping systems, corn-double cropped wheat/soybeans (C-W/S; two sites) and corn-full season soybeans-double cropped wheat/soybeans (C-S-W/S; two sites), with or without P added during six years were evaluated. The objectives were to: (i) quantify the effects of continuous P fertilization on the size of total C and P (TOC and TP) and associated with particulate organic matter (POM) fractions, (ii) establish a relationship between P in particulate organic matter (POM-P) with corn plant nutrition and (iii) evaluate these fractions as soil quality indicators. The farm fertilization experiments were established in the year 2000 and the average P rate was 34 kg P ha-1, accumulating a total of 204 kg P ha-1. All parameters were measured at 0- to 5 cm, 5- to 10 cm and 10- to 20 cm soil depths. In all P fertilized treatments a significant increase was observed for TOC, TP, POM-C and POM-P concentrations, reaching an average value of 1.1 g kg-1, 51.8 mg kg-1, 0.7 g kg-1 and 3.8 mg kg-1, respectively, at 0- to 20 cm soil depth. For all evaluated parameters the greatest differences appeared at 0- to 5 cm soil depth. POM-P was a variable that showed a high response (47%) to P fertilization. The POM-C/POM-P ratio presented the lowest values in the fertilized treatment. The POM-C/TOC ratio was in average 22.9%. In average, for each ton ha-1 of POM we found 1 kg P ha-1. The POM-P/TP ratio was in average 1.7%, greater in the fertilized P treatment than in the check. At corn silking time, a quadratic model was established between accumulated P in maize plants and POM-P soil fraction, which implies a close relationship between these two P fractions.