Soil Carbon and Phosphorus Pools in Field Crop Rotations in Pampean Soils of Argentina.

CIAMPITTI, IA, FO GARCIA, LE PICCONE, RUBIO G.

SOIL SCIENCE SOCIETY OF AMERICA JOURNAL

SOIL SCI SOC AMER

Año: 2011 vol. 75 p. 616 - 625

0361-5995

In temperate cropping systems, a better understanding of soil C and P transformations is pertinent to evaluate crop management consequences in the medium term. Six-year cropping systems experiments consisting of corn (Zea mays L.)–double-cropped wheat (Triticum aestivum L.)/soybean [Glycine max (L.) Merr.] (two sites) and corn–soybean–double-cropped wheat/soybean (two sites), with (Fp) or without P added (Wp), were evaluated in the Pampean soils of Argentina. The objectives were (i) to quantify the effects of continuous P fertilization on the size and vertical distribution of C and P in total organic C (TOC) and particulate organic matter (POM) fractions and (ii) to evaluate the POM-P fraction as a potential indicator of crop P availability. Annually, an average P rate of 34 kg P ha−1 was applied in Fp plots. The TOC, total P (TP), POM-C, and POM-P were measured in the 0- to 5-, 5- to 10-, and 10- to 20-cm soil depths at the end of the 6-yr period. Phosphorus fertilization increased TOC from 0.5 to 2.5 g C kg−1 and TP from 24.1 to 77.4 mg P kg−1 in the 0- to 20-cm depth. The POM-C andPOM-P fractions were more sensitive than TOC or TP to P fertilization, increasing by 14 and 47%, respectively,in the 0- to 20-cm depth under continuous P addition. The greatest differences in POM-C and POM-P among treatments occurred in the surface soil layer. A significant relationship was found between POM-P and corn P uptake at anthesis.