Fig. 4.

Influence of tropical pasture grass cultivation (in field plots, over 3 years: September 2004 to November 2007) on soil microorganism populations at 1 day after ammonium sulfate fertilization by estimating copy number of AOB amoA genes (A); AOA amoA genes (B); bacterial small-subunit (SSU) rRNA genes (C); and archaea SSU 16S rRNA genes (D). Plots are identified in Fig. 3 legend. Gene copy number was expressed as copy number per gram of dried soil and obtained through absolute quantification by using real-time PCR. Values are means ± SE from three replications.