Chin J Plan Ecolo ›› 2009, Vol. 33 ›› Issue (2): 397-404.DOI: 10.3773/j.issn.1005-264x.2009.02.018

• Research Articles • Previous Articles     Next Articles


LIU Xiao-Mei1; FANG Jian2;ZHANG Jing1; LIN Wu-Ying1;FAN Ting-Lu3;FENG Hu-Yuan1*   

  1. 1School of Life Sciences, Lanzhou University, Lanzhou, 730000, China; 2School of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China; 3Gansu Academy of Agricultural Sciences, Lanzhou, 730070, China
  • Online:2009-03-31 Published:2009-03-31
  • Contact: FENG Hu-Yuan

Abstract: Aims Soil depth and fertilizer application affect soil biological properties. A few studies in China have focused on the influence of soil depth and long-term fertilizer application on microbial activity. Our objective was to study changes in microbial activity in different soil layers under 28-year fertilizer treatments in wheat (Triticum aestivum) field soil to provide basic data on microbial activity and structure and function of farmland ecosystems.
Methods In 1978, six different treatments were established in the Gaoping Agricultural Experimental Station in Pingliang, Gansu Province of China for an experiment on long-term fertilization and wheat-maize rotation. We chose two treatments, no fertilizer application treatment (CK) and mineral fertilizer plus manure application treatment (MNP). The amount of fertilizer per year was 75 000 kg∙hm–2 manure, 90 kg∙hm–2 N, and 75 kg∙hm–2 P. Five soil layers were sampled in both treatments: 5−15, 15−20, 25−30, 35−40 and 45−50 cm. The microbial activity of the different soil layers and the effect of fertilizer on its vertical distribution were determined with microcalorimetry. All experiments were repeated three times. Analysis was done using integrative method combining correlation and component analyses in SPSS.
Important findings With an increase of soil depth, the number of bacteria colonies decreased. This was negatively correlated with Pt values, which indicates time from the growth of microbes to the peak. Thermal power-time curves changed from steep to flat and from regular to irregular, shoulders were shorter and peak height lower. The microbial growth rate constant µ and the peak height Ph values in different soil layers also varied significantly, and both decreased with increased soil depth. There were different kinds of curve shapes in CK and MNP, particularly in the former two layers of soil samples. Curves of MNP were steeper than for CK, and their shoulders before the peak were significantly much shorter. The Ph and μ values of MNP were greater than for CK, and the Pt values of MNP were less than for CK.