The negative relationship between phosphorus and fungal in soil

To discuss the egative relationship between phosphorus and fungal in soil, a series of research were done.

In Quzhou and Shouguang, external input of fertilizer was in the rank of OF>CF>U and GH>FA>FL. As a result, the available phosphorus concentrations in OF, CF, and U plots in Quzhou reached 42-93 ppm, 25-27 ppm, and 7-10 ppm, respectively. From the samplings taken in Oct 2010, it could found clearly how phosphorus accumulated in agricultural soils http://www.cusabio.com/. The background value of available phosphorus in FL is 5ppm. In the farmland of ten years tillage experiment, the concentration of available phosphorus increased into 17 ppm, while in the soils of ten years greenhouse experiment, the concentration of available phosphorus reached 560ppm, it was over tenfold of the background value.

In Shouguang, because of the long-term intensified agricultural management, the accumulation of phosphorus in soil is remarkable, and the available phosphorus concentrations in the GH, FA, and FL were 351, 48, and 27 ppm, respectively. Since both the FA and FL in Shouguang were converted from a GH, they exhibited a much higher level of phosphorus than in Quzhou (Supplementary Information).

The research also indicated PLFA concentration of fungi and bacteria in agricultural soils (Shouguang and Quzhou). Samplings were taken at intervals from May 2006 to Oct 2010, and the total PLFA concentration fluctuated between 13- 92 nmol g -1 soil, and the average was 42 nmol g -1 soil. However, for the 2006-2008 data, the average of total PLFA was 57 nmol g -1 soil, which was much higher than that of 20 nmol g -1 soil in 2010 data.

For the 2010 PLFA measurement, because the water content was not adjusted prior to the isolation of soil solution, soil bacteria in GH and OF did not proliferate into the maximum concentration and the ratio of bacterial PLFA to total microbial PLFA was much lower than in 2008. This comparison indicated that the bacterial PLFA concentration was severely underestimated, while in the U treatment, the extent of underestimation was not so obvious.

Although the absolute PLFA concentrations for bacteria and fungi waved seriously in various soil samplings, the fungal to bacterial ratios (F/B) fluctuated between a small scope (0.07-1.19) and shown a trend that F/B ratio in unfertilized soil (U) was higher than in fertilized soil (OF, CF). And in fallowed land, F/B ratio was also higher that in cultivated land (GH, FA). For the data in 2010, this trend was not so obvious because of the underestimated bacterial PLFA concentration. While for the data in 2006-2008, this change trend of F/B ratios between treatments was very obvious (U>CF>OF), except in Nov 2006, which shown an opposite trend (OF>CF>U).

The trend of changes in various fungal PLFA molecules in agricultural soil. Oleic acid 18:1w9 (c, s, t), linoleic acid 18:2w6,9 (c, t), 18:2w10t, 18:3w6c, and 16:1w5c were used as indicators of fungal in this study. The percentage of 18:1w9, 18:2w6, 9, and 16:1w5 in the total PLFA were 0-0.25 mol%, 0-0.16 mol%, and 0.01-0.04 mol%, respectively. They were much lower than in other observations around the world, which were 6.7-8.3 mol%, 0.5-6.7 mol%, and 1.8-4.1 mol%, respectively. As summarized from reported data, the average percentages of 18:1w9, 18:2w6,9, and 16:1w5 in total PLFA in arable soil are 7.7±0.8 mol%, 2.5±1.1 mol%, and 3.1±1.3 mol%, respectively. Although the percentage of 18:2w6,9 declined remarkably in agricultural soil worldwide compared to that in natural ecosystems, the volume of fungi in agricultural soil in China was much lower than the average global level, according to the present preliminary study.

Furthermore, the correlation analysis indicated that F/B ratios in all treatments were negatively correlated with the phosphorus levels in most of the sampling events. Although the absolute fungal volume (nmol g -1 soil) also increased with phosphorus accumulation, the fungal/total PLFA declined with the increase in phosphorus concentration, because, in general, high phosphorus levels were always accompanied by high levels of nitrogen and organic carbon.

You may like this>>> http://www.cusabio.com/Recombinant-Protein/Recombinant-Autographa-californica-nuclear-polyhedrosis-virus-AcMNPV-Viral-cathepsin-11089554.html