The use of cow manure as an organic amendment in agroecosystems is a widespread practice. This application increases soil organic-matter content and improves soil fertility. However, cow manure is known to contain endogenous sex hormones (progesterone, testosterone, 17β estradiol, estrone) that may induce abnormal development of the endocrine system in a wide range of organisms during excretion to the environment. Estrogen in low concentrations (ng/L) can cause feminization in male fish, thus, these sex hormones are considered Endocrine Disrupting Chemicals (EDCs). The microbial community is a part of soil organic matter and is responsible for degradation of macromolecules into simpler components available for utilization by plants. Therefore, microbial biomass and its activity are considered to be bioindicators of environmental changes. This study evaluates the hormonal load from cattle-manure accumulation in the soil during 40 years on a vertical (0-35 m) soil microbial community and its functional diversity. 17β estradiol was detected using radioimmunoassay (RIA), and biotic parameters were evaluated using MicroResp.  

Results/Conclusions

The results indicate that the vertically distributed soil moisture and total soluble nitrogen values were higher in the area with cattle-manure accumulations compared to values found at a control site; 17β estradiol at a cattle-manure site was found to reach different levels to a 35-m depth. The vertical distribution of the microbial community showed differences in biomass, CO₂ evolution, and physiological profiles as a result of substrate availability and utilization ability. Thus, the preliminary results elucidate the effect of sex hormones originating from cattle manure on soil microbial community and function. This effect may lead to changes in soil biotic structure, function and in physical and chemical stability of soil structure.