Effect of the application of manure of cattle on the properties chemistry of soils in Tizayuca, Hidalgo. México.

Large amounts of fertilizers and pesticides applied annually to agricultural soils improve the physical and chemical properties of soil but, when they are appliedwithout control they can cause serious environmental problems. The farms of Tizayuca in Hidalgo State produce about 30000 tons of manure per day, which are applied indiscriminately in the same region for agricultural use. The aim of this study was to determine the effect of cow manure application in soil chemical properties. Soil samples were collected in two cultivated sites with a history of six and seven years of manure application in uncultivated plot for ten years (control) and they were analyzed according to Mexican Official Standard 021 which sets the specifications of soil fertility. The results showed in the sites with manure application, organic matter content increased significantly compared to the control plot (1.24 and 1.43%), the addition of manure for several years contributed to lower soil pH. The decreased conductivity (0.66 and 0.7 2 dS?m-1). The inorganic nitrogen and phosphorus concentrations were significantly higher than the values in the plot with seven years of manure application; there was a process of leaching of these, which may affect the groundwater contamination.