Fertilizers provide essential nutrients for crops, however, they may also inadvertently provide trace elements that in certain concentrations represent a risk to the soil and the food chain. The objective of this research was to determine the concentrations of Cd, Pb, Cu, and Zn in the most common fertilizers used in Peruvian agriculture. Twenty-one products including inorganic, organic mineral, and organic fertilizers were analyzed by microwave plasma atomic emission spectrometry. The results were compared against international standards. The content of the trace elements was variable and related to the type of fertilizer. Phosphorus fertilizers showed higher concentrations of Cd (3.3-42.3 mgkg-1), most of which exceeded the regulatory limits of several countries. In the case of Pb, none of the fertilizers analyzed exceeded the regulatory limits. Chicken manure showed the highest concen...

The objective of this research was to evaluate extraction methods for β-glucosidases comparing three buffer solutions (MUB, acetate, and maleate) at different incubation times (0.5 h to 10 h) and in three different soil orders (Mollisols, Andisols and Ultisols). Seven acidic soils were evaluated, showing differences in pH, OM, and clay contents. To evaluate the effect of OM as enzymes source, one soil of each order was treated to partially remove its OM and then the enzyme assay was performed. When using MUB and maleate buffers the highest (32 and 31 µg-pNP g-soil-1h-1 in average, respectively) were found, and the latter was significantly (p < 0.050) correlated with the soil clay content. The activity obtained with acetate buffer was much lower (38.2 µg-pNP g-soil-1h-1 in average). The use of MUB buffer with 1 h of incubation is suggested as extraction method, showing good reprod...

The objective of this research was to evaluate extraction methods for β-glucosidases comparing three buffer solutions (MUB, acetate, and maleate) at different incubation times (0.5 h to 10 h) and in three different soil orders (Mollisols, Andisols and Ultisols). Seven acidic soils were evaluated, showing differences in pH, OM, and clay contents. To evaluate the effect of OM as enzymes source, one soil of each order was treated to partially remove its OM and then the enzyme assay was performed. When using MUB and maleate buffers the highest (32 and 31 µg-pNP g-soil-1h-1 in average, respectively) were found, and the latter was significantly (p < 0.050) correlated with the soil clay content. The activity obtained with acetate buffer was much lower (38.2 µg-pNP g-soil-1h-1 in average). The use of MUB buffer with 1 h of incubation is suggested as extraction method, showing good reprod...