Metal enrichment of soils watered with pig slurry. Evaluating a mathematical model

An analytical study was carried out of the metal elements contained in pig slurry from a pig farm with a herd of 7,000 pigs (in varying physiological states) together with the accumulation of these metals in soils watered wit h waste deriving from the farming operation. The same amount of pig slurry (same volume, equally concentrated) was added per square meter of surface a rea in each of the plots studied. Soil samples were taken on different date s from watered plots and from a "blank plot" in order to make a quantitativ e analysis of the metal components. The metals analysed were: Na, K, Ca, Mg , Fe, Zn, Cu, Mn, Co, Ni and Cr. The degree of metal enrichment of plots wa tered with slurry was monitored, and a mathematical model was proposed to r elate the concentration of metals in the slurry with the number of watering s of the plots. The greatest soil enrichment occurred with potassium, givin g enrichment values of 1.66 for six waterings and 7.94 for nine waterings, Sodium and magnesium also accumulated in large proportions due to their hig h concentration in pig manure. The mathematical model presented gives a high degree of accuracy for all th e metals studied, with the exception of chromium and nickel.