Drainage, Liming and Fertilization of Organic Soils.: II. Distribution of Macro Elements and Heavy-Metal Accumulation
Mobility, exchangeability and accumulation of macro elements and heavy metals after liming and fertilization of organic soils were studied on three sites, two oligotrophic and one mesotrophic. These were drained, fertilized and/or limed in 1953–1956 and sampled in 1991–1992. Fertilization and liming caused marginal changes in bulk density, N stores and C/N ratios, while percentage ash content increased significantly to 40 cm depth at the two oligotrophic sites and to 10 cm at the mesotrophic site. Applied P was relatively immobile and liming caused more P to accumulate in the surface layer, whereas applied K and Mg were mobile with elevated concentrations being measured to 60 cm depth at the oligotrophic sites. Even if liming reduced the relative exchangeable pools of Fe and Al these elements moved to this depth after combined fertilization and liming, but mobility was less after liming alone. Relative exchangeable pools of K, Ca and Mg were high, of Fe and Al intermediate to low and of S and P low. The relative exchangeable P pools were site and treatment specific. The “old P pool” of organic soils seemed quite stable and strongly fixed, while the “new P pool” from fertilizer P probably had higher exchange ratio. Increased stores of Cr, Ni, Sr and Ti resulted from impurities in both fertilizer and lime, Cu from the compound fertilizer, and V and Y probably from the P fertilizer. Stores of Pb were not significantly changed by the treatments; those of Zn was unchanged after liming or even reduced after combined fertilization and liming. The Cu and Pb concentrations were sometimes above the suggested critical levels of toxicity.