Effects of Gypsum Addition on Solubility of Nutrients in Soil Amended With Peat

Abstract

It is widely accepted that the accumulation of gypsum in gypsiferous soils results in very low fertility, even with application of fertilizers and organic amendments. The objectives were to investigate, in laboratory experiments, the effect of gypsum on the solubility of 13 nutrients and how amending the soil with organic peat moss may mitigate the impact of gypsum on nutrients and soil fertility. A 100-g sample of gypsum-free soil (Sharpsburg Fine, montmorillonitic, mesic Typic Argiudolls) was treated with increasing amounts of gypsum (0, 1, 5, 10, 15, 20, 30, and 50 g), then water was added to the mixtures to reach 50% of the water saturation capacity. Another set of soil/gypsum mixtures received 5-g peat to study the effect of peat application. All mixtures were incubated at 32 degrees C for 15 weeks. After incubation, the concentration of water-soluble nutrients was measured. In general, the addition of gypsum increased the solubility of N, K, Ca, Mg, Mn, Cl, and S, whereas it decreased the solubility of P, Na, Fe, Cu, Zn, and B. The application of peat increased the solubility of all nutrients investigated, except for N and S. Chemical reactions and mechanisms were applied to interpret the effects of both gypsum and peat treatments on nutrient solubility and their relationship to soil fertility and crop production. The application of peat improved the solubility of most nutrients and proved to be useful as an amendment for gypsum-rich soils and increases its productivity.