Wheat yield and leachability of phosphorus and mineral nitrogen in pig slurry amended Soils

An outdoor pot experiment was conducted using wheat plants (Triticum aestivum L. cv. Lotti). Each pot was filled with the upper layer of either a Cambic arenosol (soil A) or a Dystric cambisol (soil B) removed from the correspondent lysimeter where a two‐year wheat experiment (1993–1995) had been carried out with an equivalent experimental design as in the present study. The main objectives of this research were (1) to study the effects of increasing applications (5, 15, and 25 t ha‐1) of solid phase from pig slurry (SP) on wheat yield and tissue elemental composition and (2) to investigate the risk of contamination of drainage water by leaching of phosphorus (P) and mineral nitrogen (Nmin) as a result of those applications to the soil. The control consisted of a basic dressing of NPK fertilizer. Results from the study showed that grain production was lower in the 5 and 15 t ha‐1 SP treatments compared to the control in soil A probably due to a potassium (K) deficiency. Increasing application rates of SP significantly enhanced P and Nmin leaching losses in both soils. Finally on soil A high rates of SP amendments led to the contamination of water with P.