The effect of MSW compost on metal uptake and yield of wheat, barley and canola in less productive farming soils of Alberta

Experiments were started in May 1998 at two sites to measure various crop r esponses to a mixed municipal solid waste-biosolids cocompost (named Nutri Plus) and examine the fate of certain metals associated with Nutri Plus com post. There were six treatments: Cheek, 50, 100, and 200 T compost/ha, NPKS (75 kg nitrogen (N)/ha, 20 kg phosphorus (P)/ha, 45 kg potassium (K) and 1 8 kg sulphur (S)/ha), PK (20 kg P, 45 kg K/ha), and three crops: canola (Br assica rapa cv. 'Hysyn 110'), wheat (Triticum aestivum L. cv. 'Roblin') and barley (Hordeum vulgare L, cv. 'Lacombe'). Each treatment was replicated f our times and was in a complete randomized block design. In the compost tre atments, 20 kg P and 45 kg K were applied due to low concentration of: thes e two nutrients in the compost. Soil and plant samples were analyzed for nu trient content such as N,P and K. In addition, plant samples and soil sampl es after the compost application were also analyzed for elemental content o f As, B, G; Co, Cu, Zn Se, Mo, Cd, Hg and Pb. The research results show tha t the compost slightly increased heavy metal concentrations in the soil but did not cause any phytoxicity to crops. Meld from 100 and 200 T/ha applica tion was higher with the compost than with NPKS treatment. However, the yie ld of the 50 T/ha application was similar to that of NPKS treatment. Compar ing the two sites, the compost apparently was more beneficial at Site 1 tha n at Site 2 in the year of application. This is Likely due to the lower ind igenous soil fertility and poor soil physical Properties at Site 1. The N c ontent in cereal grains was similar among the compost treatments but lower than the Check and NPKS treatments due to the diluting effect of higher yie ld. The oil content in canola seed was similar among all treatments. The re sults suggest that Nutri Plus compost applications generated positive yield responses in all three crops. Crop yield increased as the application rate increased. Heavy metal loading was not an immediate problem with the compo st application, although it will limit total compost application over time to the same soil.