Effect of composts and inorganic fertilizers on spring wheat growth and N uptake

Abstract

The nutrient availability of composts has to be known for their safe use in crop production. A field study was carried out to assess the effect of a spring application of composts and inorganic fertilizers on spring wheat (Triticum aestivum L. 'Messier') growth and N uptake in eastern Québec (Canada). The experiment was conducted in 1994 and 1995 on two different soils: a Kamouraska clay (Orthic Humic Gleysol) and a Saint-André sandy loam (Fragic Humo-Ferric Podzol). Four composts were applied at rates of 0, 90, 180 and 360 kg total N ha−1. Inorganic fertilizers were applied at rates of 0, 50, 100 and 200% of wheat N, P or K requirements. Treatments in which inorganic fertilizers (IN) were added to composts were also included. Grain yield was increased by N rates whereas composts alone at 90 kg total N ha–1 resulted in lower yields than the control in the first year on the sandy loam. Commercial composts resulted in higher yields than dairy manure composts. Wheat showed no significant response to P and K fertilizers on either soil. Compost rates had no effect on grain N content but commercial composts increased straw N by 36 to 63%. Addition of IN to composts increased grain yield by 0.1 to 1.5 Mg ha−1 and N uptake by 4 to 55 kg N ha−1, depending on soil and weather conditions. Apparent recovery efficiency of added N for composts was −14 to 15% whereas it ranged from 24 to 56% for IN. In spring wheat production, composts should be considered more as organic matter amendments because of their limited N efficiency. Key words: Composted dairy manure, shrimp wastes, peat moss, apparent N recovery