Alkaline stabilized sewage sludge cake as an organic fertiliser for spring barley

Abstract

Five consecutive annual crops of spring barley (Hordeum vulgare L.) were grown in a field experiment on a sandy clay loam with an initial low exchangeable K status. Four rates of alkaline stabilised sewage sludge cake and four rates of fertiliser K (as KCl) were compared together with controls receiving no applied K. Grain and straw yields, grain quality estimates and plant population results were averaged over the five crops. Plots receiving K fertiliser or sludge cake gave higher yields than controls, but there was no further yield response to increasing K or increasing sludge cake application. Grain yield was higher (p < 0.05) using sludge cake compared with inorganic fertiliser K, with no difference in straw yield. Grain weight (p < 0.001) and number per ear (p < 0.01) were also higher using sludge cake. The increases in grain yield and quality using sludge cake may be due to, inter alia, high soil pH and alleviation of S deficiency.