Anaerobically Digested Dairy Manure as Fertilizer for Maize in Acid and Alkaline Soils

Abstract

Anaerobically digested animal manure is a potentially useful by-product from CH4 generation facilities on farm businesses. Two greenhouse experiments were conducted using an acid and alkaline soil to determine the relative effectiveness of anaerobically digested dairy manure compared to undigested dairy manure and inorganic N for increasing maize (Zea mays L.) growth in the early vegetative stage of development. The first experiment compared digested manure with (NH4)2SO4 at 0 to 400 mg total N kg−1 dry soil applied to Mardin (pH 4.9; coarse-loamy, mixed, active, mesic Typic Fragiudepts) or Honeoye (pH 7.2; fine-loamy, mixed, mesic Glossoboric Hapludalfs) soils. In the second experiment, digested manure at 200 mg total N kg−1 dry soil was applied to the soils and compared with fresh dairy manure, Ca(NO3)2, NH4NO3, and (NH4)2SO4 applied at the same total N rate. Also, an unamended treatment was included. In both experiments, shoot dry wt and total plant N after manure applications were equal or greater than inorganic fertilizer applications across both soil types, and maize yields from digested manure in the acid soil were as good or better than the yields in the alkaline soil. Differences could not be attributed solely to plant available nitrogen (N) (NH4-N + NO3-N) in the soil as there was similar or greater quantities of available N in the inorganic fertilizer treatments as in the digested manure treatment. Anaerobically digested dairy manure appears to be more effective for increased maize growth in early stages of development than inorganic fertilizer N sources if applied to an acid soil rather than to an alkaline soil.