Nitrogen dynamics of cattle dung and urine patches on intensively managed boreal pasture

Abstract

SUMMARYThe aim of the present study was to investigate the nitrogen (N) dynamics in soil and N utilization by grass in dung pats and urine patches, and to quantify the amount of soluble organic N (SON) in grassland soil. The experiment was conducted in 2003/04 at MTT Agrifood Research, Maaninka, Finland. The study consisted of three treatments: dung pats, urine patches and a control patch without excreta. The soil (to a depth of 0·6 m) and herbage were sampled on 10 occasions over the course of 1 year. TN and SON in soil averaged 14 400 and 60 kg/ha N, respectively. Changes in soil mineral N were short-lived and a large proportion of excreta N was immobilized. The grass took up 27 kg excretal N/ha from the dung pat and 71 kg N/ha from the urine patch, which equals 0·07 and 0·19 of the excretal N given to each treatment, respectively. As a large proportion of the excretal N is immobilized and accumulates in soil, re-evaluation of the recommendations for N fertilization of pastures older than 2 years is justified.