Ruminant livestock manure impacts on N cycling in the soil-plant continuum. Most studies of manure N cycling are short-term and rely on indirect methods, i.e. apparent N recovery, fertiliser N equivalents or incorporate 15N into ammonium-N fractions. Direct and perhaps more precise measurements may be achieved by long-term studies using 15N incorporated into all manure N components. This paper summarises results of a 6- year trial to compare indirect and direct measures of manure N uptake by corn for 3 years after application
