Effect of manure handling system, N fertilizer use and area of sugar beet on N surpluses from dairy farms in southern Sweden

Abstract

Nitrogen balances from 283 conventional dairy farms situated in southern Sweden were investigated using the farm gate method. Nitrogen balances were determined for 1997 and 1998. Three N balances were calculated; for the whole farm, for crop production and for milk production. The aims of the investigation were to study if factors such as manure handling system, the amount of N obtained from mineral fertilizer per hectare and the proportion of sugar beet have an influence on the N balance. There was no significant effect of manure handling system on the N surplus per hectare or on N efficiency. The results showed that N efficiency was significantly improved by including sugar beet in the crop rotation and was negatively correlated with milk yield per hectare and fertilizer N per hectare. The N surplus per hectare was positively correlated with milk yield per hectare and fertilizer N per hectare. The comparison did not find a strong relationship between the amounts of N obtained from mineral fertilizer per hectare and supplied as manure. The latter was calculated theoretically. There was a weak, but significant, negative correlation between N from manure in 1997 and N from mineral fertilizer in 1998.