Data on soil analyses, fertilizer use and yields were collected from carrot
and pea producers converting to integrated production in 1997, with the ai
m of identifying changes in fertilizer practice and effects on yield.
On carrot fields, the average total N rate was 80 kg hd(-1), which was unaf
fected by soil organic matter content and by the preceding crop. Correspond
ing P rates averaged 35 kg ha(-1) and K rates 131 kg ha(-1). The P rate was
reduced when soil P analyses were high, but K rate was not adjusted for so
il K. The resulting changes in N, P and K rates had no influence on the car
rot yield, which averaged 49 t ha(-1) (close to the national average).
On pea fields, the average N rate was 42 kg ha(-1) with rates reduced where
soil organic matter content was high. P rates averaged 16 kg ha(-1) and K
rates 52 kg ha(-1). There was no evidence that these fertilizer rates were
adjusted for soil P or K content. Changes in N, P and K fertiliser practice
again had no influence on the yield, which averaged 5.4 t ha(-1).
The data showed that as a rule farmers followed fertilizer recommendations.
Nitrogen rates were adjusted according to the estimated yield, but results
of soil analyses were often not used in fertilization planning. Yield data
showed that the existing fertilizer recommendations are sufficient to achi
eve average yields in Finland, and that the recommended rates could be redu
ced even further.