EFFECTIVENESS OF FERTILIZER RECOMMENDATIONS IN FINNISH CARROT AND PEA PRODUCTION

Data on soil analyses, fertilizer use and yields were collected from carrot and pea producers converting to integrated production in 1997, with the aim of identifying changes in fertilizer practice and effects on yield.

On carrot fields, the average total N rate was 80 kg ha^-1, which was unaffected by soil organic matter content and by the preceding crop. Corresponding 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 soil K. The resulting changes in N, P and K rates had no influence on the carrot 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 achieve average yields in Finland, and that the recommended rates could be reduced even further.