Årlig gödsling med NPK bäst för gröda, miljö och ekonomi
Yesterdays common fertilizing strategy was to apply phosphor (P) and potassium (K) in thefall a few times in the crop rotation. In the spring only nitrogen (N) was applied. Recent trialsand studies has shown that this strategy, N+P/PK, is ineffective compared with the systemwhere NPK is spread every year in the spring. The strategy with annual NPK-fertilizer in thespring has proven to be better for the crop, the environment and the farmers economy.In the NPK-system the crop responds with higher yields and better quality, especially in thespring cereals. This is mainly because of an interaction between the different nutrients in thefertilizer. Phosphorus increase the crops nitrogen efficiency and potassium increase thephosfor efficiency.Leakage of phosphor must be reduced in order to prevent the ongoing eutrofication of lakes,seas and streams. When applying phosphor in the fall the risk for leakage is greater than if it isapplied in the spring. The NPK-strategy therefore means less impact on the environment andbetter economy because the phosphor stays in the soil available for the crop.NPK-products are more expensive than single fertilizers. Because of this it is often said thatthe system with annual NPK-fertilizing is more expensive. But when calculating over theentire crop rotation the result is in favour of the NPK-system. This is due to the even moreexpensive PK-products which are used in the N+PK-system. The N+PK-system also meansmore applications of fertilizer when spreading P/PK in the fall and the result is additionalcosts for fuel and labour. The higher yields and improved quality that is often observed in theNPK-system is also beneficial.