Should P fertilizer be added after spring frost season?
Yes, that is the right timing, but irrigation for frost protection is only peripherally involved. P is released as soils begin to dry out but are still cool after the winter flood melts. Once the soils warm, P is not released as quickly. It is coincidental that frost protection ending and soils warming occur at the same time. • Do large levels of natural iron disrupt P uptake? They dont directly disrupt P uptake, but rather the iron forms insoluble compounds with the P and makes it unavailable for uptake by cranberry roots. • What available fertilizers contain P? See the table below. Phosphoric acid can be used as a foliar P source, but should not be applied during flowering or on fresh-fruit plantings. Rock phosphate is almost insoluble and is not a good P source.
