Hope everyone is enjoying there Christmas! So what I've been reading up on is how the uptake of P really works. Since P&K is mostly needed for more than just the veg stage it's really important during he flowering as that is what produces the fruits (yield). So I'm focused on trying to give the right amounts of NPK Mg&Ca. They all correspond differently but each effects the uptake of P. So light is half of the process in trying to get the biggest yield and dialing into the soil is he other. Check out the image I've added and read what I e posted to see where I'm going with this. This is also good for Brix!
Interactions
Nitrogen: Many observations have found that P uptake is enhanced when in combination with ammonium N (NH4-N). In most cases, NH4-N has been shown to be superior to other forms of N at enhancing P uptake. This benefit typically requires that the N and P be applied in either a chemically combined form or as a concentrated mixture, such as a banded fertilizer blend. The exact mechanism for this reaction is not clearly understood. However, it is thought that as the NH4-N undergoes nitrification, P uptake is increased. It is also well known that increased N uptake stimulates the uptake of many other elements, and this may play a role in the effect.
Potassium: Potassium has been shown to co-precipitate with P when soluble phosphoric fertilizers are applied to soils. This effect is more pronounced in soils with high exchangeable K levels or with easily decomposed K-bearing minerals. However, this reaction has rarely been demonstrated to have a significant effect on plant growth. There is little or no evidence to show an interaction between P and K within the plant.
Calcium: As mentioned in the section on pH, calcium will combine with P to make insoluble compounds that are unavailable to plants in the short term. The general trend in the reaction is that as the soil Ca content and pH increase more P will combine with Ca to form compounds with ever-decreasing solubility. In these situations, it is typical to find that crops will require a correspondingly higher soil P test for equal growth. Alternatively, growers have seen that banding P fertilizers, especially when the band can be made acidic, improves crop growth in these conditions.
Magnesium: Phosphorus and Mg are often highly reactive in fertilizer manufacturing processes. The result of the reaction being the formation of highly insoluble compounds that coat or clog equipment. However, this effect has not been demonstrated to be a concern in the soil. In fact, much work has shown that Mg fertilization can enhance P uptake by plants. Within plants, Mg is an activator of certain enzymes that are critical to P transfer and as such, proper Mg nutrition would be essential to the uptake and utilization of P within the plant.