aruzinsky

I don't care about Dr. Ruehr. It is immoral to resolve objective issues by taking a opinion poll. The objective issue is the form of P in fertilizer solution that is applied to the top of the soil and not the P already at the root zone. It is a stupid mistake to formulate soluble fertilizers for application to soil surfaces using conventional P compounds because conventional P compounds remain near the soil surface until tilled under.

Here is more literature about the mobility of phosphorus compounds within the soil:

Use of Phosphorous Fertilizers in Pressurized | Maher Saleh - Academia.edu

Note:

"Using conventional P sources in sprinkler systems, P did not penetrate more than 4 to 6 cm from the surface of a sandy loam soil (Lauer, 1988). With drip systems and such P sources, movement was limited to a few cm vertically – and even less laterally – from the emitter point (Ryan et al., 1988a; O’Neill et al., 1979;Bar Yosef and Sheikloslami, 1976). Again, mobility increased with lighter texture and the amount of P applied. However, substantial increases in mobility were recorded with less conventional P fertilizers. Thus, it is of interest to consider properties of various fertilizers in relation to precipitation /mobility. ...

Urea Phosphate

The study of Ryan et al. (1988a) showed higher water-soluble and NaHCO3
–soluble P after addition of acid fertilizers such as urea-phosphate (UP) compared toTSP, but noted the greater lateral and depth-wise movement of P within a heavy clay soil than with H3PO4 or conventional materials. Other studies with up showed much greater mobility in the soil than TSP and, as a consequence, greater fertilizing efficiency for tomato (Mikkelsen and Jarrell, 1987) and lettuce (Chase, 1985). In the latter case, P movement downwards was 12 cm and 10 cm laterally – all encompassing the crop root zone"