How the amount of phosphate in agriculture field soil can be calculated i required method?

Question

How the amount of phosphate in agriculture field soil can be calculated i required method?

Answer 1

As far as I know the amount of phospahte in soil cannot be calculated. It is highly variable from location to location depending on natural phosphate levels, additions by humans and depletions by crops.

You must have soil analyzed for phosphate by a laboratory.

There are some sloppy methods for estimating soil phosphate levels, say 5 years after a phosphorus test has been run on a soil, with given inputs (fertilizer, manure, etc.) and outputs (crop removal) but they are highly dependent upon soil texture and soil chemical properties.

Answer 2

First you need to get a soil test, then this site will help you calculate the amount of phosphate in the field.

http://taipan.nmsu.edu/mvpfpp/phosphor.h...

Answer 3

We have used some weird methods on soils that are very high pH (8.5 and above) with free marl at the 50 cm depth. Our soil tests indicated we had just lots of phosphate, as calcium phosphate, and we could get early season response by adding fertilizer phosphate, but invariably we were seeing deficiency after early August.

We switched to mixing our phosphate as superphos into our manure before storing it, with really good results. But when we applied a dusting of sulphur to the soil, we discovered that we no longer needed to use superphos to avoid symptoms of deficiency.

Does this mean that sulphur was substituting for  phosphorus? Perhaps not. It may simply mean that our pH made naturally occurring phosphate more available. I do not know how to determine which.

Answer 4

Soil test P (STP) is used to determine the amount of phosphate (P) needed for crop production as well as to

determine environmental risks associated with elevated levels of soil P. Phosphorus is an environmental concern,

because excess P often promotes weed and algae growth in bodies of fresh water. Decomposition of the weed and

algae material reduces dissolved oxygen levels, leading to odors, fish kills, and a general degradation of the aesthetic

and recreational value of the environment

method:

Wisconsin soils tested. Selected soil samples from incubation studies by Ebeling et al. on Phosphorous Buffer

Capacity (PBC) of various Wisconsin soils13 (“PBC Inc” sample set) and the effect of biosolids application on soil

PBC14 (“BIO Inc” sample set) were used to describe this method.

Soil P extraction of Wisconsin soils. PBC Inc soil samples were extracted for soil P by a deionized water (DI)

extraction method5 with a soil:extractant ratio of 1:10. Samples were shaken in 50 mL conical tubes for 60 minutes

at 180 RPM on an orbital shaker. The tubes were centrifuged for 10 minutes at 2500 RPM. After centrifugation,

extracts were decanted and filtered. Filtered extracts were stored at room temperature for analysis by Murphy Riley

and MS.