How Much P K is Enough????

Posted a similar thread on another forum, but thought I'd post it here too....

Sent off some soil samples on some fields I'm starting to reclaim and they are in bad shape.

I understand staging N - nitrogen, but what about P - phosphorus and K - Pot Ash? Stage it or apply the mother load all at once/now? Planting Teff in these fields next spring, Timothy the following fall. Don't anticipate plowing - except one field (possibly), but doing roundup and no till planting.

Here is one field's test results:

I am to apply the following:

N = 90
P = 110
K = 185
PH = 5.7
Lime = 1.25 tons per acre.

With other fields, I have divided similar test results in half for application, except lime, where I limit it to 1 ton per acre per application for no till.

All of my test results are somewhat similar - in magnitude.

Question is - this fall do I dump 110 lbs per acre of P and 185 lbs per acre of K on no till at once or divide up the application like I do lime and N? Will the P and K stay put and soak into the ground or wash away from rain? Land is pretty much flat on these fields, but a few rolling places too. Creek borders one field.

What are some typical N, P and K numbers you see off of your grass hay fields?

Any tips are much appreciated.

Thanks!
Bill

Those quantities are not unusual for reclaiming ground in my experience but I am curious why you do not want to till the nutrients in? A fall application of P,K and lime plowed in then ground prep and plant a cover crop that will grow in your area if not too late, then spread the N next spring after the Teff is up. With tillage you get immediate incorporation into the soil structure and first year results.

P doesn't move, and maybe K too...don't remember. If you want it to stimulate the plant root systems, you have to get it in the "root zone". I can look it up, but K is probably the same. Anything you toss on top is likely to wind up in the nearest creek, especially in a no till environment.

Texas Agricultural Research Station at Renner, TX. has done exhaustive studying of Texas soils after the cotton years to restore productivity. It started out with some PhD's from Texan A & M (College at the time...University now...TAMU) and some concerned farmers in the area, with some donations from local folks. I have a hard bound copy of a 2" thick publication of many of their experiments on what and how much, how and when fertilizers are to be used and the results. Makes for good reading.

That's kinda a light load for 175-200bu corn and the following year bean requirements, so would certainly do one shot here, that is common.

You need the lime, do that above all things. Acid soils hang onto nutrients, the roots can't pry it loose and so it doesn't matter what else you apply if you don't get the ph fixed.

You are in a difficult spot with notill and a grass setup in your plan.

It is really best to get the lime and nutrients in the top 3 inches of soil, somewhat into the top 6 inches is better. N gets there on its own, as does sulphur and k.

But the lime and the P are gonna sit on the top one inch for some time, before nature can work them in deeper over the next 5 years.

If it were a row crop you could strip till it in, or at least band it in with coulters, but in a grass situation banding doesn't help either.

I don't know the answer, but you have to consider how the lime and P will get in the root zone in a timely manner. With time and fertilizer on a good schedule you will be good in 7 years, but getting from now to then might be tough. Would you be able to rent a low disturbance machine and run that over after the fert application at least? (They are a disk, but without curved blades and barely any angle at all to them, they very lightly cut into the soil and don't disturb the cover much. About useless in my type of ground, but they are getting to be populate in drier, lighter soils across the country.... Or some of the harrows would at least help get the fert in the top inch to start you out?)


Paul

Thanks everyone - great info!

I usually put N P and K on all at once in late March. Sometimes its hard enough to get the fertilizer trucks in once. This year they came at 1 am with a floater truck and tenders.

Lime I try to get summer and fall. Even in 100 % notill I put it all on all at once, never less than 2 tons of lime per acre and sometimes as much as 5. It will get there, if not this year then the next few.