Hi

When you analyse soil you can notice soil pH and select the suitable fertilizer containing the element you need to apply with positive effect on soil pH,for example if you deal with alkaline soil with little nitrogen content  you can add ammonium sulphate  which can offer nitrogen ion  and affected soil pH toward acidity. as well as you must estimate available elements taking in consider soil structure.

I wish it interesting answer.

You need to know at least the macronutrients levels, N, P, K, and also check Ca. Some elements like Mn, Mg, Na, are also important. Plant available P could be measured by (Bray test I).

Other possibility is: Soil samples can be air-dried and ground, then each extracted for nitrate-N and P using 0.5 M sodium bicarbonate extraction, K using 1.0 M ammonium acetate extraction (Carter 1993). Nitrate-N concentration in the extract was measured colorimetrically with an autoanalyser, P, K and Zn with an ARL 3410 ICP unit, and Cd on a Varian 300/400 atomic absorption spectrophotometer. Also soil total N and organic C can be determined by Kjeldahl digestion and colorimetrically at 590 nm, respectively (Lu 2000).

With Mehlich 1 (0.0125 M H2SO4 and 0.05 M HCl)- extractable P, Fe, Al, Ca, and Mg can be determined using a 1:4 soil to Mehlich 1 ratio (Mehlich 1953). Mehlich 1 Al, Fe, Ca, and Mg concentrations were determined by atomic absorption spectroscopy. Water soluble P was determined by extracting the soil with distilled deionized water using a 1:10 soil to water ratio. This mix was shaken on a mechanical shaker for 1 hour and filtered through a 0.45-μm filter using vacuum filtration. Phosphorus in solution was determined by an autoanalyzer (USEPA 1993; Method 365.1) using the Murphy and Riley (1962) method.

For possible soil emendation please consult that work:

Fertilization response and nutrient diagnosis in peach palm (Bactris gasipaes): a review J. Deenik, A. Ares & R.S. Yost. Nutrient Cycling in Agroecosystems 56: 195–207, 2000.

It depends on how you have to invest in lime and fertilizers.

One of the chemical analysis is pH determined in water in a proportion of 1:2,5 (soil:solution). According to the result its possible to know about soil H+ activity and infer about acidity, neutral ou alkali soil.Some soil chemical informations are required to do a better reccomedation. The base saturation which indicates the percentage of exchangeable bases (Na, Ca, Mg and K) that occupy the cation exchange capacity.

Mr.Geoffery,as  per the details given by Dr. Eduardo,one need to determine  plant-available soil nutrients both macro and micronutrients to apply fertilizers to crops. Available nitrogen is estimated by determining ammoniacal and nitrate N(in some countries profile nitrate N).Phosphorus by Olsen/Bray method(based on soil pH neutral to alkaline or acid soils) and potassium by ammonium acetate method .If needed, Ca and Mg can also be estimated by ammonium acetate method.Fe,Mn,Cu,ans Zn are estimated by DTPA  extraction method.Boron and Mo are estimated by hot water soluble and  ammonium  oxalate method, respectively.Sulphur is estimated by 0.01 M monocalcium phosphate or  calcium chloride method.Organic carbon is also used as a measure of available N in soil.These soil tests  for different nutrients need correlation and calibration with  crop response.Based on soil test crop response calibration the crop specific recommendations are generated.We can apply fertilizers to crops referring to calibration tables for different nutriments in respect of a crop.

If you can access you may refer to our paper  Soil testing and  nutrient recommendations by A.Subba  Rao and others Journal of the Indian Society of Soil Science,vol 57,no.4 pp.559-571( 2009)

The previous answers all point in the right direction.  In the U.S., there are several regional groups that have published methods for soil nutrient determination. attached is a document used in the North Central Region of the USA.

To provide the best recommendations for nutrient applications, the soil test results need to be calibrated for the soils and climate of a region as well as the crops being fertilized.  This requires field evaluations of fertilizer rates with crop responses over the range of soils and crops grown.  Most of the tests in the attached document have been calibrated by individual states or regions to provide the most efficient applications of nutrients. So, a large scale evaluation may not be necessary if you can find crops and conditions similar to the ones you are experiencing.  You can utilize the calibrations already established.

Endorsing the earlier responses please follow the fertilizer practices of highly priductive field in annual crops and orchards in perennial crops, in addition to other options as discussed above

The pdf attached by Dr.Larry is a good source of various soil test methods listed by me.However calibration of soil tests is needed for fertilizer recommendations.The following FAO publication gives simple but detailed account of soil test crop response calibration.

The calibration of soil tests for fertilizer recommendations. by Hauser,g.f. FAO Soils Bulletin 18 Food and Agriculture  Organization of the United Nations Rome,1973.Though the publication is old ,gives good basic information.Another good publication is

Soil test interpretation by Dahnke,W.C .Commun.Soil Sci.Plant Anal.,24(1&2),11-27 1993.

Dahnke,W.C.and Olson,R.A.1990.Soil test correlation,calibration and recommendation,pp 45-71.IN:R.L.Westerman(ed.) Soil Testing and plant Analysis,3rd ed.,SSSA Book series 3 .Soil Science Society of America.Madison,WI.

Geoffrey , best way is to carry out a comprehensive field ( Preferably) experiment for developing the soil-test crop respose data,  before you subject your data for developing fertilizer response equation  .  This is the standard procedure tht everyone follows. Sometimes , exploratory data generated out of the field surveys , they help a lot , in generating such kind of data and indirectky arriving at soil test valuse vis-avis fertilizers used abd yield.. You can try that since conventional procedure has no short cut , and surely time consuming , no doubt.

There is no single extraction method to make fertilizer suggestions for all type soils and plants. The extraction methods are only an approximation of nutrient uptake crops. The extraction methods should be tested for any specific soil and plant. Then you can make fertilizer suggestion by using the soil test for a spefic region.

 Dr.Veli, your points are valid.However there is  new(not so new) development where in more nutrient elements can be extracted and estimated in stead of single extractant for an element.The extract ants include Mehlich 3(for ,Ca,Cu,Fe,K,Mg,Mn,Na,P,Zn),AB-DTPA(Cu,Fe,K,Mn,Na,P,Zn).Even 0.01M CaCl2 and saturation extract have been tried as univerasal or multinutrient extractants.Instruments like ICP-AES,ICP-MS,GF-AAS etc facilitate analysis of more elements in single a extractant.These extractants  were also tried in specific soils and regions with some success and adoption.There is need for more research on these  multinutrient  extractants particularly where one can spend money on costly  instruments.

most methods suggested are not properly calibrated: here is the posibly best

and widest tested method: http://www.fao.org/3/a-at167e.pdf

Ewald , we will have to calibrate a typical tripartite relation between soil test-crop response -fertilizer doses fro a given crop and soil in a given agropedological condition . Such relations are hardly universal in application . A soil test value considered optimum with respect to a given yield level , will become sub-optimum if we fix our yield target at a much higher level. Such is the dynamism of such relation .

Dr.Schnug,The FAO publication is good for micronutrient studies.The universal extractants or the multinutrient extractants are for determination of several macro and micronutrients.If properly correlated, calibrated and interpreted in a given agroecosystem,with good instumentaion,they save lot of time and energy.

Soil analyses for org C by wet digestion method, 0.5(M) sodium bicarbonate extractable P, 1(M) neutral ammonium acetate extractable K, and DTPA extractable Fe, Mn, Zn and Cu are the most widely used methods to know the application need of N, P, K and micro nutrients fertilizers.