Subject: Re: Nutrient balance in soils

From: Steve Diver <[email-masked]>
Date: Wed, 13 Jan 1999 10:18:52 +0000

Hi Victoria, 

Most university labs have soil test guidelines which say
how many pounds P and K fertilizer per acre are needed 
to produce a crop.  These guidelines are based on low-medium-high 
levels of existing nutrients extracted via a soil test.  Typically, 
the fertilizer inputs  are calibrated for crop yield response, 
and the rate of application is based on several years of field 
trials. Generally, this is known as the Sufficiency Level of Aquired 
Nutrients, or SLAN. 

A number of private labs talk about base saturation ratios
of Ca-Mg-K.  This method is known as Basic Cation 
Saturation Ratio, or BCSR.  

Lots and lots of information exists on fertilizer guidelines
based on the SLAN approach.  Quite a few extension service 
publications are accessible on the web. 

Less is published on BCSR.  The Soil Science Society of America
compared SLAN vs BCSR in a couple of different reviews and largely 
discards BCSR.    

Most of the useful information on BCSR comes directly from the 
crop advisors working with commercial farmers.  The fertilizer 
guideline manuals published by these labs are particularly 
informative.  There is a long history of crop advisors and 
farmers who trained under or follow base saturation concepts and 
practices advocated by William Albrecht and others.  Acres USA, 
through its monthly publication and annual conference, is a major 
forum for crop advisors and farmers following eco-farming methods. 

The ATTRA publication titled "Alternative Soil Testing
Laboratories" at <http://www.attra.org/attra-pub/soil-lab.html> 
identifies some of the key labs following BCSR concepts 
and practices.  

Steve Diver

> Hi everyone,
> 
> Pardon me if this topic came up recently and I wasn't paying attention 
>-- Does anyone know of scientific articles which deal with nutrient 
>balance in soils?  How much of each nutrient in what proport> 
> 
> Thanks,
> 
> Victoria
> 
>Victoria Mundy
> Dept. of Agronomy
> N106R Ag. Sci. North, UK
> Lexington, KY  40546-0091
> 606/257-2103

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