re: Interpreting Soil sample results

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Craw, help me out since you are more familiar with it. Since testing for N is a moot point does LSU test for it or are the recommendations on their soil sample results simply based on grass type? I met with Dr Ron several times but for the 4 years I worked at Scott’s in BR we never once discussed their soil sample results.

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ronk that is correct, the LSU AgCenter does not test for N in a routine soil analysis test, though it can be requested for an added fee. Yes - nitrogen fertilization recommendations, amount and frequency, for the 4 warm season grasses are based on field trials not only at LSU, but other land grant universities in the Deep South with similar soil and climatic conditions.

Nitrogen is such a soluble, reactive compound, with rapid uptake by plants, volatilization, leaching from the soil, etc - there is not good correlation between soil concentration of N with the annual Nitrogen requirements of the warm season grasses as to their optimal nitrogen requirements - hence the reason for not including it in a routine soil analysis. It honestly causes more confusion to most in trying to interpret the results as opposed to clarification.

Now concentration of N in foliage samples is routinely used for for N fertilization recommendations in fruit, nut and vegetable crops if a deficiency is suspected - that information is more meaningful and better correlated with crop performance.