Joel Brooks Gruver wrote:
> Hello to all...
> Last night, I was browsing an old issue of the Journal of
> Agronomic Education (~ 1991, so it may have been the newly named
> incarnation) and read a case study article titled "Dick and Sharon
> Thompson's problem child". The article was presented in the form of a case
> study that one would discuss with undergrad agronomy students or crop
> consultants in training.
> The case study presented that
> after ~20 years of organic integrated livestock and row crop
> production, the Thompsons decided that they had to start banding muriate
> of potash (KCl) to alleviate K deficiency. Tissue tests of their corn
> indicated a serious K deficiency but soil tests indicated K levels that were
> more than adequate.
> Since adopting organic management practices in 1969, the Thompsons had
> not applied any salt fertilizers but had ammended all fields with
> manure from their integrated cattle operation. For a number of years, they
> composted the manure prior to field application but eventually decided
> to abandon composting. Despite the fact that their soil test K levels had
> increased during their 20 years of organic management, something was
> causing their crops to become increasing K deficient.
> The article indicated that following the initiation of KCl banding,
> crops did show a yield response in most fields but continued to have low
> tissue levels of K. The article suggested that the Thompson's ridge
> tillage system may have been partly responsible for the unsual K dynamics.
> Sooo... ~ 7 years have gone by since this article was written... I am
> wondering whether the Thompsons have resolved or continued to struggle
> with their "K problem child" and/or what mechanisms were underlying the
> problem... Can anyone enlighten me ?
> Joel Gruver
> Center for Agriculture, Food and Environment
> Tufts University
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