ABSTRACT
A survey soil and plant nutrient status of 114 Georgia cotton fields at maturity in 1990 and 1991 showed that pH and Mg status are primary areas needing attention in fertility management in Georgia. Low pH (< 5.8) was a problem in 33% of the fields, while high pH ( > 6.5) was found in 17% of the field. These frequencies were much higher than found in soil test summaries of samples submitted to the University soil testing lab. Low soil test ratings for Mg (15%), Mn (12%), Zn (10%), K (8%), P (6%) and Ca (6%) indicated areas of needed improvement in fertilization practices. An unexpectedly high percentage of samples contained "less than adequate" concentrations of P (57%) and Zn (37%) and Mg (16%). Although the frequency of low leaf Mg levels were in line with observed soil Mg concentrations, this was not the case for P and Zn. Low P levels were somewhat more common during the drier growing season of 1990 than in 1991. Further work on season-long P and Zn concentrations is needed to ascertain if there is a need for concern and action. Although increased incidence of K deficiencies are being reported throughout the cotton belt, our results indicate the frequency of less than adequate concentrations in soil (8 %), leaf tissue (11 %) and petiole (4%) samples is not very high considering that samples were taken at maturity rather than prior to bloom. Although soil and plant tissue K concentrations were not well correlated, low plant tissue levels were found only where soil test K was less than 115 lbs/A. Correlations between soil and plant nutrient concentrations levels were significant (r=0.41, p=0.05) only for soil pH and leaf Mn levels.
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