| Abstrakt: |
Manganese deficiency continues to be a yield limiting factor in soybean [Glycine max(L.) Merr.] production on many Atlantic Coastal Plain soils. Field research was conducted in order to refine the double acid (also known as the Mehlich I) extractable Mn soil test and to determine critical Mn deficiency levels for whole plant, leaf and seed plant parts. Experiments on Mn deficiency in soybeans were conducted at 30 field locations with 13 soil types, spanning 7 years. A total of eight soybean cultivars were used in this field research. A yield prediction equation was developed (r = 0.68**, significant at the 0.01 level) with the inverse relationship of pH and double acid extractable Mn in the Ap horizon. Inclusion of organic matter and the same soil parameters in the B horizon did not improve the equation's predictive ability. Yield prediction equations were developed for whole plant (r = 0.44*, significant at the 0.05 level), leaf (r = 0.94**), and seed (r = 0.73**) Mn concentrations. Based on 90% of maximum yield as the definition of the critical deficiency level, the critical Mn levels for whole plant, leaf, and seed were 45, 17, and 20 mg/kg, respectively. The eight soybean cultivars evaluated in this study had similar responses to low levels of available Mn. |
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