External and internal critical phosphorus requirements of soybean [Glycine max (L.) Merrill] in three Ghanaian soils
1992
Ankomah, A.B. | Osei-Kofi, V. (University of Science and Technology. Department of Crop Science)
A glasshouse pot experiment was conducted to investigate the effect of phosphorus fertilization on growth and P uptake of soybean in three Ghanian soils, and to estimate critical P levels in soybean plant tissue and soils. Soybean cultivar Jupiter, was grown at six different P rates in each of the three soils and harvested at the flowering stage (45 days after planting). The whole plant tops were analysed for P content. Samples of incubated soils similarly treated with P were analysed for available P by Bray P1 extractant. Plant height, dry matter (DM), yield and percentage P content in plant tops increased with P fertilization up to the application rate of 30 mg P/kg of dry soil. Phosphorus utilization efficiency (PUE) decreased from a mean value of 0.56 to 0.40 g DM/mg P in plant tops at zero P and 30 mg P/kg soil application rates, respectively. Optimum DM yield, 93 % of maximum, was attained at a P application of 30 mg P/kg soil in all three soils.
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