| Abstrakt: |
Most published results with southern determinate soybeans [Glycine max(L.) Merr.] are concerned with only a single fertilizer treatment and/or one or two sampling dates. Consequently, field experiments were conducted to determine effects of applied N and K on dry matter yields, nutrient concentrations, and nutrient uptake at several sampling dates and on final grain yields. Rates of 0, 86, and 172 kg of applied K/ha and 0 and 70 kg of N were compared in a field experiment on Sango sil (Ochrepic Fragiudult) in 1973 and K rates of 0, 75, and 150 kg/ha in 1974. Marked responses to applied K were obtained. Maximum dry matter yields and nutrient uptake occurred during the early pod filling stage of growth. Dry matter yields then declined as a result of greater loss of leaf and petiole drop than of increase in grain filling. Concentrations of K in leaves, topgrowth, and grain increased with amount of applied K, but top trifoliate leaf blade concentrations were lower than some published recommended levels for high yields. Marked reciprocal relationships occurred among concentrations of K and Ca or Mg in top trifoliate leaves and topgrowth. Several combinations of N, P, K, and S foliar‐ and soil‐applied during pod filling were also compared in a 1976 pot experiment on Sango sil. Grain yields and concentrations of each applied nutrient were increased in leaves and grain. Pod numbers were highly correlated with grain yields. |
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