Boron Source and Lime Effects on the Yield of Three Crops Grown in Peat1

Abstract

AbstractThe necessity of adding B in peat soils is recognized. A limited amount of information is available regarding toxic levels of B in these soils. A greenhouse experiment was therefore carried out to measure effects of three levels of lime × four levels of B (including control) × two types of B source on tomato (Lycopersicon esculentum Mill cv. Eurocross BB), cucumber (Curcumis sativus L. cv. Sporu), and sweet corn (Zea mays L. cv. Golden Cross Bantam) in a peat soil. The two sources of B were sodium tetraborate and B‐frit. The crops were grown for about 7 weeks.“Lime had a significant effect on yield of tomato, cucumber and corn, while B‐rate had a significant effect on yield of tomato and cucumber only. B‐rate had a significant effect on B‐concentration of all three crops — B‐source had a significant effect on B‐concentration of sweet corn only.”Visible toxicity symptoms were recorded with cucumber and corn at three times the normal rate of B application. The plant levels of B at which toxicity occurred were 115 and 53 ppm for cucumber and corn, respectively. Hot water soluble B up to 10 ppm failed to produce toxicity symptoms.Significant correlations between hot‐water soluble B and B concentration in plant and B‐uptake suggested that hot‐water soluble B was an effective soil test for peat soils in spite of the fact that it can overestimate the availability of B at high lime levels. The critical values of hot‐water soluble B for deficiency and toxicity are much higher than in mineral soils.