See more from this Session: General Nutrient Management & Soil & Plant Analysis
A pot experiment was carried out under greenhouse conditions with two typical Brazilian soils (Oxisol and Entisol) collected under forest and amended with lime to correct soil acidity. Four rates of Ba-nitrate were added to the soils: 75; 150; 300 e 600 mg kg-1 of Ba, and a control treatment was also included. Plants were grown until flowering stage, and then harvested, dried, ground and acid digested. SO4²- concentration in the digests was determined turbidimetrically after reaction with BaCl2. Available SO4²- in soils was also determined turbidimetrically after extraction with monocalcium phosphate.
Ba rates reduced the availability of SO4²- in both soils, the reduction being higher in the Entisol. SO4²- mean concentration in the Oxisol was 98 mg kg-¹ at the control treatment and was reduced to 25 mg kg-¹ when 600 mg kg-1 of Ba were added. Conversely, available SO4²- concentration was 130 mg kg-¹ the Entisol at the control treatment and was reduced to 12 mg kg-¹ at the highest added Ba rate.
The uptake of SO4²- decreased in sorghum in the Entisol, and in pea and maize in both soils. Pea plants grown in the Entisol were severely affected. In this soil SO4² accumulation decreased more than 90% when compared to the control. SO4²- uptake by soybean was not reduced in both soils regardless of Ba rates.