Magnesium sulphate and the development of the common bean cultivated in an Ultisol of Northeast Australia

Abstract

Magnesium applications (MgS0(4).7H(2)0) to achieve 8 and 16 mmol c/cm3 of Mg (324 and 1284 kg of MgS0(4) ha-1) were made on one Ultisol from Australia Northeast to correct Mg deficiency in plants and to verify the optimum level of Mg to grow common bean (Phaseolus vulgaris L). Magnesium was applied together with lime, N, K, Cu, Zn, B, and Mo as calcium carbonate, ammonium nitrate, potassium phosphate, cupric and zinc sulphate, boric acid and sodium molybdate respectively a month before planting and P as phosphoric acid at the planting. The pH reached the equilibrium after six weeks of incubation. Higher electrical conductivity (EC) was observed in soil where Mg was applied to reach 8 mmol c/cm3 in the absence of common bean and 16 mmol c/cm3 when the plant was present. Higher plant height, leaf area, dry matter weight:leaf area ratio and nutrient concentrations were observed in plants cultivated in soils treated with Mg to reach 8 mmol c/cm3 and 16 mmol c/cm3 when the plant was present. The plant top P content was very low but N, Ca and Mg contents can be considered normal for the common bean.