High-analysis granular sulphur assemblages as sources of sulphur for lucerne

Abstract

A growth chamber study was conducted to compare five granulated sulphur assemblages and a commercially available prilled sulphur with gypsum and flowers of sulphur as sources of sulphur for lucerne grown on two sulphur deficient soils, one from the Armstrong area of B.C. and one from California. Following one surface application of the various sulphur supplying materials at rates of 37.5 mg, 75 mg and 150 mg of sulphur per 3750 g of soil, four consecutive harvests were removed from the Enderby silt loam during a 145 day period and three cuttings were taken over a 119 day cropping interval on the Willits soil from California. Although gypsum and finely divided sulphur were the most effective sources, three of the five assemblages also had a favourable influence upon yield of lucerne, sulphur concentration and sulphur uptake. The three acceptable assemblages were sulphur-bentonite, sulphur-goulac-ammonium sulphate and sulphur-gypsum-goulac and they produced beneficial effects upon lucerne growth that were often comparable to those obtained with finely divided sulphur. On the basis of this investigation, it appears that certain granular high-analysis sulphur assemblages made from finely divided sulphur and binding agents, such as gypsum, ammonium sulphate, goulac and bentonite have satisfactory agronomic properties. Because these assemblages have suitable agronomic and physical properties they should be ideal for bulk blending with other granular fertilizer materials or for use in direct application to the soil. Wider scale testing of the sulphur-bentonite, sulphur-goulac-ammonium sulphate and sulphur-gypsum-goulac assemblages would seem to be justified.