I think a hay grower near Susanville CA may have told me that she dresses her orchard grass hay fields with something that increases the sulphur levels in the soil.  Does tat sound right?  Several list members in Sonoma County purchase her hay, known to me as "Sharon's Hay."  It seems to test well, and my EMS Fjord horse who was formerly very fat and with very high leptin and insulin levels tests in mid ranges of those values while eating Sharon's hay from 2021 plus California Trace Plus.