Foliar application of CUSO4 to mature grass to increase the Cu content of the hay crop was markedly affected by rainfall within 24 h of the time of application. The mean Cu concentration of hay treated with 5·6 and 11·2 kg CuSO4/ha was 100 and 208 ppm, respectively, when no rainfall occurred during this period, but only 24 and 41 ppm when rain fell within 24 h. Rain 4 or 5 days after spray application had no effect on the ultimate Cu concentration of the hay. It is suggested that sheep could safely graze the aftermath as, with one exception, concentrations of Cu found were only from 11·4 to 20·6 ppm. l±l kg CuSO4/ha applied in dry conditions was sufficient to raise Cu concentrations in hay to levels which should preclude the occurrence of Cu deficiency when fed to cattle in winter. Reductions in hay yield following CUSO4 applications in dry weather suggest a need to examine the use of more dilute sprays, or other means for increasing the Cu content of hay.
|Number of pages||4|
|Journal||Grass and Forage Science|
|Publication status||Print publication - Jun 1975|