Evaluation of glassy frits as micronutrient fertilizers. II. Manganese frits.

In pot and field tests MnSO4 and the frits FTE Z 4 (13 % Mn), HZ 1 (15.9 % Mn) and HZ 17 (21 % Mn) increased reducible soil Mn for at least 1 1/2-2 years. Mn content of pasture increased four-fold in the first cut after application of 400 kg/ha MnSO4 but sharply decreased in later cuts and became negligible by the second year. 400 kg/ha HZ 17 did not affect pasture Mn. In peas 400 kg of soil- or foliar applied MnSO4 controlled marsh spot better than 800 kg HZ 1; spraying at the middle and again at the end of the blooming stage gave the best control. With sugar beet, soil dressings of MnSO4, HZ 1 and HZ 17 equally increased yield, sugar production and leaf Mn, and decreased incidence of Mn deficiency. When the rates of these fertilizers were increased from 100, 179 and 86 kg respectively to 400, 714 and 343 kg, sugar production was not significantly improved; leaf Mn and incidence of deficiency symptoms responded to the higher Mn rates. Soil application was rather better than foliar treatment. No treatment controlled Mn deficiency throughout the entire season. The % of Mn-deficient plants was related, negatively, to leaf and reducible soil Mn, but not to yield. Soil-applied Mn did not control gray spot in oats or increase yields but sprayed Mn did. (Abstract retrieved from CAB Abstracts by CABI’s permission)