Research has shown that Mn is ineffective banded in a liquid stream at seeding – irrespective of whether it is banded as a sulphate, oxide or chelate. On the other hand, foliar applications can be quite effective BUT responses may not be as reliable as banding Mn in a granule at seeding. Deficient crops may need two or three foliar applications to be fully effective.
This year CSBP has been investigating the need for Mn in several trials across the state. Some of these trials are investigating the effectiveness of manganese oxides (MnO and MnO2) to the manganese sulphate supplied in all of CSBP’s Mn products.
Our biggest responses to Mn have been at a trial at Bolgart where there were responses to 4 kg Mn/ha supplied by Agstar Manganese and Agflow Manganese, but no response to 4 kg Mn/ha supplied by the oxide (coated onto Agstar). Plant tests showed that none of the Mn from the oxide had become available (Figure 1).
Figure 1. Manganese (mg/kg) in barley whole tops at Bolgart
Agstar MnO2 (4 kg Mn) v Agstar Manganese (2 kg Mn)
At Badgingarra, plant tests show that yield responses are unlikely but indicate that the sulphate form (supplied by AgMn and K-Till Manganese) is more effective than oxides coated onto K-Till Extra Plus (Figure 2).
Figure 2. Manganese (mg/kg) in wheat whole tops at Badgingarra.
Both trials highlight the importance of using effective fertiliser sources.