If the nutrient formulation is in a chemical form which is acceptable to the plant, for example suspension gels or flowable forms of Copper oxychloride, then these flowables are a legitimate way of manufacturing effective products.

However, several products are on the market whose formulations are not in a plant available form. Flowable Sulphur has been used for many years as a simple fungicide but it is not suitable as a foliar nutrient because the elemental sulphur has to be oxidised on the leaf surface into the sulphate form before it can be absorbed by the plant. This process is determined by temperature and can be slow under unfavourable conditions.

Flowable forms of Manganese carbonate containing 44 - 50 % w/v ( 440 - 500 g/l) Mn have been recommended for seed dressings and have enjoyed limited success. Recently they have been recommended for foliar application but again the carbonate form is practically insoluble and has to be oxidised before it can be taken into the plant. In cases where deficiency needs to be remedied quickly, this delay may prove very costly in terms of yield.

Inorganic Flowables - Pros and Cons

• Often elemental form not available to plant - Poor uptake

• Elemental Sulphur

  Manganese carbonate

  Zinc oxide

  Magnesiumhydroxide

• High concentration

• - 90% Sulphur

  - 50% Manganese

  - 70% Zinc

  - 50% Copper

  - 20% Magnesium

• Good compatibility due to unreactive form

• Occasional mixing problems

• Problems with extended storage