Words and images supplied by Ballance Agri-Nutrients.
Fertilisers differ in more than just nutrient content.
Using fertiliser to apply a single nutrient is fairly straightforward, but what about when two (or more) nutrients are needed?
“Applying multiple nutrients can present some challenges. Choosing what type of fertiliser or blend of fertiliser to use will depend on the targeted crop or pasture, nutrient quantity as well as targeted spread width,” says Ballance Agri-Nutrients Science Extension Officer Aimee Dawson.
There are two ways nutrients can be applied as fertiliser – as a compound fertiliser or a fertiliser blend.
A compound fertiliser consists of multiple nutrients combined into individual, evenly sized granules. Each granule contains a specific ratio of nutrients, and is manufactured to be as uniform as possible in terms of shape, size and weight. This means nutrients can be applied more evenly, promoting even growth and reduced risk of striping.
Compound fertilisers can easily be spread or drilled. Products such as YaraMila compound fertilisers Actyva S and AmidaS have smooth, hard, free-flowing granules that are not prone to chips or dust. This makes them ideal for drilling or broadcasting at wide bout widths. Other examples of compound fertilisers are di-ammonium phosphate (DAP), Cropzeal Boron Boost or sulphate of ammonia (SOA).
The alternative for applying multiple nutrients is a fertiliser blend. They can be cost-effective, but distribute nutrients less uniformly. Not all the nutrients are contained in each granule, and the particles are more varied in size, shape and weight. If blends are not physically compatible differently sized particle in blends can segregate during transport.
When spreading blends there can be a risk of striping, especially at wide bout widths, as particles are not thrown as evenly. Blends are also not usually recommended for drilling due to the risk of seed burn, especially if there is muriate of potash (MOP) in the mix. Products such as the Cropzeal range, SustaiN Ammo and Pasturemag range are examples of fertiliser blends.
The method used to apply the fertiliser plays a part in achieving the desired uniformity. When using a spreader, the size, shape and weight of a fertiliser granule can affect how far it is thrown. Spread testing, completed annually or biannually, can help determine optimal spread widths for different products and blends.
Making the choice
“Consider the value of the crop, application methods and what’s right for your farm when choosing between a compound and a blend,” says Aimee.
For high value seed and vegetable crops, premium compound fertiliser YaraMila Actyva S is an extremely useful starter and/or side dressing fertiliser, and is also ideal for wheat, barley, maize, and fodder beet. It can be drilled and has been spread tested up to 32 m (Ballance recommends spread testing yourself to determine optimum spread width for your conditions and spreader). Each granule contains 15 per cent nitrogen, 12.5 cent potassium, 7 per cent phosphorus, 3 per cent sulphur, a small amount of magnesium as well as the micronutrients zinc, manganese and boron.
Cropzeal Boron Boost is an ideal compound fertiliser containing nitrogen, phosphorus and boron in every granule. Ideal as a starter fertiliser for brassicas and fodder beet, the boron in every granule increases the uniformity of boron across the paddock, decreasing the risk of brown heart rot.
Cropzeal 16N, 15P and 20N are blends and offer varying ratios of nitrogen, phosphorus, potassium and sulphur to meet the needs of a variety of crops, particularly cereals, brassicas and lucerne. The entire range is designed to be used as starter fertilisers. As blends, Cropzeal products are usually broadcast, but can be drilled using a cross slot drill that separates the seed and the fertiliser in the soil, or if soil moisture is sufficient.
“Quality compound fertilisers offer benefits including reduced risk of blockages, lower risk of striping, better performance when spreading to wide bout widths, as well as uniform nutrient spread. When determining if it is better to use a compound or a blend look at your crop value, spread width and its subsequent risk of striping to determine which option is best for your farm.”
For more information talk to your local Ruralco Representative.