Series 2: Liquid, Suspension or Granular Fertiliser, which is better?

Waikato-based Soil Scientist Gordon Rajendram PhD is considered one of New Zealand’s experts in soil fertility. He is committed to helping New Zealand farmers get the most out of their soil so that their farm can work more proficiently, be sustainable while still increasing the farm profitability. Dr Gordon Rajendram worked at AgResearch, Ruakura Research Centre, Hamilton.  He has developed two field calibrated soil tests (N & S) which are used for agronomic advice in NZ and his work on leaching has been included in the Overseer nutrient model.

In this second article I further explore the above question, which is better liquid, suspension, or granular fertiliser?

This year the farming industry has seen unprecedented price rises for two of the major nutrients required for pasture and crop growth, phosphate, and nitrogen. The price of phosphate has increased from $2.70 to $4.27 for a kilo of the nutrient, and likewise nitrogen has increased from $1.15 to $2.89. Other nutrients such as sulphur ($0.60 to $0.90 per kilo of S), potassium and trace elements have also increased appreciably. 

Due to the increase in fertiliser costs farmers are faced with keeping pasture or crop production at similar or higher levels. They will look to solutions, methodology or technologies which will be more nutrient efficient. i.e., get more pasture response with less nutrient use.   

In this article I will concentrate more on my experiences with technologies/methodology which may achieve the above goal. 

In the 22 years I worked at MAF and its predecessor AgResearch, Ruakura Research Centre in Hamilton, the products we researched were generally all granular based.  We did Government funded research or did projects for companies who could afford us and there weren’t many of these companies in New Zealand. 

In 2016 I gave a talk in the Far North, near Taipa, to a group of farmers. At question time one of the farmers sitting in the front asked me, what I thought of fine particle application (FPA)? FPA is a trade name, but I call it suspension technology. I told him I knew nothing about it.  After the talk I approached him and asked if I could visit his farm to see what he meant as I wanted to know more. 

The farmer was Arthur Beazley who runs red devon cattle on a 120ha farm just north of Kaeo. I visited him the next day and he showed me his tow n fert machine. Therefore, this started me on my journey of learning about suspension technology and foliar/liquid fertilisers. 

Suspension technology uses finely ground nutrients. There are companies in New Zealand who have specialised in this technology for more than 30 years. Companies such as Uptake,  based in Taupo owned by John Davis, Mainfert, based in Timaru owned by Marty Kimble and Dean White, and there are others as well who specialise in this technology in New Zealand.

Suspension technology requires specialised ground-based equipment such as the tow n fert machine (Metalform in Dannevirke) or Cylone mixers (Chaos farming in Waihi). These machines require robust pumps and large nozzles. The ground up nutrients are very abrasive and therefore require specialised equipment. There are helicopter operators and SuperAir who have the equipment to apply it from the air. 

Therefore 16 elements (or more), fine lime, including growth promotors, inhibitors, hard round seeds like clover, fungicides or insecticides can be applied together.  Suspensions are in between liquid and granular and are ground up nutrients, and rates of application of a nutrient per hectare can be as high as granular if required.

So, how can these technologies be more efficient and cost-effective? These questions will be answered in the following series of articles.

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