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  • Rights: University of Waikato
    Published 30 July 2013 Referencing Hub media
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    Dr Ross Monaghan from AgResearch at Invermay in Otago talks about fertilisers1 – what they are and why they are used on farms.

    Point of interest: Ross talks about using a nutrient2 budget for farms. The Overseer® Nutrient Budgeting model is an online tool to assist with nutrient management.

    Transcript

    DR ROSS MONAGHAN

    Since the arrival of Europeans, fertiliser3 has been a key part of our agricultural systems. Fertilisers are just chemicals4 really.

    There’s a vast array of fertiliser products that are developed for specific applications. So there’s a suite for cropping farms, and a suite for pasture farms for dairy. Sometimes they need a mix that’s higher in other fertiliser elements5 such as potassium.

    The most commonly used fertiliser has been developed from rocks that are very high concentrations of phosphorous. We call that rock phosphate. We import a lot of that product from North Africa. That is either ground up and spread on pastures or is ground up and reacted with sulfuric acid6 to produce a fertiliser known as superphosphate7.

    If you do a nutrient budget, which is an inventory of inputs and outputs of nutrients8, you realise that there’s quite a lot of nutrient that is removed off farm just in product alone, particularly in milk. So farmers are trying to replace that and maintain the fertility, because we want to avoid situations of providing too little and thus stripping the soil of its fertility. And likewise, we don’t want to overfertilise, because if we have too much fertility, that poses an increased environmental risk.

    Acknowledgements:
    Dr Ross Monaghan, AgResearch, Invermay
    Horse-drawn fertiliser spreader, Waiorau Sheep Station, Otago. Photographer unknown: Views of Waiorau Sheep Station. Ref: 1/4-023070-F. Alexander Turnbull Library, Wellington, New Zealand. http://natlib.govt.nz/records/23107717
    Islington fertiliser. Webb, Steffano, 1880?–1967: Collection of negatives. Ref: 1/1-019461-G. Alexander Turnbull Library, Wellington, New Zealand.
    http://natlib.govt.nz/records/23128514
    McDonald’s Lime9
    Dennis ‘SK’ http://creativecommons.org/licenses/by/3.0/deed.en
    Ravensdown

    1. fertiliser: Compounds that are given to plants to promote growth.
    2. nutrient: A substance that provides nourishment for growth or metabolism.
    3. fertiliser: Compounds that are given to plants to promote growth.
    4. chemicals: Everything is made up of chemicals. All matter (anything made of atoms) can be called chemicals. They can be in any form – liquid, solid or gas. Chemicals can be a pure substance or a mixture.
    5. element: A substance made of atoms that all have the same atomic number. Elements cannot be split into simpler substances using normal chemical methods.
    6. acid: A hydrogen-containing substance that is capable of donating a hydrogen ion to another substance.
    7. superphosphate: New Zealand’s premium fertiliser. Superphosphate provides the essential nutrient phosphorus and first went on sale in England in 1843. It is produced by treating rock phosphate with sulfuric acid.
    8. nutrient: A substance that provides nourishment for growth or metabolism.
    9. lime: Chemically, lime is the compound calcium oxide. Commercially, lime could refer to ground-up calcium carbonate marketed as AgLime.
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      fertiliser

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    2. Compounds that are given to plants to promote growth.

      element

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    4. A substance made of atoms that all have the same atomic number. Elements cannot be split into simpler substances using normal chemical methods.

      lime

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    6. Chemically, lime is the compound calcium oxide. Commercially, lime could refer to ground-up calcium carbonate marketed as AgLime.

      nutrient

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    8. A substance that provides nourishment for growth or metabolism.

      acid

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    10. A hydrogen-containing substance that is capable of donating a hydrogen ion to another substance.

      chemicals

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    12. Everything is made up of chemicals. All matter (anything made of atoms) can be called chemicals. They can be in any form – liquid, solid or gas. Chemicals can be a pure substance or a mixture.

      superphosphate

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    14. New Zealand’s premium fertiliser. Superphosphate provides the essential nutrient phosphorus and first went on sale in England in 1843. It is produced by treating rock phosphate with sulfuric acid.