HST : HydroStatic Transmission.

  HTA : Horticultural Trades Association.

  HWIN : Hot Water Insoluble Nitrogen.

  HWSN : Hot Water Soluble Nitrogen.

  IAG : Information Advice and Guidance.

  IBA : Irish Bowling Association, formed in 1904.

  IBDU : Isobutylidene Diurea.

  IBI : International Biochar Initiative.

  ICBN : International Code of Botanical Nomenclature, now called the ICN (since 2011).

  ICE : Internal Combustion Engine.

  ICM : Integrated Crop Management.

  ICN : International Code of Nomenclature for algae, fungi, and plants, formerly known as the ICBN (changed in 2011).

  ICT : Information Communication Technology.

  IDM : Integrated Disease Management.

  IfA [1] : Institute for Apprenticeships. On 1st February 2019 this was renamed the IfATE.

  IFA [2] : Irish Football Association (Northern Ireland). See also FAI.

  IOG : Institute of Groundsmanship.

  IPCC : Intergovernmental Panel on Climate Change.

  IPM [1] : Integrated Pest Management (the most commonly used acronym).

  IPM [2] : Integrated Plant Management.