Reducing N leaching by adapting N application timing and quantities to weather and grass growth - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Access content directly
Conference Papers Year : 2023

Reducing N leaching by adapting N application timing and quantities to weather and grass growth

Abstract

The EU Green Deal Farm to Fork strategy has set a target to reduce nutrient losses by at least 50% and fertilizer use by at least 20% by 2030. This will require more appropriate management of Nitrogen (N) fertiliser increasing N use efficiency leading to a reduction of N available for loss. A modelling exercise has been conducted, using the MoSt GG model, to highlight the potential for N precision management to reduce N leaching. Four scenarios were simulated over 19 years (2003 to 2021) using weather data recorded by the Met Eireann synoptic weather station, located in Moorepark Co. Cork, Ireland. The base fertiliser application had a total annual N fertilisation of 225 kg N/ha/yr. Then, the following rules were set to adjust the timing and quantity of the fertilisation: The N application had to be delayed if (1) the average temperature recorded over the preceding and/or the coming week dropped below 5 °C, (2) heavy rainfall occurred in the four preceding days or if it was expected in the three coming days, (3) from April onwards, if the predicted grass growth for the following week was below 30 kg DM/ha/d, fertilisation was cancelled. In each case, if the N application was delayed by more than seven days, the N application was reduced (or even cancelled if over 21 days). For each scenario, four paddocks cut every four weeks in rotation with a total of 10 cuts/yr paddock were simulated. The precision N management led to an average reduction in N leaching of 3%, associated with an average reduction of 10 kg of N applied/ha/yr and a grass dry matter (DM) yield decrease of 1%. While the highest impact on the amount of N leached was the weather (yearly effect), the positive impact of precision fertiliser application has been shown on specific years. In 2014, for example, the N leaching decrease of 7% with 5 kg DM less grass produced. The years with the greatest N leaching reduction due to the reduction of N applied are often associated with a loss of grass DM production, highlighting that trade-offs will have to be found.
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Dates and versions

hal-04198723 , version 1 (07-09-2023)

Identifiers

  • HAL Id : hal-04198723 , version 1

Cite

Laeticia Bonnard, Elodie Ruelle, Michael O'Donovan, M Murphy, Luc Delaby. Reducing N leaching by adapting N application timing and quantities to weather and grass growth. 74. Annual meeting of the european federation of animal science (EAAP), EAAP, Aug 2023, Lyon, France. pp.306. ⟨hal-04198723⟩

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