The world’s population continues to grow each year and by 2050, the United Nations predicts that there will be 9.7bn people on the planet. Along with increased human global activity, we also have record carbon emissions resulting in climate change. This is linked to extreme weather events, for example extreme high temperatures in Australia and flooding and the Midwest of the USA last spring.

An expanding global population creates a continuous demand for high-quality food products and this food must be produced efficiently to conserve the planets natural resources. Meeting this growing global food demand will be challenging. However, it presents opportunities and responsibilities for food producers like Ireland. In responding to this challenge, we must be careful to replenish and manage our soil resources in order to maintain and/or increase productivity per hectare, while curbing the impacts of climate change.

Fertiliser inputs have been crucial for increasing global food supply and efficient use of fertiliser is critical to minimise effects of climate change in the future. This has been the goal of the Fertilizer Association of Ireland since its formation back in 1968, with the aim of promoting the efficient use of fertilisers to produce quality food in an economical and sustainable manner.

Maximising nitrogen use efficiency

Nitrogen (N) is a primary driver of plant photosynthesis and grass and crop production in our climate. With our rich soils and wet climate, Ireland has the ability to grow high grass yields (15/16t DM/ha) and in some years, grass will grow for 365 days of the year.

However, N fertilisers also contribute to the production of greenhouse gas (GHG) and ammonia emissions. In relation to gaseous emissions, agriculture accounts for 33% of national GHG emissions and 98% of ammonia emissions.

We must be careful to replenish and manage our soil resources in order to maintain and/or increase productivity per hectare, while curbing the impacts of climate change

Technologies such as protected urea fertiliser, low-emission slurry application and inclusion of clover in swards are key practices that help farmers better manage N fertiliser use and help Irish agriculture meet its commitments to reduce emissions.

In addition, we must explore every other avenue of using N more efficiently on farms, including selecting the right N fertiliser source and applying N at the correct rate, at the right time of the year and in the right place.

Soil test to fertilise

Maximising nutrient and fertiliser use efficiency starts with the most important resource on a farm - the soil. Regular soil analysis will provide critical information about the basic soil chemistry, pH, phosphorus (P), potassium (K), magnesium (Mg), and create the basis for nutrient management and fertiliser planning to ensure an adequate supply of nutrients for the crop during the growing season. Soil testing is a low-cost tool and will provide accurate field-by-field soil nutrient advice for your farm.

Lime and soil pH

Soil pH plays a critical role in both the supply of stored soil nutrients (N, P and K) and the efficient use of freshly applied nutrients. For example, on mineral grassland soils where soil pH is maintained in the optimum range of 6.3 to 6.5, soils can release up to 80kg N/ha/year.

We must explore every other avenue of using N more efficiently on farms

This will greatly increase fertiliser N use efficiency on farms, by helping to reduce the overall applied N requirements and the annual costs. Soil pH is essential for maintaining productive grass-clover swards, which can increase grass dry matter production and has the potential to reduce levels of fertiliser N applied.

Optimum P and K

Maintaining sufficient levels of soil P and K is essential for maximising the grass growth over a long growing season. Phosphorus is needed for early grass growth and animal health, while K is a key building block that tends to be most important on areas used for silage and crop production where K demand is highest.

However, the recycling of cattle slurry or manures, which typically have a rich source of K, back to these areas may not always happen on many farms, due to the location of the silage fields and the logistics and costs in transporting slurry over longer distances.

Use slurry efficiently

Slurry and manures are valuable on-farm sources of N, P, K and Sulphur (S). Managing slurry efficiently during the growing season will result in more N availability to grow grass. The timing and method of slurry applications influence N losses both during and after application.

Managing slurry efficiently during the growing season will result in more N availability to grow grass

Apply cattle slurry in the spring time, where possible, to maximise the recovery of total slurry N. Low-emission slurry spreading, such as trailing shoes or ground injections, will further reduce N losses and increase N recovery by up to 50% compared to the splash-plate application method. Recycle slurry on silage areas to return the important nutrients that were removed at harvest time. For example, an application of 33.3m3/ha (circa 3,000gals/ac) of cattle slurry (7% DM) will supply circa 33kg N/ha, 17kg P/ha and 116kg K/ha. This will supply circa 60% of a grass silage crop’s total nutrient requirement.

Prepare a fertiliser plan

Preparing a fertiliser plan at the start of each growing season provides the basis for planning the applications of N, P, K and S over the growing season.

Supplying the correct nutrient balance at key times during the year for grass and crops is critical. For example, early season N requirements tend to be low on many farms due to cold and wet soil conditions, which leads to a poorer response to N at that time of year. A fertiliser plan will provide advice on the correct rates of N, P, K and S and the most suitable fertiliser to apply in a planned and timely manner. This will ensure that nutrients are used as efficiently as possible to reduce N losses to air or water.

Supplying the correct nutrient balance at key times during the year for grass and crops is critical

Maintaining healthy soils is paramount for underpinning our farming systems, reducing emissions of nutrients to the environment and mitigating climate change. Good soil fertility is essential to driving productivity and nutrient efficiency. Good soil structure provides favourable conditions for rooting, sufficient water supply and helps to protect the soil from extreme weather events such as heavy rainfall. Good soil biology helps to ensure good nutrient recycling, carbon capture and storage through building soil organic matter.

Where soils are maintained and managed effectively, they will function correctly and produce quality food sustainably. It is the Fertilizer Association of Ireland’s mission to support farmers and the industry to do just that.