Plan your spring fertiliser applications

There are three areas of focus planning for 2022 which require careful planning: limiting the increase in expenditure in fertiliser, growing sufficient grass to feed animals and protecting the soil fertility on the farm for the future. Find out how and avoid waste with the advice outlined here.

The spike in fertiliser prices in the late noughties (2008 & 2009), combined with other factors, led to a big decline in fertiliser use on Irish farms. Around this time farmers reacted to increased regulation (new Nitrates rules) and high prices by dramatically cutting their fertiliser applications, particularly of P and K. This led to a dramatic fall in soil fertility, one which we have spent the last decade trying to reverse.

For 2022 the industry is facing into a year with extremely high fertiliser prices and potential shortages in fertiliser supply. Planning now is essential to ensure that crops and animals will be fed during 2022 at a reasonable cost. Better nutrient management planning can also lay the foundation for meeting sustainability challenges ahead.

There are three areas of focus planning for 2022 which require careful planning:

• limiting the increase in expenditure in fertiliser,
• growing sufficient grass to feed animals
• protecting the soil fertility on the farm for the future.

“Cut down on waste”

One of my mother’s favourite expressions when we were growing up was ‘Waste Not, Want Not’ meaning if you don’t waste it you won’t be short. It’s not a bad motto for the year ahead. The dictionary definition of waste is “to consume, spend, or employ uselessly or without adequate return”. Faced with the price and availability of fertiliser nutrients for 2022 avoiding waste is absolutely essential.

Avoid waste - Know your Soil Fertility

The 2020 soil analysis results show that for soil test P approximately ¼ of samples were in each of the P index categories. Soil test K showed a somewhat similar breakdown into K index categories with the exception of having a higher proportion of samples in index 2 and less index 1. However, large variations between farms exist as well as significant variation in soil fertility within farms especially between blocks of land e.g. silage versus grazing areas. It is impossible to plan effectively without knowing the fertility status of your soil’s so if you haven’t got recent samples get them now.

Avoid Waste - Use your soil sample results

Apply lime as recommended to achieve optimal soil pH in all fields which will improve the availability and efficiency of chemical fertiliser and organic N and P applications. After that the key to avoiding waste this year is to use your slurry in the right place at the right time and the right application rate. Use your maps from your nutrient management plan (NMP) or your soil sample results to identify where slurry should go:

• Unless absolutely necessary, slurry should not be spread in January and if slurry needs to be spread you should be having a serious look at your slurry storage capacity.
• Identify the lowest P and K fertility grazing plots to receive an application of slurry
• Apply sparingly at this time of year, approximately 1,500 gal per acre, as grass nutrient uptake demand is very low. Approximately 75% of the fertilizer replacement value from organic manure is from P and K. Where possible slurry should be used from late February to early April to maximise its benefit to grass growth and avoid losses to the environment.
• Leave sufficient slurry for your silage ground, which has the largest crop nutrient removal.
• Know the value of your slurry. Get it tested or use a slurry hydrometer to estimate the dry matter and nutrient (N-P-K) constituents.
• If you are not already doing so, use a low emission slurry spreading method, trailing shoe or trailing hose, to maximise the N availability of slurry that you are applying (up to 50% more compared to splash-plate applied slurry.

Avoid Waste - Chemical fertiliser will be like gold dust – sprinkle it wisely

Following a few simple guidelines can help. One of the best ways of avoiding wasteful nutrient losses to air and water is to wait for soil temperature (>5.5oC), soil moisture and weather to be suitable for crop growth. There will be a lot of media focus on providing this information for farmers next spring so hang tough until the advice indicates conditions are good to go.

On P & K Index 4 soils:

These soils have high levels of nutrients and no additional P and, or, K is required for grass growth.

• Plan fertiliser applications to these soils around protected urea for the season – it is cheaper than CAN and less losses mean there is 10-15% more N available than normal Urea.
• Where K and, or, Sulphur are required use an appropriate protected urea compound.

On P & K Index 1-3 soils focus on feeding the crop and at least maintain soil fertility levels for the year ahead. Decisions may be made to postpone additional fertiliser nutrient applications for soil fertility build-up until prices fall back somewhat.

• Where slurry has not been used apply a high P-K compound in mid-spring i.e. March, to drive grass growth.
• On soils with very low P and K fertility i.e. Index 1 soils, a further round of a compound will be beneficial in the May-June period

Ensure your supply of chemical fertilisers

It is highly likely that chemical fertilisers will be in short supply in the Spring. Early discussions with your supplier will be essential to ensure that you will have the product you need when you need it.

If you have maps for your NMP take them out and use them. See NMP map below for Phosphorus (P). It shows where different amounts of cattle slurry (CS) are to be applied on the farm according to fields requiring it most.

If you liked this article you might also like to read Ask for your Nutrient Management Plan

See Soil & Soil Fertility for more information.

Follow what the Signpost Demonstration Farmers are doing here