Nutrient management planning for 2025
Shay Phelan, Crops Specialist at Teagasc, shares seven things to consider for effective nutrient management planning in 2025.
The fertiliser register has been in operation for a year now and it is clear from the Department of Agriculture, Food and the Marine (DAFM) website that there is very little room for error when purchasing fertilisers. All 2024 purchases and organic nitrogen (N) and phosphorus (P) applications are now recorded in one place, so any over application can now be quickly identified. This highlights the need for every farmer, not just tillage, to complete a Nutrient Management Plan so that you can plan your purchases for the coming season.
The following are a number of steps to consider over the coming weeks:
1). Soil analysis
The Teagasc soil database shows that ~31% of tillage soils are at phosphorus (P) and potassium (K) index 4. Identify these fields and make savings on P and K applications in 2025. Where soil results are over four years old, resample fields over the coming weeks.
2). Lime and soil pH
Apply recommended lime rates based on recent soil analysis. This is the first step to increasing the availability of soil nutrients and increasing the utilisation of applied nitrogen (N), P and K, as either organic or chemical fertilisers.
3). Organic manures
Where organic manure supplies are available, they will help to replace chemical fertilisers, and are a cost-effective source of N, P and K.
To maximise the recovery of N from high N manures (pig and poultry), it is important to apply and incorporate within three to six hours of application. Ideally, test manures in advance of application to know their nutrient values and adjust application rates to supply ~50% of the crop’s P and K requirements. For example, an application of 25mᶾ/ha of pig slurry (2,200 gallons/ac) can supply 52kg N, 20kg P and 50kg K/ha, which is ~30% of the N and ~50% of the P and K requirements for a crop of spring barley.
Now is a good time to look at local sources of organic fertilisers and plan for spring crop utilisation.
4). Straw incorporation
Straw contains approximately 10% and 50% of total crop P and K, respectively. For example, the straw from a 10t/ha grain crop of winter wheat will return ~4kg P and 50kg K/ha. This offers significant savings of ~€45/ha in fields where straw is chopped.
5). Beans and peas
Where N-fixing crops are grown in a rotation, these fix atmospheric N, thus increasing soil N supply, so the following crop’s N requirement is reduced. Cereals grown after legume crops have up to a 30kg/ha lower N requirement, reducing N costs by ~€40/ha.
6). Combine drilling P
At sowing time, placing P fertiliser with seed will increase its efficiency. Research evaluating P fertiliser application methods for spring barley clearly shows the importance of delivering P fertiliser close to the germinating seed on low fertility soils (Index 1 and 2).
7). Grow crops with lower N requirements
Grow crops, where possible, with lower crop N requirements such as beans/peas, spring barley or spring oats, depending on crop rotations and market requirements.