This time of the year is the best time to get soil sampling for the farm, as there will be no nutrients recently applied.
The use of organic and artificial fertiliser is a key driver of grassland production on dairy farms, and utilising it effectively is crucial.
Artificial fertiliser is a huge expense on dairy farms, as it accounts for 17% of variable costs and 10% of total costs on spring-calving dairy farms.
It can be said that in a lot of ways, the National Fertiliser Database (NFD) is making farmers realise how important it is to be efficient with the fertiliser they buy and utilise.
Testing your soil is the key to optimal soil fertility, as there is no point in applying fertilisers to land if you do notknow what nutrients they are lacking or the pH of the soil.
Farmers should be targeting appropriate types and rates of artificial fertilisers to make up any shortfalls in requirements and in order to effectively do this, soil sampling is essential.
Soil sampling
A standard soil test will provide major nutrient analysis such as soil pH, lime requirement, phosphorus (P), and potassium (K) for a cost of €1.23/ha/year, according to Teagasc.
Considering the cost of soil testing, it can minimise the need for an excessive amount of fertiliser purchased, as the data can be collected and put towards a fertiliser plan, which allows optimal fertiliser efficiency.
The first step, is to take the soil sample and the second step is to complete a nutrient management plan (NMP) on your farm, which will allow for clear identification of the areas that require certain nutrients.
The plan will calculate chemical nitrogen (N) and phosphorus (P) allowances for the year ahead, while providing recommendations of what quantifies to apply a suitable fertiliser shopping list.
Farmers with a grassland stocking rate of over 130kg organic N/ha are now required to have valid soil samples (>4 years old) if they wish to purchase chemical phosphorus fertiliser, or import organic manures.
Getting the timing right
As there has been no nutrients applied to land in recent weeks, soil samples if they are taken now will give a good indication of the baseline nutrient levels in the soil.
By going out with the soil auger now, you will be providing yourself with up-to-date information on where to target spring applications of slurry so you can get the maximum benefits from it.
How to collect soil samples is as follows:
- Collect soil samples at the right time of the year;
- The area sampled should be 2-4ha;
- Use a suitable soil corer;
- Sampling depth should be top 10cm of soil;
- Take 20 cores/samples in a ‘W’ shape, ideally;
- Wait three to six months after P and K applications;
- Leave a gap of two years after lime is applied.
When you have the results, you need to firstly identify the paddocks that will require a lime application, followed by targeting organic manures to low fertility paddocks (soil index 1 and 2 for P and K).
Any of the soils with a good fertility status at a soil index of three, the nutrient P and K offtake should be replaced in order to maintain the good soil fertility.
Any crops that are demanding crops like silage fields, should receive sufficient nutrient applications and any paddocks with a fertility status of index 4, will not require additional fertiliser.