New P and K calculator for grassland and tillage crops

Following from the success of the ‘Nutrient Calculator Wheel’ launched last year, the Fertilizer Association of Ireland has launched an online version of its simple user-friendly P and K calculator for grassland and tillage crops.

This is now available to everyone with access to the web either via smartphone or computer and going to their website.

The online calculator for P and K off-take and fertilization was developed in association with Teagasc and K+S UK & Eire Ltd.

It is designed to provide fertilizer advice and to calculate the guideline P and K recommendations for a range of grassland, forage and tillage crops on varying fertility sites.

It is easy to use and the minimal information required is easy to input. Your details can be entered to get advice on a field-by-field basis using specific field information, like the crops to be grown and the base fertility indices for both P and K. The online calculations will give you your specific P and K advice in seconds.

Range of factors

The calculator takes account of a range of factors that will differ between individuals.

For example, it is influenced by your farming system, stocking rate, crop yield level, soil test results and organic manure usage. It is designed to give simple bottom-line estimation of fertilizer P and K requirements.

The site also includes useful notes on soil test results and soil fertility levels, organic manures, lime, sulphur and magnesium.

Getting ‘hooked up’

The calculator is located on the website of the Fertilizer Association of Ireland. Simply go to their website and follow the link to 'P & K Calculator for Grassland and Tillage Crops', as shown in Figure 1.

If you have a QR code reader installed on your smartphone, you can click on the QR code here (Figure 2) and it will bring you directly into the site.

Once you are in the site, there is a list of steps included to help you use the calculator. The first step is to select the enterprise or crop you are interested in.

The options available include dairy grazing, drystock grazing, grass silage, maize silage, whole crop silage, cereals, oilseeds, peas, beans or root crops.

Then enter the details required, depending on the crop category you choose, for the soil P and K index for that field, the crop type you are interested in, your stocking rate where relevant, your concentrate feed usage, your crop yield, and any organic manure used with the type and rate. Then click submit.

Example

The following example is for a field growing 7t/ha of spring barley where the straw is removed.

This field is soil P Index 2 and K Index 1. It received 20t/ha of pig slurry to grow this crop. All of these inputs are shown on the screen shot in Figure 3. Once the details are entered, click on submit.

The calculator will then calculate the P and K off-take for the crop, as well as additional P and K required to build up soil fertility where the soil index for P or K is low.

The contribution of the organic manure to P and K requirements is also shown. The net nutrient advice shown is the estimated chemical P and K fertilizer required by the crop based on the data entered.

The results of the calculations for this example are shown in Figure 4.

Easy access

This online tool makes nutrient advice information more accessible and available to advisers, consultants, industry reps and farmers.

Fertilizers are an important and expensive input for agricultural production and it is essential to use them efficiently to maximise returns to the farmer whilst protecting the environment.

As well as providing an easy way to calculate phosphorus and potassium requirements, the tool also helps farmers to appreciate the nutrient off-take by different land uses and also the fertilizer contribution from a range of organic manures.

The Fertilizer Association stresses, however, that a farmer must still comply with the regulatory requirements for P application.

Whole farm limits under the Nitrates Regulations or other schemes must still be cross-checked and adhered to.

This online calculator provides the agronomic requirement for P and K based on the inputs entered for each individual field.