GP NK 15-0-20

GP NK 15-0-20

GP SPORT • UF PREMIUM TECHNOLOGY • PHOSPHATE-FREE

Professional phosphate-free functional fertiliser for turf affected by Poa annua and soils with high phosphate levels

Short description: product section

GP NK 15-0-20 is a professional phosphate-free functional fertiliser designed for two precise applications: fertilising established turf on naturally phosphate-rich soils and agronomic control of annual meadow grass (Poa annua), a particularly troublesome unwanted grass on professional sports turf. High potassium (20 % K₂O), magnesium, sulphur and iron combine with UF technology (urea formaldehyde) for stable nutrition up to 3 months and intensive turf colour.

For professional maintenance of sports pitches, golf courses and intensively used green spaces, plus high-quality prestigious and utility turf.

Key properties

Professional phosphate-free fertiliser for naturally phosphate-rich soils;

Functional fertiliser for Poa annua control: absence of phosphate reduces annual meadow grass competitiveness;

High potassium (20 % K₂O) for water balance regulation and stress tolerance;

Nitrogen in UF technology (urea formaldehyde), with biologically regulated, gradual release;

Iron (1.0 % Fe, of which 0.9 % as water-soluble sulphate) for intensive colour and tissue strengthening;

Increased sulphur trioxide (22 % SO₃) supports efficient nitrogen use;

Low in chloride, safe for sensitive sports turf species;

Dust-free spreading thanks to uniform granules (2.0–5.0 mm);

Effective for up to 3 months after a single application.

Functional fertiliser: a precise agronomic solution

GP NK is for professionals managing turf from soil analyses and deliberately selecting grass species within the sward. Its phosphate-free NK formulation addresses two precise agronomic situations:

Scenario 1: naturally phosphate-rich soils

Phosphorus accumulates in soil. Unlike nitrogen and potassium, it is relatively immobile and remains available for years. On established sites after long-running fertilisation programmes, phosphate levels stabilise or rise. Continuing phosphate inputs causes excessive accumulation, raises environmental risks through surface-water eutrophication and can disturb uptake relationships with other elements.

Scenario 2: controlling annual meadow grass (Poa annua)

Poa annua is among the most troublesome weeds in professional sports and golf turf. It displaces desirable fine grasses, creates uneven structure, produces abundant seed and is disease-prone.

A key characteristic of Poa annua is high phosphate demand. It favours phosphorus and actively accumulates in soils with elevated P. Limiting phosphate availability is among the most effective agronomically based methods of reducing its spread.

GP NK addresses this problem by fully supplying nitrogen, potassium and trace elements without simultaneously encouraging Poa annua. Used systematically, it supports grass species selection in favour of fine grasses.

Formulation: key components

High potassium (20 % K₂O), the highest in the GP Sport line alongside GP Finale, has a central physiological role. It regulates plant water balance and stomatal opening and closure, strengthens stem structure and increases natural resistance to drought, heat, frost and intensive play.

15 % nitrogen includes three forms: immediately available ammonium nitrogen (3 %), medium-speed urea nitrogen (8 %) and UF nitrogen (4 %) biologically released over up to 3 months.

Magnesium (3 % MgO, of which 2 % water-soluble), sulphur trioxide (22 % SO₃) and two iron forms (1.0 % Fe total) together ensure intensive, deep colour and support photosynthesis and protein synthesis.

Low chloride is an important property for sensitive sports turf species.

How does UF technology work?

UF technology (urea formaldehyde), known in German as Formaldehydharnstoff, is an advanced nitrogen form with slow, biologically controlled release.

Part of GP NK's nitrogen (4 % N) is bound in long polymer chains synthesised from urea and formaldehyde. Soil bacteria and fungi gradually break these down, releasing plant-available nitrogen. The rate depends on microorganism activity and soil temperature and moisture.

UF nitrogen in GP NK includes two subfractions:

Hot-water-soluble nitrogen (HWIN, 2.8 %): long-term nitrogen reserve;

Cold-water-soluble nitrogen (CWS, 1.2 %): medium-speed availability.

This mechanism supplies nitrogen at a rate matching actual turf demand, without growth surges typical of fertilisers using only readily available forms.

Application results

Stable long-term turf nutrition for up to 3 months;

Reduced Poa annua spread with systematic use;

Significantly stronger stress tolerance thanks to high potassium;

Intensive, deep colour from iron, magnesium and sulphur;

Reduced nitrogen losses through leaching and emissions;

Improved turf water balance, particularly important during drought;

Limited phosphate accumulation in the soil profile;

Consistent with sustainable fertilisation principles.

Applications

Fertilising established turf where soil analysis confirms sufficient phosphate;

Grass species selection, reducing Poa annua spread in professional programmes;

Summer and early autumn sward strengthening before intensive use;

Sports and golf turf fertilisation based on soil analysis;

Sites with sustainable fertilisation programmes.

GP NK: application and parameters

Application rate and coverage (25 kg)

Application instructions

Calculate the area to be fertilised and measure the appropriate quantity of fertiliser at the chosen application rate.

Spread evenly on dry turf, preferably using a calibrated spreader.

Avoid overlapping spreading passes and locally exceeding the application rate.

Water after application (2–4 mm) to initiate nutrient dissolution and movement into the root zone.

Good professional practice

Apply on the basis of soil analyses confirming sufficient or elevated phosphate levels.

In Poa annua selection programmes, systematic use of GP NK as the sole fertiliser during summer and autumn is recommended.

Application is recommended in the second half of the season (summer / autumn), when turf needs stronger resistance before intensive use.

Do not apply during prolonged drought without irrigation, or to frozen or waterlogged soil.

Two passes in a cross pattern are recommended on larger areas.

Application conditions

Do not apply during frost, drought or strong sunlight. Do not exceed the recommended rate. Contains iron: avoid light-coloured surfaces because permanent stains may occur. Immediately remove residual granules from paths, shoes and pets' fur.

Declared composition

Role in the GP Sport programme

GP NK is a specialised functional element of the professional GP Sport programme:

New establishment / overseeding / turf laying → GP Starter: high phosphate, rooting, up to 6 weeks

Spring / summer / autumn → GP Klassik: universal seasonal fertiliser, colour, up to 3 months

All season → GP Allround: balanced NPK formulation + trace elements, up to 3 months

Summer / early autumn (Poa annua selection) → GP NK: phosphate-free, up to 3 months

Late autumn → GP Finale: highest potassium with magnesium, winter hardening, up to 2 months

Frequently asked questions

When should GP NK be applied? Ideally in the second half of the season, from summer to autumn, when turf needs stronger resistance before intensive use and preparation for autumn conditions. In Poa annua selection programmes, apply systematically in each summer-autumn cycle.

Why is GP NK phosphate-free? First, phosphorus accumulates and reaches sufficient or elevated levels on established sites; continued P supply causes excessive accumulation. Second, omitting phosphate is an agronomic species-selection tool against phosphate-loving annual meadow grass (Poa annua).

How does GP NK act against Poa annua? The grass requires high phosphate availability for prolific seed production and competition with fine grasses. Systematic phosphate-free fertilisation, combined with programme adjustment and mechanical care, gradually reduces its competitiveness. Selection effects are generally observed after 2–3 seasons of systematic use.

When should GP NK or GP Finale be chosen? Both contain high potassium (20 %) but differ in nitrogen profile, additions and purpose. GP NK contains 15 % N including UF and iron, for summer, autumn and Poa annua selection. GP Finale has 10 % N and more magnesium (4 %), optimised for winter hardening.

Can GP NK be used on young turf? This is not recommended. Young turf requires high phosphorus for roots; use GP Starter at that stage. GP NK is designed for established turf with stable soil phosphate supply.

Does it contain chlorides? No, GP NK is low in chloride, particularly important for sensitive sports grasses and sites with naturally elevated salinity.

Is GP NK suitable for domestic lawns? Yes, especially established, well-maintained lawns where owners seek sustainable soil-analysis-based fertilisation or observe annual meadow grass spreading. High potassium and iron improve drought and wear tolerance and give intensive, deep colour.

Declaration and application instructions

Ingredients:

Potassium sulphate1 (CAS No. 7778-80-5); ammonium sulphate11 (CAS No. 7783-20-2); urea1 (CAS No. 57-13-6); methylene urea8 (CAS No. 9011-05-6)

1 CMC 1: Stoffe und Gemische aus unbearbeiteten Rohstoffen

8 CMC 8: nutrient polymers

11 CMC 11: Nebenprodukte im Sinne der Richtlinie 2008/98/EG

Directions for use:

Apply only where a recognised need exists. Do not exceed the rate. Spread 25-30 g/m2 per application and water in.

CAUTION: contains iron! Avoid contact with flooring (stone paving, wooden floors, etc.) or clothing to prevent staining. Remove spilled product immediately. This also applies to residues on shoes or pets.

Recommended storage conditions:

Store only in original packaging; close opened containers tightly. Do not allow into drains or watercourses. Long-term storage temperature: +2 °C to +30 °C. Avoid major temperature fluctuations and direct sunlight. Keep out of reach of children and pets.

Safety and environmental information:

EUH210: Safety data sheet available on request.

This fertiliser contains urea, which can release ammonia and affect air quality. Take appropriate remedial measures according to local conditions.