Catch NPK data on the web

1 May 1998




Catch NPK data on the web

By Ian Marshall

FERTILISER recommendations are now available through the world wide web after Hydro Agris introduction of its Hydro Precise service.

The service is designed to supply customers with suitable suggestions for NPK fertiliser use and provide variable rate application maps via the internet.

Hydro Precise comprises two parts: The NPK Online and the N-sensor. NPK Online differs from accepted practice with P & K, based on nutrient removal by the previous crop, being applied in the spring with the first N top dressing.

Participants need to be set up for variable rate, site specific, input application. Additional components of the system comprise a personal computer (PC) with internet installed and a chip card to access Hydro Agri Europes central server, on which will be held all the agronomic information needed to make the calculations to produce the application maps.

In operation, GPS-generated yield maps – with relevant information such as soil type and P & K status, organic fertilisation, previous cropping and main crop – are all downloaded onto a chipcard into the users PC and from there, via the internet, to Hydros central server, where it is processed.

The user is then presented with a choice of suitable NPK blend formulations based on their nutrient ratios, together with an application map and crop-specific upper and lower limits for the first N application which is downloaded to the PC and from there to the tractors on-board computer.

The N-sensor – part two of the Hydro Precise concept – is designed to allow the second and subsequent N applications to be tailored to the site specific needs of the crop at the time of spreading.

In principle the system uses sensors, mounted ahead of the spreader tractor, to measure the crops chlorophyll content, which is claimed to reliably indicate the actual N status of the plant. Readings are continuously processed by an on-board computer, which matches it with the spread rate stored on the application map.

That comparative information, together with details of the spread characteristics of the particular fertiliser being used, enables the computer to calculate the optimum application rate, on the move, according to the requirements of the left and right sectors of the spread pattern. Actual application rate is displayed on an LED monitor in the cab and the operator can manually override the computer.

As on the prototype seen at Cereals 97 the sensors are still boom-mounted, but now on a level plane on the tractors front linkage. Refinements include reducing the size of the sensors, mounting them within the boom profile, and linking them (via fibre optics) in series of four on the left and right boom sections.

Developments are continuing. The number of sensors needed and their location, whether on the spreader or on the tractor cab (boom mounting limits working speed to that of spraying) are still being investigated. But Hydros confidence in the system is such that this season it intends to field demonstrate nine prototype machines, one in the UK. &#42

Axel Link helped develop on-line fertiliser and application information.

Sensors feed information back to a central control using fibre optics cables.


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