Precise application of AD plant biodigestate and slurry and according to pre-determined crop nutrient requirements or legal limits is now possible using near infrared sensor technology.

That is according to John Deere, which is developing a manure sensing system based on a NIR sensor mounted on a slurry tanker to achieve precise control of application rates.

Developed in conjunction with Kotte Lantechnik, Fliegl Agartechnik and Vervaet BV, the Harvestlab sensor used is the same technology used on John Deere forage harvesters for on-the-move analysis of a range of crop constituents including sugars, starch, protein and crude fibre content.

Using complementary data from yield and soil maps and N-Sensor nitrogen management technology, the required application rate - either a target nutrient rate or a limit rate - can be set in the Greenstar 2630 cab display prior to application.

The NIR sensor measures levels of key ingredients of the slurry, from almost the total flow, including dry matter, nitrogen, ammonia, potassium and phosphorus content, in real time. The system then adjusts the slurry flow to deliver the exact quantity of nutrients required.

If a John Deere tractor is used with the spreader, this process can also be enhanced by the firm's Tractor Implement Automation (TIA) system. This enables automatic speed control of the application rate adjustment, based on the tractor's forward speed, without changing the flow pattern of the slurry, says John Deere.

Benefits of the system to farmers and contractors include optimising use of organic manures and easy and accurate documentation for compliance purposes, says the company.

The development has been driven by increasingly tight rules governing application of organic manures across Europe and in Germany and the Netherlands in particular.

Jurgen Audenaert says: "There is increasing regulation on what you apply, when and where, and increasing demand for documentation in support of this."

The system also marks a move away from per cubic metre application rates to rate based on kilograms per hectare, he adds.

"Precision farming with organic manures is, for the first time, possible," says Mr Audenaert.

According to John Deere Intelligent Solutions Group product manager Steve Siegel the Harvestlab sensor can be installed on any type of slurry spreader, including umbilical systems.

But it must be rear mounted so it can measure manure flow.

An initial nutrient analysis of the FYM to be spread is required and Harvestlab sensor calibrations are currently being developed for a range of manures. The first to be available will be pig manure, followed by a calibration for cattle manure and then biogas digestate.

Test systems are running currently in Germany and the Netherlands and a commercial launch is planned for November 2015, with a limited release spring 2015.

Summary table - John Deere manure sensing capabilities

Site-specific application

• Target rate based on N, P or K  (kg/ha)
•  Limit rate for second ingredient (eg target rate for N, limit rate for P)

Tractor-implement automation

• Automated speed control (John Deere tractors only)
• Manual speed control (other makes)

Documentation

• Applied rates of ingredients (as applied maps)
• Applied amounts of ingredients (total by fields and maps)

John Deere manure sensing

Benefits:

• More precise application and site specific optimisation of nutrient balances in forage maize, grass, wheat
• Immediate information available on ingredients of manure
• Addresses issues of variability within and between tank loads of manure
• Enables automatic rate control based on kg/ha of nutrient ingredients
• Easier and more precise manure documentation for compliance
• Cost savings - on mineral fertiliser; on sampling costs; invoice on quality not quantity