We have been asked recently “why don’t we measure the hay moisture at the pickup of the hay baler”?

The answer is all about sample presentation. The more consistent a sample is presented to an instrument the more accurate the result.

(As an aside, correct sample presentation is why hay samples have to be partially dried and then ground up to allow NIR instruments to measure the properties of hay).

A compressed hay bale with a fixed path length through it will always provide a much more accurate moisture measurement than the loosely flowing and inconsistent bulk density of the hay being collected at the pickup. In the pre-compression chamber just before it trips to be loaded into the main bale chamber does present an opportunity for moisture measurement. However, once again the variability of the final bulk density there is less consistent than the made bale. Plus, if microwaves are being used to measure the moisture at this point, all the metal around the chamber causes microwave reflections that distort the spectrum. These distortions have to be electronically and or software rejected or they will cause a reduction in the accuracy. Such rejection systems are never as accurate as having a clean spectrum in the first instance.

From the feedback we get from our many Gazeeka model 870 users we have concluded the following.

• Generally, the Gazeeka is not used to determine when to start baling (a trial baling). Most operators can assess the windrows and determine when the hay is ready to bale without first making a few bales.
• Needing to measure the moisture at the pickup is generally only required when there are two things happening. One is that the moisture in the windrows is very inconsistent, and secondly, a hay preservative is being used which requires the exact moisture level to change the dose rate of additive. Generally, a change in additive dose rate is only the case if one is using propionic acid as a hay preservative. All other preservatives generally have a fixed dose rate per tonne and vary the flow rate based on mass flow (tonnes per hour).
• The main use of the Gazeeka is to determine when to stop baling as the dew comes in, or when the hay becomes too dry, without having to stop and measure moisture by some other means.
• Measuring the moisture as the bale exits the chamber also allows bales that have a moisture level greater than a pre-determined moisture set point to be marked with the marking system and thus possibly handled differently to the rest of the hay bales made. This process would be extremely difficult and prone to errors if the moisture at the pickup was used to determine which bales and where the high moisture points were to be marked. ... See MoreSee Less

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Feb 24th