Wednesday, August 27, 2014

Combine moisture readings likely inaccurate


The recent and prolonged rain has created problems for Idaho grain producers in eastern and central Idaho, where harvest has been delayed and grain has started to sprout in the head. Grain still standing in the field has been damaged by rain.

Each rain event contributes to additional deterioration of grain quality. While the objective is to harvest as quickly as possible, if the grain is going to be stored for later use as feed (or ethanol, etc), please DO NOT harvest at high moisture content. Already moldy grain will continue moldy growth unless the moisture is below 12%. To arrest growth, harvest below 12% and keep air flowing in the bins.

Moisture sensors in the combine are unlikely to be accurate for sprout damaged grain!


Moisture sensors are calibrated to read sound grain - that is, grain with density of 60 pounds per bushel. Rain-damaged and sprouted grain lose density and test weights are coming in at 50 to 56 pounds per bushel. The combine moisture sensors cannot recalculate moisture based on these lower test weights and this increases the likelihood that moisture readings are inaccurate!!

Grain reading 12% moisture as you are harvesting MAY ACTUALLY BE 13 - 14% MOISTURE. 

IF you decide to “push it” and harvest at 13% moisture, you may actually be at 14-15% moisture! Please be aware that those conditions will allow for the development of “hot spots’ in storage, and molds will continue to grow. You may end up taking grain out of the bins with a jack hammer and respiration gear!

The “official” instruments for measuring grain moisture are the Perten (http://www.perten.com/) and / or the Dickey John (http://www.dickey-john.com/). If your elevator does not have the correctly calibrated instrumentation, they may not be getting accurate moisture measurements, either. 



REFERENCE:

Wheat Test Weight Decreases With Delayed Harvest  

http://www.sites.ext.vt.edu/newsletter-archive/cses/2006-06/wheattestweight.html


Crop and Soil Environmental News, June 2006
Wade Thomason, Extension Grains Specialist, Dept. of Crop & Soil Environmental Sciences, Virginia Tech 

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