An inside look at the silo-bag system

Author: Bartosik, R.

EEA INTA Balcarce

Abstract: The silo-bags are a hermetic type of storage widely adopted. This paper summarizes the results of the effect of silo-bag storage on the commercial quality of corn, soybean, wheat, sunflower, malting barley, canola and beans. The effect of the modified atmosphere on insect population and storage fungi, and recommendations for proper storage conditions in the silo-bags are also presented.
Overall, when dry grain is stored in silo-bag, the CO2 ranges from 3 to 10% and the O2 from 18 to 10%. The degree of modification of the interstitial atmosphere increases with the grain m.c. and temperature having typical CO2 concentration of 15-25% and O2 of 2-5% for wet grain.
There are few reports of insect presence in silo-bags. Analysis of data indicates that unfavorable environmental conditions negatively affect insect development. Thus, storage in silo-bags under the analyzed climate conditions help to maintain grain without notable insect populations.
When grain is stored in silo-bags at m.c. that would allow for mold development, the mold activity is lower compared with that of normal atmosphere storage conditions.
Additionally, grain temperature inside the silo-bag is mainly affected by the ambient temperature. Silo-bags have a high heat exchange rate with the air and soil (double surface/volume ratio than regular bins), so no heat damage is observed, even when wet grain is stored in temperate weathers.
The overall results indicate that dry grain (equilibrium relative humidity below 67%) can be stored in silo-bag for more than six months without losing quality (measured as percentage of mold damaged grain, test weight, germination, fat acidity, and nutritional and organoleptic parameters, among others). When grain m.c. increases, commercial quality could be maintained for up to six months in winter time, to less than three months
in summer time. In all cases, maintaining the airtightness of the bag is a key factor for successful storage. A monitoring system for silo-bags based on measuring CO2 concentration was also developed.