System Design and Validation of a Wireless Sensor Monitoring System in Silage

Abstract

Silages have become the main feed for ruminants and biogas production and are often stored in large stacks. When a silo is filled, a plastic cover is laid out and fermentation begins. From this moment, the entire silo becomes a black box for farmers: if any spoilage due to air breaches takes place, it often will only be recognized when the stack is opened and massive losses have already occurred. In the present work, a wireless sensor monitoring system for silage stacks is designed that shall detect changes in the silage environment until feedout and can therefore enable the farmer to prevent biomass losses. The nail-shaped node design offers elevated feed safety opportunities and can be easily removed before feedout. For data transmission, LoRaWAN is used in combination with a hardware-based timer. The sensor nodes are able to endure the full extent of a silage stack storage period in a full-scale silage test of approximately 40 weeks without battery shortage. The resulting measurements show that CO2, O2, relative humidity and temperature sensors at the silage surface can detect changes within the silage environment due to air breach. Temperatures in stable regions beneath 40 cm can be detected and give information about long-term stability.