Nitrogen as an Alternative to Phosphine

Abstract

The use of nitrogen gas in grain storage has a history of over 30 years. However, it wasn't until the recent emergence of economically efficient pressure swing adsorption (PSA) and membrane separation (MS) nitrogen production equipment that this technology became viable for grain storage. This study first conducted laboratory bioassays over 4, 3, and 2 weeks on wheat, barley, oats, lupin, and canola seeds, exposing them to environments of 25 ℃, 30 ℃, and 35 ℃ with nitrogen concentrations of 99%, 98%, and 97%. The study focused on assessing the adult and immature stages of Trogoderma variabile, Tribolium castaneum, Rhyzopertha dominica, and Sitophilus oryzae. Subsequently, in-field verification was carried out at the Lake Grace terminal and the Cooperative Bulk Handling (CBH) grain export terminal in Albany, evaluating the efficacy of controlling various storage grain pests and field pests in wheat, barley, and canola seeds, as well as assessing the quality of treated grains. The results showed that pest mortality increased with decreasing oxygen concentration, increasing exposure time, and temperature. However, under low-temperature conditions, nitrogen-rich low-oxygen treatment did not achieve 100% mortality of Trogoderma variabile larvae. There was no significant difference in the efficacy of controlling storage pests resistant or sensitive to phosphine. Canola seeds showed better control efficacy compared to other grains. Furthermore, the moisture content, protein, oil content, starch, and grain color quality indicators of various grains were unaffected. A commercially scalable nitrogen-rich low-oxygen application model was successfully developed, providing a solution for controlling pests resistant to phosphine and meeting the growing market demand for insect-free and chemical residue-free grains.

Keywords

• controlled atmosphere storage
• pest management
• phosphine resistance
• grain quality
• application model