New research will help improve grain storage in India

A small research study could yield big results for the agriculture industry in India. Kent Rausch, an associate professor in the University of Illinois Department of Agricultural and Biological Engineering (ABE) worked with Haryana Agricultural University (HAU) on a limited study to determine quality changes in wheat stored in hermetic silo bags. The study was funded by the Archer Daniels Midland Institute for the Prevention of Postharvest Loss.

Wheat stored in the more conventional metal bins and jute bags typically used for storage was also analyzed. Because high temperatures and high humidity in some of the main crop production areas of India promote microbial and insect proliferation in food grain, metal bins and jute bags are often ineffective and unsafe. An estimated 7 to 15 percent of grains are damaged due to moisture, insects, rodents, and fungi.

Faculty and students from HAU worked in collaboration with Rausch and ABE researchers Vijay Singh, Grace Danao, and Marvin Paulsen. The study was conducted in a lab on the campus of HAU. Haibo Huang, a postdoctoral research associate in ABE, met with the HAU collaborators in New Delhi to go through the research plan in detail.

Twenty jute bags, two metal storage bins, and four hermetic silo bags were used in the study. Each jute bag held 100 kilograms of grain, and the bags were stored in two stacks of 10. In the jute-bag stacks, sensors were installed in the upper, middle, and bottom bags. Each storage bin and each silo bag held one ton of grain. Sensors were installed in three different positons in every bin and silo bag – upper, middle, and bottom layers. Temperature and relative humidity were measured every hour, and each sensor was connected to a USB cable so recorded data could be downloaded to a laptop. Wheat samples were collected at the beginning of the experiment and at one-month intervals thereafter.

“Insects and mold are the two major problems in grain storage,” said Rausch. “Insects have easy access to the metal bins and jute bags. We actually introduced insects into all of the silo bag treatments. We also wanted to test for differences in moisture content so the grains in the metal bins, jute bags, and two of the silo bags were at 12 percent moisture content. The grain in the other two silo bags had 14 percent moisture content.”

The silo bags were the clear winners in the study, said Rausch. “Because they’re hermetically sealed, air can’t circulate. The grain naturally respires and gives off CO₂, which kills insects and prevents mold.

“The researchers knew the exact species and numbers of insects introduced, and they came back at different intervals to evaluate for the various life stages of the insect—egg, larvae, and adult,” he continued. “Insects fared pretty well in the jute bags, and even in the metallic bins, because they weren’t air tight. But there was nothing in the silo bags; all the insects died.”

Rausch noted that the moisture content did not prove to be a problem. “If the grain is too dry, it doesn’t respire and it doesn’t make its own C0₂ so it’s not protected. That’s why we tested it at two different moisture levels. Both worked reasonably well.”

Rausch said when they visited HAU for a follow-up meeting, it was noted that the hermetic silo bags could also be used to store mustard seed, a high-value crop in India.
“So we have another application that should probably be evaluated. These bags could also be used for rice or just about any crop that respires. Now we need to determine if they are cost effective and look at some of the other pluses and minuses.”

Rausch said he believes ADM has a strong interest in continuing the study.
“We need to move off the campus to surrounding villages and start showing how the silo bag could work for smallholder farmers and villages.”