Rice Farming

You struggle throughout the season, trying to balance fertility, battling disease and insects, and timing harvest to optimize grain yields and quality. But you’re only partway home.

What you do after harvest in terms of drying and storage can either detract or enhance the efforts you put toward the crop during the growing season, say university food scientists.

To help with the challenge, an increasing number of farmers are turning to controllers that automatically turn fans on and off based on outside temperature and relative humidity. Although the computer-controlled units save time and labor, they by no means replace regular grain sampling.

“It’s not a set and forget type of instrument. It’s a management tool,” says Doug Hartz, who sells SentryPAC controllers through his company Harco in Stuttgart, Ark. You still have to collect probe samples regularly to ensure the stored grain is still in good condition.

Just how many farmers have on-farm drying and storage facilities and how many are using automatic controllers is unknown, says Terry Howell, a University of Arkansas research assistant professor in the Food Science Department. Through a three-year U.S. Department of Agriculture grant, Howell and his UA team will be surveying growers this spring and summer in Louisiana, Texas, Mississippi, Arkansas and Missouri to get a better handle on the subject.

Howell also has been experimenting with automatic controller units to determine their usefulness. Trials using the devices were conducted the past winter using on-farm bins near Grady, England and Hickory Ridge, Ark. Although Howell is still reviewing the data, he says preliminary results show the units worked well.
Based on the information gleaned from the first year, Howell says he hopes to expand the on-farm experiments into other production areas, such as Texas, Arkansas, Missouri and possibly Louisiana this fall.

How dry I am
On-farm rice storage typically involves two steps: drying the rice after harvest and then maintaining rice quality during storage.

For optimum head rice yields, harvest at between 18 percent and 19 percent moisture content, says Terry Siebenmorgen, a University of Arkansas food science professor and coordinator of the rice processing program. If you harvest above 21 percent or 22 percent moisture content, you’ll likely see reductions in head rice yields due to the presence of immature kernels, he says.

And if you let the rice dry to less than 15 percent moisture content in the field, Siebenmorgen says your chances of reduced head yields also increase.

Because the target moisture content level is an average, some kernels on the head will actually have higher moisture levels and some will have lower levels. The drier kernels could be subject to fissuring from rewetting if it rains while they’re still in the field.

Once the grain is in the bins, the goal is to bring the grain temperature and moisture levels down as quickly as possible without overdrying.

Grain moisture levels are directly affected by ambient air conditions. By passing large amounts of dry air through the grain, you can quickly lower grain moisture content.

This balance between air and grain moisture content is called the equilibrium moisture content, or EMC. The EMC is the moisture content that rice will settle to if exposed to air at given conditions for an extended time. If the air temperature and relative humidity correspond to a rice EMC of 12 percent, the grain moisture will eventually reach 12 percent if enough air at those conditions is moved through the grain.

Bringing in large amounts of air with high relatively humidity, such as during the winter, can add moisture to the grain.

“We know through what we experience that grain is a product of the environment it sets in,” Hartz says. “If it’s setting in a wet environment, it gets wet. If it’s setting in a dry environment, it gets dry.”

Siebenmorgen recommends drying rice to 12.5 percent after harvest. If the relative humidity drops during drying, you can quickly take the rice to below 11 percent moisture content, which hurts you two ways, he says.

“You’re pulling water out that represents weight that you could be selling,” Siebenmorgen says.

Taking rice below the target also increases chances of fissuring should you bring high-moisture air through the bins to cool the grain during the winter. The fissures weaken the grain structure and can cause the kernel to break during milling.

Chill out with insect control
But relative humidity and grain moisture are just part of the equation—temperature also comes into play. As part of the USDA grant, Howell is studying insect control since some grain fumigants may be lost during re-registration review required by the Food Quality Protection Act.

During trials the past winter, Howell placed insect eggs and caged live insects into bins and monitored the effects of temperature on them over time.

He and his team found that temperatures below 60 degrees F stopped insect movement and reproduction.
“At 60 degrees, we start seeing a major benefit, and it doesn’t take a whole lot to get it to 60 degrees,” Howell says. “If you get it to 45 degrees, it will kill the insect and have a devastating effect on the eggs that were laid.”

Typically, air temperatures are the coldest after midnight. But Howell says he knows of few farmers who want to get up and turn fans on to cool stored rice during the wee hours of the morning.

So a controller, which automatically switches fans on and off based on temperature and relative humidity, could be a useful tool. But as both Howell and Hartz point out, the controllers don’t eliminate the need to probe and collect samples to ensure you’re maintaining grain quality.

Hotlinks

For more information on rice drying, visit the University of Arkansas at http://www.uaex.edu/Other_Areas/publications/PDF/MP192/MP192_chapter13.pdf.

UA Cooperative Extension covers rice drying concepts as well as other information in MP 283, Rice Drying on the Farm. The publication is available from Arkansas county Extension offices.

Contact Vicky Boyd at (209) 571-0414 or vlboyd@att.net.

Money in the bin Follow proper drying, storage techniques to boost bottom line
By Vicky Boyd Editor
You struggle throughout the season, trying to balance fertility, battling disease and insects, and timing harvest to optimize grain yields and quality. But you’re only partway home. What you do after harvest in terms of drying and storage can either detract or enhance the efforts you put toward the crop during the growing season, say university food scientists. To help with the challenge, an increasing number of farmers are turning to controllers that automatically turn fans on and off based on outside temperature and relative humidity. Although the computer-controlled units save time and labor, they by no means replace regular grain sampling. “It’s not a set and forget type of instrument. It’s a management tool,” says Doug Hartz, who sells SentryPAC controllers through his company Harco in Stuttgart, Ark. You still have to collect probe samples regularly to ensure the stored grain is still in good condition. Just how many farmers have on-farm drying and storage facilities and how many are using automatic controllers is unknown, says Terry Howell, a University of Arkansas research assistant professor in the Food Science Department. Through a three-year U.S. Department of Agriculture grant, Howell and his UA team will be surveying growers this spring and summer in Louisiana, Texas, Mississippi, Arkansas and Missouri to get a better handle on the subject. Howell also has been experimenting with automatic controller units to determine their usefulness. Trials using the devices were conducted the past winter using on-farm bins near Grady, England and Hickory Ridge, Ark. Although Howell is still reviewing the data, he says preliminary results show the units worked well. Based on the information gleaned from the first year, Howell says he hopes to expand the on-farm experiments into other production areas, such as Texas, Arkansas, Missouri and possibly Louisiana this fall. How dry I am On-farm rice storage typically involves two steps: drying the rice after harvest and then maintaining rice quality during storage. For optimum head rice yields, harvest at between 18 percent and 19 percent moisture content, says Terry Siebenmorgen, a University of Arkansas food science professor and coordinator of the rice processing program. If you harvest above 21 percent or 22 percent moisture content, you’ll likely see reductions in head rice yields due to the presence of immature kernels, he says. And if you let the rice dry to less than 15 percent moisture content in the field, Siebenmorgen says your chances of reduced head yields also increase. Because the target moisture content level is an average, some kernels on the head will actually have higher moisture levels and some will have lower levels. The drier kernels could be subject to fissuring from rewetting if it rains while they’re still in the field. Once the grain is in the bins, the goal is to bring the grain temperature and moisture levels down as quickly as possible without overdrying. Grain moisture levels are directly affected by ambient air conditions. By passing large amounts of dry air through the grain, you can quickly lower grain moisture content. This balance between air and grain moisture content is called the equilibrium moisture content, or EMC. The EMC is the moisture content that rice will settle to if exposed to air at given conditions for an extended time. If the air temperature and relative humidity correspond to a rice EMC of 12 percent, the grain moisture will eventually reach 12 percent if enough air at those conditions is moved through the grain. Bringing in large amounts of air with high relatively humidity, such as during the winter, can add moisture to the grain. “We know through what we experience that grain is a product of the environment it sets in,” Hartz says. “If it’s setting in a wet environment, it gets wet. If it’s setting in a dry environment, it gets dry.” Siebenmorgen recommends drying rice to 12.5 percent after harvest. If the relative humidity drops during drying, you can quickly take the rice to below 11 percent moisture content, which hurts you two ways, he says. “You’re pulling water out that represents weight that you could be selling,” Siebenmorgen says. Taking rice below the target also increases chances of fissuring should you bring high-moisture air through the bins to cool the grain during the winter. The fissures weaken the grain structure and can cause the kernel to break during milling. Chill out with insect control But relative humidity and grain moisture are just part of the equation—temperature also comes into play. As part of the USDA grant, Howell is studying insect control since some grain fumigants may be lost during re-registration review required by the Food Quality Protection Act. During trials the past winter, Howell placed insect eggs and caged live insects into bins and monitored the effects of temperature on them over time. He and his team found that temperatures below 60 degrees F stopped insect movement and reproduction. “At 60 degrees, we start seeing a major benefit, and it doesn’t take a whole lot to get it to 60 degrees,” Howell says. “If you get it to 45 degrees, it will kill the insect and have a devastating effect on the eggs that were laid.” Typically, air temperatures are the coldest after midnight. But Howell says he knows of few farmers who want to get up and turn fans on to cool stored rice during the wee hours of the morning. So a controller, which automatically switches fans on and off based on temperature and relative humidity, could be a useful tool. But as both Howell and Hartz point out, the controllers don’t eliminate the need to probe and collect samples to ensure you’re maintaining grain quality. Hotlinks For more information on rice drying, visit the University of Arkansas at http://www.uaex.edu/Other_Areas/publications/PDF/MP192/MP192_chapter13.pdf. UA Cooperative Extension covers rice drying concepts as well as other information in MP 283, Rice Drying on the Farm. The publication is available from Arkansas county Extension offices. Contact Vicky Boyd at (209) 571-0414 or vlboyd@att.net.
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