Rice Farming

Sacramento Valley rice grower Al Montna loves to look out his back door in the winter and see water fowl enjoying his winter-flooded rice fields. “It’s a tremendous feeling to look across the farm and see these amazing creatures out in the field,” he says.

Montna, a self-described game fowl enthusiast, has been incorporating straw residue and winter flooding his 2,200 acres of rice in Yuba City, Calif., for the past eight to 10 years. The benefits extend beyond providing habitat for migrating ducks and geese. In fact, straw incorporation and winter flooding have altered the way Montna fertilizes his fields and reduced by 50 to 60 pounds per acre the amount of applied nitrogen required to maximize yield.

“We are definitely applying less nitrogen,” Montna says. “We used to use nitrogen rates as high as 180 pounds per acre of applied N, depending on soil quality and other factors. Now we’re down to 125 to 130 pounds on our incorporated fields. We’re looking at an average savings of $10 per acre on our nitrogen inputs, depending on fertilizer prices.”

At the same time, Montna says, incorporating straw residue, followed immediately by a shallow flooding during the winter, helps build soil structure. This, which ultimately provides for less tangible benefits such as higher organic matter, fewer trips through the field, and less wear and tear on equipment.

“The organic matter increases the level of activity of microorganisms in the soil, so we are getting better utilization of nutrients in the soil and applied fertilizers and better availability of micronutrients and other inputs,” he says. “It’s hard to quantify but we know we are getting increased benefits due to the more efficient microbiological activity.”

Incorporation + flooding = 25 to 50 pounds N
A long-term study conducted by University of California, Davis, soil scientist William Horwath and others in the Agricultural Experiment Station reveals growers who incorporate straw and follow with winter flooding of fields help improve the breakdown of residue. As a result, they can reduce nitrogen inputs in the long term an average of 25 to 50 pounds per acre compared to burning.

Horwath says that growers practicing straw incorporation and flooding afterward for three years consistently begin to see a significant benefit to soil nitrogen status and availability. Yields on incorporated and flooded fields after eight years, with no added nitrogen, are 60 percent to 75 percent of normally fertilized fields with straw removed, simply by relying on nitrogen in straw residue returned back to the soil.

“Our research shows that after three years, growers can reduce up to 25 pounds of applied N depending on their soil. And, and by five to eight years, they can reduce it by as much as 50 pounds,” Horwath says. “It’s a cumulative effect, so you need to do it for a number of years before you see the full benefits.”

However, not consistently managing straw residue in the same way year after year may reduce the nitrogen benefit significantly.

Waterfowl: Another beneficiary
In fact, Montna says, growers should not be surprised to have to add additional nitrogen the first couple years because nutrients are bound in the soil’s organic matter before the benefits kick in the third season.
For Montna, his nitrogen savings benefits now average about $10 per acre annually. While not enough to offset the $60 peran acre or so he spends on incorporating and flooding, Montna says the long-term benefits to the soil, as well as the side benefits of creating a winter refuge for migrating birds, make the practice worthwhile. The ducks and geese present actually seem to improve residue breakdown and also feed on weed seeds that help reduce some of the additional weed pressures characterized by straw incorporation.

“Although none of us like the cost—it’s extremely expensive and decreases margins in the short run—in the Sacramento Valley, we’re not going to be burning much straw, so we have to find the most efficient program we can for sustainable yields and sustainable profits.”

Be careful not to overfertilize with straw incorporation
Jack Williams, a UC Cooperative Extension farm advisor in Sutter and Yuba counties, suspects many growers who have turned to straw incorporation may be overfertilizing their fields because they haven’t adjusted rates to account for the nutrients returned to the field with straw residue.

Research shows that incorporating residues adds an average of 75 pounds of nitrogen per acre, compared to about 25 pounds per acre under a burning program. Straw incorporation also adds about 100 pounds of potassium. The residual nitrogen and potassium accumulate and are gradually released over subsequent seasons.

“What you do when you put the straw back in the field is you are saving the nutrients that would otherwise go back up in the air with burning or carried away with straw,” Williams says. “With incorporation, at least initially those nutrients are returned to the soil, so the fertility base increases over time.

“You can easily over-fertilize in a situation like this. We see it often in fields that are very dense at harvest time but have small heads with few kernels on them. The fields look like they will have record yield, but come harvest they’re don’t; they’re just OK.”

Keep close tabs on fertility during growing season
Montna says figuring out optimum fertilizer levels once he moved to straw incorporation was a gradual process. Using soil and leaf analysis at critical periods of plant growth, along with visual analysis of leaf color, he kept a close tab on nutrient levels and began backing off gradually the third year until a balance was achieved between inadequate and excess nitrogen.

“Once you start to overfertilize you know it, because the rice grows very tall, it can have some blanking and it also lodges and goes down,” he says. “You can tell by the appearance in the field and just by trial and error whether you’re overfertilizing. So we started backing off the next year little but little. It takes two or three years to get the optimum fertilizer for the optimum yield.”

Montna says it’s important growers by the third year learn to expect the fertilizer response from straw incorporation and flooding and back off early fertilizers to allow for the response later in the season.

“Don’t fertilize early. You have to know it will kick in and you have to trust it,” he says. “It will happen and it happens about the third year. The first two years you’re adding more fertilizer but by the third year you have to start backing off or else it will get you.”

For questions or comments about this article, contact Rice Farming editor Vicky Boyd at (209) 5710-0414 or vlboyd@att.net.

$$$$ Profit tip:
By the third year of straw incorporation, begin backing off of nitrogen rates. Use soil and leaf analysis during critical plant growth stages as well as visual leaf color assessment to determine actual fertility. Eventually, the incorporated straw should provide 50 to 60 pounds of N or about a $10-per-acre fertilizer savings.

Waste product yields green benefits Though costly, incorporating straw may provide nitrogen fertililzer savings
By Marni Katz
Sacramento Valley rice grower Al Montna loves to look out his back door in the winter and see water fowl enjoying his winter-flooded rice fields. “It’s a tremendous feeling to look across the farm and see these amazing creatures out in the field,” he says. Montna, a self-described game fowl enthusiast, has been incorporating straw residue and winter flooding his 2,200 acres of rice in Yuba City, Calif., for the past eight to 10 years. The benefits extend beyond providing habitat for migrating ducks and geese. In fact, straw incorporation and winter flooding have altered the way Montna fertilizes his fields and reduced by 50 to 60 pounds per acre the amount of applied nitrogen required to maximize yield. “We are definitely applying less nitrogen,” Montna says. “We used to use nitrogen rates as high as 180 pounds per acre of applied N, depending on soil quality and other factors. Now we’re down to 125 to 130 pounds on our incorporated fields. We’re looking at an average savings of $10 per acre on our nitrogen inputs, depending on fertilizer prices.” At the same time, Montna says, incorporating straw residue, followed immediately by a shallow flooding during the winter, helps build soil structure. This, which ultimately provides for less tangible benefits such as higher organic matter, fewer trips through the field, and less wear and tear on equipment. “The organic matter increases the level of activity of microorganisms in the soil, so we are getting better utilization of nutrients in the soil and applied fertilizers and better availability of micronutrients and other inputs,” he says. “It’s hard to quantify but we know we are getting increased benefits due to the more efficient microbiological activity.” Incorporation + flooding = 25 to 50 pounds N A long-term study conducted by University of California, Davis, soil scientist William Horwath and others in the Agricultural Experiment Station reveals growers who incorporate straw and follow with winter flooding of fields help improve the breakdown of residue. As a result, they can reduce nitrogen inputs in the long term an average of 25 to 50 pounds per acre compared to burning. Horwath says that growers practicing straw incorporation and flooding afterward for three years consistently begin to see a significant benefit to soil nitrogen status and availability. Yields on incorporated and flooded fields after eight years, with no added nitrogen, are 60 percent to 75 percent of normally fertilized fields with straw removed, simply by relying on nitrogen in straw residue returned back to the soil. “Our research shows that after three years, growers can reduce up to 25 pounds of applied N depending on their soil. And, and by five to eight years, they can reduce it by as much as 50 pounds,” Horwath says. “It’s a cumulative effect, so you need to do it for a number of years before you see the full benefits.” However, not consistently managing straw residue in the same way year after year may reduce the nitrogen benefit significantly. Waterfowl: Another beneficiary In fact, Montna says, growers should not be surprised to have to add additional nitrogen the first couple years because nutrients are bound in the soil’s organic matter before the benefits kick in the third season. For Montna, his nitrogen savings benefits now average about $10 per acre annually. While not enough to offset the $60 peran acre or so he spends on incorporating and flooding, Montna says the long-term benefits to the soil, as well as the side benefits of creating a winter refuge for migrating birds, make the practice worthwhile. The ducks and geese present actually seem to improve residue breakdown and also feed on weed seeds that help reduce some of the additional weed pressures characterized by straw incorporation. “Although none of us like the cost—it’s extremely expensive and decreases margins in the short run—in the Sacramento Valley, we’re not going to be burning much straw, so we have to find the most efficient program we can for sustainable yields and sustainable profits.” Be careful not to overfertilize with straw incorporation Jack Williams, a UC Cooperative Extension farm advisor in Sutter and Yuba counties, suspects many growers who have turned to straw incorporation may be overfertilizing their fields because they haven’t adjusted rates to account for the nutrients returned to the field with straw residue. Research shows that incorporating residues adds an average of 75 pounds of nitrogen per acre, compared to about 25 pounds per acre under a burning program. Straw incorporation also adds about 100 pounds of potassium. The residual nitrogen and potassium accumulate and are gradually released over subsequent seasons. “What you do when you put the straw back in the field is you are saving the nutrients that would otherwise go back up in the air with burning or carried away with straw,” Williams says. “With incorporation, at least initially those nutrients are returned to the soil, so the fertility base increases over time. “You can easily over-fertilize in a situation like this. We see it often in fields that are very dense at harvest time but have small heads with few kernels on them. The fields look like they will have record yield, but come harvest they’re don’t; they’re just OK.” Keep close tabs on fertility during growing season Montna says figuring out optimum fertilizer levels once he moved to straw incorporation was a gradual process. Using soil and leaf analysis at critical periods of plant growth, along with visual analysis of leaf color, he kept a close tab on nutrient levels and began backing off gradually the third year until a balance was achieved between inadequate and excess nitrogen. “Once you start to overfertilize you know it, because the rice grows very tall, it can have some blanking and it also lodges and goes down,” he says. “You can tell by the appearance in the field and just by trial and error whether you’re overfertilizing. So we started backing off the next year little but little. It takes two or three years to get the optimum fertilizer for the optimum yield.” Montna says it’s important growers by the third year learn to expect the fertilizer response from straw incorporation and flooding and back off early fertilizers to allow for the response later in the season. “Don’t fertilize early. You have to know it will kick in and you have to trust it,” he says. “It will happen and it happens about the third year. The first two years you’re adding more fertilizer but by the third year you have to start backing off or else it will get you.” For questions or comments about this article, contact Rice Farming editor Vicky Boyd at (209) 5710-0414 or vlboyd@att.net. $$$$ Profit tip: By the third year of straw incorporation, begin backing off of nitrogen rates. Use soil and leaf analysis during critical plant growth stages as well as visual leaf color assessment to determine actual fertility. Eventually, the incorporated straw should provide 50 to 60 pounds of N or about a $10-per-acre fertilizer savings.
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