Rice: A Journey from Planting to Rice Flour


Adam Roberts,
Bay State Milling Company's Brenden Olson in a rice field during a 2018 supplier visit in California.

Rice is one of the most important food staples on the planet, as it is currently responsible for feeding roughly half of humanity. The key to the overall supply and demand picture resides in most of the countries in Southeast Asia, where combined, represent the largest production and consumption points globally. The rest of the world produces rice mainly to satisfy that demand, but also for their own domestic consumption.

Rice has 3 classes that represent the length of the kernel, short grain, medium grain, and long grain. These classes have their own unique varieties, quality attributes, characteristics, and uses, all of which help define the regions of production and demand points.

When rice is harvested from the field, the grain is designated as paddy rice. In its raw form, the kernel of rice is enclosed by a hard bearded husk, which must be removed before being consumed by humans. The process by which this is removed has been dubbed rice milling, a term many wrongly confuse with the actual milling of the rice kernel into flour, which is actually a separate process and demand point all together.

Once the husk is removed, all rice, regardless of class, is now classified as brown rice, due to the fact that the bran layer is still present and is brown. The next step for rice millers is to remove the bran, which once accomplished, now classifies the seed to its most popular form, white rice. For most involved, the story ends here, whole kernel white and brown rice is then shipped across globe and consumed in multitude of ways.

For rice flour millers, the story is just beginning, for their interest lies mainly in the byproduct of this rice milling process, which are called brokens. De-hulling, handling, and cleaning takes a toll on the rice kernel, all of which result in broken kernels, hence the term brokens. These brokens become ever more apparent after the bran has been removed as the kernel loses much of its stability following that removal. These brokens are further segregated into 2 separate streams called second heads and brewers, both of which are actual broken kernels with different parts and sizes. The rice flour millers prefer these byproducts to mill into flour because they are significantly cheaper than buying whole white rice.

In the United States, rice is grown in the southern delta region and the Sacramento valley in California. Both of these areas were traditional flood plains that are now irrigated, and along with their soil profiles, are ideal for growing rice. Roughly 70% of the total acreage is in long grain rice as it is the main driver of global and domestic consumption. Over 50% of the long grain rice acres are in Arkansas, while the rest is in the surrounding states of Louisiana, Mississippi, Missouri and Texas. The remaining 30% of total acres are heavily skewed towards medium grain rice and is the vast majority of all the acres in the Sacramento valley. Short grain rice is also planted in the Sacramento valley and as whole, is around 1% of the total acreage in the U.S.

In the Sacramento valley, medium grain and short grain rice are planted in Butte, Sutter, Yuba, and Yolo counties. Compared to the sandier soils in the delta, most of the Sacramento valley sits on dense clay, which prevents water from soaking into the earth. This is ideal for the flood irrigation technique used for rice as it helps the deter weeds and pests.

Rice field life cycle


Once the rice has been harvested, the straw from the rice plant left in the field is plowed into the ground, and the field is flooded with a few inches of water to aid in decomposition. This also creates an instant wetland with food and water for almost 230 different wildlife species, including millions of migratory birds. If the field experienced blight or other controllable plant diseases during the growing season the farmer can get permission to burn the field instead, to prevent recurrence. Sometimes a winter cover crop such as Purple Vetch is planted, which helps to replenish the soil.


Fields are drained and allowed to dry, and then prepared for planting. In March, the top few inches of ground are plowed up to speed drying, disking later breaks up the larger clods.


The fields are leveled using GPS. Some fields are so large that the curvature of the earth needs to be taken into account, and so the corners of the plot need to actually be slightly higher than the center in order to assure that the ground is uniformly flat. GPS makes it possible to level to within 1/10 of an inch of error.


Fertilizer is applied, and then the seedbed is finished with corrugated rollers that eliminate remaining clods, pack the soil, and cover the field in shallow grooves. The field is flooded with 4 inches of water prior to sowing. Paddy rice for planting is soaked in water for 1-3 days, in order to begin the process of germination and to help the seed sink in the flooded field. The rice is then sown by small, low-flying, single engine propeller planes that drop it over the fields where it settles into the grooves left by the corrugated rollers.


The rice takes 4-6 months to mature, depending on the varietal. Different varietals of short and medium grain rice can take between 120 to 185 days to grow. Additional fertilizers or pesticides may be added during this phase, if the field requires treatment.


By the end of summer, long panicles of grain “head out” of the stalks, beginning to show at the tops of the plants, and are typically ready to harvest by end September. Fields are drained a couple of weeks before harvest and allowed to dry before mechanized harvesting begins. Each acre will yield an average of 8,000 lbs. of rice, with lower yield for organic rice and specialty varietals.

Milling and Storage

The paddy rice, still in its husk, can be stored year-round as long as it’s well ventilated to prevent buildup of moisture. The milling season is typically at its peak in the months immediately after harvest, when export demand for the new crop is strongest, but millers work to spread the milling out over the whole year in order to help manage fixed costs.

 This blog was a team effort from the Mini-Milling and Blending Supply Chain Team.