سایت منابع جزوات ارشد دکتری

By Preston Sullivan

NCAT Agriculture Specialist

April 2003

In general, rice planting dates, seeding rates, preferred varieties, and harvesting

methods vary among regions, but they are largely the same for

conventional and organic systems. The state or county Cooperative Extension

Service provides such general information. This publication focuses

on the special considerations relevant to organic rice production.

Organic Production

Organic systems avoid the use of synthetic fertilizers, pesticides, and

growth regulators. Instead they rely on crop rotations, crop residues,

animal manures, legumes, green manures, off-farm wastes, mechanical

cultivation, mineral-bearing rocks, and biological pest control to maintain

soil health, supply plant nutrients, and minimize insects, weeds, and

other pests.

While anyone can choose to grow organically, federal regulations now

control the labeling and marketing of all organic products. If you plan to

represent your farm products as organic, you must be certified. To learn

about the steps toward organic certification, see ATTRA.s Organic Farm

Certification and The National Organic Program.

Weed control and soil fertility are the principal challenges associated with organic rice production.

Primary weed-control practices include crop rotations, land leveling, seedbed preparation, water

management, and rotary hoeing.

To reduce weed pressure, lengthen the standard two-year rice/soybean rotation to a three-year

rotation of rice/soybeans/grain crop (sorghum, wheat, corn, etc.). The longer rotation allows

additional time to break weed life cycles and reduce the number of weed seeds in the soil. Other

weed-control options center on the use of field flooding to suppress weeds directly and to give the

crop a competitive advantage. Flooding will be more effective if fields are precision leveled. Leveling

makes the water depth uniform and facilitates rapid flow onto and from the field (1).

CURRENT TOPIC

Organic and reduced-input producers have developed some innovative means for growing rice

without chemicals. Some examples follow:

. An Arkansas organic rice producer rotates his crops in the following sequence:

rice/soy-beans/winter wheat/summer fallow. His weed-control plan includes timely

water management, precision-leveled fields to ensure uniform flooding depth; levees

on a 1.0- to1.5-inch drop; and a pumping system that floods and drains fields

rapidly. After applying composted barnyard manure and drilling rice seed,

he floods to 4 inches to drown weeds. The water is allowed to stand for 10 to 12

days. He controls water weevils either by draining and drying the ground until it

firms up or by a fresh water flush. This producer has been raising organic rice

for 18 years. He declined to serve as a contact person and prefers that we not use

his name.

. The Lundbergs of Richvale, California, are large-scale organic rice producers who

use a purple vetch green-manure crop as their nitrogen source (2). They mow the

vetch in spring to 6 inches and drill rice seed directly into the vetch mulch (3). Following

planting, they flood the field to kill the vetch and germinate the rice

seed. Following germination, they drain the field and allow it to dry, and then the

field is re-flooded for the season. Weed control is based primarily on water-level

control. Some weediness is tolerated, reducing yields in some years. Water weevils

seldom present a problem, since the Lundbergs practice dry planting. The Lundbergs

harvest their rice at 17% moisture, disk the straw down, and fallow the ground for

a year. Permanent levees are maintained with a sickle mower.

. Arkansas grower Steven Rutledge uses a wheat/rice relay intercrop that reduces his

input costs $50 to $70 per acre and requires no land preparation or herbicides (4). By

applying pre-flood fertilizer with a ground rig, he saves an additional $4 to $8 per

acre over aerial application costs. He plants (by airplane) between 140 and 180

pounds of seed per acre of a short-season rice variety, into standing wheat at the

milk stage. He then floods the field to sprout the seed. After germination, he drains

the field to allow the rice to peg down, and to dry the ground for wheat harvest.

Rutledge believes that flooding the wheat in the milk stage does it no harm. By

wheat harvest, the rice is only a few inches high.too low for damage by the combine

header. After wheat harvest, he applies nitrogen fertilizer by ground rig.of

course, this fertilizer application would not be allowed in an organic system. A

major advantage to his system is the weed control provided by the wheat straw.

Rutledge has used this system since the late 1970s and has never failed to get a rice

stand.

. Rice growers in Arkansas (5) are capturing winter rainwater and allowing it to stand

in their fields. They close the levees in early November and don.t drain the fields

until early February or March. The benefits of this include more rapid decomposition

of stubble, less soil erosion, increased habitat for waterfowl, and some control of

red rice, a major weed problem. Other Arkansas growers are trying to suppress red

rice by water- seeding their rice crop into tilled fields that have been flooded. Waterseeding

suppresses red rice germination by keeping the soil anaerobic. The final

seedbed must be prepared immediately prior to flooding to kill those red rice seeds

that have already germinated. The University of Arkansas recommends using only

pre-germinated rice seed when water-seeding (6). Wintering ducks are also a major

factor in managing red rice. An Arkansas study showed that duck foraging resulted

in a 97% reduction of red and white rice seed in a winter-flooded field (1). Ducks

and geese also feed on such weeds and seeds as barnyard grass, smartweed, beggar

tick, crabgrass, panicum, and other agronomic pest species.

Maintaining soil fertility in organic cropping typically involves some combination of crop rotation

with deep-rooted legume crops or green manure/cover crops, and applying rock minerals, animal

manures, composts, and other approved organic amendments. Leguminous green-manure crops

can supply 30 to 50 percent of the nitrogen needs of high-yielding rice varieties. The availability of

green-manure nitrogen depends on the quantity, quality, and type of green-manure crop; the time

and method of application; soil fertility; and cropping method (7).

USDA researcher Dr. Seth Dabney (8) studied rice production in two Louisiana fields that had

been green-manured with subterranean clover. The sub-clover provided enough nitrogen to produce

high rice yields without additional nitrogen at one location, but the other required 50 pounds

of additional nitrogen per acre to achieve similar yields. He also demonstrated that the sub-clover

would naturally re-seed itself following no-till-planted rice. The reseeded sub-clover stands were

more productive than those that were manually seeded. These results verified what other Louisiana

researchers had seen in re-seeded sub-clover stands.higher re-seeded-stand densities and

earlier growth commencement in the fall. In addition, clover-planting costs were eliminated with

the naturally re-seeded stand.

Because rice is grown in flooded fields, insect pests are usually a minor problem. Fall armyworm

and chinchbug populations can build up in the absence of flooding, but are easily controlled by a

flush of water. Rice water weevil and rice stinkbugs are less affected by flooding. Timely planting,

variety selection, and cultural practices to suppress weeds and encourage dense stands of rice will

help control stinkbugs and water weevils (9).

Rice blast and sheath blight diseases are often controlled by appropriate variety selection. Excessive

nitrogen levels, rarely a problem in organic production, can encourage sheath blight, kernel smut,

and other diseases.

Economics

Organic rice is typically sold in niche and specialty markets, where it commands a price two to

three times higher than that of conventionally grown rice (10). But while it sells at higher prices,

organic rice also costs more to produce (11). Recent cost information, however, is difficult to find.

In 1992, the University of California Cooperative Extension Service calculated the costs of organic

rice production in the Sacramento Valley for both water-seeded and no-till, drill-seeded rice (12,

13). The no-till, drill-seeded organic rice cost $653.65 per acre to produce, and the water-seeded

organic rice cost $677.94 per acre.

More recently, Missouri grower Andy Turman calculated that organic rice cost $22 more per acre

to produce than conventionally grown rice in 2000 (14). He attributed the difference to fertilizer

shipping costs, extra tillage, and labor for hand weeding. (Turman uses furrow irrigation, rather

than flood irrigation, requiring 30% to 50% less water.)

Yields from organic rice production tend to be lower than conventional yields. Turman calculated

his yield to be one-third that of a conventional rice crop. Similarly, Lowell Farms of Texas estimate

their organic rice yield at 50% to 60% of conventional yields (15).

While marketing organic products presents a challenge, there are some places to find buyers for

your crops. Many .conventional. farm magazines and websites can be good sources of information

on buyers of organic crops. The ATTRA publication Marketing Organic Grains identifies several

organic grain buyers.

The Organic Consumers Association is a public-interest organization dedicated to building a healthy,

safe, and sustainable system of food production and consumption. They act as a global clearinghouse

for information and provide grassroots technical assistance. Their website includes information

on a host of organic issues. Contact:

The Organic Consumers Association

6101 Cliff Estate Rd.

Little Marais, MN 55614

Tel: 218-226-4164

Fax: 218-226-4157

E-mail: info@organicconsumers.org

FarmWorld <http://www.farmworld.com/> was established as a worldwide trading site for information

on agricultural commodities and products. The site offers free buy/sell/trade listings in

a variety of categories, including grains.

Growers also can list their products in the Organic and Natural Foods News Industry Buyer.s

Guide, available online at <http://www.organicandnaturalnews.com/>.

Sustainable Farming Connection <http://www.ibiblio.org/farming-connection/links/home.htm>

provides useful information on organic farming, including links to a number of marketing resources.

agAccess Information Services offers business, marketing, and strategic planning services as well as

market research. Services are oriented toward specialty and organic producers. Contact:

agAccess Information Service

424 Second St., Suite B

Davis, CA 95616

Tel: 530-756-0778

Fax: 530-756-0484

E-mail: aginfo@ceresgroup.com

1. Sullivan, Preston, and Robert Strader. 1993. Precision-Leveled Fields Prove Excellent

Long-Term Investments. Rice Farming. April. p. 28-29, 32.

2. Anon. No date. A Partnership With Nature: The Rice Farming Techniques of Lundberg

Family Farms. http://www.lundberg.com/partnership/text.html.

3. Kotzsch, Ronald E. 1988. Close-up on organic rices. East West. April. p. 14-21.

4. Cook, Klink. 1994. Doublecropped rice/wheat cuts weed control costs. Mid-South Farmer.

May. p. 8-9.

5. Bennett, David. 1996. Can Waterfowl Help Rid Your Fields Of Red Rice. Delta Farm Press.

February 16. p. 16-17.

6. Guy, Charlie B. 1993. Consider Water Seeding For Control Of Red Rice. Delta Farm Press.

April 2. p. 8.

7. Westcott, M.P., and D.S. Mikkelsen. 1988. Effect of green manure on rice fertility in the

United States. p. 257-274. In: Green Manure in Rice Farming: Proceedings of a Symposium

on Sustainable Agriculture. International Rice Research Institute, Philippines.

8. Dabney, S.M., et al. 1989. Subterranean clover cover crop used to increase rice yield.

Agronomy Journal. Vol. 81, No. 3. p. 483-487.

9. Anon. 1989. 1989 Rice Production Guidelines. Texas Agricultural Extension Publication

D-1253. Texas A&M University. College Station, TX. 72 p.

10. McClung, Anna, and Christine Bergman. No date. Potential for Using Asian Rice

Germplasm in Organic Culture in the U.S. USDA-ARS Rice Research Unit, Beaumont,

TX. http://usda-ars-beaumont.tamu.edu/asian.html.

11. Lundberg Family Farms. 1990. Lundburg Rice Paper. Vol. 6, No. 2. October. p. 1-2.

12. Williams, J., et al. 1992. U.S. Cooperative Extension Sample Costs to Produce Organic

Rice in the Sacramento Valley. Water Seeded. California Extension Service. 23 p. http:/

13. Williams, J., et al. 1992. U.S. Cooperative Extension Sample Costs to Produce Organic

Rice in the Sacramento Valley. No-till Drill Seeded. California Extension Service. 23 p.

14. Turman, Andy. No date. Organic Rice Production Project. http://www.fao.org/ag/maga

Further Resources:

University of California

Agriculture & Natural Resources

By Preston Sullivan

NCAT Agriculture Specialist

Edited by Paul Williams

Formatted by Cynthia Arnold

April 2003

The electronic version of Organic Rice Production is

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