Summary: Rice transplanted within 1 yard of a termite mound yields 19% more grain on average than rice grown 3 yards away.

Experimental Location: Koh Kong, Kingdom of Cambodia. 11 degrees 37 minutes 3 seconds North Latitude. 102 degrees 58 minutes 50 seconds East Longitude. Koh Kong is a port on the eastern edge of the Indian Ocean.

Climate: Koh Kong has a tropical monsoon climate. Elevation: 9.843 feet = 3 meters above sea level. Average yearly temperature: 80.33 degrees Fahrenheit = 23.68 degrees Centigrade. Monthly temperature range: 78 to 82 degrees Fahrenheit = 24.44 to 27.77 degrees Centigrade. Average yearly rainfall = 75.45 inches = 191.64 centimeters. The monsoon months are June through October (53 inches = 134 centimeters). The dry season is December through February (4 inches = 10 centimeters). The frost-free growing season = 365 days.

Geography: Koh Kong is one of the wildest and most inaccessible provinces in Cambodia. Roads into the Cardamom Mountains are few and poor. Villages are scattered with small populations. Most transportation is along the coast by ship. The Thailand border is about 6 miles north of Koh Kong city.

Agricultural Year: Nitrogen fixing cover crops like velvet bean (Mucuna utilis) can be sown as early as March, although few farmers practice modern agronomy. Rice is planted with the arrival of the monsoon in June. Early harvest starts in November, main harvest is in December, and late rice is gathered in January. Typically, only one crop is grown annually because of the difficulty of drying grain in rainy weather.

Soil Type: Soils on the coastal plain are porous and contain 40% to 60% sand. Soils in the hills are mostly highly weathered clays, low in nutrients and unsuitable for plowing or row crops.

Farm Management: On the coastal plain sow cover crops to add nitrogen and organic matter to the soil. In the mountains grow tree crops. Because of the warm climate and heavy rainfall, it is best to keep fields covered with live plants year-round. Sow orchards and plantations with perennial ground covers to control weeds and prevent erosion.

Experimental Design: 16 live termite colonies were selected for this trial. Rice growing within 1 yard of a termite mound was compared to an equal number of plants 3 yards away. Only 1 season (1955) of harvest data is available so results should not be considered definitive, merely suggestive. A ring 1-yard wide around a termite mound contains approximately 150 rice plants. These were harvested collectively and compared with 150 plants randomly sampled from a similar ring 3 yards away. For convenience, yields are expressed in pounds per acre based on a standard population of 130,680 plants per acre = 43,560 hills x 3 plants per hill. 871.2 is the conversion factor (871.2 x 150 plants = 130,680 plants per acre).

Field Size: Most local farmers grow just enough rice to feed their families. In a good year, a small surplus is available to market. Subsistence farms are small so rice fields usually range from 1 to 2.5 acres = 0.40 to 1 hectare.

Varieties: Local “land races” = unimproved farmers varieties range from 3 to 5 feet tall and yield 1/2 to 1 ton per acre with minimal care. Yields are low but reliable. Native strains have considerable resilience to environmental stress and broad tolerance of insects and diseases.

Termite Mounds: The average termite colony is approximately 9 feet in diameter and 4 1/2 to 5 feet tall. Distribution of live termite mounds averages about 1 per acre = 2 or 3 per hectare. Colony density increases along tree lines: Up to 14 or 15 per hectare = 5 or 6 per acre.

Termite Farming: Local farmers transplant rice seedlings around live termite colonies. Abandoned termite mounds are used to grow pumpkins, melons, and loofa = sponge gourds. Termites gather clay to build their mounds. Clay is ideal for strengthening sandy soils. Local farmers often “mine” dead mounds for their clay. This is hard work as termite clay is difficult to dig and crush into powder. Farmers broadcast termite clay on their fields as fertilizer. Application rates vary widely (1/2 to 1 ton per acre) depending on available mounds and the industry of farmers.

Industrial Uses for Termite Mounds: Termite clay is dense yet surprisingly soft and flexible. Craftsmen use mound clay to make terra cotta pots, tiles, and bricks. The unique properties of termite clay are probably due to the action of organic compounds in termite saliva. Chinese potters add rice flour to clay then ferment the mixture underground for 30 days before use. Chinese masons mix rice cooking water (which contains large amounts of starch) with slaked lime and sand to make mortar for repair of old buildings. These composite materials have improved strength and durability.

Rotation: Progressive farmers use 2-year rotations, alternating rice with some other crop, often beans. Most local farmers grow continuous rice with a short fallow of weeds between seasons.

Cultivation: Conventional fields are plowed before seeding. Plowing is shallow, typically not more than 6 inches deep.

Fertilizer: Average fields receive little or no fertilizer as manure is always in short supply. Good farmers apply a handful of composted manure to each hill when planting, about 3 or 4 scale ounces = approximately 5 tons per acre or about 50 to 65 pounds of nitrogen. Local soils are often deficient in phosphate. Adding small amounts of phosphorus (40 pounds per acre) can double rice harvests.

Rice Seedlings: Average transplants are 40 days old and 8 to 12 inches high with 4 or more leaves. The range in seedling age varies by farm and season. Most transplants are set between 35 and 45 days from seeding.

Spacing: Transplanting is done by women who judge distances by eye. Local custom is to set clumps or “hills” of 3 to 6 seedlings approximately 1 foot = 30 centimeters apart. Average clumps contain 4 or 5 seedlings.

Plant Density: Plant population varies widely by farm and field depending on who is doing the transplanting. Up to 20% of the seedlings die before harvest so average stands range from about 104,000 to 174,000 plants per acre. 139,000 is a good “middle” value. Rice compensates for plant density by producing more or less tillers. Thus, fields with hills spaced 8 inches = 20 centimeters apart can yield nearly the same amount of rice as fields with 15 inches = 38 centimeters spacing.

Weed Control: Local farmers pull weeds by hand or cultivate with hoes. Typical fields are cultivated 4 times, once every 10 to 14 days until rows close. When rice foliage covers the field, weeds are shaded and further hoeing is unnecessary.

Rule-of-Thumb: Under local conditions, every weeding increases rice yields 250 to 500 pounds per acre. If fields are well fertilized (22 tons of cow manure per acre = about 1 pound per square foot) each weeding can boost grain yield by 1,000 pounds per acre if shorter strains of rice are sown. (Native varieties tend to lodge = fall over if given too much nitrogen. Lodging risk increases with height so it is better to plant varieties that do not grow tall).

Agronomy Note: It is possible to control weeds without hoeing if cover crops like velvet bean (Mucuna utilis) are sown. Broadcast rice into flowering velvet beans then immediately cut vines at the soil surface. Rice grows through the decaying mulch. Rice sown into velvet beans yields 2 to 3 tons per acre without plowing, weeding, or fertilizer. Velvet beans fix 150 pounds of nitrogen per acre in 90 days from seeding. (Unfortunately, new ideas are hard to take root. Few local farmers grow cover crops).

Productivity: Typical harvests are small, only 1/2 to 1 ton per acre in most years. Yields tend to be lower on sandy soils and higher on heavier soils because clays contain more nutrients. Local varieties are adapted to produce modest but reliable yields under difficult conditions.

Irrigation: Local farmers rely on monsoon rains to water their crops. During the wet months it rains at least 1 hour daily, more than enough water to grow a good rice crop. Thus, irrigation is unnecessary and rice does not need flooding. This saves money as paddies require considerable labor to build and maintain. Upland rice is easier to grow than polder rice because farmers do not have to work in the mud.

Insecticides: No pesticides were used on experimental rice. Insecticides are not available and small farmers cannot afford agricultural chemicals. Local crops have wide tolerance or resistance to insects and diseases. Vegetation along field borders contain large populations of beneficial predators and parasites. Thus, pest outbreaks are rare and generally self-correcting.

Summary of Experimental Results

Field Rice Yield in Pounds per Acre

741

816

856

834

886

704

874

901

848

872

890

806

905

788

917

893

13,531 Total Weight / 16 termite mounds = 845.6875 pounds per acre.

Termite Mound Rice Yield in Pounds per Acre

904

1015

1103

1078

1175

899

1029

1050

991

978

1017

905

1036

889

1086

1040

16,195 Total Weight / 16 termite mounds = 1,012.1875 pounds per acre.

1,012 mound rice – 845 field rice = 167 difference

(Part / Whole) x 100 = Percent %

(167 part / 845 whole) = 0.1976331 x 100 = 19.76%

Rice grown around termite mounds has a 19% yield advantage.

Commentary: Soil near termite mounds is better than ordinary field soil. Thus, if you need to grow only a few crops, plant your garden within 1 yard of a termite mound.

There is no practical use for the results of this experiment other than the caution to leave termite colonies alone. The insects do no harm and the rice does not seem to mind.

Related Articles: Chemical to Organic Rice Conversion Trials, Trino, Italy 2014 – 2019; French Intensive Rice Agronomy 1930 – 1980; Garden Rice Trials, Paia, Hawaii 1924 – 2020; Intensive Rice Culture Primer; Paddy Rice Agronomy Trials, Trino, Italy 1853 – 1910; Ratoon Rice Trials, Paia, Hawaii 1877 – 1924; Rice and Gram Polyculture, Pondicherry, India 1763 – 1865; Rice Polder Trial, Butler, Pennsylvania 1972; Rice Rotation Trial, Puerto Limon, Costa Rica 1950 – 1973.

Would You Like to Know More? For more information about biological agriculture and rice farming please visit: http://www.worldagriculturesolutions.com — or — send your questions to: Eric Koperek, Editor, World Agriculture Solutions, 413 Cedar Drive, Moon Township, Pennsylvania 15108 United States of America — or — send an e-mail to: http://www.worldagriculturesolutions@gmailcom.

About the Author: Mr. Koperek is a plant breeder who farms in Pennsylvania during the summer and Florida over winter. (Growing 2 generations yearly speeds development of new varieties).

Index Terms: Rice (Oryza sativa japonica); Monsoon Rice; Termite Mounds; Upland Rice; Velvet Bean (Mucuna utilis).

Original Publication Date: February 1955, Koh Kong, Cambodia.

Update: June 2023, Homestead, Florida.

Author’s Note: WordPress is hostile to scientific and technical publishing. There is no way to align columns to make tables. There is no TAB key and the software is incompatible with Microsoft Word. I have complained repeatedly to the WordPress “Happiness Engineers” without result. I apologize for the klutzy numerical formatting but this is the best that I can do.