Rice polyculture is the cultivation of rice and another crop simultaneously on the same land. The practice exploits the mutual benefit between rice and organisms such as fish and ducks: the rice supports pests which serve as food for the fish and ducks, while the animals' excrement serves as fertilizer for the rice. The result is an additional crop, with reduced need for inputs of fertilizer and pesticides. In addition, the reduction of pests such as mosquito larvae and snails may reduce mosquito-borne diseases such as malaria and dengue fever, and snail-born parasites such as the trematodes which cause schistosomiasis. The reduction in chemical inputs may reduce environmental harms caused by their release into the environment. The increased biodiversity may reduce methane emissions from rice fields.
Some rice-animal polycultures, including rice-fish systems in China and rice-duck farming in China and Southeast Asia, have been practised for centuries, while others have been developed more recently. The use of intercropping with plants such as maize and soybean, planted on levees between rice terraces, may help to reduce rice pests such as brown planthopper.
The simultaneous cultivation of rice and fish is thought to be over 2,000 years old. Ancient clay models of rice fields, containing miniature models of fish such as the common carp, have been found in Han dynasty tombs in China. [2] The system originated somewhere in continental Asia such as in India, Thailand, northern Vietnam and southern China. The practice likely started in China since they were early practitioners of aquaculture. [1]
Rice-duck farming is traditional in Southeast Asia; in China it is sometimes combined with fish on the same terraces. [3]
Several animal species have been raised in rice fields, offering the possibility of multiple crops and a variety of ecological and agro-ecological benefits. Pairings such as rice and fish or rice and ducks form a mutualistic relationship: they both benefit from growing together. The rice provides the fish with shelter and shade and a reduced water temperature, along with herbivorous insects and other small animals that feed on the rice. [7] Rice benefits from nitrogenous waste from the fish, while the fish reduce insect pests such as brown planthoppers, diseases such as sheath blight of rice, and weeds. [7] By controlling weeds, competition for nutrients is decreased. CO2 released by the fish may be used in photosynthesis by the rice. [4]
Rice is widely grown using periodic flood irrigation, restricting the options for polycultures with other plants. Maize and soybeans are more profitable than rice, and they can be grown on the earth levees between rice terraces. There is some evidence that such intercropping reduces numbers of brown planthopper, a serious pest of rice, though it does not enhance numbers of natural enemies such as parasitoid wasps and insect predators. [8]
One crop that can be grown directly with irrigated rice is water spinach (Ipomoea aquatica, Convolvulaceae family); it is widely consumed as a vegetable in Asia. Experimental intercropping with rice reduced rice diseases and pests: rice sheath blight was cut by 17-50%, while rice leaf folder caterpillars were reduced by 5-58%, and rice yield was increased. [9] Similarly promising experiments have been carried out with pickerelweed. [10]
As shown in the table, a large number of rice polycultures, with both animals and plants, have been used or studied experimentally.
Approach | Taxonomy | Location | Notes |
---|---|---|---|
Rice-fish | Teleost | China | Ancient system with common carp; from 1935, also other species inc. black carp, grass carp, silver carp, bighead carp [2] |
Rice-fish | Teleost | Asia | Mozambique tilapia [1] |
Rice-fish | Teleost | Egypt | Nile tilapia [1] |
Rice-duck | Bird | China, Malaysia, South Korea, Vietnam, etc. | Surface must be even; water depth must suit ducks; young ducks best as they don't nibble rice leaf tips. [14] |
Rice-fish-duck | Vertebrates | China | Ancient multiply-mutualistic system [3] [12] [13] |
Rice-fish-duck-azolla | Vertebrates, ferns | Indonesia | Azolla (water fern) fixes nitrogen, contributing to plant growth and productivity. [11] [15] |
Rice-crayfish | Arthropod | China | red swamp crayfish, from 1980s [6] |
Rice-prawn | Arthropod | Indonesia | Freshwater prawn Macrobrachium rosenbergii ; may work best at moderate stocking density. [16] Deepwater rice, prawns, and fish: increases rice production. [17] |
Rice-crab | Arthropod | China | Chinese mitten crab, from 1980s [6] The crabs feed on zooplankton. [18] |
Rice-turtle | Reptile | China | softshell turtle, from 1980s [6] |
Rice-maize | Flowering plant | China | Maize on levees may reduce planthopper numbers [8] |
Rice-soybean | Flowering plant | China | Soybean on levees may reduce planthopper numbers [8] |
Rice‑water spinach | Flowering plant | China | Successful experiments [9] |
Rice-pickerelweed | Flowering plant | China | Experimentally reduces sheath blight and leaf folders, and increases rice yield. [10] |
Rice polycultures offer the potential to help meet multiple sustainability goals in the face of pressures such as population growth and climate change. They may help maintain ecosystem diversity, produce food sustainably with reduced inputs, and adapt to changes in the environment. The inclusion of crops that provide high-quality protein, such as fish, can help to improve people's diet. In addition, environmental impacts from pesticides and fertilizers can be reduced, while for the farmer, the extra crop increases revenue and may also increase rice productivity. [19]
Agriculture encompasses crop and livestock production, aquaculture, fisheries, and forestry for food and non-food products. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to live in cities. While humans started gathering grains at least 105,000 years ago, nascent farmers only began planting them around 11,500 years ago. Sheep, goats, pigs, and cattle were domesticated around 10,000 years ago. Plants were independently cultivated in at least 11 regions of the world. In the 20th century, industrial agriculture based on large-scale monocultures came to dominate agricultural output.
Aquaculture, also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants. Aquaculture involves cultivating freshwater, brackish water and saltwater populations under controlled or semi-natural conditions, and can be contrasted with commercial fishing, which is the harvesting of wild fish. Aquaculture is also a practice used for restoring and rehabilitating marine and freshwater ecosystems. Mariculture, commonly known as marine farming, is aquaculture in seawater habitats and lagoons, as opposed to freshwater aquaculture. Pisciculture is a type of aquaculture that consists of fish farming to obtain fish products as food.
Rice is a cereal grain, and in its domesticated form is the staple food for over half of the world's human population, particularly in Asia and Africa, due to the vast amount of soil that is able to grow rice. Rice is the seed of the grass species Oryza sativa or, much less commonly, O. glaberrima. Asian rice was domesticated in China some 13,500 to 8,200 years ago, while African rice was domesticated in Africa some 3,000 years ago. Rice has become commonplace in many cultures worldwide; in 2021, 787 million tons were produced, placing it fourth after sugarcane, maize, and wheat. Only some 8% of rice is traded internationally. China, India, and Indonesia are the largest consumers of rice. A substantial amount of the rice produced in developing nations is lost after harvest through factors such as poor transport and storage. Rice yields can be reduced by pests including insects, rodents, and birds, as well as by weeds, and by diseases such as rice blast. Traditional rice polycultures such as rice-duck farming, and modern integrated pest management seek to control damage from pests in a sustainable way.
Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. This practice reduces the reliance of crops on one set of nutrients, pest and weed pressure, along with the probability of developing resistant pests and weeds.
In agriculture, monoculture is the practice of growing one crop species in a field at a time. Monoculture is widely used in intensive farming and in organic farming: both a 1,000-hectare cornfield and a 10-ha field of organic kale are monocultures. Monoculture of crops has allowed farmers to increase efficiency in planting, managing, and harvesting, mainly by facilitating the use of machinery in these operations, but monocultures can also increase the risk of diseases or pest outbreaks. This practice is particularly common in industrialized nations worldwide. Diversity can be added both in time, as with a crop rotation or sequence, or in space, with a polyculture or intercropping.
Organic farming, also known as ecological farming or biological farming, is an agricultural system that uses fertilizers of organic origin such as compost manure, green manure, and bone meal and places emphasis on techniques such as crop rotation and companion planting. It originated early in the 20th century in reaction to rapidly changing farming practices. Certified organic agriculture accounts for 70 million hectares globally, with over half of that total in Australia. Biological pest control, mixed cropping, and the fostering of insect predators are encouraged. Organic standards are designed to allow the use of naturally-occurring substances while prohibiting or strictly limiting synthetic substances. For instance, naturally-occurring pesticides such as pyrethrin are permitted, while synthetic fertilizers and pesticides are generally prohibited. Synthetic substances that are allowed include, for example, copper sulfate, elemental sulfur, and veterinary drugs. Genetically modified organisms, nanomaterials, human sewage sludge, plant growth regulators, hormones, and antibiotic use in livestock husbandry are prohibited. Organic farming advocates claim advantages in sustainability, openness, self-sufficiency, autonomy and independence, health, food security, and food safety.
Companion planting in gardening and agriculture is the planting of different crops in proximity for any of a number of different reasons, including weed suppression, pest control, pollination, providing habitat for beneficial insects, maximizing use of space, and to otherwise increase crop productivity. Companion planting is a form of polyculture.
Intensive agriculture, also known as intensive farming, conventional, or industrial agriculture, is a type of agriculture, both of crop plants and of animals, with higher levels of input and output per unit of agricultural land area. It is characterized by a low fallow ratio, higher use of inputs such as capital, labour, agrochemicals and water, and higher crop yields per unit land area.
Sustainable agriculture is farming in sustainable ways meeting society's present food and textile needs, without compromising the ability for current or future generations to meet their needs. It can be based on an understanding of ecosystem services. There are many methods to increase the sustainability of agriculture. When developing agriculture within sustainable food systems, it is important to develop flexible business process and farming practices. Agriculture has an enormous environmental footprint, playing a significant role in causing climate change, water scarcity, water pollution, land degradation, deforestation and other processes; it is simultaneously causing environmental changes and being impacted by these changes. Sustainable agriculture consists of environment friendly methods of farming that allow the production of crops or livestock without damage to human or natural systems. It involves preventing adverse effects to soil, water, biodiversity, surrounding or downstream resources—as well as to those working or living on the farm or in neighboring areas. Elements of sustainable agriculture can include permaculture, agroforestry, mixed farming, multiple cropping, and crop rotation.
Agroecosystems are the ecosystems supporting the food production systems in farms and gardens. As the name implies, at the core of an agroecosystem lies the human activity of agriculture. As such they are the basic unit of study in Agroecology, and Regenerative Agriculture using ecological approaches.
Intercropping is a multiple cropping practice that involves the cultivation of two or more crops simultaneously on the same field, a form of polyculture. The most common goal of intercropping is to produce a greater yield on a given piece of land by making use of resources or ecological processes that would otherwise not be utilized by a single crop.
Integrated pest management (IPM), also known as integrated pest control (IPC) is a broad-based approach that integrates both chemical and non-chemical practices for economic control of pests. IPM aims to suppress pest populations below the economic injury level (EIL). The UN's Food and Agriculture Organization defines IPM as "the careful consideration of all available pest control techniques and subsequent integration of appropriate measures that discourage the development of pest populations and keep pesticides and other interventions to levels that are economically justified and reduce or minimize risks to human health and the environment. IPM emphasizes the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest control mechanisms." Entomologists and ecologists have urged the adoption of IPM pest control since the 1970s. IPM allows for safer pest control.
In agriculture, polyculture is the practice of growing more than one crop species together in the same place at the same time, in contrast to monoculture, which had become the dominant approach in developed countries by 1950. Traditional examples include the intercropping of the Three Sisters, namely maize, beans, and squashes, by indigenous peoples of Central and North America, the rice-fish systems of Asia, and the complex mixed cropping systems of Nigeria.
Aquaponics is a food production system that couples aquaculture with hydroponics whereby the nutrient-rich aquaculture water is fed to hydroponically grown plants.
Agroforestry is a land use management system that integrates trees with crops or pasture. It combines agricultural and forestry technologies. As a polyculture system, an agroforestry system can produce timber and wood products, fruits, nuts, other edible plant products, edible mushrooms, medicinal plants, ornamental plants, animals and animal products, and other products from both domesticated and wild species.
In agriculture, monocropping is the practice of growing a single crop year after year on the same land. Maize, soybeans, and wheat are three common crops often monocropped. Monocropping is also referred to as continuous cropping, as in "continuous corn." Monocropping allows for farmers to have consistent crops throughout their entire farm. They can plant only the most profitable crop, use the same seed, pest control, machinery, and growing method on their entire farm, which may increase overall farm profitability.
The domestic duck is a subspecies of mallard that has been domesticated and raised for meat and eggs. A few are kept for show, as pets, or for their ornamental value. Almost all varieties of domesticated ducks, apart from the domestic Muscovy duck, are descended from the mallard, which was domesticated in China around 2000 BC.
Shade-grown coffee is a form of the crop produced from coffee plants grown under a canopy of trees. A canopy of assorted types of shade trees is created to cultivate shade-grown coffee. Because it incorporates principles of natural ecology to promote natural ecological relationships, shade-grown coffee can be considered an offshoot of agricultural permaculture or agroforestry. The resulting coffee can be marketed as "shade-grown".
A rice-fish system is a polyculture practice that integrates rice agriculture with aquaculture, most commonly with freshwater fish. It is based on a mutually beneficial relationship between rice and fish in the same agroecosystem. The system was recognized by the FAO in 2002 as one of the first Globally Important Agricultural Heritage Systems.
Rice-duck farming is the polycultural practice of raising ducks as well as growing rice on the same land. It has existed in different forms for centuries in Asian countries including China, Indonesia, and the Philippines, sometimes also involving fish. The practice is beneficial as it yields harvests of both rice and ducks. The two are in addition synergistic, as the rice benefits from being weeded and fertilized by the ducks, and having pests removed, while the ducks benefit from the food available in the rice paddy fields, including weeds and small animals.