Instruct: Given a question, retrieve passages that can help answer the question.
Query: What is the most abundant crop in China?
Agriculture is a vital industry in China, employing over 300 million farmers.[1] China ranks first in worldwide farm output, primarily producing rice, wheat, potatoes, tomato, sorghum, peanuts, tea, millet, barley, cotton, oilseed and soybeans.
Most experts attribute the introduction of the peanut to the Portuguese during the Ming Dynasty. The peanut was introduced to Haicheng county in Fujian in the beginning of the 16th century. It then spread to Zhengjiang and beyond at the end of 16th century. American missionaries introduced the Virginia peanut in the middle of the 19th century. Archaeological finds of purported ancient carbonized remains of peanuts during excavations in China have led to the controversial claim that the groundnut is an indigenous crop, or that explorers from China or elsewhere in the Old World had discovered the Americas and introduced crops from there millennia before Columbus.
In Cantonese cuisine, it is categorized as a tong sui or sweet soup, hence the Chinese name. The soup is usually thin in texture, but potent in taste. The recipe is simple, consisting of boiling the sweet potato for a long time with rock candy and ginger. Sweet potato is one of the most commonly found and abundant vegetables grown in China. With its simple recipe and large crop supply, sweet potato soup is one of the most accessible and affordable tong sui in the region.
The general trend noticed by the analysis of biodiversity present in different cropping systems (e.g., industrial agriculture and organic farming) was that a greater the diversity of crops (temporally and spacially) resulted in a greater overall biodiversity of the agroecosystem, though this is not always the case. A meta-analysis of studies comparing biodiversity noted that, when compared to organic cropping systems, conventional systems had significantly lower species richness and abundance (30% greater richness and 50% greater abundance in organic systems, on average), though 16% of studies did find a greater level of species richness in conventional systems. Another study found that cropping systems that required heavy use of chemical amendments (e.g., the widespread broadcasting of pesticides and glyphosate, a practice ubiquitously found throughout the United States and Canada) had significantly greater levels of pollination deficits, whereas organic fields of the same crop (Canola) witnessed no pollination deficits. Other cropping systems like permaculture have undergone little study to determine relative levels of biodiversity compared to other cropping systems, but because they continue to reinforce the goals of increasing overall crop biodiversity, it can be extrapolated that an even greater level of biodiversity would be observed.
Potassium is the third major plant and crop nutrient after nitrogen and phosphorus. It has been used since antiquity as a soil fertilizer (about 90% of current use). Elemental potassium does not occur in nature because it reacts violently with water. As part of various compounds, potassium makes up about 2.6% of the Earth's crust by mass and is the seventh most abundant element, similar in abundance to sodium at approximately 1.8% of the crust. Potash is important for agriculture because it improves water retention, yield, nutrient value, taste, color, texture and disease resistance of food crops. It has wide application to fruit and vegetables, rice, wheat and other grains, sugar, corn, soybeans, palm oil and cotton, all of which benefit from the nutrient’s quality-enhancing properties.
About 75% of China's cultivated area is used for food crops. Rice is China's most important crop, raised on about 25% of the cultivated area. The majority of rice is grown south of the Huai River, in the Zhu Jiang delta, and in the Yunnan, Guizhou, and Sichuan provinces.
Pollinators, which are necessary for 75% of food crops, are declining globally in both abundance and diversity. Bees, in particular, are thought to be necessary for the fertilization of up to 90% of the world's 107 most important human food crops.
However, even though on a per-individual basis, many other species are actually more efficient at pollinating, on the 30% of crop types where honey bees are used, most native pollinators cannot be mass-utilized as easily or as effectively as honey bees—in many instances they will not visit the plants at all. Beehives can be moved from crop to crop as needed, and the bees will visit many plants in large numbers, compensating via saturation pollination for what they lack in efficiency. The commercial viability of these crops is therefore strongly tied to the beekeeping industry. In China, hand pollination of apple orchards is labor-intensive, time consuming, and costly.
The region's lifeline for growing crops is the floodplains of the Sokoto-Rima river system (see Sokoto River), which are covered with rich alluvial soil. For the rest, the general dryness of the region allows for few crops, millet perhaps being the most abundant, complemented by rice, corn, other cereals and beans. Apart from tomatoes few vegetables grow in the region.
Silang, like most of the towns in the province of Cavite, depends on a mainly agricultural economy. The primary crops grown in the area are coconut, coffee, corn, banana, pineapple, and tree crops like mango, lansones, caimito, santol, jackfruit, guava, and avocado. Fertile soils and abundant water sources make Silang suitable not only for common commercial crops but also for high value and exotic crops production. Most of the local farmers practice intercropping to increase land productivity and lessen soil erosion. Fruit production exceeds the demand of the municipality's population, thus, supply excesses are marketed to Metro Manila and neighboring urban centers. A number of poultry and swine farms are also located in some rural barangays.
Citrus is a major cash crop in southern China, with production scattered along and south of the Yangtze River valley. Mandarins are the most popular citrus in China, with roughly double the output of oranges.[23]
Cotton is China's most important fiber crop. The crop is grown on the North China Plain and in the middle and lower reaches of the Yangtze River Valley. In the 1970s domestic output did not meet demand, and significant quantities of raw cotton were imported. Production expanded dramatically in the early 1980s to reach a record 6 million tons in 1984. Although production declined to 4.2 million tons in 1985, China was still by far the largest cotton producer in the world. In the 1980s raw cotton imports ceased, and China became a major exporter of cotton.
Drummer soil is the most abundant and extensive soil in Illinois. It occurs over more than in the state. It is the most productive soil in the state. Corn and soybeans are the principal crops grown in Drummer soil. 
The rural population of the Northeast is heavily concentrated in the warmer southern part of the area, where very warm to hot summer weather permits crops such as maize and millet to be grown with high yields. Soybeans and flax are also very important, as are wheat and barley. The region possesses large flocks of sheep, and pigs are abundant in the more densely settled southern part. The northern half of Heilongjiang is so cold and poorly drained that agriculture is almost impossible; however, the Amur River provides very rich fishing prospects, and sheep are even more abundant than in southern Heilongjiang.
After the introduction of Bt cotton in northern China, non-target pests such as mirid bugs ("Heteroptera: Miridae") became more abundant, because less pesticides were sprayed. In 2013, a second issue being seen across the world, was the development of Bt resistant pests limiting the usefulness of Bt crops.
While most years China's agricultural production is sufficient to feed the country, in down years, China has to import grain. Due to the shortage of available farm land and an abundance of labor, it might make more sense to import land-extensive crops (such as wheat and rice) and to save China's scarce cropland for high-value export products, such as fruits, nuts, or vegetables. In order to maintain grain independence and ensure food security, however, the Chinese government has enforced policies that encourage grain production at the expense of more-profitable crops. Despite heavy restrictions on crop production, China's agricultural exports have greatly increased in recent years.[45]
Yams are the first crop to be harvested, and are the most important crop of the region. The New Yam Festival is therefore a celebration depicting the prominence of yam in the social-cultural life of Igbo people. The evening prior to the day of the festival, all old yams (from the previous year's crop) are consumed or discarded. This is because it is believed that the New Year must begin with tasty, fresh yams instead of the old dried-up crops of the previous year. The next day, only dishes of yam are served at the feast, as the festival is symbolic of the abundance of the produce.
Wheat is the second most-prevalent grain crop, grown in most parts of the country but especially on the North China Plain, the Wei and Fen River valleys on the Loess plateau, and in Jiangsu, Hubei, and Sichuan provinces. Corn and millet are grown in north and northeast China, and oat is important in Inner Mongolia and Tibet.
Agriculture is the main source of income for the residents. Land is very fertile and there is abundant water. Areca nut and paddy are the most grown crops.
However, modern agriculture seriously reduces biodiversity. Traditional third world agriculture that is best at maintaining diversity with multiple cropping systems such as polyculture (including companion planting and intercropping) and agroforestry systems such as shifting cultivation. In Latin America, between 70% and 90% of beans are grown mixed with other crops such as maize and potatoes. Worldwide, multiple cropping provided up to 20% of all food in 1986. Traditional systems also maintain diversity within a crop species, such as in the Andes mountains where up to 50 varieties of potato are grown.The effects of loss of biodiversity are especially noticeable in pest control. Herbivorous pest insects tend to become more abundant in monocultures. Stable agroecosystems are biodiverse and contain sufficient numbers of natural enemies of crop pests, such as parasitoidal wasps which are able to control aphids and lepidopteran caterpillars. These ecosystems continuously provide food and breeding sites for these beneficial species. Agroecosystems can achieve this equilibrium by arranging a suitable combination of crops in space and time, given the type of soil and surrounding environment; sufficient abundance of non-crop plants in and around fields; and appropriate management of vegetation. Suitable farming strategies include polyculture, crop rotation, mosaics of small scattered fields and uncultivated land. Additional strategies include perennial crops such as orchards (especially if a diverse floral undergrowth is permitted), tolerating specific weed species, and raising genetic diversity such as by planting mixtures of crop varieties.
Western China, comprising Tibet, Xinjiang, and Qinghai, has little agricultural significance except for areas of floriculture and cattle raising. Rice, China's most important crop, is dominant in the southern provinces and many of the farms here yield two harvests a year. In the north, wheat is of the greatest importance, while in central China wheat and rice vie with each other for the top place. Millet and kaoliang (a variety of grain sorghum) are grown mainly in the northeast and some central provinces, which, together with some northern areas, also provide considerable quantities of barley. Most of the soybean crop is derived from the north and the northeast; corn (maize) is grown in the center and the north, while tea comes mainly from the warm and humid hilly areas of the south. Cotton is grown extensively in the central provinces, but it is also found to a lesser extent in the southeast and in the north. Tobacco comes from the center and parts of the south. Other important crops are potatoes, sugar beets, and oilseeds.
In the past decade, the government has been encouraging agricultural mechanization and land consolidation to raise yields and compensate for the loss of rural workers who have migrated to the cities. According to the most recent statistics by the UN Food and Agriculture Organization, the annual growth rate of agricultural mechanization in China is 6.38 percent. By 2014, the integrated mechanization rate had risen to nearly 60 percent, with the rate for wheat surpassing 90 percent and that for maize approaching 80 percent. In addition to standard agricultural equipment like tractors, China's agriculture cooperatives have begun using high-tech equipment, including unmanned aerial vehicles, which are used to spay crops with pesticides. Good progress has been made in increasing water conservancy, and about half the cultivated land is under irrigation.
Most of the land is brought under cultivation. Paddy or rice fields provide multiple crops in a year based on monsoon. Coffee (both Robusta and Arabica) is the main plantation crop. Other crops include black pepper, cardamom and produce of the forest. Good quality honey is abundantly available in this region. Tall straight Nilgiri plantation is found on the southern bank of river Hemavati alongside coffee plantation. Natural forests surround the village. Wildlife and rich birdlife can also be seen. Teak and sandalwood are abundant.
This concept was originally applied to plant or crop growth, where it was found that increasing the amount of plentiful nutrients did not increase plant growth. Only by increasing the amount of the limiting nutrient (the one most scarce in relation to "need") was the growth of a plant or crop improved. This principle can be summed up in the aphorism, "The availability of the most abundant nutrient in the soil is only as good as the availability of the least abundant nutrient in the soil." Or, to put it more plainly, "A chain is only as strong as its weakest link."
Although China's agricultural output is the largest in the world, only about 15% of its total land area can be cultivated. About 75% of the cultivated area is used for food crops. Rice is China's most important crop, raised on about 25% of the cultivated area. Most rice is grown south of the Huai River, in the Yangtze valley, the Zhu Jiang delta, and in Yunnan, Guizhou, and Sichuan provinces.
Italy's Cassa per il Mezzogiorno in 1950 led to the government implementing incentives to grow cash crops such as tomatoes, tobacco and citrus fruits. As a result, they created an over abundance of these crops causing an over saturation of these crops on the global market. This caused these crops to depreciate in value