What is the difference between the natural geographical conditions of corn and rice cultivation?

Division of maize planting area and planting system

Spring sowing corn area in northern China

1. Partition range

This area includes all of Heilongjiang, Jilin, Liaoning, Ningxia and Inner Mongolia, most of Shanxi, and parts of Hebei, Shaanxi and Gansu. It is one of the main corn producing areas in China. From 65438 to 0995, the sown area of corn was about 8.93 million hectares, accounting for 39.2% of the national corn area, and the total output accounted for 43.8% of the national corn area (Wu Jingfeng).

The northern spring sowing corn area belongs to the humid and semi-humid climate zone of cold temperate zone, with low temperature and dryness in winter and frost-free period of 130- 170 days. The annual precipitation is 400-800 mm, of which 60% is concentrated in July-September. The northeast plain is flat and fertile, with suitable temperature and sufficient sunshine in most areas, which is suitable for planting corn. It is the main corn producing area and an important commodity grain base in China. Corn is mainly planted in dry land, and the area of corn with irrigation conditions is less than one fifth. The corn yield in this area is very high, averaging about 6 tons per hectare. The highest yield reached per hectare 15 tons.

2. Planting system

The northern spring sowing corn area is basically a one-year cropping system. There are three planting methods:

(1) corn seed cleaning. It accounts for more than 50% of the corn area, and is distributed in the plains of the three northeastern provinces and the alpine regions of Inner Mongolia, Shaanxi, Gansu, Shanxi and northern Hebei. Because of the short frost-free period and low temperature, corn is planted in one season, but it plays an important role in crop rotation, usually with spring wheat, sorghum, millet, soybean and other crops. This situation has changed a lot since the 1970s. Due to the rapid increase of corn planting area, it is very difficult to rotate crops, so continuous cropping system of corn has been developed.

(2) Intercropping corn and soybean. It accounts for about 40% of this area and is the main form of corn planting in Northeast China. Corn-soybean intercropping makes full use of the morphological and physiological differences between the two crops, and reasonable collocation improves the utilization rate of light energy, water, soil and air resources. Corn-soybean intercropping can generally increase the yield of grain and beans by about 20%.

(3) Spring wheat interplanting with corn. Since 1970s, the planting mode of spring wheat interplanting with corn has gradually formed in northern Shaanxi, northwestern Shanxi and some areas with good water and fertilizer conditions in Liaoning, Gansu and Inner Mongolia. Generally, sowing wheat in wide border, interplanting on ridge or transplanting spring corn can increase yield by 20-30%.

3. Main corn varieties planted

In fact, the northern spring sowing corn area includes northeast and north China. Northeast China needs varieties with medium or early maturity, low temperature tolerance and good yield. There are basically no virus diseases and leaf spot diseases in Northeast China, but there are leaf spot diseases, head smut and sometimes corn borer, so it is required to resist these diseases and insect pests. According to the statistics of 1997, the main maize hybrids planted in Northeast China are Benyu No.9, Ji Dan 159, Sidan 19, Zhongdan No.2, Ye Dan 19, Yudan 13 and Ye Dan1.

In addition to stem rot and leaf spot, there are also serious virus diseases (SCMV and MRDV) in spring sowing corn in North China, so the requirements for varieties are more stringent. The main cultivated varieties are: Ye Dan 13, Ye Dan 12, Ye Dan 19, Xiyu No.3, Yedan No.2, Zhongdan No.2 and Yandan 14.

4. Analysis of production conditions

The favorable conditions for developing corn production in the northern spring sowing area are: flat terrain, deep soil layer, fertile soil and rich light and heat resources. The agricultural production level in this area is relatively high, with great potential for increasing corn production and advantages in commodity production.

There are five main factors limiting the increase of corn production in this area: first, the production areas are concentrated and the circulation is not smooth, so it is very difficult to store, transport, process and sell corn after harvest; Second, early autumn frost, low temperature, slow grain dehydration, reduced quality grade and increased energy consumption; Third, drought and lack of rain, insufficient irrigation facilities and water resources; Fourth, the input is small, especially the fertilizer is insufficient, and the ratio of nitrogen, phosphorus and potassium is unreasonable; Fifth, there is a lack of new varieties with stable and high yield. To further develop corn production in this area, the strategy of stabilizing the area and increasing production should be adopted.

5. Measures to further increase output

(1) Replace with new varieties. It is urgent to cultivate or introduce new hybrids with early maturity, high yield, lodging resistance and suitable for close planting and mechanized operation. New varieties with fast dehydration, good quality and resistance to head smut, leaf spot, gray spot and corn borer are needed in the late filling stage.

(2) Increase investment. The average fertilizer application per mu in this area 196 is only 14 kg, and that in Heilongjiang Province is 8.4 kg, which is less than that in Tibet, ranking the third lowest in the country. Inner Mongolia Autonomous Region uses the least amount of chemical fertilizer, only 7 kilograms per mu. The input of chemical fertilizer in this area is far from the demand of nitrogen, phosphorus and potassium for 1000 kilograms of corn per mu. If fertilizer input is not increased, long-term continuous cropping of corn will seriously destroy soil fertility and make the agricultural system lose its sustainability. If fertilization can be balanced according to the site, the yield will be greatly improved.

(3) Expand the coverage area of plastic film. The coverage area of corn plastic film in Heilongjiang Province has reached 3 million mu. At present, the new technology of mechanized transplanting of factory seedling is being tested, which is one of the powerful measures to greatly increase the yield. Shanxi, Inner Mongolia, Liaoning and parts of Jilin are also suitable for developing corn plastic film mulching technology.

(4) Reform the grain circulation system, expand circulation channels, and increase drying machinery and storage and processing facilities. In the case of high moisture content of varieties, drying machinery should be equipped to speed up the dehydration of corn seeds after harvest, properly solve the problems of safe storage, transportation and circulation of grain, improve the quality level and expand the export capacity. We should also attach importance to the development of postpartum processing industry, protect farmers' enthusiasm for growing grain through various means, and stabilize production.

Two. Yellow summer maize planting area

Located in the south of the northern spring corn area, north of Huaihe River and Qinling Mountains. Including Shandong. Henan, south-central Hebei, south-central Shanxi, central Shaanxi, Jiangsu and northern Anhui are the largest corn producing areas in China, with a planting area of 7,333,300 hectares (about1/kloc-0,000,000 mu), accounting for more than 30% of the national corn planting area, and the total output accounts for about 50% of the national total. This area belongs to temperate semi-humid climate, with frost-free period 170? /FONT & gt； In 220 days, the average annual precipitation is 500 ~ 800 mm, mostly from late June to early September. Natural conditions are extremely beneficial to the growth and development of maize. However, due to high temperature, large evaporation and concentrated rainfall, droughts in spring and floods in summer often occur, as well as natural disasters such as wind and hail, salinity and low temperature. The farming system is basically double cropping a year, and the main factors limiting maize yield are various planting methods, interplanting and multiple cropping, high multiple cropping index and insufficient soil fertility. In corn cultivation, we should pay attention to the following points:

(1) Promote compact maize hybrids with early maturity, high yield and strong stress resistance.

(2) Increase fertilizer input and give full play to the yield-increasing potential of fertilizer. In this area, corn fertilization area accounts for about two-thirds of the total area, and phosphorus fertilizer is insufficient, and potassium fertilizer is even less. Therefore, the fertilizer application rate should be increased to 12 kg of pure nitrogen and appropriate amount of phosphorus and potassium fertilizer.

(3) Intercropping corn with wheat stubble and summer sowing corn in North China are in the driest season of the year, and the plough layer is very dry. Combined with watering the last crop in the later stage, sufficient soil moisture is prepared before sowing, and appropriate deep sowing (6? /FONT & gt； 7 cm), strict mulching is an important measure to strive for complete seedlings. For interplanting corn, in order to reduce the shading during the wheat growth period, it is necessary to water it again before and after the wheat harvest to prevent drought, protect seedlings and promote strong seedlings and early development.

(4) The rainy season in North China generally begins in late June, and summer maize is prone to bud waterlogging after wheat stubble. Therefore, early sowing or interplanting can promote seedling jointing before the rainstorm, and avoid and reduce waterlogging damage. If the precipitation gradually decreases after the end of August and autumn drought occurs, water should be used to promote grain filling and increase grain weight.

Three. Corn region in mountainous and hilly areas of southwest China

Including Sichuan, Guizhou, Guangxi, Yunnan, Hubei and western Hunan. A small part of southern Shaanxi and Gansu. The sown area of corn is about 4 million hectares (60 million mu), accounting for a quarter of the national corn area. It belongs to temperate and subtropical humid and semi-humid climate. Abundant rainfall, good hydrothermal conditions and poor lighting conditions. More than 90% of the land is hilly and plateau, and the frost-free period is 200? /FONT & gt； 260 days, annual average temperature 14? /FONT & gt； The air temperature 16℃ and the annual precipitation are 800 ~ 1200mm, mostly 4 ~ 10, which is beneficial to multi-season corn planting. Intercropping corn with wheat, sweet potato or legume crops is mainly carried out in mountainous grassland, and only one season of spring corn can be planted in alpine mountainous areas. In corn cultivation, we should pay attention to the following points:

(1) Expand the planting area of hybrid corn, fully tap the local germplasm resources (pure breeds with excellent genetic characteristics are called germplasm for cultivating hybrid varieties), and select single cross, double cross, triple cross and group replanting according to the ecological division, so as to expand the area of excellent hybrid varieties to more than 80%.

(2) Popularize plastic film mulching for maize in mountainous and hilly areas, strive for cultivation time and accumulated temperature, and increase the yield per unit area by 30%-50%.

(3) Expand the intercropping area, improve the multiple cropping index, and popularize the standardized planting of corn.

(4) Expand some winter corn planting in Yunnan and southern Guangxi.

(5) Most mountainous and hilly areas in this area have poor soil and rainy weather, so attention should be paid to strengthening pest control.

Four. Southern hilly corn region

Including Guangdong, Hainan, Fujian, Zhejiang, Jiangxi, Taiwan Province and other provinces, southern Jiangsu and Anhui, as well as eastern Guangxi, Hunan and Hubei. The area of corn is small, accounting for about 5% of the national area.

Verb (abbreviation of verb) corn irrigation area in northwest China

Including Xinjiang, Gansu Hexi Corridor and Ningxia Hetao Irrigation District. It accounts for 2%-3% of the national corn planting area.

The intransitive verb-the corn region of Qinghai-Tibet Plateau

Including Qinghai and Tibet, is an important pastoral and forest area in China. Corn is one of the emerging crops in this area, with short cultivation history and small planting area.

Huanghuaihai summer sowing corn area

1. Partition range

Including all of Shandong and Henan in the middle and lower reaches of the Yellow River, Huaihe River and Haihe River, most of Hebei, south-central Shanxi, Guanzhong in Shaanxi and Xuhuai in Jiangsu, it is the largest corn producing area in China, with a planting area of about 7.47 million hectares, accounting for 32.7% of the national corn area and a total output of 35.5% (Wu Jingfeng). The output per unit area is 5.3 tons/hectare.

This area belongs to warm temperate semi-humid climate type, with frost-free period 170-220 days and abundant rainfall. This area is located in the lower reaches of the Three Rivers in the Huang-Huai-Hai area, with abundant surface water and groundwater resources, and the irrigated area accounts for about 50%.

The temperature in this area is high, the evaporation is large, and the rainfall is excessively concentrated. Summer rainfall accounts for more than 70% of the whole year, and there are often droughts in spring and floods in summer, and there are often natural disasters such as wind, hail, salinity, pests and diseases, which are unfavorable to production.

2. Planting system

This area belongs to an ecological region with two crops a year, and corn planting methods are diverse, and interplanting and multiple cropping coexist. The interplanting of wheat and corn accounts for more than 60%.

(1) Double cropping of wheat and corn was the main planting method in the Huang-Huai-Hai Plain in 1950s. However, two crops a year can only plant early-maturing maize varieties, which can not make full use of light and heat resources and has low yield. Moreover, corn after wheat harvest is often threatened by rain and waterlogging, so in the 1970 s, the northern region was gradually replaced by interplanting corn. In 1980s, with the improvement of water and fertilizer conditions and the requirement of mechanized operation, double cropping was developed again.

The advantages of double cropping a year are suitable for mechanized operation, beneficial to seedling protection, uniform plant distribution in the field and reasonable population structure. The disadvantage is that it is vulnerable to drought, flood and low temperature disasters, and its stability is poor. At present, there are no excellent varieties with early maturity, high yield and strong stress resistance, and the planting area is limited. The whole growth period of early-maturing corn sown in summer is 80- 100 days, and the required effective accumulated temperature is1900-2300℃; The growth period of mid-mature varieties is100-10 days, and the effective accumulated temperature is 2300-2700℃. The growth period of late-maturing varieties is 1 10- 130 days, and the effective accumulated temperature needs 2700-2900℃. If these heat requirements can't be met, the corn will grow poorly, and the low temperature stress will affect the filling, which will not mature normally and reduce the quality grade.

The distribution of heat resources in Huang-Huai-Hai Plain is limited. Sow corn again after wheat harvest until the next winter wheat is sown in time, and the growth period from north to south is only 90- 1 10 days. If agricultural consumption is deducted, the accumulated temperature will be even less. In order to ensure the high and stable yield of wheat and corn, high yield can only be obtained by planting multiple cropping corn in areas with high mechanization level and good water and fertilizer conditions. Popularizing industrial seedling raising and mechanized transplanting technology can further improve the yield potential and quality grade of multiple cropping corn.

(2) Wheat-maize intercropping can make full use of light and heat resources and land space, replant mid-late maturing maize varieties, and obviously improve the yield level without affecting the normal sowing of winter wheat in the next season. Therefore, it accounts for a large proportion in the Huang-Huai-Hai Plain, and there are mainly four forms of intercropping.

One is flat sowing and interplanting. Widely distributed in the southern part of the Huang-Huai-Hai Plain, including southern Shandong, southern Shijiazhuang, northern Henan, Guanzhong, Shaanxi and other places. It is characterized by dense planting of wheat, no special interplanting rows are reserved, or only 30 cm narrow rows are left. Corn is usually interplanted 7- 10 days before wheat harvest. Due to the selection of mid-late maturity maize varieties, the yield is obviously improved, and the maize plants in the field are evenly distributed, the population structure is reasonable, and the light and heat resources and land use are reasonable, which alleviates the contradiction between wheat harvest and summer sowing labor shortage and is beneficial to the double harvest of wheat and maize. The disadvantage is that harvesting wheat and interplanting corn are completely manual operations, which is not conducive to mechanized operation and difficult to protect seedlings.

Second, narrow-band interplanting. Make the wheat field into ridges with a width of 1.5m, and plant 6-8 rows of wheat in the ridges with an area of about1m.. Reserve 0.5m wide ridge and interplant two rows of late-maturing corn one month before wheat harvest. After the wheat harvest, the corn becomes wide and narrow. Wheat occupies less land than double cropping a year, but corn can be replaced by late-maturing varieties, so the overall yield is higher. This intercropping method can win the season, make full use of light and heat resources and obtain higher yield in areas with shorter frost-free period and better water and fertilizer conditions in northern Hebei Province and suburbs of Beijing and Tianjin.

Third, interplanting in the middle. Also known as small bed and big back interplanting method. 8-9 rows of wheat are sown by machine in the two-meter wide border, and about 70 cm is reserved for interplanting two rows of corn. Generally, late-maturing corn is interplanted 30-40 days before wheat harvest. This method can use small agricultural machinery operations, including wheat harvesting, intertillage, fertilization and so on. After wheat harvest, beans or green manure can be interplanted between wide rows.

Fourth, broadband interplanting. The border is about 3 meters wide, and the machine-sown wheat 14- 16 rows. 25-35 days before wheat harvest, interplanting two rows of medium-mature corn varieties on the reserved ridge. After wheat harvest, interplant corn, beans, potatoes or green manure in wide rows.

(3) The intercropping of corn and beans is mainly corn and soybean, and some of them are mixed with adzuki beans and mung beans. In principle, corn does not reduce production, and beans increase production appropriately. Usually, 6:2 or 4:2 intercropping is adopted to achieve double harvest of grain and beans, increase farmers' economic income and adjust their lives.

3. Main corn varieties planted

Huang-Huai-Hai region is mainly a summer sowing corn producing area, and the growing season of corn is restricted by two continuous cropping winter wheat, so it needs middle and early maturing varieties. The planting system in this area is complex, especially maize virus disease, and serious leaf spot, stem rot and Curvularia leaf spot also occur, so the requirements for disease resistance of varieties are particularly strict. The backbone hybrids planted are: Yedan No.2, Ye Dan 13, Yudan 13, Yandan 14, Ye Dan 19, Ye Dan 12, Zhongdan No.2, Zheng Dan 14, etc.

4. Analysis of production conditions

The summer sowing corn area in Huang-Huai-Hai Plain is an important grain and cash crop producing area in China, and the contradiction between the two crops is very prominent. Wheat and corn are the main food crops, and there are also land competition problems. Therefore, intercropping and interplanting have become the remarkable characteristics of maize production in this area.

The area is rich in light, heat and water resources, with flat terrain and deep soil layers, and the irrigated corn area accounts for more than 50%. The yield of maize in the Huang-Huai-Hai Plain varies greatly, with an average of 5.3 tons per hectare, 7.5-9 tons in large-area high-yield fields, and a high-yield record of 15 tons in small areas. For most areas, there is great potential for increasing production. The strategy of developing corn production in this area is to stabilize the area and increase the yield.

5. Measures to further increase output

Huang-Huai-Hai Plain is one of the key corn producing areas in China, but there is a lack of new hybrids suitable for the production characteristics in this area, so it is urgent to breed and popularize high-yield new varieties suitable for multiple cropping or interplanting. At present, the yield potential and disease resistance of hybrid varieties still can not meet the production needs, and the quality of commercial corn is very poor, and the disease resistance is not satisfactory. In the future, excellent hybrids with high yield, disease resistance, lodging resistance, close planting tolerance and moderate growth period are needed.

According to the statistics of 1996, the average application amount of chemical fertilizer in this area is about 480 kilograms per hectare. However, due to the high multiple cropping index, the actual fertilizer used in corn production is less than half, which is far from meeting the demand of nitrogen, phosphorus and potassium for 7.5 tons per hectare. Therefore, we should continue to increase fertilizer input, focus on developing balanced fertilization technology, improve fertilizer utilization efficiency and reduce production costs. At the same time, it is necessary to improve the level of mechanized operation, adopt late-maturing varieties, make full use of the light and heat resources in the growth period of summer-sown corn, and further increase the yield.

The natural conditions in this area are more than one crop and less than two crops; Therefore, it is necessary to continue to popularize the planting method of interplanting corn in wheat field, arrange the effective filling period of corn in a suitable temperature range as far as possible, and improve the grain plumpness and the quality of commercial corn. Generally, the yield of interplanting corn is about 14% higher than that of direct seeding and multiple cropping corn. In places with high degree of mechanization, we can try to popularize factory seedling raising and mechanized transplanting technology to increase output and reduce labor intensity.

Southwest mountainous corn region

1. Partition range

Southwest mountainous corn area is also one of the main corn producing areas in China, including all of Sichuan, Yunnan and Guizhou, southern Shaanxi, hilly areas in western Guangxi, Hunan and Hubei, and a small part of Gansu. 196 The corn planting area was 4510.9 million hectares, accounting for10.8% of the national total output, accounting for10.3%, and the output per unit area was 3.79 tons (Wu Jingfeng), equivalent to 73% of the national average.

Nearly 90% of the land in this area is distributed in hills, mountains and plateaus, and only 5% is in valley plains and mountain plains. Most of the land is distributed in the range of 200-5000 meters above sea level, and the vertical distribution characteristics of planting industry are very obvious. This area belongs to temperate and subtropical humid and semi-humid climate zone, with abundant rainfall and abundant water and heat resources, but poor lighting conditions. The frost-free period in this area is long, generally 240-330 days, the effective growth period of maize is 150- 180 days, and the annual rainfall is 800- 1200mm, mostly in April-10, which is suitable for maize planting. However, the rainy weather is more than 200 days throughout the year, and spring drought and summer drought often occur. The occurrence of pests and diseases is complex and serious. The Yunnan-Guizhou Plateau is characterized by great vertical difference in topography, poor soil, extensive farming and low corn yield.

2. Planting system

The southwest of China has complex terrain and a wide variety of crops, mainly including rice, corn, wheat and potatoes. Intercropping and interplanting is an important feature of corn planting in this area, and the planting methods are complex and diverse. Planting systems range from one year to more than one year. There are three basic ways:

Spring corn is harvested once a year in alpine mountain areas, or spring corn and potato are intercropped in strips;

Intercropping corn in hilly and mountainous areas, mainly early spring crops such as potato, broad bean, pea, rape or spring wheat intercropping corn or multiple cropping corn;

The triple cropping system centered on corn in plain areas, such as wheat-corn-sweet potato, wheat-corn-rice and green manure-corn-rice, has intercropping and multiple cropping, among which the dry cropping system composed of wheat-corn-sweet potato has the largest promotion area and the greatest yield-increasing effect.

(1) Maiyu potato triple cropping system. Summer drought and summer drought often occur in hilly areas below 600 meters above sea level in Sichuan, Yunnan and Guizhou provinces. In the past, wheat and summer corn were sown repeatedly, and high temperature and drought often occurred in late July, which seriously reduced the yield of summer corn. After the popularization of drought-resistant triple cropping system, empty rows should be reserved when sowing winter wheat, spring corn should be interplanted 35-40 days before wheat harvest, and sweet potatoes should be planted between rows of corn after wheat harvest to avoid summer drought and summer drought, make full use of rainfall and improve the utilization rate of light energy. In drought, the annual yield per mu of intercropping three crops can reach 700-800 kg, which is 150-200 kg higher than that of double cropping a year.

(2) Corn interplanting with wheat or potato. In hilly and cold areas with short growth period above 800 meters above sea level, more than one season is planted every year, and two seasons are insufficient. Since 1970' s, the interplanting of wheat or potato with corn has solved the problems of stable yield of two crops and balanced utilization of light and heat resources. About 3 million mu has been planted in the north-central part of Yunnan Province, which is generally about 30% higher than that of single corn.

(3) Wheat-maize-rice interplanting and double cropping rice rotation. The temperature in early spring in southwest double-cropping rice producing areas is unstable, and early rice seedlings are easy to rot after sowing. In autumn, the temperature drops rapidly and there are many rainy days, and the sunshine hours are only 1200- 1600 hours, which affects the heading and flowering of late rice and reduces production. Interplanting wheat, corn and rice, interplanting corn between wheat rows in advance, can plant early and harvest early, which is more stable than early rice. At the same time, one-season late rice was sown 10 days earlier than double-season rice, avoiding the late cold weather. This method also has the advantage of paddy-upland rotation. In terms of commodity grain demand, the production of low-quality early rice has been reduced, the production of wheat and corn urgently needed in the south has been expanded, and the contradiction between oversupply of early rice and insufficient supply of dry food has been alleviated.

3. Main corn varieties planted

The geographical and climatic conditions and planting systems in Southwest China are complex and changeable, and the epidemic of pests and diseases is also complicated, mainly including leaf spot, stem rot, virus disease, rust, sheath blight and downy mildew. In addition, there are dangers of autumn armyworm and corn borer. The main varieties planted are: Cheng Dan 14, Zhongdan No.2, Chuandan No.9, Yayu No.2, Ye Dan 13, Shen Dan No.7, Cheng Dan 13, Miandan 1 etc. In addition, some improved open pollination varieties and top cross varieties are planted here.

4. Analysis of production conditions and further measures to increase production

Corn has a long history in southwest mountainous areas and has always been an important local food and feed crop. This area has complex terrain, changeable climate, poor soil and underdeveloped economy. Although the intercropping system is implemented, the input is low, the cultivation is extensive and the farmers live in poverty, which limits the further improvement of corn production level. However, this special geographical climate and human production conditions determine that the southwest mountainous area is the region with the richest maize germplasm diversity in China.

The main measures to further develop corn production in southwest mountainous areas include:

Expand the planting area of hybrids. China's corn hybrids have accounted for 90% of the total corn area in China, but only 50% in southwest China. Expanding hybrid area is an important technical measure to improve maize yield. One of the reasons for the small hybrid area in southwest China is that there are no suitable varieties. In the past, many northern hybrids were introduced. Although they have great yield potential, their adaptability is poor, and it is difficult to popularize and apply them in poor areas. Southwest China is the region with the richest corn variety resources in China, and more than half of the corn resources in China come from this region. Therefore, it is necessary to breed and popularize new hybrids with strong adaptability based on this area. These local hybrids don't have to follow the northern model, but can be bred by single cross, improved single cross, triple cross and top cross. In poor mountainous areas, production and living conditions are very difficult, and improved open pollinated varieties or groups can continue to be popularized.

Popularizing plastic film mulching or seedling transplanting technology in alpine mountain areas can generally increase production by 30-50%. It is necessary to expand the intercropping and multiple cropping area of two crops a year and three crops a year. Yunnan and Guangxi should expand winter corn planting, replace part of early rice area, and change the structure of commodity grain to meet market demand.

Southern hilly corn region

1. Partition range

The southern hilly corn areas are widely distributed, including all of Guangdong, Hainan, Fujian, Zhejiang, Jiangxi and Taiwan Province provinces, southern Jiangsu and Anhui, and eastern Guangxi, Hunan and Hubei. It is the main rice producing area in China, and the planting area of small corn is about 6.5438+million mu/year, accounting for 3.2% of the whole country and 2.2% of the output (Wu Jingfeng

This area belongs to subtropical and tropical humid climate, with high temperature and abundant rainfall. The time suitable for crop growth is as long as 220-360 days, and the effective accumulated temperature time suitable for corn growth and development is more than 250 days. The annual rainfall 1000- 1800 mm is evenly distributed. Annual sunshine 1600-2500 hours, and corn can be planted all year round. However, the climatic conditions in this area are more suitable for planting rice, so the corn area is small and unstable. However, there are good conditions and great potential for developing maize production in autumn and winter in this area.

2. Planting system

Multiple cropping system has been implemented in this area, from two crops a year to three or four crops. Corn can be planted all year round, but mainly in autumn and winter. Representative planting methods are:

Wheat-corn-cotton (Jiangsu)

Wheat (or rape)-rice-autumn corn (Zhejiang, Hubei)

Spring Corn-Late Rice (Jiangxi)

Early rice-middle rice-corn (Hunan)

Spring Corn (Intercropping Green Manure)-Late Rice (Guangxi)

Double Cropping Rice-Winter Corn (Hainan)

Autumn corn in this area is mainly distributed in Zhejiang, Jiangxi, Hunan and Guangxi. It is often used as the third crop of triple cropping system, and also has the effect of paddy-upland rotation. Winter corn is mainly distributed in southern areas of Hainan, Guangdong, Guangxi and Fujian. After the 1960s, it developed into a southern breeding base for dryland crops such as corn and sorghum, and gradually became a national anti-season melon and vegetable production base after the 1980s. Corn has become a fixed crop in multiple cropping system and an important part of paddy-upland rotation.

This area has rich experience in transplanting corn seedlings, such as autumn corn areas in Zhejiang, Jiangxi and Hunan provinces. Generally, raising seedlings in nutrient pots and transplanting corn in time after mid-season rice harvest can significantly increase corn yield.

3. Main corn varieties planted

The area of maize in the hilly area of South China is relatively small, so some subtropical maize varieties can be planted. The varieties planted in winter require resistance to low temperature and early maturity, as well as resistance to many diseases and insect pests, such as stem rot, rust and sheath blight. The main varieties planted in this area are: Guiding 1, Ye Dan 13, Yayu No.2, Ye Dan 12, Yun Dan 1 etc.

4. Analysis of production conditions and further measures to increase production

The southern hilly corn region is an important production base of commodity grain and various cash crops in China, which is rich in water and heat resources and high in production technology. However, the soil texture is poor, the fertility of red and yellow soil is low and soil erosion is serious. Land use heavy paddy field light dry land. Hilly dry land, poor irrigation and water conservancy facilities, extensive management of corn planting and low yield. Local farmers and technicians lack corn planting experience and adaptive varieties, which also limits the improvement of corn yield.

Southern provinces are the main consumption areas of commercial corn, and a large amount of corn is transported from the north or imported from abroad every year. Many farmers want to raise livestock and poultry with rice, which is not cost-effective. Developing corn production in autumn and winter in South China will alleviate some contradictions between supply and demand and help to establish a sustainable agricultural production structure. At the same time, with the development of irrigation and water conservancy construction, increasing fertilizer, applying green manure and improving soil fertility will be beneficial to expand the production and development of autumn and winter corn. To develop corn production in autumn and winter in South China, the following problems need to be solved:

(1) Develop winter fallow fields. There are1.800 million mu of dry land in rice producing areas in southern China, of which about1.000 million mu is suitable for planting corn. By reforming farming system, increasing multiple cropping index and developing intercropping and interplanting, maize production in southern China can be effectively promoted. At the same time, it is necessary to popularize advanced cultivation techniques, such as reasonable close planting, seedling transplanting, feeding cattle with corn stalks, and then increasing fertilizers to improve dry land, barren slopes and beaches.

(2) Expanding paddy-upland rotation. Hunan and Hubei provinces reformed the planting system and promoted the multiple cropping of spring corn-late rice or early rice-summer corn in the paddy-upland rotation. The yield per mu of corn can reach 400-500 Jin, that of rice can reach 500-600 Jin, and the yield per mu in two seasons exceeds grain tons. Guangdong, Jiangxi and Fujian are also demonstrating this yield-increasing technology.

Popularize intercropping and interplanting technology with corn as the main crop in hilly dryland. For example, intercropping corn with sweet potatoes, peanuts and beans can increase the yield of corn by 200-250 kg per mu on the basis of the original crops.

Popularizing plastic film mulching technology in alpine mountain areas. The corn yield can be increased by 30-50%.

Cultivate improved varieties. There is a lack of hybrid with strong adaptability in the south, and the varieties usually introduced from other areas can not fully adapt to the ecological requirements and natural conditions of multi-cropping system in the hilly areas of the south, and the disease resistance is not fully adapted, so the yield potential of these varieties can not be exerted normally. Cultivating adaptable hybrids is an important measure to develop autumn and winter maize production in southern China.

Increase fertilizer, research and popularize local corn high-yield cultivation techniques.

Northwest corn irrigation area

1. Zoning scope and characteristics of natural conditions

Northwest corn irrigation area includes Xinjiang, Hexi Corridor in Gansu and Hetao Irrigation Area in Ningxia. It belongs to continental arid climate zone, with little precipitation, and the planting industry relies entirely on snowmelt water or river irrigation system. With the increase of farmland irrigation area, the corn area has gradually expanded since 1970s, accounting for about 6,543,800 mu per year, accounting for about 3% of the national corn area (Wu Jingfeng,).

The frost-free period in this area is generally 130- 180 days, with abundant sunshine, 2600-3200 hours a year, and the accumulated temperature above 0℃ is 3000-4 100℃, and the effective accumulated temperature above 10℃ is 2500-2600. Generally speaking, the northwest region is rich in heat resources and the temperature difference between day and night is large, which is very beneficial to the growth and development of corn and to obtain high quality and high yield. But the climate is dry, and the annual precipitation is less than 200mm. Therefore, the characteristic of planting industry in this area is that the irrigated agricultural system is relatively developed. Some places rely on snowmelt water to irrigate farmland, and the water source is reliable, so the crop yield level is high.

2. Planting system

Mainly spring sowing corn once a year, but also a small amount of wheat-corn interplanting. No matter which planting method, the yield and quality of corn are high.

3. Main corn varieties planted

Northwest China has a relatively dry climate, large temperature difference between day and night, few pests and diseases, and great potential for increasing production, but droughts often occur, resulting in reduced production. Therefore, varieties with particularly high yield potential, drought tolerance and head smut resistance are mainly: Zhongdan No.2, SC704, Ye Dan 13, Ye Dan 12, He Dan 1 and Jingzao No.8.

4. Analysis of production conditions and further measures to increase production

Northwest irrigated corn area has dry climate and scarce precipitation, but it is rich in light and heat resources, with large temperature difference between day and night, slight pests and diseases, reliable irrigation system and great potential for crop yield increase. In the irrigated agricultural area of Hexi Corridor in Gansu and Hetao Irrigation Area in Ningxia, the yield of interplanting corn in a large area is 500-600 kg per mu, and the seventh division of Xinjiang Agricultural Reclamation once created the yield of 1 103.8 kg per mu.