What are dry land and paddy field respectively? What do you usually plant separately? What is the dividing line between paddy field and dry land in China?

Dryland usually refers to cultivated land where dryland crops are planted, and seasonal irrigation is generally not needed. It can be divided into flat dryland and sloping dryland. Including irrigated land with irrigation conditions and general dry land without irrigation conditions. China's dry land is concentrated in the vast northern area north of Qinling-Huaihe River, and also widely distributed in hilly and mountainous areas without irrigation conditions in the south.

Dryland crops mainly include naked oats, potatoes, corn, sorghum, wheat, millet, cotton, buckwheat, various vegetables, rape and so on.

Paddy field mainly refers to the farmland where aquatic crops such as rice are planted and there is seasonal water accumulation every year, which is divided into two categories: flat paddy field and terraced field. Paddy fields are mostly distributed in areas with abundant water resources and guaranteed irrigation. Paddy fields in China are concentrated in the vast southern area south of Qinling-Huaihe River, where rice is mainly planted. In places with good water resources in the north, paddy fields are mostly distributed in a "large dispersion and small concentration" pattern. Rice is the main crop in the rice field distribution area in northern China.

Cultivated land for planting aquatic crops such as rice, lotus root and mat grass, including paddy-upland rotation land without irrigation facilities.

Along the Kunlun Mountains-Qinling Mountains-Huaihe River, the dry land area in the north is 491910.6 thousand hectares, accounting for 66.5% of the total dry land area in China. In the south is the southern dry land, with an area of 24,729.8 thousand hectares, accounting for 33.5% of the national dry land area.

Extended data:

The soil in paddy fields in southern China is called paddy soil. Paddy soil is formed under the influence of certain natural environment and various farming measures after human beings grow rice.

Because of long-term irrigation and dry-wet alternation, soil properties different from dry land have been formed. When paddy soil is irrigated, the topsoil is saturated with water and in a reduced state; In autumn and winter, in the seasons of drainage, air drying and dry field, the plough layer is in an oxidation state. This periodic dry-wet alternating process forms the unique physical, chemical and biological properties of paddy soil.

Under the condition of flooding and anoxia, the decomposition of organic matter is slow, the humification degree is high, the fertilizer efficiency is stable and long, and the nutrient loss is less. However, if the soil is highly reductive and the organic matter is decomposed anaerobically, a variety of organic acids will be produced, which will hinder the oxygen secretion ability of rice roots. When the reducibility is strong, it will also produce toxic substances such as methane and hydrogen sulfide to poison the rice roots, and in severe cases, the rice roots will turn black, rot and die.

References:

Baidu encyclopedia-paddy field