According to the source of green manure, it can be divided into: ① Cultivation of green manure refers to artificially cultivated green crops. ② Wild green manure refers to wild plants that have not been artificially cultivated, such as weeds, leaves and fresh shrubs.
According to botany, it can be divided into: ① Leguminosae green manure with root nodules, which can fix nitrogen in the air, such as Chinese milk vetch, vetch seed, pea and cowpea. (2) Non-leguminous green manure refers to all plants that have no nodules and cannot fix nitrogen in the air by themselves, such as rape, cauliflower, chrysanthemum, etc.
According to the growing season, it can be divided into: ① Winter green manure refers to green manure sown in autumn and winter and harvested in spring and summer of the following year, such as Chinese milk vetch, vetch seed and broad bean. ② Summer green manure refers to green manure sown in spring and summer and harvested in summer and autumn, such as sesbania, bamboo beans and pig manure beans.
According to the length of growth period, it can be divided into: ① 1 annual or perennial green manure, such as tamarind, bamboo bean, cowpea, vetch, etc. ② Perennial green manure, such as edamame, cajanus cajan and Leucaena leucocephala. ③ Short-term green manure refers to green manure with short growth period, such as mung bean and soybean.
Alfalfa, a perennial leguminous green manure, is a typical calcium-loving plant, which is cold-tolerant, drought-tolerant and barren-tolerant, and is suitable for sandy loam growth. Pay attention to intercropping years and fruit tree spacing. Sweet clover, 1, a two-year-old leguminous green manure crop, has strong adaptability, barren tolerance, drought tolerance, cold tolerance and salt tolerance. Shadawang, a perennial green manure crop, has strong adaptability, barren tolerance, drought tolerance, salt tolerance and wind resistance, and is suitable for acidic to strongly acidic soil. Peanut, also known as groundnut and ground fruit, is mainly cultivated in Shandong, Henan, Anhui and other places, among which Shandong is the most common. Strong drought resistance, most suitable for sandy soil. Plants are short, grow horizontally on the ground, and have good soil and water conservation performance, so they are better green manure in sandy orchards. However, due to the large amount of sowing and high cost, it is generally appropriate to bury the green after harvesting. Soybean, also known as soybean and edamame, is planted everywhere. However, soybean has high economic value and less green burial. There are wild soybeans, miscellaneous beans, edible beans, adzuki beans and edamame in soybeans. Green manure soybean has strong stress resistance, thick stems and leaves, rich nutrients and is easy to rot after being buried. There are azure, Chinese milk vetch, Chinese milk vetch and clover.
Intercropping green manure crops in pear orchards should keep a certain distance from fruit trees according to the types of green manure, stem height and root exudates, so as not to affect the growth and development of fruit trees. Perennial deep-rooted green manure, such as alfalfa, consumes a lot of water and has a great influence on fruit trees. Besides paying attention to fertilizer and water management, it is not suitable for continuous cropping for many years. When the plants and roots grow strongly, the soil should be ploughed in time to achieve the effect of green manure. For silty soil and cohesive soil with poor soil structure, it is considered that proper planting of Gramineae green manure is better.