Peas should not be planted continuously in the same field. White peas are more sensitive to continuous cropping than purple peas. In various agricultural systems, semi-leafless peas, along with some dwarf, early-maturing, and temperature/light-insensitive varieties, are frequently used in crop rotation, intercropping, relay cropping, and mixed planting, in addition to monoculture. Peas grow slowly and have limited ground cover, so they require minimal weed competition. It is recommended to use medium-tillage crops before planting peas. In autumn sowing areas, peas are often used as a pre-crop or after-crop for rice, corn, and sweet potatoes. In spring sowing regions, peas are commonly intercropped with corn, cotton, sorghum, eggplant, and melons, or planted along field edges. They can also serve as a preceding crop for millet, corn, sweet potato, and potato, or be intercropped with barley, spring wheat, and oats.
Planting peas not only helps accumulate nitrogen in the soil but also improves its physical structure, making it an excellent choice for crop rotation. Additionally, since peas mature earlier in the season, the labor demands during harvest are spread out, which makes it easier to manage the timing of summer crop harvesting and labor scheduling.
1. Crop Rotation
Through long-term farming practices, various rotation models have been developed across different regions in China. Common patterns include:
(1) Southern Model: In southern provinces like Sichuan, Hunan, Hubei, Jiangxi, Zhejiang, Guangdong, Guangxi, Fujian, and Yunnan, where there are two or three rice harvests per year, peas are a major winter crop. With abundant water and heat resources and a high population density, the winter fallow period usually lasts 4–5 months, with average winter temperatures between 9–14°C—ideal for cold-season crops. Dry peas are often grown in three cycles per year, yielding over 1500 kg per hectare, with green peas being more suitable in many cases. A typical rotation sequence is:
Year 1: Peas (or broad beans or green manure) – early rice – late rice (or single rice crop)
Year 2: Wheat – early rice – late rice (or single rice crop)
Year 3: Rape – early rice – late rice (or single rice crop)
(2) Northern Model: In northern regions such as Qinghai, Xinjiang, Gansu, Ningxia, Inner Mongolia, Shanxi, Hebei, and parts of the northeastern China, peas are commonly rotated with corn, spring wheat, barley, oats, rapeseed, and other crops. The rotation pattern often includes pea-corn-pea-rapeseed-spring wheat-pea-spring wheat-potato-pea-barley-corn, with dry pea yields exceeding 2200 kg per hectare. In Qinghai and Gansu, yields can surpass 3000 kg per hectare.
2. Intercropping and Mixed Cropping
To make better use of natural resources like light, temperature, water, and soil, peas are often intercropped or mixed with other crops. This practice helps suppress weeds, reduce pests and diseases, and increase total annual yield per unit area.
(1) Mixed Cropping: This traditional method is still practiced in some areas like Henan, Qinghai, and Gansu, where peas are mixed with spring wheat or barley. It is important that the maturity periods of peas and other crops align. Dwarf varieties are preferred, and seed ratios must be carefully managed. A 3:7 ratio of peas to wheat is ideal, as too many peas may cause wheat lodging. Although this method increases yield compared to growing them separately, it is not suitable for mechanized harvesting.
(2) Intercropping: This method is more efficient than mixed cropping, allowing better land use and crop adaptation to environmental conditions. It facilitates management, harvesting, and threshing, leading to higher output and value per unit area. In regions like Xinjiang, Gansu, and Qinghai, peas are often intercropped with spring wheat and rapeseed. To address the growth period conflict between crops, farmers often interplant peas with the next season's crops, such as "pea-corn," "pea-potato," or "pea-sunflower." In eastern coastal areas like Jiangsu, Shanghai, and Zhejiang, and inland provinces like Henan and Anhui, "cotton-pea" intercropping was once common, and now new models like "early-late," "high-dwarf," and "legume-non-legume" rotations are being explored. Peas are becoming a promising crop in these evolving agricultural systems.
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