What crops are suitable for intercropping under prickly ash trees?

Prickly ash, also known as dajiao, Qin pepper, and Shu pepper, is a common plant in China. It is widely cultivated because it can be used both as a seasoning and as a traditional Chinese medicine. However, since young prickly ash trees are not easy to establish successfully, farmers adopt intercropping patterns to enhance soil fertility. So what crops are suitable for planting under prickly ash trees? What crops can be intercropped under the trees?

In young prickly ash orchards or orchards with low prickly ash tree coverage, intercrops can be planted between the rows of prickly ash trees. Planting intercrops in prickly ash orchards can cover the soil, prevent erosion, reduce weed damage, increase soil humus, and improve soil fertility. At the same time, it allows rational use of the land, intercropping grain and other cash crops, which can both increase grain production and raise income, achieving the goals of "using the orchard to support the field" and "using short-term crops to support long-term crops." Planting intercrops also has certain disadvantages, as they can easily compete with prickly ash trees for water, nutrients, sunlight, and other unfavorable effects. However, if the types of intercrops are chosen appropriately and planted properly, the unfavorable effects can be reduced to a minimum.

The trunk of prickly ash is relatively low, so intercropping is only suitable during the young stage or early fruiting stage; large trees in full fruiting stage are generally no longer suitable for intercropping. Even during the young stage, attention should be paid to selecting the types of intercrops, following the principle of not affecting the growth and development of prickly ash. Excellent intercrops should meet the following conditions: a short growth period and low absorption of nutrients and water, with periods of high water and fertilizer demand different from those of prickly ash trees; relatively short plants that will not affect the light conditions of prickly ash trees; the ability to improve soil fertility, with fewer pests and diseases, and without worsening the pests and diseases of the fruit trees; and relatively high economic value of the intercrops themselves.

Generally, legumes, tuber crops, wheat and barley, melons, and vegetables are suitable. Suitable legumes for intercropping include peanuts, mung beans, soybeans, red beans, and so on. Such crops are generally relatively short, and their nitrogen fixation can improve soil fertility, with less conflict over fertilizer with prickly ash trees. Among them, peanuts are short in plant height and require less fertilizer and water, making them a good intercrop for prickly ash orchards in sandy land.

Tuber crops are mainly sweet potato and potato. Sweet potato requires less fertilizer and water in the early stage, so it has little effect on prickly ash trees; in the later tuber formation stage, it requires more fertilizer and water, and for excessively vigorous prickly ash trees, planting sweet potato can make them stop growing earlier. However, for trees bearing a large amount of fruit, it can easily affect later growth. Because sweet potato has strong adaptability and high yield, it is a commonly used intercrop in prickly ash orchards. But when sweet potato grows vigorously, its green leaves completely cover the ground, and very little light is reflected from the ground toward the canopy, so the inner part and lower part of the canopy appear to lack light, and fruit coloring is less satisfactory.

Potato has a relatively shallow root system, a short growth period, and an early sowing period, so the conflict over light with prickly ash trees is relatively small. As long as attention is paid to increasing fertilizer and irrigation, both can achieve a good harvest. Therefore, it is a commonly used intercrop in prickly ash orchards on flat land with good fertilizer and water conditions.

Wheat, barley, and others are also used for intercropping in prickly ash orchards. Such crops are not very tall and mainly grow in spring. Their fibrous roots are dense and can increase the granular structure of the soil, and wheat and barley themselves have relatively high economic value. However, because wheat and barley crops have relatively deep root systems and strong fertilizer absorption, they easily compete with prickly ash trees for fertilizer and water in early spring. Therefore, when used as intercrops, fertilizer and water should be increased, which can reduce the unfavorable effects on prickly ash trees.

Intercropping prickly ash trees with vegetables is relatively beneficial to the fruit trees because of fine cultivation and relatively sufficient fertilizer and water. However, planting vegetables in autumn that require more fertilizer and water or mature late can easily prolong the growth of prickly ash trees, which is unfavorable for overwintering and often causes new shoots to "dry up" or the trees to die. At the same time, it easily worsens the damage to prickly ash branches by leafhoppers.

Intercrops should be planted at a certain distance from prickly ash trees, usually limited to the outer edge of the canopy; otherwise, it will have unfavorable effects on both the prickly ash trees and the intercrops. Young prickly ash trees have underdeveloped root systems and a poor ability to compete with intercrops for fertilizer and water, so intercrops should be planted closer to the canopy. Large trees have well-developed root systems, so intercrops can be planted farther from the canopy. In addition, where fertilizer and water conditions are good, prickly ash trees are taller, root systems are deeper, and canopy branches are sparse, intercrops can be planted closer to the trees.