Jujube-grain intercropping technique

1 the scientific basis of jujube-grain intercropping

1.1 seize the time difference between jujube and crop growth, and make full use of fertilizer and water resources jujube is a fruit tree with late germination, early defoliation and short annual growth period. Generally, it begins to sprout in mid-April, leaves fall in mid-late October, then sow in late September and harvest in early June of the following year. The symbiotic period of jujube and wheat is about 80-90 days. From the middle of May to the first ten days of June, wheat blossoms, grain filling to maturity, mainly absorbing phosphorus and potassium fertilizer, supplemented by nitrogen fertilizer. Jujube is the period of long leaves, differentiation of young buds and growth of new jujube heads, mainly absorbing nitrogen fertilizer and supplemented by phosphorus and potassium fertilizer. Therefore, there is little contradiction between jujube and wheat intercropping for fertilizer and water. In early June, jujube trees entered the flowering and fruit-setting period, the need for fertilizer was at the peak, and wheat began to harvest. The newly sown millet, summer corn and other crops are still in the seedling stage, requiring less fertilizer, which generally does not affect the flowering and fruit setting of jujube trees. After the jujube was harvested in the middle and late September, the amount of phosphorus and potassium fertilizer required for jujube leaves increased in order to reserve nutrients, but the wheat was still in the seedling stage, the absorption of phosphorus and potassium fertilizer was relatively small, and the base fertilizer was fully applied before wheat sowing, so there is little contradiction between jujube and wheat.

1.2 making full use of the poor distribution of jujube roots and inter-crop roots in the soil, making full use of fertilizer and water resources, the distribution of jujube roots is mainly horizontal, concentrated in the 30cm-70cm soil layer within the crown, accounting for 65%-75% of the total roots. the root system outside the crown is sparse and the density is small, while the root system of inter-crop is concentrated in the plough layer of 0cm to 20cm. Jujube tree mainly absorbs fertilizer and water in the deep soil layer below 30 cm, and mainly in the crown. On the other hand, the intercrop mainly absorbs 20 cm of fertilizer and water in the inner plough layer, mainly outside the crown. Therefore, jujube-grain intercropping can improve the utilization rate of fertilizer and water better than that in the field.

1.3.Jujube tree has low crown, sparse branches, small leaves, small shading degree and high light transmittance, which basically does not affect the requirements of ① jujube-wheat intercropping for light intensity and daylighting. From turning green to jointing stage, wheat requires a certain light intensity and amount of light, but at this time the jujube tree has just germinated, which basically does not affect the light of wheat. From early May to early June, wheat entered the mature stage of heading, flowering and grain filling, requiring that the light intensity and amount of light should be only 25%-30% of the full light. At this time, the branches and leaves of jujube trees entered a rapid period, and after the jujube leaves unfolded, the average single leaf surface was 7.4-9.8 square centimeters, which could not be fixed in the shaded area swinging with the wind, which could basically meet the light requirements of wheat at all growth stages. ② jujube intercropped with cereals or beans. Millet and legumes are shade-tolerant crops with low light saturation point, so intercropping can meet the light requirements of crops. Intercropping of ③ jujube and summer corn. Summer corn can be rotated after wheat harvest. Summer corn has a high light saturation point and is a temperature-loving crop. However, the compensation point of light is low, and it has the characteristics of short illumination and high light efficiency. Moreover, summer corn is also a C4 plant, which can still accumulate some dry matter under weak light conditions, so intercropping between jujube and summer corn can also meet the requirements of light, and higher yield can be obtained.

2 the mode of jujube-grain intercropping

2.1 the intercropping model based on jujube and supplemented by grain is suitable for areas with more land and less population. That is, the row spacing of jujube trees is 4 meters × 6 meters, 37 jujube trees are planted per mu, covering an area of 432 square meters, and food crops cover an area of 235 square meters. Or adopt double-row strip intercropping model, that is, large and small row spacing of 4 meters, small row spacing of 4 meters, large row spacing of 10 meters, 24 jujube trees planted per mu, covering an area of 384 square meters, and food crops covering an area of 283 square meters.

2.2 the intercropping model based on grain and supplemented by jujube is suitable for areas with large population and little land. the row spacing of jujube trees is large, the general row spacing is 15 meters, the plant spacing is 4 meters, and 11 jujube trees are planted per mu, covering an area of 176 square meters. Grain crops cover an area of 491 square meters, or adopt double-row strip intercropping mode with plant spacing of 4 meters, small row spacing of 4 meters and large row spacing of 18 meters. There are 15 jujube trees planted per mu, covering an area of 240 square meters, and food crops covering an area of 427 square meters.

2.3 the intercropping model of jujube and grain is suitable for areas with balanced population and land. Jujube tree spacing is 4 meters, row spacing is 8 meters, 21 jujube trees are planted per mu, covering an area of 336 square meters, food crops cover an area of 331 square meters, or adopt double-row strip intercropping mode with plant spacing of 4 meters, small row spacing of 4 meters, large row spacing of 12 meters, and 21 jujube trees per mu.

3Technical points of jujube-grain intercropping

The key technology of jujube-grain intercropping is to adjust the contradiction between jujube trees and crops for fertilizer, water and glory, so as to achieve mutual benefit and mutual benefit and realize the high yield of jujube and grain.

3.1 mastering the appropriate row spacing of planting density has obvious effects on air temperature, humidity, light and wind speed, and it is also an important factor affecting jujube grain yield. Therefore, it should be arranged as a whole according to the purpose of cultivation and local conditions. The row spacing of jujube is 6 meters, that of grain is 15 meters, and that of jujube and grain is 8 meters.

3.2 the selection of suitable planting direction has a certain effect on the yield of jujube trees. Practice shows that when jujube trees are planted in the north-south direction, the light time under the canopy is more uniform, and the amount of daily daylighting is also larger than that in the east-west direction. Therefore, it is generally better to plant jujube trees in the north-south direction, and at the same time, we should adjust measures to local conditions and master flexibly.

3.3 proper control of jujube tree height has a certain relationship with the amount of direct light received. In order to improve the utilization rate of light energy and economic benefit, the height of the tree should be controlled below 6 meters, so the fixed stem height should be 1-1.5 meters.

3.4 reasonable pruning and controlling tree shape according to the investigation, the crown shape has different effects on the growth and yield of jujube and intercrop. The canopy is closed, the branches are crowded, ventilated and poorly transparent, the fruit position moves outward, the fruit setting rate decreases, and aggravates the effect on the intercrop. Therefore, the shape of the crown should be evacuated and happy.

The selection and planting of 3.5 crops is one of the key techniques to adjust the contradiction between jujube and inter-crops. The selected intercrop should have the characteristics of mutual stagger between phenological phase and jujube phenological phase, short plant size, strong shade tolerance, short growth period and early maturity. According to practical experience, the following crops are more suitable for intercropping.

Wheat includes winter wheat, spring wheat, barley and so on. these food crops have small plants, shallow root distribution, and the phenological phase is interlaced with the phenological phase of jujube, so it is an ideal crop for jujube-grain intercropping.

Beans include soybeans, peas, mung beans, adzuki beans and so on. These crops have short plant size, strong shade tolerance, short growth period and early maturity. Moreover, it has the effect of self-nitrogen fixation, so it is a better crop for intercropping with jujube.

Miscellaneous grains, including corn, millet, sesame, peanuts and cotton, can be intercropped with jujube trees. However, it is necessary to do a good job in rational distribution and planting, because these crops are light-loving crops, but there are great differences between light saturation point and compensation point. When intercropping with jujube, on the side near the jujube, sow several rows of legume crops first, and then sow millet, corn, sesame, cotton and so on. Adopting the combination of "short-high-short or short-medium-high-medium-dwarf" is not only beneficial to ventilation and light transmission, meet the requirements of light intensity and daylighting of crops, but also help to alleviate the contradiction between jujube and crops for fertilizer and water. It is also conducive to the prevention and control of diseases and insect pests and convenient management under the tree.