How to correctly apply biogas fertilizer in jujube tree cultivation
The Yulin area in northern Shaanxi is a nationally famous red jujube production area, with a citywide jujube tree area of 75,000 hectares and an annual output of 56,500 tons of fresh jujubes. The jujube areas are mainly distributed in Jiaxian County, Suide County and Qingjian County along the Yellow River. These areas belong to the Loess Plateau region, with poor soil and poor farming conditions. In recent years, we have strengthened rural biogas construction in the jujube areas, built a cumulative total of 12,000 household biogas digesters, and carried out experimental demonstrations of applying biogas fertilizer in jujube orchards, achieving very good results.
The effect of biogas fertilizer on jujube trees. In addition to being rich in major elements such as nitrogen, phosphorus and potassium, biogas fertilizer also contains trace elements such as boron, copper, iron, manganese, calcium and zinc that play an important role in jujube tree growth, as well as large amounts of organic matter, various amino acids and vitamins. Applying biogas fertilizer to jujube trees can meet the nutrients needed for jujube tree growth, and the nutrients are easily absorbed and utilized; it increases the organic matter in the soil, and years of continuous use can improve soil structure, enhance the soil's ability to retain water and fertilizer and resist drought, increase jujube tree yield (yield increase rate about 18%), enhance stress resistance, significantly reduce pests and diseases, and make the fruit uniform in size, bright in color and sweet in taste.
Fertilization methods. There are two commonly used types of biogas fertilizer: one is biogas residue used as base fertilizer, and the other is biogas slurry used as topdressing and foliar fertilizer.
Base fertilizer. Base fertilizer should be applied during the non-fruiting period. Generally, in early April or at the end of November each year (during the period of discharging or major replacement of material from the biogas digester), biogas residue is applied as base fertilizer. According to the size of the tree, apply 15-30 kg of biogas residue per jujube tree. The specific method is to dig 4-6 pits around the jujube tree, with a depth of 30-40 cm, apply fertilizer, irrigate, and after the water has infiltrated dry, promptly cover with soil and level it to preserve fertilizer efficiency and prevent frost damage to the tree roots.
Topdressing. The application time for biogas slurry as topdressing is in May during the bud promotion period, from June to August during the flowering and fruiting period, and in September during the fruit strengthening period, applying 3-5 times each year, with about 40 kg of biogas slurry per plant each time. The specific method is: dig strip-shaped trenches along the roots or dig 4-6 pits around the tree, or dig arc-shaped trenches, 30 cm deep and 20 cm wide, and promptly cover with soil after the biogas slurry has infiltrated dry. Fertilization during this period is conducive to flower bud differentiation, increases the number of effective flowers, supplements more nutrients, improves the fruit setting rate, and promotes fruit growth.
Foliar spraying. Foliar spraying can be carried out during the budding, flowering, young fruit and fruit strengthening periods. The amount used per plant is generally 10-15 kg. Use clarified and filtered middle-layer biogas slurry produced for more than 1 month to spray the tree canopy, spraying once every 10-20 days, with the leaf backs thoroughly wet but without fertilizer liquid dripping as the suitable standard. Foliar spraying can make jujube leaves thicker and darker in color, significantly reduce the occurrence of diseases and insect pests, and enhance tree stress resistance. Spraying during the fruit growth period can increase yield and improve jujube fruit quality.
Precautions. 1. When biogas residue and biogas slurry are applied as base fertilizer and topdressing, a certain distance should be kept from the tree roots to prevent digging them broken and burning them. 2. Foliar spraying should be carried out in the morning or afternoon when the temperature is low, and it is not suitable to spray during the high-temperature period at noon. 3. If pests and diseases occur, pesticides can be mixed into the biogas slurry for spraying. 4. For jujube trees that are too tall, foliar spraying is somewhat difficult, and attention should be paid to safety.