Detailed Explanation of Key Points of the Two-Stage Olive Seedling Cultivation Technique

    Nutrition Bag Preparation 

First, prepare the nutrient soil. Take fertile paddy soil, burnt soil and decomposed compost in a 5:3:2 ratio and mix them, add 2% calcium-magnesium phosphate fertilizer and stir well for later use, then take plastic bag film measuring 24×18 cm, cut openings at both sides of the bottom of the bag, and punch holes in the bag walls to facilitate drainage and aeration. Mix a small amount of insecticide and fungicide into the prepared nutrient soil for soil disinfection, that is, spray with 0.4% formalin solution until the substrate moisture content reaches 60%, and add 50% phoxim (10-15 grams per cubic meter) mixed into the substrate, stir evenly, cover with airtight material for 3-5 days, and use after turning and mixing when there is no odor. After the nutrient soil is prepared, adjust the acidity, with PH5-6.5 being suitable.
 
    Container Soil Filling and Arrangement 

Mix the prepared nutrient soil with base fertilizer evenly, fill into 24×18 cm plastic bags, and compact the soil layer by layer until full, then neatly arrange them on the prepared seedling bed, with a bed width of 1 m and bed length depending on the terrain. When arranging, the containers should stand upright and close together, arranged in rows, not tilted, with the gaps between containers filled with fine soil, and the surroundings of the seedling bed banked with soil, preferably not exposing the plastic bags, and keep the containers at the edge of the bed moist. 

    Seedling Site Selection and Land Preparation 

The nursery site should be selected as loam or sandy loam with flat terrain, sufficient water source, convenient drainage and irrigation, convenient transportation, sufficient sunlight, deep soil layer and rich organic matter. Soil that is heavy and poorly drained is not suitable as a seedling site. Land preparation is best carried out in winter. First deep-plow and harrow the seedling site flat, finely prepare the land before sowing, carry out soil disinfection and weed control, achieve level ground, broken soil and no grass roots, then form long beds 1 m wide on the leveled nursery land, with a bed height of 25-30 cm and a ditch width of 30 cm. 

    Sowing 

From February to March, take out the sand-stored seeds, soak them in hot water at 60-70 °C for half a minute, then soak in cold water for 2-3 hours, and then sow. Generally, sow 2.5 kg of seeds per square meter. Evenly broadcast the seeds on the seedling bed, press flat with a wooden board, then cover with a layer of fine sand, with a thickness such that the seeds are not visible, then cover with rice straw, and then water thoroughly. After sowing, set up arched bamboo frames on the seedling bed and cover with plastic film to facilitate heat preservation and moisture retention, promote early seed germination; generally 30-50 days after sowing, they will germinate and emerge. After the olive seedlings emerge, management should be frequent; on sunny days, the film should be removed during the day and covered at night, and water should be replenished in time to promote the growth of sprouts and seedlings. 

Fifteen days after the olive seedlings emerge, when 3-5 true leaves have grown, they can be transplanted into bags. Before transplanting, water the sand bed thoroughly. When lifting seedlings, gently pry up the sprouts with a bamboo stick, trying not to damage the fibrous roots, so that the root system carries more fine soil, and transplant the seedlings into bags as they are lifted. When transplanting, use a bamboo stick to make a hole in the center of the container bag for planting, then place the seedling into the planting hole, and press back soil beside the seedling with the hand to firm it, so that the roots and soil are in close contact, preventing too-deep planting, root curling, root breakage or exposed roots. After transplanting, water thoroughly immediately to improve the survival rate. Transplanting should preferably be carried out in the evening. 

    Seedling Management 

Olive seedlings have relatively strict water requirements. Generally, the soil moisture content in the nutrient bags should be kept at 60%-70%. Within one week after transplanting, water once each morning and evening every day, watering evenly and thoroughly with a watering can; afterward, water once a day, in principle keeping the layer where the seedling root system is distributed in a moist state. 

When the olive seedlings grow to 5-10 cm, begin topdressing. During the rapid growth period, nitrogen fertilizer is mainly used; in the later growth stage, phosphorus and potassium fertilizers or compound fertilizers are suitable. Fertilization should follow the principle of "light fertilizer applied frequently, first dilute then concentrated," combined with watering, using a mixed fertilizer of nitrogen, phosphorus and potassium in a certain proportion diluted into a 200-fold aqueous solution for spraying. Topdressing should preferably be carried out in the evening; after topdressing, promptly rinse the seedling leaf surfaces with clean water to prevent fertilizer damage and promote root absorption. 

Timely weed control and pest and disease control. The main pests and diseases at the olive seedling stage are anthracnose and the olive psyllid. For control, agents such as 50% carbendazim wettable powder 800-1000 times dilution, or 0.6% Bordeaux mixture, 40% omethoate emulsifiable concentrate 1000 times dilution, or 50% trichlorfon soluble powder 800-1000 times dilution can be selected. In winter, set up frames and cover to prevent frost damage, so as to help the seedlings overwinter safely.