Detailed Explanation of Key Spruce Seedling Management Techniques
Spruce is an evergreen tree widely distributed in China, with 20 species and 5 varieties, plus 2 introduced and cultivated species. It is a major reforestation tree species in China's frigid and cold-temperate alpine forest regions. It is relatively shade-tolerant, with trees reaching up to 50 m in height and 1.5 m in diameter at breast height. The flowering period is in late May, and cones mature from September to October. It originates from southern Xiaoxing'anling and the Huma River basin on the northern slope of the Greater Khingan Range in Heilongjiang Province, among other places. It adapts to environments with deep, moist, well-drained soil layers, has strong cold resistance, flat-spreading lateral roots, and weak wind resistance, making it prone to windthrow. It is an acidic tree species of temperate mountain regions, with high silicon dioxide content and a lifespan of over 300 years. Its timber is good and elastic, with straight grain, light and soft texture, fine and uniform structure, good bending flexibility and acoustic properties, and a slightly glossy planed surface that is easy to work. It is a good material for construction, bridges, railway sleepers, aviation, shipbuilding, plywood and furniture, and is also a raw material for musical instrument manufacturing and high-grade papermaking.
Spruce needles can be used to extract aromatic oil, and the bark contains tannins from which extract glue can be obtained. Spruce has a beautiful tree form, fast growth and strong pollution resistance, and is now an excellent tree species for timber plantations and roadside greening.
I. Site Selection, Land Preparation and Fertilization, and Bed Making
1. Site selection. Soil is the foundation of seedling production, and the key to successful seedling cultivation lies in land selection. It is best to choose neutral or slightly acidic soil, sandy soil or light clay soil, with a soil layer generally more than 70 cm thick and a black soil layer more than 20 cm thick. It is best to choose a location that is flat, fertile, sunny, convenient for water access and well-drained. Absolutely avoid cultivating spruce seedlings in saline-alkali land, waterlogged lowlands, loess slopes, peat land and gravelly soil.
2. Land preparation and fertilization. In the seedling stage, spruce has many fine, weak roots with extremely poor ability to root and spread. Without fine-grained, loose soil conditions, the seedling roots have difficulty extending and penetrating downward. Therefore, careful and thorough cultivation is necessary to lay a good foundation for the next stage of production. During land preparation, it is necessary to plow, harrow, level, and clear residues. While preparing the land, fertilizer should be applied well. The best manure is farmyard manure, using human feces mixed with decomposed peat soil and a small amount of sawdust, plus some livestock manure compost.
3. Bed making. The height of the bed should be determined according to site conditions. Beds in low-lying areas should be made higher, while those on higher ground should be made lower, adapting to local conditions. Generally, the bed surface is 1.1 m-1.2 m wide and 10 m-20 m long, with paths 20 cm-30 cm wide. The bed surface should be fine and level. Seven days before sowing after the bed is made, disinfect the bed surface with a 1% ferrous sulfate solution.
II. Seed Germination Treatment
The purpose of germination treatment is to promote the transformation of seed contents, advance germination, enhance germination vigor, shorten emergence time, strengthen cold resistance, extend the growth period, and achieve fast, uniform, even and complete emergence. At present, there are four seed germination methods: 1. Sand mixing for germination. 2. Water soaking for germination. 3. Low-temperature stratification for germination. 4. Snow storage for germination.
To adapt to the climate conditions of Northeast China, snow storage for germination can be used. The specific method is: before the soil freezes, choose a well-drained, shady place and dig a pit; the pit should be about 50 cm deep and 50 cm wide, and the length depends on the quantity of seeds. First lay straw curtains or mats at the bottom of the pit, spread a layer of crushed ice about 10 cm thick, then mix the seeds and snow evenly at a ratio of 1:3 (seeds, sand and snow can also be mixed at 1:2:3) and place them in the pit, pile snow into a mound on top, and cover with straw curtains or soil. In spring, gradually remove the snow but still keep the straw curtains. One week before sowing, remove the covering and turn it over 2-3 times at noon every day to melt the ice and snow, and inspect the seeds. If germination is good, low temperature can be maintained until the seeds are taken out at sowing time. If germination is uneven or incomplete, exposure to sunlight or indoor heating for 1-3 days will suffice. If the quantity of seeds is small, iron barrels, large vats or other containers can also be used, but the containers should be placed in a cold room to prevent sunlight exposure, and the snow mixing ratio is the same as above.
III. Sowing
1. When sowing, first pay attention to whether the soil moisture is suitable. If it is too dry, irrigation should be carried out before sowing to ensure sufficient bottom moisture, and timely early sowing should be mastered. Early sowing leads to early emergence, strong resistance, a long growth period and good lignification. If late frost occurs during the seedling emergence period, weather changes must be monitored at all times and frost protection work done well. Firewood and grass mixed with sawdust can be burned to produce smoke to prevent late frost.
2. After sowing, soil should be covered immediately to prevent the soil and seeds from drying out and affecting germination. The thickness of the covering soil is extremely closely related to seed germination and seedling emergence. Generally, the covering thickness should be 2-3 times the diameter of the seed. The covering thickness must be uniform; otherwise, seedlings will emerge unevenly, directly affecting seedling yield and quality. The covering material is a certain proportion of peat soil, decomposed manure and sawdust, carefully mixed together. These materials not only absorb water well but also have a certain fertility. After covering with soil, press it down promptly.
3. Cover in time. The purpose of covering is to keep the soil moist, regulate surface temperature, prevent surface soil from crusting and weeds from growing, and it is even more important for covering small seeds. Using pine needles as a covering material can achieve the goals of being sterile, saving labor, saving time and money, and greatly reducing seedling costs, with very good results.
IV. Tending and Management
1. Emergence stage. From seedling emergence until shell shedding, bird damage must be prevented. Dedicated personnel can be used to drive away birds, or some scarecrows can be set up to frighten them, or some wind-driven sound devices can be installed.
2. Growth period (seedling forcing period). First, create good growing conditions for the seedlings to promote robust growth and enhance resistance. Second, carry out chemical prevention. This period is an important time for seedling tending, and timely work should be done in topdressing, spraying and watering, weeding and thinning, and pest control. Spruce seedlings grow slowly; 1-year-old seedlings are only 2 cm-4 cm tall. Water 2-4 times a day, preferably in small amounts but frequently. Reduce watering or stop irrigation during the rainy season. For chemical weed control, reference can be made to larch management, but the dosage must be lower than for larch. For thinning, generally 2-year-old seedlings should retain an average of 600-800 seedlings per sq m, and 3-year-old seedlings 400-600.
3. Cold protection. Cold protection is a key measure to reduce losses during seedling overwintering. Use soil banking for cold protection, with a thickness exceeding seedling height by 4 cm-5 cm. The time to remove the soil is after the dry spring winds; doing so too early will cause physiological drought.
V. Do a Good Job in Pest and Disease Control
The occurrence and spread of pests and diseases are closely related to local climate, temperature, humidity, soil conditions, etc. The policy of "prevention first, active elimination" must be implemented to do good prevention work. This includes selecting seedling land, strengthening management, timely early sowing, doing good work in land preparation, sprinkler irrigation, weeding, environmental sanitation, etc., and carrying out timely chemical prevention.