Fertilization Techniques for Garlic Cultivation
The main pests of garlic include onion maggot, seedcorn maggot, root mites, thrips, and leafminers. Control methods: (1) Agricultural control. Before sowing garlic, deep plow the soil and sun-dry the clods for more than 15 days to reduce the residual pest and disease population in the soil. The base fertilizer must be fully decomposed to destroy insect eggs in the manure and prevent adults from laying eggs in it...
According to the growth and development of garlic and its fertilizer requirements and uptake characteristics, garlic fertilization should adhere to the principle of "organic fertilizer as the main source, chemical fertilizer as a supplement; base fertilizer as the main application, topdressing as a supplement; coarse fertilizer applied finely, chemical fertilizer applied skillfully," so as to maximize the satisfaction of garlic's nutrient requirements during growth and development. Garlic fertilization is generally divided into base fertilizer and topdressing.Base fertilizer. The base fertilizer should be mainly organic fertilizer. Organic fertilizer usually refers to pen manure, chicken manure, duck manure, barnyard manure, compost, cake fertilizer, etc. Whether the application rate of base fertilizer is sufficient directly affects the marketability of garlic bulbs and the overwintering performance of the plants, so sufficient base fertilizer should be applied in production.
The application rate of base fertilizer should be determined by comprehensively considering various factors such as the target yield of garlic and the fertilizer requirement per unit area yield. It is required to apply 2500-3000 kg of pig pen manure, or 4500-5000 kg of barnyard manure. Where conditions permit, 50-100 kg of cake fertilizer such as cottonseed cake may be applied. Green manure crops such as alfalfa can also be used for green manuring, or fresh grass composted, and applied as base fertilizer. The chemical fertilizers usually applied together with organic fertilizer as base fertilizer include superphosphate, nitrogen-phosphorus compound fertilizer, nitrogen-potassium compound fertilizer, or ternary compound fertilizer, etc. Apply about 75 kg of standard nitrogen fertilizer per 667 sq m. Two-thirds of the nitrogen fertilizer should be applied as base fertilizer, and one-third as topdressing. The vast majority of phosphorus and potassium fertilizers should be applied as base fertilizer. For phosphorus fertilizer, use about 30 kg of superphosphate. When phosphorus fertilizer is applied as base fertilizer, whether it is superphosphate or calcium magnesium phosphate, it must be mixed with organic fertilizer and shallowly plowed into the plow layer. For the application rate of potassium fertilizer, generally apply about 30 kg of potassium sulfate per 667 sq m.
The application method of base fertilizer is generally to apply half of the organic fertilizer before plowing, evenly broadcasting it on the soil surface, and turning the fertilizer into the ground together with plowing; the other half is applied in concentrated furrows at sowing time, mixed with soil, and then sowing is carried out. If ammonium bicarbonate or organic fertilizer is used as base fertilizer, it should be buried in furrows or applied with irrigation water, and after application, the fertilizer should be mixed evenly with the soil during land preparation. Phosphorus fertilizer is best applied shallowly, in a concentrated manner, or in layers. Part of it can be applied before plowing, and the other part after plowing when planting garlic, or shallowly applied 6-10 cm below the soil surface after land preparation, so as to facilitate absorption and utilization by seedlings, cultivate strong seedlings, and improve the seasonal utilization rate of phosphorus fertilizer. Potassium fertilizer can be broadcast during plowing and turned into the ground.
② Topdressing. During each growth stage of garlic from the seedling stage to before bulb harvest, fertilization is carried out in stages according to its growth and development and fertilizer requirement and uptake characteristics; this is topdressing. Garlic topdressing is generally based on nitrogen fertilizer, and when needed, nitrogen, phosphorus, potassium fertilizers and various elements should be applied in combination, which is beneficial to the normal growth and development of garlic, promotes the absorption and utilization of nutrients, and improves quality. Nitrogen fertilizer has a significant yield-increasing effect on garlic. When topdressing nitrogen fertilizer, attention should be paid to possible adverse effects. In addition, according to experiments, the effect of nitrogen topdressing is closely related to the size of the seed garlic cloves: the smaller the seed garlic cloves, the greater the yield increase from nitrogen application. Therefore, when using small-clove garlic as seed garlic, the application rate of nitrogen fertilizer should be appropriately increased.
Topdressing phosphorus and potassium fertilizers can enhance the balanced absorption and utilization of nitrogen fertilizer, promote the growth and development of garlic, and increase the yield of garlic scapes and bulbs. In the later stage, garlic not only needs nitrogen topdressing but also phosphorus and potassium topdressing, and nitrogen, phosphorus, and potassium fertilizers should be applied in a 2:1:1 ratio, or compound fertilizer should be applied. This is beneficial for preventing premature senescence of leaves in the later stage of garlic and promoting the transport of leaf nutrients to the bulb, and can significantly increase the yield of garlic scapes and bulbs.
The topdressing periods can generally be divided into pre-overwintering topdressing, regreening stage topdressing, garlic scape elongation stage topdressing, and garlic bulb growth stage topdressing.
Pre-overwintering topdressing: Pre-overwintering topdressing mainly promotes normal germination and seedling emergence of garlic and cultivates strong seedlings. The appearance of strong seedlings before winter is: 5 leaves, plant height about 25 cm, fresh weight per plant about 10 g, uniform root system with about 30 roots. After sowing autumn-planted garlic, seedlings generally emerge completely in 7-9 days. To improve the safe overwintering performance of garlic, apply seedling-promoting fertilizer. Seedling-promoting fertilizer generally accounts for about 25% of the total topdressing amount. For varieties prone to outer-layer cross growth, seedling-promoting fertilizer should be applied sparingly or not at all. When garlic enters the overwintering period, overwintering fertilizer, namely winter manure, can be applied. Winter manure commonly uses compost, soil-mixed manure, or horse manure spread as a cover, to thicken the protective layer for the root system during overwintering, improve the overwintering performance of seedlings, and ensure safe overwintering. At the same time, it also helps early regreening and rapid growth the following year.
Regreening stage topdressing: When the average daily temperature in spring reaches 7°C, garlic seedlings begin to regreen and grow. At this time, the covering should be removed promptly, and the seedlings should be exposed to the sun for 2-3 days. Around the Spring Equinox, before the plants start vigorous growth, apply 1 application of regreening fertilizer. Generally, apply 1000-1500 kg of organic fertilizer per 667 sq m, or 10-15 kg of standard nitrogen chemical fertilizer. For those that have already been given seedling-promoting fertilizer and overwintering fertilizer, no topdressing may be applied at the regreening stage, or the regreening fertilizer may be postponed and applied together with the scape-promoting fertilizer.
Garlic scape elongation stage topdressing: Garlic scape elongation stage topdressing refers to topdressing from the beginning of clove differentiation to before scape extraction. This period is when garlic scapes and bulbs grow simultaneously. In Shandong, this is generally late March to early April, that is, before Qingming, garlic enters the scape and clove differentiation stage, and on May 20, around Xiaoman, it enters the scape-emerging stage. In this period, the elongation of garlic scapes overlaps with the early growth of garlic bulbs, and the plants are in a period of vigorous growth. At this time, all leaves have emerged, the aboveground growth of the plant has reached its maximum, and the underground bulb yield has already formed nearly 50%; the root system actively expands laterally, and growth and absorption gradually reach a peak, so the topdressing amount should account for about 40% of the total topdressing amount. Increase the application of compound fertilizer and potassium fertilizer to promote garlic scape emergence and bulb enlargement.
Garlic bulb growth stage topdressing: Before garlic scapes are harvested, garlic bulb growth is mainly volume increase; after garlic scapes are harvested, garlic bulb growth is mainly weight increase, with an average daily weight gain of about 1 g and a daily diameter increase of about 0.06 cm. During the garlic bulb growth stage, quick-acting nitrogen fertilizer should be the main fertilizer, combined with phosphorus and potassium fertilizers. The amount of this topdressing should account for 25%-30% of the total topdressing amount.
The methods of garlic topdressing generally include band application, application with irrigation water, or buried application. When applying soil-mixed manure, open furrows along the rows and scatter it in strips; when applying chemical fertilizer, generally adopt furrow broadcasting or hole application, then cover with soil, water, or apply with irrigation water, or broadcast during rain. Attention should be paid to strengthening intertillage and weeding, keeping the soil loose and preserving soil moisture, so as to speed up the root system's absorption and utilization of nutrients.
③ Foliar fertilization. Foliar fertilization allows nutrients to enter the plant body from the leaves and directly participate in the plant's metabolic processes and the synthesis of organic matter. Its effect responds more quickly than soil fertilization and is an economical and reasonable fertilization technique. Research has shown that after applying Suanzhuangsu to garlic, the enzyme activity in the roots, stems, and leaves of garlic seedlings can increase by 15%-31%, and the yield can increase by 12%-14%. To spray Suanzhuangsu on the leaves, dilute it with clean water, using about 125-150 g of stock solution per 667 sq m each time, plus 50 L of water. The spraying periods can be once each during the garlic growth period (March), the garlic scape differentiation stage, the bulb growth stage, and 2-3 days after garlic scape harvest. When spraying, both the front and back of the leaves should be sprayed. It is best to spray after 4 p.m., and the weather should be clear when spraying. If it rains within 24 h after spraying, it must be sprayed again.
Garlic should be fertilized in combination with watering, and intertillage, ridge (bed ridge) digging, and weeding should be carried out in a timely manner. After the seedlings emerge completely, shallow hoeing and weeding should be done at the two-to-three-leaf stage to loosen the soil and preserve moisture. At the four-to-five-leaf stage, deep hoeing of about 15 cm should be carried out; after regreening the following year, shallow hoeing should be done, and one bed ridge should be dug and repaired every 4 rows of garlic to facilitate topdressing and irrigation.