What are the characteristics of garlic's fertilizer requirements?
What are garlic's fertilizer requirements? Please explain that garlic is one of the vegetables that needs more fertilizer and is relatively tolerant of fertilizer. The dynamics of nutrient absorption by garlic at different growth stages increase with the increase in plant growth. From sowing to the emergence of the primary leaves above the ground is the germination stage, and the characteristic of this stage is that the root system...
What are garlic's fertilizer requirements? Please explain
Garlic is one of the vegetables that needs more fertilizer and is relatively tolerant of fertilizer. The dynamics of nutrient absorption by garlic at different growth stages increase with the increase in plant growth.
From sowing to the emergence of the primary leaves above the ground is the germination stage. The characteristic of this stage is that the root system grows mainly vertically, the growing point gradually differentiates new leaves, and the main role of the root system is to absorb water. Because the growth amount is small and the growth period is short, the nutrients consumed are also few, and the various nutrients needed are provided by the seed garlic.
From the unfolding of the primary leaves to the beginning of differentiation of the bulbils and flower buds is the seedling stage. During this stage, new leaves are continuously differentiated, laying the foundation for the differentiation of bulbils and flower buds. From germination to seedling growth, the plant relies on the seed garlic for nutrient supply. As the seedlings grow, the stored nutrients in the seed garlic are gradually consumed. After the nutrients are absorbed and utilized, the mother garlic begins to shrink, which in production is called "mother retreat." The mother retreat stage generally occurs around the end of the seedling stage. During this stage, garlic growth depends entirely on soil nutrient supply, and the amount of fertilizer absorbed increases markedly. If soil nutrients are insufficient, the plant is prone to a gap in nutrient supply and shows dry leaf tips.
After the garlic seedling stage ends, it enters the bulbil and flower bud differentiation stage. During this stage, new leaf differentiation stops, leaf growth predominates, the plant's growing point forms the flower primordium, and at the same time bulbils form in the axils of the inner leaves. Root growth strengthens, nutrient accumulation increases, laying the foundation for the growth of garlic bulbs and garlic scapes, and accelerating the absorption and utilization of soil nutrients. This is a critical period for garlic growth and development.
From the end of flower bud differentiation to the harvest of garlic scapes, vegetative growth and reproductive growth proceed together, and the growth amount is the greatest. While the garlic scapes elongate rapidly, the bulb also gradually forms and expands. During this period, root growth and fertilizer absorption capacity reach a peak, and it is the period of greatest fertilizer demand and the key period for fertilization. After the garlic scapes are harvested, it is the peak period of bulb expansion. The root system begins to age, and the absorbed nutrients as well as the stored nutrients in the leaves and sheaths are transported in large amounts to the bulb, and the bulb expands and fills rapidly. At this time, because the leaves and roots gradually age, the amount of fertilizer absorbed is not large, and most of the nutrients needed for bulb expansion come from the redistribution of the plant's own nutrients.
Garlic's requirements for various nutrients and their physiological roles: According to research, among the various nutrient elements absorbed by garlic, nitrogen is absorbed the most, followed by potassium, calcium, phosphorus, and magnesium. If the absorption of nitrogen is taken as 1, then the absorption ratio of the various elements is nitrogen:phosphorus:potassium:calcium:magnesium = 1:0.25-0.35:0.85-0.95:0.5-0.75:0.060. For every 1,600 kg of garlic produced, 13.4-16.3 kg of nitrogen, 1.9-2.4 kg of phosphorus, 7.1-8.5 kg of potassium, and 1.1-2.1 kg of calcium are absorbed. After the differentiation of bulbils and flower buds, garlic reaches the peak period of absorption of the three major elements in its life cycle; before scape extraction is the peak period of absorption of the trace elements iron, manganese, and magnesium; after scape harvest, the absorption of the three major elements and boron reaches a small peak again, and zinc absorption reaches a peak. Among the three major element fertilizers, nitrogen deficiency has the greatest impact on yield, followed by phosphorus deficiency, while potassium deficiency has the smallest impact. When the three major elements are deficient at the same time, the impact on garlic yield is even greater.
After garlic emerges, it begins to absorb nitrogen nutrition, and in each subsequent growth and development stage, this increases rapidly, especially in the bulb expansion period after scape removal, when nitrogen absorption is greatest. Test results show that nitrogen absorption at the garlic seedling stage is about 5.8 kg, accounting for about 30% of total absorption; absorption during the garlic scape elongation period is about 7.4 kg, accounting for about 38% of total absorption; absorption during the garlic bulb expansion period is about 6.0 kg, accounting for about 30.7% of total absorption. During garlic's growth and development, if nitrogen fertilizer supply is sufficient, plant growth speeds up, the vegetative body is large, and the leaves are dark green and thick; if nitrogen is insufficient, plant growth is slow and weak, and the leaves are small and yellow. If nitrogen is deficient at the seedling stage, growth is slow, leaves are narrow and long, and leaf color is light green; if nitrogen is deficient in the middle and late stages, in addition to the whole plant fading green, the especially obvious characteristic is that yellow leaves easily appear in the lower part, and in severe cases the leaves easily wither. Therefore, in production, attention should be paid to increasing nitrogen fertilizer application.
Phosphorus is indispensable for promoting the growth and development of the garlic root system and the differentiation and growth of garlic scapes and garlic cloves. At the garlic seedling stage, phosphorus absorption per 667 sq m is 0.855 kg, accounting for 17% of total absorption; absorption is highest during the garlic scape elongation period, at 3.095 kg per 667 sq m, accounting for about 62% of total absorption; after scape removal, entering the garlic bulb expansion period, absorption decreases, at 1.1 kg per 667 sq m, accounting for 21% of total absorption.
Potassium is one of the main nutrient elements absorbed by garlic. Like nitrogen, it is absorbed in large amounts throughout garlic's entire growth and development process, and its content in the plant body is also high. It plays an important role in garlic growth and development, especially having a direct relationship with the sugar content in the garlic body and the quality of garlic. Therefore, in production, great attention should be paid to the use of potassium fertilizer to ensure garlic's need for potassium. Garlic's absorption of potassium is relatively high: at the seedling stage, absorption per 667 sq m is 4.883 kg, accounting for about 21.2% of total absorption; during the garlic scape elongation period, absorption per 667 sq m is 12.25 kg, accounting for about 53.2% of total absorption; during the garlic bulb expansion period, absorption decreases, at 5.889 kg per 667 sq m, accounting for about 25.6% of total absorption.
Applying calcium on acidic soil can reduce soil acidity. When garlic is deficient in calcium, necrotic spots appear on the plant leaves. As the necrotic spots enlarge, the leaves bend downward, the leaf tips die quickly, and root growth is greatly inhibited; increasing calcium application can increase garlic bulb yield.
Magnesium is a component of chlorophyll. Magnesium deficiency in garlic causes leaf chlorosis. The symptoms first appear at the base of old leaves and gradually develop toward the leaf tip, and the leaves eventually turn yellow and die; symptoms of magnesium deficiency in garlic generally appear relatively late, with slow plant growth, and only 6-7 leaves appear 30 days after sowing. Increasing magnesium application can rapidly increase garlic bulb yield and can promote the absorption of nitrogen, phosphorus, and potassium, but it has a certain effect on calcium absorption. As magnesium concentration increases, calcium absorption decreases; however, calcium has almost no effect on magnesium absorption.
Sulfur is a quality-constituent element of garlic. Proper sulfur application can enhance garlic flavor and tends to increase garlic bulb weight and lengthen garlic scapes. Test results show that applying copper sulfate and potassium sulfate can reduce the rates of malformed scapes and split bulbs (garlic bulb splitting caused by secondary growth), improving the marketability of garlic bulbs. In production, urea combined with copper sulfate is often used as a sulfur source, with good results.
Garlic Fertilization Techniques
According to the characteristics of garlic's fertilizer demand and fertilizer absorption, in garlic fertilization, the principle should be adhered to of mainly using organic fertilizers with chemical fertilizers as a supplement; mainly using base fertilizer with topdressing as a supplement; applying coarse fertilizers finely and chemical fertilizers skillfully, so as to maximize the satisfaction of garlic's needs for nutrient elements during growth and development.
Garlic fertilization is generally divided into two types: base fertilizer and topdressing.
1. Base fertilizer. Garlic has a shallow root distribution, few root hairs, and weak fertilizer absorption capacity, so it has relatively high requirements for the quantity and quality of base fertilizer. Base fertilizer should mainly be organic fertilizer. Organic fertilizers usually refer to pigsty manure, human excrement and urine, chicken and duck manure, barnyard manure, cake fertilizer, compost, and so on. These fertilizers have comprehensive nutrients, high content, long fertilizer efficiency, and great effect. According to the characteristic that garlic needs more fertilizer, whether the base fertilizer application rate is sufficient directly affects the marketability of garlic bulbs and the overwintering performance of the plants, so in production the base fertilizer should be applied as sufficiently as possible. The base fertilizer application rate for garlic should be comprehensively considered based on various factors such as the target yield of garlic and the fertilizer absorption amount for forming a unit yield. Generally, when the target garlic bulb yield is 1,000-1,500 kg per 667 sq m, it is required to apply 2,500-3,000 kg of pig manure and urine, or 4,500-5,000 kg of barnyard manure, or 500-750 kg of human excrement and urine. Where conditions permit, 50-100 kg of cottonseed cake per 667 sq m, or about 50 kg of soybean cake, may be applied. Green manure such as alfalfa can also be turned under, or fresh grass composted, for use 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, and so on. On the basis of the above yield level and fertilization, it is generally required to apply about 75 kg of standard nitrogen fertilizer per 667 sq m. For the application of nitrogen chemical fertilizer, 2/3 is required to be applied as base fertilizer and 1/3 as topdressing. The vast majority of phosphorus and potassium fertilizers are applied as base fertilizer. For the application amount of phosphorus fertilizer, generally about 30 kg of superphosphate can be applied per 667 sq m, and in new garlic areas deficient in phosphorus it can be applied up to 45 kg. In old garlic areas, where the content of available phosphorus in the soil is relatively high and the application amount of organic fertilizer is also large, about 15 kg can be applied. Whether superphosphate or calcium-magnesium phosphate fertilizer, both should be mixed with organic fertilizer and applied as base fertilizer, and shallowly plowed into the soil tillage layer. For the application amount of potassium fertilizer, generally about 30 kg of potassium sulfate is applied per 667 sq m. If the content of available potassium in the soil is low and potassium application conditions are available, it can be applied up to 45 kg. If the content of available potassium in the soil is relatively high, about 15 kg can be applied. There are many types of potassium fertilizer, commonly used ones include potassium sulfate, potassium chloride, and so on, all of which can be applied as base fertilizer.
The method of using base fertilizer is generally to apply half of the organic fertilizer before land preparation, evenly broadcast it on the soil surface, and plow it into the ground together with land preparation, and apply the other half in concentrated furrow application at sowing time, so that fertilizer and soil are mixed, and then sow. If ammonium bicarbonate, ammonia water, or human excrement and urine is used as base fertilizer, it should be applied by opening furrows and burying it or applied with irrigation water, and after application, combined with land preparation, it should be mixed evenly with the soil. After phosphorus fertilizer is applied to the soil, it has the characteristics of low mobility and strong fixation. If applied too shallowly, most of the phosphorus fertilizer will remain in the surface layer and not move downward; if applied too deeply, most of the phosphorus fertilizer will remain below the tillage layer. At the same time, because phosphorus fertilizer is also fixative, after phosphorus fertilizer is applied to the soil, the larger the contact area with the soil and the longer the time, the more phosphorus is fixed. Therefore, for phosphorus fertilizer, it is best to apply it shallowly, in a concentrated manner, or in layers, or after land preparation to apply it 6-10 cm underground, so as to facilitate absorption by seedlings, cultivate strong seedlings, and improve the seasonal utilization rate of phosphorus fertilizer. Potassium fertilizer can be broadcast during plowing as the soil is turned, and then plowed into the ground.
2. Topdressing. During the garlic growth process, from the seedling stage to each growth stage before bulb harvest, fertilization carried out in stages according to its growth and development and the characteristics of fertilizer demand and fertilizer absorption is topdressing. Garlic topdressing is generally mainly nitrogen fertilizer, but the combined application of nitrogen, phosphorus, potassium, and various elements not only benefits the normal growth and development of garlic, but also helps promote the absorption and utilization of nutrients and improve quality. A large number of tests show that nitrogen fertilizer has a significant yield-increasing effect on garlic, and during the garlic growth process, attention should be paid to the application of nitrogen fertilizer. However, at present in garlic fertilization, there is a phenomenon of emphasizing nitrogen fertilizer and neglecting phosphorus and potassium fertilizers. Excessive application of nitrogen fertilizer easily causes abnormal growth of garlic (such as secondary growth, etc.), reduces the marketability of garlic, and results in late scape extraction and more branching. Whether urea or ammonium sulfate is used as nitrogen fertilizer, when the application amount is large, both will significantly increase aboveground fresh weight, bulb diameter, and garlic bulb weight, while garlic scape yield tends to decrease, and secondary growth increases significantly. Therefore, for varieties prone to secondary growth, when topdressing nitrogen fertilizer, attention should be paid to the possible adverse effects. In addition, according to tests, 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. For example, when the seed garlic clove weight is 0.7-1 g, the yield increase from nitrogen application is 0.6%; when the seed garlic clove weight is 2.0-3.0 g, the yield increase from nitrogen application is 35.7%. Therefore, when using small garlic cloves as seed garlic, the application amount of nitrogen fertilizer should be appropriately increased. Topdressing phosphorus fertilizer or potassium fertilizer can enhance the absorption and utilization of nitrogen, promote garlic growth and development, and increase garlic scape and garlic bulb yields. When topdressing, the topdressing in the late growth stage of garlic should be strengthened. Late-stage topdressing can promote the plant's absorption of nitrogen, phosphorus, and potassium, making the absorption peak higher and extending its duration. In the late stage, garlic not only needs nitrogen but also phosphorus and potassium fertilizers. Nitrogen, phosphorus, and potassium fertilizers should be applied in combination, with a ratio of 20:10:10, or compound fertilizer should be applied. This is beneficial for preventing premature aging of garlic leaves in the late stage and promoting the transport of leaf nutrients to the bulb, and can significantly increase garlic scape and garlic bulb yields.
Garlic topdressing periods are generally divided into pre-winter topdressing, regreening stage topdressing, garlic scape elongation stage topdressing, and garlic bulb growth stage topdressing.
(1) Pre-winter topdressing. Pre-winter topdressing is mainly to promote normal germination and emergence of garlic and cultivate strong seedlings. The appearance of strong garlic seedlings before winter is: 5 leaves, plant height about 25 cm, fresh weight per plant about 10 g, uniform root system, about 30 roots. For autumn-sown garlic, after sowing, complete emergence generally occurs in 7-9 days. About one month after emergence, apply a seedling-promoting fertilizer once to promote rapid rooting and seedling growth of the seedlings and improve the safe overwintering performance of garlic. For varieties whose seedlings grow relatively quickly in the early stage, application can be appropriately delayed. Seedling-promoting fertilizer generally accounts for 25%-30% of the total topdressing amount. If the soil is fertile and the base fertilizer is sufficient, especially for varieties prone to outer-layer secondary growth, the seedling-promoting fertilizer should be applied less, applied in a dispersed manner, or not applied. When garlic enters the overwintering period, apply overwintering fertilizer, namely winter manure, commonly using compost, soil miscellaneous fertilizer, and so on, spread as a cover, to thicken the overwintering protective layer of the root system. This improves the overwintering performance of the seedlings, ensures safe overwintering, and also helps early regreening and rapid growth the following year.
(2) Regreening stage topdressing. When the average daily temperature in spring reaches 7°C, garlic seedlings begin regreening and growing. The covering should be removed promptly, and the plants should be exposed to the sun for 2-3 days. Around "Spring Equinox," before garlic begins vigorous growth, apply a regreening fertilizer once. Generally, 1,000-1,500 kg of organic fertilizer per 667 sq m, or 10-15 kg of standard nitrogen chemical fertilizer, is applied. For those that have already been applied with seedling-promoting fertilizer and overwintering fertilizer, topdressing may be omitted at the regreening stage, or the regreening fertilizer may be postponed and applied together with the scape-promoting fertilizer.
(3) Topdressing during the garlic scape growth period. Topdressing during the garlic scape growth period refers to topdressing from the beginning of garlic clove differentiation to before scape extraction, during the period when garlic scapes and garlic bulbs coexist. In Shandong, generally at the end of March and the beginning of April (that is, before Qingming), garlic enters the scape and clove differentiation stage, and around May 20 (that is, Xiaoman) it enters the scape extraction stage. This stage is a period when garlic vegetative growth and reproductive growth proceed together. The elongation period of garlic scapes and the early growth period of garlic bulbs overlap. Garlic growth is in a vigorous period, all leaves have grown out, the aboveground growth of the plant reaches its maximum, the yield of underground garlic bulbs has already formed nearly 50%, the root system actively expands laterally, and growth and absorption gradually reach a peak. Therefore, during this period, heavy fertilization is required. The topdressing amount should account for 30%-40% of the total topdressing amount. Where conditions permit, additional compound chemical fertilizer and potassium fertilizer should be applied. This lays a good foundation for garlic scape extraction and garlic bulb expansion.
(4) Topdressing during the garlic bulb growth period. After garlic scapes are harvested, the roots, stems, and leaves of garlic basically stop growing, and nutrients are concentrated and transferred to the garlic bulbs. Before garlic scapes are harvested, garlic bulb growth is mainly an increase in volume; after garlic scapes are harvested, garlic bulb growth is mainly an increase in weight, with an average daily weight increase of nearly 1 g and a daily diameter increase of 0.06 cm. Within 8 days after garlic scape harvest, it is the fastest growth stage in the life of the garlic bulb, with an average daily weight increase per bulb of up to 1.4 g and a daily diameter increase of 0.08 cm. To protect roots and prevent premature aging, extend the functional period of leaves, and promote the transfer and accumulation of dry matter, during the garlic bulb growth period, appropriate heavy fertilization should be applied, mainly with quick-acting nitrogen fertilizer, combined with phosphorus and potassium fertilizers, avoiding excessive nitrogen application. The amount of this topdressing should account for 25%-30% of the total topdressing amount.
The application methods for garlic topdressing generally use furrow application, application with irrigation water, or buried application. When topdressing with soil miscellaneous fertilizer, furrows are often opened along the rows and the fertilizer is broadcast in strips; chemical fertilizers are generally applied by opening furrows and broadcasting, then covering with soil and watering, or applied with irrigation water, or broadcast during rain. After topdressing at the seedling stage, attention should be paid to intertillage and weed control, keeping the soil loose and preserving soil moisture, reducing nutrient loss, and accelerating the absorption and utilization of nutrients by the root system.
(5) Fertilization techniques for garlic sprouts. Garlic sprout cultivation aims at harvesting young seedlings, and the growth period experienced is mainly the seedling stage. Multiple crops can be cultivated in one year. Garlic sprouts grown under light conditions have green leaves and are called green garlic. Those grown under dark conditions have yellow leaves and are called garlic yellow. Garlic sprout cultivation has a short growth period and requires relatively little fertilizer, but the planting density of the plants is high, and the amount of fertilizer absorbed per unit area is relatively large. At the same time, garlic sprout cultivation mostly uses smaller garlic cloves as seed garlic, and the mother cloves provide few nutrients, so the soil's fertilizer demand increases. In addition, the edible part is the false stem (that is, the leaf sheath part, also called garlic white) and tender leaves, requiring garlic sprouts to be tender and juicy with a delicious taste. Therefore, fertilization in garlic sprout cultivation cannot be ignored. Fertilization in garlic sprout cultivation, first, requires sufficient base fertilizer, and second, does not require seedling hardening but should be promoted throughout. For base fertilizer, combined with land preparation, 4,000-5,000 kg of decomposed pen manure per 667 sq m, or 2,500-3,000 kg of human and livestock manure, or 5,000 kg of farmyard manure plus 15-20 kg of ammonium bicarbonate and 50 kg of superphosphate can be applied as base fertilizer. Topdressing is generally applied 2-3 times, preferably with quick-acting fertilizer, mainly nitrogen chemical fertilizer. The first topdressing is generally carried out after the seedlings emerge completely, applying 1,000-1,500 kg of decomposed human excrement and urine per 667 sq m, or 10-15 kg of urea; the second topdressing can be carried out about 15 days before harvest, with the same application amount as the first. If harvest is relatively late, one additional topdressing can be applied between the two topdressings, generally applying 15-20 kg of urea per 667 sq m. For those harvested after spring, combined with watering for regreening, apply regreening fertilizer to accelerate regreening and improve the quality and yield of garlic sprouts. For greenhouse cultivation of garlic sprouts, fertile culture soil should be prepared. Topdressing is mainly carried out through foliar feeding. After the seedlings are 5 cm tall, apply 20 g of urea in water per sq m, and thereafter spray a 300-fold diammonium phosphate aqueous solution once every 7 days. After each foliar fertilization, the leaf surface should be rinsed with clean water to avoid fertilizer burn.
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