What are the common mistakes in grape fertilisation? Growers should be careful to avoid them
In recent years, as grape prices have climbed steadily and the profitability of grape growing has risen steadily, farmers have become more enthusiastic about investing in grape cultivation. A few days ago a fruit grower from Shaanxi got in touch and said that on one mu and three fen of land, about 50 kg of chemical fertiliser was applied - 5 bags! Excessive input leads to haphazard and excessive fertilisation, causing frequent fertiliser damage and serious root burn. Below, several common fertilisation mistakes are summarised for the reference of growers everywhere.
1. Newly planted grapevines are fertilised before new roots have grown out, or the base fertiliser is applied too shallowly, causing the young plants to die.
With newly planted grapevines, new roots generally do not grow out until the tendrils appear. Applying too much fertiliser before the new roots grow out, on the one hand makes it difficult for the young plants to take up water, and on the other hand makes it hard for the new roots to grow; when hot weather arrives, the above-ground part dries up and dies.
Note: when the new roots have just grown out, it is also not suitable to use fertiliser of too high a concentration.
2. Applying large amounts of fertiliser and watering heavily just because the leaves turn yellow after budding.
From budding to flowering, 65% of a grapevine's nutrition comes from reserves stored in the plant the previous year. Yellowing of the plant at this time is mainly caused by insufficient nutrient accumulation in the plant the previous year. The related factors are as follows: (1) high yield the previous year, late harvest, insufficient nutrient accumulation; (2) downy mildew the previous year causing early leaf fall; (3) too much nitrogen fertiliser in the later part of the previous year, so the shoots could not mature normally at leaf fall; (4) excessive soil moisture in the later part of the previous year causing root suffocation, or excessive fertiliser burning the roots and causing massive root death; (5) base fertiliser applied too late or trench fertilisation in spring, causing extensive root damage. Basically all these causes are related to few and weak roots. In early spring the air temperature rises quickly while the soil temperature rises slowly; if you choose to apply large amounts of fertiliser and water heavily, the soil temperature will be even lower and the roots' ability to absorb will be even worse. Add to that the fact that the roots themselves are few and weak, and you get the phenomenon that the more you water and fertilise, the less it grows. In this situation, on the one hand loosen the soil to let air in and raise the soil temperature, and at the same time supplement nutrition through the leaves; you can refer to the foliar feeding plan above.
????3. Blindly supplementing iron fertiliser just because the shoot tips or the whole vine turn yellow.
In some orchards, the leaves at the shoot tips turn yellow, or even the leaves of the whole vine turn pale yellow. The symptoms look very much like iron deficiency, but it is not necessarily a soil iron deficiency; it is often that the soil is cold and wet, the roots respire poorly and have weak absorption capacity, making it difficult for them to absorb iron and other elements, which causes yellowing of the upper part of the vine. This phenomenon mostly occurs in greenhouse grapes or in orchards covered with plastic film where the soil moisture is excessive. At this time, fertilising or watering will lower the soil temperature and worsen the iron deficiency symptoms. Supplementing iron and other elements through the leaves cannot replace root absorption; it only treats the symptoms, not the root cause. The first thing to do is loosen the soil to let air in, and drain away water to reduce moisture. For greenhouse grapes, loosen the soil and ventilate in good time, ventilate more; this both lowers the temperature inside the greenhouse and reduces water consumption, and also reduces humidity. For orchards covered with plastic film, uncover the film as soon as possible and loosen the soil. At the same time, supplement nutrition through the leaves to meet the needs of grape growth and development.
4. Applying large amounts of fertiliser just because the grapevines are growing slowly.
Many grapevines do not seem to grow and it is hard for new shoots to emerge; the main cause is excessive soil moisture or compacted, airless soil, so the roots have difficulty respiring, their absorption capacity is low, or the roots are few and weak. Fertilising at this time makes the soil even wetter and its aeration even worse. When the amount of fertiliser is too large, it very easily burns the roots. In this situation the first thing to solve is soil permeability and root respiratory vitality; loosening the soil and draining off moisture are the effective measures. I very much agree with the saying of one teacher: "the root system is the engine".
????5. The more fertiliser the better; emphasis on heavy fertilisation and neglect of absorption.
Many grape growers take it for granted that the more fertiliser they apply, the better the grapes grow and the higher the yield. According to research by Liu Ailing, Wang Shiping and others at Shanghai Jiao Tong University, grapes given high-concentration fertiliser actually have lower yields and poorer quality than grapes given medium- and low-concentration fertiliser. As mentioned above, being able to put 5 bags of fertiliser on just over one mu of land means there are simply no roots left to grow, let alone absorb; since they cannot absorb it, why bother applying the fertiliser? Many fruit growers are very blind when fertilising, competing with one another, and the amounts applied grow larger and larger. In a sense, applying more fertiliser is not as good as finding ways to raise the utilisation rate of the fertiliser and increase absorption, or rather, applying more fertiliser is not as good as growing more roots. Only by creating a loose, airy, neither dry nor wet soil environment rich in organic matter will root growth and absorption be favoured. When the soil environment is good, the roots will be good; healthy, good roots are the guarantee of healthy above-ground growth, and only then will there be healthy, good fruit.
6. Fertiliser applied too concentrated and too close to the trunk.
The distance fertiliser can move in the soil is limited; that is to say, when fertiliser is applied in a fairly concentrated way, only part of the root system absorbs the nutrients. Concentrated fertilisation easily causes the fertiliser concentration in a local spot to become too high, causing root burn. The roots absorb nutrients mainly through the fine hair roots, and close to the main trunk there are very few hair roots; most are thicker roots, whose main job is to transport the nutrients and water absorbed by the hair roots - they have no absorption function. When fertiliser is applied too close to the trunk, not only is the absorption and utilisation rate low, it very easily burns the thicker roots, with a huge impact on the growth of the vine. If a large number of thick roots died the previous year, pathogens spreading along the dead roots can cause shoots growing the following year to suddenly wither and die.
7. When drip irrigating, dripping only fertiliser, not clean water.
In some orchards, fertiliser is added every time drip irrigation is used, and the clean-water drip is stopped immediately after the fertiliser is dripped. Since the amount of water dripped each time is limited, after the surface water evaporates the fertiliser concentration in the soil becomes higher and higher, eventually burning the roots. Integrated water and fertiliser should mean dripping clean water for 15 minutes before dripping the fertiliser, and then dripping clean water for 30 minutes after the fertiliser.
8. Treating organic fertiliser as equivalent to organic matter.
Organic fertiliser and organic matter are two different concepts, and many people equate them. Organic fertiliser refers to carbon-containing material mainly derived from plants and/or animals, applied to the soil with the main function of providing plant nutrition. Organic matter refers to organic substances that possess the functions of life. Soil organic matter (humus) generally refers to the substances in the soil that come from life. It includes: soil microorganisms and soil animals and their secretions, as well as plant residues and plant secretions in the soil body. Regulating soil permeability, buffering capacity, increasing beneficial microorganisms, and raising the utilisation rate of fertiliser all depend on soil organic matter. The purpose of applying organic fertiliser is to increase soil organic matter. But many fruit growers place more value on how much nitrogen, phosphorus, potassium and other nutrients the organic fertiliser contains, while ignoring the truly most useful thing - the organic matter. The organic material in organic fertiliser needs to undergo biological transformation before it can become humus; there is a humification coefficient issue. Quite a few organic fertilisers are labelled with a very high organic matter content, but very little of it can be transformed into humus, so when choosing organic fertiliser you should consider not only the organic matter content but also the humification coefficient.