Causes and Countermeasures of Salt damage to Flowers in greenhouse

The amount of fertilizer applied to flowers in the greenhouse is relatively large, and the soil in the greenhouse can not rain and get wet like the open field, and it is in a state of salt accumulation all the year round, which is easy to cause salt damage. The main manifestations of crops are that the flower plants are short and the leaves are thick; some begin to dry up from the leaves, or turn brown and roll inward or outward; some plants wilt, like Fusarium wilt, and the roots are poorly developed; or the roots gather around the main root, unable to spread and stick, shaped like a fist. All these seriously affect the growth and quality of flowers. The causes and treatment methods of salt injury of flowers in greenhouse are introduced as follows.

The cause of salt damage

1. The annual planting of flowers in the greenhouse takes away too many base elements from the soil, such as potassium, calcium, magnesium and so on, which leads to excessive consumption of potassium and trace elements in the soil and makes the greenhouse soil develop towards acidification.

two。 The application of a large amount of acid fertilizer leads to high temperature and humidity in the greenhouse, and less leaching by Rain Water. With the increase of flower cultivation years, acid ions accumulate in the plough layer, which is easy to cause soil acidification.

3. The multiple cropping index of planting flowers in greenhouse is high, and the use of fertilizer is large, so that the content of organic matter in soil decreases year by year, the buffering capacity of soil solution decreases, and the problem of soil acidification is aggravated.

4. The input proportion of nitrogen, phosphorus and potassium is too large, while the base elements such as calcium and magnesium are easily replaced by hydrogen ions, thus improving the acidity of the soil.

5. The soil microflora is alienated and some biotoxic substances are produced. In the flower greenhouse, if a single kind of flower is planted for a long time, the root exudates of the same crops are the same, resulting in a large number of soil microorganisms, while some soil microorganisms are inhibited, which is prone to the alienation of soil microorganisms. thus, it is not conducive to soil ripening and the decomposition and differentiation of fertilizer nutrients, resulting in a sharp increase in soil acidity.

Measures to prevent salt damage

1. Apply more organic fertilizer. It is best to apply organic fertilizer with high cellulose (high ratio of carbon to nitrogen). Organic matter will form humic acid and other organic colloids in the process of decomposition. The colloids have strong adsorption properties and can adsorb cations such as ammonium ions, potassium ions and calcium ions around themselves. This adsorption is dynamic. When the concentration of soil solution is low, it will be released into the solution. The application of organic fertilizer can enhance the buffering capacity (regulating capacity) of soil nutrients, prevent the accumulation of salt damage, and delay the process of soil secondary salinization.

two。 Dig deep into the soil. The salts of the soil in the greenhouse are concentrated in the topsoil layer. In general, the salinity index of 0-5 cm soil layer is 100, the salinity index of 5-25 cm soil layer is 60, the salinity index of 25-50 cm soil layer is 40. Turning over the soil deeply after the flower crop harvest, turning the salt-rich topsoil to the lower layer, and the lower soil with less salt to the upper layer, can reduce the soil salt damage.

3. Deep application of base fertilizer, limited application of topdressing. When chemical fertilizer is used as base fertilizer, it is applied deeply, and when it is used as topdressing, a small amount of fertilizer is applied many times. The mixed application of chemical fertilizer and organic fertilizer is ploughed and turned over, and the fertilizer is turned into the soil so as not to increase the salt content of the topsoil. Strictly controlling the amount of fertilizer applied each time during topdressing can increase the number of fertilization and avoid the increase of soil solution concentration.

4. Drain salt and wash salt. In order to drain salt, there should be a 30-40 cm deep ditch around each greenhouse. If possible, plastic corrugated hidden pipes can be buried under the greenhouse soil, irrigation water can be discharged through the upper layer, and salt can be discharged with the water flowing into the hidden pipes. This method has high desalination rate and good effect. Salt can be washed with water without salt discharge. After the spring flower harvest, open the greenhouse film in order to plough and rake the soil from the furrow, straighten out the drainage ditch, let Rain Water wash, and make the salt discharged with the water. Can also irrigate the greenhouse soil 5-7 cm deep, soak a few days to eliminate, can be carried out 2-3 times.

5. Desalination is recommended. Sudan grass with strong salt tolerance (which can be used to feed cattle and fish) was planted on the greenhouse soil with high salt tolerance by using the stubble gap at high temperature in midsummer. After growing for 40 days, the forage grass yield per mu was 1500-3000 kg, and the desalination effect was good.

6. Apply quicklime to improve acid soil. The application of quicklime to the soil can neutralize the acidity, improve the soil PH value, directly change the soil acidification status, and can supplement a lot of calcium for flowers and plants. Application method: crush quicklime so that most of it can pass through 100 mesh sieve, spread quicklime and organic fertilizer on the field respectively before sowing, and then mix quicklime and organic fertilizer with soil as well as possible through ploughing and raking. Application amount: ph 5.0-5.4 130 kg quicklime per mu; PH 5.5-5.9 65 kg quicklime per mu; PH 6.0-6.4 30 kg quicklime per mu (calculated by adjusting 15 cm acid plough soil).