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Shed room vegetable top dressing
Because of the large amount of fertilizer in greenhouses, the winter and spring seasons are closed tightly, and the temperature is low and the light is weak. The activity of nitrate reductase in vegetables is low and nitrates are easily accumulated. How to reduce the accumulation of nitrate in vegetables by topdressing is a problem that should be paid attention to when fertilizing vegetables without pollution: 1. It is forbidden to use nitrate nitrogen fertilizer. For example, ammonium nitrate, ammonium sulfate, potassium phosphorus nitrate, phosphorus nitrate, potassium nitrate, and compound fertilizer containing nitrate nitrogen can easily accumulate nitrate in vegetables after application. Because 80% of the body's ingested nitrate comes from vegetables, nitrates are converted to nitrite under reducing conditions. Nitrite and human amines in the intestine and stomach synthesize carcinogenic substances called nitrosamines, causing stomach cancer, Esophageal cancer and other cancers and diabetes, as well as blood poisoning and brain, heart and other organs lack of oxygen, resulting in difficulty breathing, nausea or even death. In addition, it is not suitable to apply chlorinated fertilizers such as potassium oxide, ammonium chloride, etc., chloride ions can reduce the starch and sugar content of vegetables, so that the quality is degraded, the yield is reduced, and residues in the soil can lead to decalcification of the soil, causing hardening. Such as magnesium sulfate, ammonium sulfate and other fertilizers, applied to the soil, the decomposition of sulfate ions, not easily absorbed by vegetables and stay in the soil, endangering the growth of vegetables. Ammonium bicarbonate is prohibited from being used because of the high volatility of ammonia, which can easily cause ammonia damage. 2, control the amount of nitrogen fertilizer. Nitrogen fertilizer is an indispensable fertilizer in vegetable production, but it cannot be used excessively. To make vegetables meet national and international pollution-free standards, the nitrate content in vegetables must be reduced. To reduce the amount of nitrogen fertilizer, it should be based on the amount of fertilizer required by different vegetables, generally 10-12 kilograms of pure nitrogen per acre is appropriate, nitrogen fertilizer should be deep, and with phosphorus and potassium fertilizer application or application of three yuan compound fertilizer. After the time to cover the soil, it is best to use chemical fertilizer canal infiltration or combined with drip irrigation under the membrane into the root, reduce the loss, increase the utilization, stop the top 20 days before harvest. 3, the application of ecological organic fertilizer. Eco-organic fertilizer produced by fermentation using livestock manure. If targeted with different elements, it will form a series of special fertilizer. The organic matter content of ecological organic fertilizer can reach 45%, and it can also play a role in fixing nitrogen, decomposing phosphorus and releasing potassium, as well as decomposing residual substances of pesticides and chemical fertilizers. One ton of ecological organic fertilizer is produced, such as 2-2.5 cubic meters of fresh chicken manure, 0.2-0.3 tons of straw powder, 5 kilograms of corn flour, and 8 kilograms of multi-dimensional complexes. First mix the chicken droppings with the straw powder to the water, squeeze into groups by hand, and the fingers are sewed with water, but do not drip, loosen and loosen, and the water content is 45%. Then, add cornmeal and multi-dimensional complex bacteria, and then Mix well and do not leave a block. They were piled up and covered with insulation film. In the spring, summer, autumn, 5-6 days, the fermentation can be mature, and in winter, it takes 7-10 days to mature. Generally within 1-3 days, the temperature in the reactor rises to 80 degrees Celsius to kill E. coli and eggs, and the odor of the chicken excrement can be eliminated. After that, the compost will become loose and dry and covered with white mycelium. Give a scent of distiller's yeast. After the compost has matured, it can be applied with a little air drying. In addition, the use of bio-organic compound fertilizers, humic acid fertilizers, soil improvement, increase fertility, create a good environment for the growth of pollution-free vegetables. 4, the implementation of formula fertilization According to the characteristics of different vegetables need fertilizer and soil fertilizer conditions, determine the appropriate amount of nitrogen, phosphorus, potassium and trace elements and the corresponding fertilization techniques. According to the research results of relevant departments, the maximum demand period of nitrogen, phosphorus, and potassium in greenhouse vegetables is: cucumber is 75-140 days after planting, tomato is 30-52 days, and sweet pepper is 30-60 days. The optimum application rates of fertilizers (nitrogen, phosphorus and potassium) were cucumber 1:0.67:1.83, tomato 1:0.38:1.75 and sweet pepper 1:0.38:1. Although micronutrients are rarely needed for vegetables, they are indispensable. For use of micro-fertilizer foliar sprays, good dosage standards should be used. Such as ferrous sulfate is 0.1% -0.3%, sulfuric acid outside is 0.05% -0.2%, borax is 0.3% -0.5%, ammonium molybdate is 0.02% -0.05%, copper sulfate is 0.02% -0.04%, can be combined with anti- Stroke multi-drug spray, both treatment and increase fertility. Or spray plus urea 0.1% -0.4%, potassium dihydrogen phosphate 0.2% -0.3%. Note that foliar vegetables should not be sprayed on the leaves to avoid increasing the nitrate content. Do not apply more diammonium phosphate, vegetables in general need a lot of nitrogen and potassium, less phosphorus, before and after flowering need potassium most, then gradually reduce. 5, limit the use of hormones. Some vegetable farmers do not talk about the quality of vegetables. In order to pursue high-yield, early-maturing, and early-morning markets, gibberellin (920), ethephon, paclobutrazol, and other hormones are used to promote long-lasting ripening, which greatly reduces the quality of vegetables. People will eat for a long time. Extremely unfavorable.