August to October is a suitable sowing period for the autumn sowing crops in southern China. For example, rapeseeds, broad beans, green manures, potatoes, and a variety of autumn sowing vegetables must all be broadcast during this period. Experienced farmers understand that the autumn sowing of crops emphasizes the application of phosphate fertilizers, which is based on the causal relationship between crops, soil and fertilizers, and is determined by the biological fertilizer effect, chemical fertilizer efficiency and location fertilizer efficiency of the phosphate fertilizer itself. Phosphate fertilizers are preferentially applied on autumn sowing crops, which can fully exert the effect of increasing phosphorus production and realize the purpose of scientific fertilizer application.
Autumn sowing phosphorus crops such as beans, peas and other crops in the legumes, cruciferous rapeseed, radish vegetables, etc., sensitive to the response of the phosphate fertilizer, requiring a large amount. Phosphate fertilization in autumn sowing can meet the demand of phosphorus in the critical period of phosphorus needed for seedling stage, and it is very close to promoting the relationship between early maturity, high quality and high yield, especially in a soil that causes phosphorus deficiency as a limiting factor for yield increase. In the application, the output can be greatly increased. According to tests conducted by the agricultural technology department, applying phosphorus fertilizer to phosphorus-deficient soil, the average yield of rapeseed was increased by 44.5 kg, which was 23.1 kg higher than that of the control; the yield rate of green manure crops was more than 50%. Phosphorous-producing crops have a well-developed root system and strong phosphorus uptake. The utilization rate of phosphate fertilizers in the current season is generally increased by about 10% compared with other crops. Therefore, the emphasis on the application of phosphate fertilizer to phosphorus crops in order to fully play the role of phosphorus fertilizer biological effects, and promote crop growth.
The autumn crops are mostly dry crops. Under dry conditions, the availability of phosphorus is low. After entering the winter, the activity of microbes in the soil is weak, and the phosphorus capacity is small, the rate is slow, and the intensity is low. Moreover, under dry conditions, the soil moisture tension is large, the mass flow and diffusion of phosphates are reduced, and the phosphorus is less mobile. The effectiveness is lower than that of rice under water conditions. 3 times. In addition, some dry crops, such as wheat crops, originally belong to crops with poor response to phosphorus, while large and wheat crops require more phosphorus during the returning green period and the tillering stage. Therefore, the sowing date of wheat crops emphasizes phosphorus application to meet the demand of phosphorus for the critical period. Phosphate fertilizer applied during the autumn sowing in the dry season has a significant effect on the roots, pods, and seedlings of crops. This is determined by the fertilizer effect of phosphate fertilizers.
The ability of dryland to fix soil phosphorus is strong. When dry land or water is changed to drought, due to the increase of soil permeability, the pH value decreases and the oxidation-reduction potential increases, the "closed storage phosphorus" in the soil increases, and the phosphorus is effective. Greatly reduced. This is mainly due to the fact that the iron oxide film covers the insoluble iron phosphate and aluminum under dry conditions. Therefore, priority should be given to phosphorus in drylands than in paddy fields. After replanting rice, due to the change of soil physicochemical properties, the post-effect of phosphate fertilizer accounts for about 75%-90% of the applied phosphorus, which is determined by the chemical fertilizer effect of phosphate fertilizer.
From the point of view of improving the stress resistance of autumn crops, after the autumn sowed crop is sown, the crops are susceptible to drought and freezing under conditions of less severe winter rain and low temperature, and the application of phosphate fertilizer can improve autumn conditions. The hydrated and adhesive nature of the cell protoplasm during the wintering season of the sown crops will reduce the freezing point, thus improving the cold resistance and drought resistance of the crops, and will help the winter sowing of crops safely in winter. In addition, the application of phosphate fertilizer for autumn sowing of winter green manure is not only the legume green manure itself is hi phosphorus crop, the application of phosphate fertilizer to strengthen the photosynthesis of plants, produce more carbohydrates, promote lush foliage, more accumulated material, but also The supply of Rhizobium grows and reproduces, and its nitrogen fixation is enhanced. Therefore, when planting green manure, it is emphasized that the application of P fertilizer is not only beneficial to the cultivation of strong seedlings, but also improves the cold resistance in winter, and lays a solid foundation for the growth of green manure and increase of fresh grass production in the next year. It is often said that the "nitrogen phosphorus" effect.
Therefore, although it is not necessary to apply phosphorus to every season crop in the different cropping systems, it is necessary to consider that the crop should be applied mainly to crops that can maximize the effect of phosphate fertilizer, and autumn crops are the best choice for phosphate fertilizers throughout the year. In terms of application method, the phosphate fertilizer should be mixed with various organic fertilizers or ammonium bicarbonate, and in the autumn sowing, acupuncture and planting should be used as base fertilizer. The general dosage is about 20-25 kg per mu, and the application depth is 6 -10 cm, can be supplemented with 3-5 kg ​​of phosphate fertilizer and 1 times dry fine soil dressing plant, the use of basal fertilizer and seed fertilizer, shallow application and deep application of a combination of methods, you can get a good effect of fertilization.
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