Corner cube Prism is also named retroreflector or trihedral prism.In the corner cube prism,three reflecting surfaces are perpendicular to each other,like the side wall of the cube.The input surface is perpendicular to the cube diagonal. Disregarding the anlge of the incidence,the output beam is parallel to the input one,but it is of opposite direction. Inset of the several corner prisms, for better matching,their extrance exit surface is often hexagonal.In case of this prism the phenomenon of full internal reflection occurs so it is not necessary,(however it is possible)to put mirror coating on the reflecting faces. Normally the reflection surfaces are AL reflection coating, and then covered with Cu and Black painting.
Pyramid prism/Corner Cube Retroreflector is always used to reflect the beam entering the prism face, regardless of its orientation to the beam. Corner cubes are widely used where precision alignment is difficult.
Corner Cube Prism
Corner Cube Prism,Corner Cubic Prism,Optical Corner Cube Prism,Glass Corner Cube Prism China Star Optics Technology Co.,Ltd. , https://www.csoptlens.com
Liu Lixin, a former researcher at the Soil and Fertilizer Institute of the Chinese Academy of Agricultural Sciences and a Chinese soil and fertilizer expert, said that under drought conditions, attention should be paid to the rational mix of fertilizers, especially potassium and boron fertilizers. Appropriate potassium can increase the ratio of root to shoot and enhance the water absorption capacity of crops. Under drought conditions, suitable potassium can also promote the accumulation of proline and regulate the cytoplasmic swell pressure to enhance the drought resistance of crops.
Fertilization should not be "one shot"
Recently, the reporter visited in the fruit producing area and found that the fruit farmers in various places still use some unreasonable fertilization methods in production. “One shelling†is one of them. The so-called fertilization “one shelling†refers to the application of fruit trees once after mixing organic fertilizers and inorganic fertilizers. Liu Lixin believes that fruit tree fertilization does not advocate "one shelling" because this method of fertilization does not meet the fertilizer characteristics of fruit trees, especially under drought conditions, the "one shelling" fertilization method is more likely to cause damage to the tree. Generally, fruit trees are crops with a long growth cycle. The absorption of nitrogen, phosphorus and potassium is the peak of nitrogen absorption in spring. The fruit expansion period after fruit setting is the peak of potassium absorption before harvesting. The absorption of phosphorus was relatively flat during the anniversary, with no obvious peak period. Liu Lixin believes that it is not appropriate to apply the inorganic fertilizer to the fruit trees at any one time.
Principles of Fertilization Hou Gaoli, a member of the expert group of the newspaper and a senior agronomist, believes that under drought conditions, the total amount of fertilization should be appropriately reduced, and “fertilization with fertilizer†should be combined with irrigation to control the growth and development of crops.
The amount of fertilizer applied should not be too large. If the amount of one-time fertilization is large during drought, it is easy to cause the applied fertilizer to be washed away when heavy rain occurs after drought. This will not only cause economic losses to farmers, but also pollute the environment. Therefore, it should be combined with irrigation for fertilization.
Deep application of fertilizer, water and fertilizer. In the case of drought, the fertilizer is volatile if only the fertilizer is applied to the surface. If there is heavy rain after a drought, it is easy to be washed away by the rain. Therefore, the fertilizer should be applied as deep as possible, and the fertilizer should be added after the application to maintain the fertilizer efficiency. Pay attention to the reasonable mix of fertilizers, especially potassium and boron fertilizers. It is understood that potassium ions can regulate the colloidal properties of protoplasts, so that water can enter the cells smoothly, and strengthen the water-holding capacity of cells; suitable potassium nutrition can also increase the ratio of root to shoot and enhance the water absorption capacity of crops.
Fertilization strategy as a fruit planting area, the first characteristic of fertilization of fruit trees in Shaanxi, Shanxi and Gansu regions is that the climate is dry and the annual precipitation is small, but the evaporation is large. Except for some farmland with river water irrigation conditions, the water shortage is The biggest obstacle to agricultural production in the region. According to this feature, Liu Lixin believes that fertilization should be combined with water-saving irrigation. In addition, drought is not good for the growth and development of crops and the process of absorbing and utilizing nutrients, so that fertilization does not achieve the desired effect.
First, pay attention to the combination of organic fertilizer and chemical fertilizer. When fertilizing, it should be noted that organic fertilizer should be decomposed, and non-fertilized organic fertilizer is easy to cause high temperature burning; it should be used as base fertilizer and combined with deep tillage to facilitate soil fertility and effective soil improvement; soil moisture under drought conditions Low, easy to cause burning seedlings, must be well seed and fertilizer isolation.
Second, pay attention to the selection of appropriate fertilization methods. If the nitrogen and potassium fertilizers needed for the whole year of the fruit tree are mixed with the organic fertilizer, the nitrogen and potassium absorption peaks are not applied to the fruit trees. Inorganic nutrients will inevitably be fixed or lost in the soil. In the second year, nitrogen or potassium deficiency will occur in the peak of nitrogen or potassium demand in fruit trees. Therefore, it is necessary to pay attention to the application of controlled release agents when applying nitrogen fertilizer. If the rainy weather is caught during the topdressing period, the topdressing should be properly supplemented.
Fertilization techniques Soil fertilization is an effective technique for improving soil nutrient supply and an important condition for obtaining high-quality, high-yield fruit, improving the productivity and quality of fruit trees at a lower cost. However, long-term unreasonable fertilization methods have increased production costs and accelerated soil degradation and environmental pollution. How to improve the utilization rate of fertilizer by fruit trees, reduce the adverse effects of fertilizer on orchard soil and reduce the labor input of fertilization is one of the problems that need to be solved in the field of fruit trees.
Liu Lixin believes that if you want to accurately and scientifically formulate fertilization, you must master the five parameters of target yield, fertilizer demand for fruit trees, soil fertilizer supply, fertilizer utilization rate and effective nutrient content in fertilizer, which is the basis of formula fertilization.
First, the target yield of fruit trees, according to tree species, varieties, tree age, tree potential, flower buds and climate, soil, cultivation management and other comprehensive factors to determine the reasonable target output of the year.
The second is that the fruit trees need fertilizer, and the fruit trees need to absorb a certain amount of nutrients in the annual cycle to form an autologous intact tissue.
The third is the amount of soil fertility, and the content of mineral elements in the soil is quite rich. However, if the fertilizer is not applied for a long time, the growth and development of the fruit trees are poor; this is because the mineral elements in the soil are mostly in a free state, and the roots cannot be absorbed and utilized. The natural supply of three elements in the soil is roughly as follows: the natural supply of nitrogen is about 1/3 of the amount of nitrogen absorbed, phosphorus is 1/2 of the amount absorbed, and potassium is 1/2 of the amount absorbed. The fourth is the fertilizer utilization rate. The fertilizer applied to the soil cannot be absorbed and utilized by the fruit trees due to the adsorption and fixation of the soil and the result of leaching with water, decomposition and volatilization; the utilization rate of fertilizer for fruit trees, due to tree species and varieties , rootstocks, and soil management systems vary.
The fifth is the effective nutrient content in the fertilizer. In the formula fertilization, the effective nutrient content in the fertilizer is an important parameter. The effective nutrient content of commonly used organic fertilizers and mineral fertilizers such as urea is 46% nitrogen, potassium sulfate is 48% to 52%, ammonium phosphate is 17% and phosphorus is 47%, and potassium dihydrogen phosphate is 52%. Others such as borax include 11.3% boron, potassium sulfate contains 23% to 25% zinc, and ferrous sulfate contains 19% to 29% iron. 
There are sayings in the farmhouse that "seeing the sky, seeing the land, and seeing the crops." The “seeing the sky†here means that the effect of climate on the fertilization effect of fruit trees should be considered when fertilizing. In the spring, the temperature gradually rises. If there is a lack of precipitation for a long time, the orchard is not watered in time, and drought often occurs. At this time, reasonable fertilization is especially important for growing fruit trees. This edition of the manuscript explains the technical knowledge of fertilization in orchard under drought conditions, and hopes to help the fruit farmers.
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