Efficient Application Technology of Potash Compound Fertilizer

Introduction

With the development of agricultural production, the area of ​​potassium deficiency in our country’s farmland is expanding day by day, and increasing the application of potassium fertilizer has become an important measure to achieve high yield and high quality of crops. Research shows that the fertilizer efficiency of potassium fertilizer is affected by various factors such as soil conditions, crop characteristics, application with other fertilizers, and application technology. Only by clarifying and mastering the effective application conditions of potassium fertilizer and rationally distributing and applying it can the current limited potassium fertilizer resources fully exert their production-increasing effects and achieve better economic benefits.

1. Soil potassium supply capacity

• Among the factors that affect potassium fertilizer efficiency, the potassium supply capacity of the soil is the most important. At present, the domestic evaluation of soil potassium supply capacity is mainly based on the soil’s available potassium content, and also takes into account the soil’s slow-acting potassium reserves.
• A large number of potassium fertilizer tests and soil analysis results from various places show that the level of soil available potassium is an important factor in determining the potassium fertilizer efficiency of crops in the current season. 
• The level of potassium fertilizer efficiency mainly depends on the content of soil available potassium. The abundance and deficiency indicators of soil available potassium vary slightly due to different climate, soil, crop and other conditions in different places. Based on the test results from various places, the Nanjing Soil Research Institute of the Chinese Academy of Sciences proposed the classification standards for soil available potassium levels and potassium fertilizer efficiency for rice and wheat.

2. Soil texture

Slow-acting potassium mostly exists in the crystal lattice of clay minerals, while exchangeable potassium is adsorbed on the surface of clay minerals. Therefore, different soil textures have different potassium content. Clay or clay loam soil with a lot of clay particles has a higher potassium content, while sandy soil has a lower potassium content. Tests from various places have proven that the effect of applying potassium fertilizer to sandy soil is better than that of clay soil

3. Crop type

The fertilizer efficiency of potassium fertilizer varies greatly among different types of crops. According to the statistics of 892 experiments in the South by the National Fertilizer Experiment Network, under the conditions of applying nitrogen, phosphorus chemical fertilizers or organic fertilizers, the yield increase of leguminous green fertilizers is 44.3% to 135.1%; the yield increase of potato, cotton, tobacco and oil crops is 11.7% ~43.3%; for cereal crops, except for barley, which increased by 32.9%, the output of rice, wheat, and corn only increased by 9.4% to 16.0%. The difference in potassium fertilizer efficiency among different crops is due to their different potassium requirements and potassium uptake abilities.

4. Crop growth stage

• The potassium requirements of crops at different growth stages are also significantly different. Generally, cereal crops require more potassium during the tillering and jointing stages, and their absorption amount is 60% to 70% of the total potassium requirement, which decreases significantly after flowering. Cotton requires the largest amount of potassium from budding to boll formation, and its absorption accounts for about 60% of the total amount. Vegetable crops such as solanaceans require the greatest amount of potassium during the flower bud stage and radish during the fleshy root expansion stage. 
• During the pear fruit development stage of pear trees and the early stages of berry coloring, the grapes also need the greatest amount of potassium. For general crops, potassium deficiency in the seedling stage is the most sensitive. 
• However, compared with phosphorus and nitrogen, its critical period appears later.
  It can be seen from the above that when potassium fertilizer is limited, it should be given priority to crops (or varieties) that require a lot of potassium, have weak potassium absorption capabilities, and have significant effects, and apply it during the period when the crops need potassium most urgently to achieve better results. production increase effect and economic benefits.

5. Combined with organic fertilizer

• The type and application level of organic fertilizers also affect the fertilizer efficiency of potassium fertilizers. Since organic fertilizers contain more potassium and are highly effective, when the amount of organic fertilizers is high, the yield-increasing effect of applying potassium fertilizers is small. In particular, the direct return of straw to the field can allow most of the potassium absorbed by the crop (for example, the straw accounts for about 70% of the total potassium absorbed by rice) to participate in biological recycling, reducing the crop’s dependence on potassium fertilizer, and the fertilizer efficiency of potassium fertilizer will be improved. Difference. When applying manure containing more potassium, the application of potassium fertilizer may be reduced or eliminated depending on the amount of manure.
• In short, the soil potassium supply level refers to the content of available potassium in the soil solution and the amount and rate of release of slow-acting potassium from the soil. During a growing season, for most crops, the available potassium content is an important factor that determines the effectiveness of potassium fertilizer. Soil texture is another factor that affects the effectiveness of potassium fertilizers. The fertilizer effect of the same amount of available potassium on clay soil is worse than that on sandy soil.
• Different crops have different potassium requirements and potassium absorption capabilities, and the effects of applying potassium fertilizer are different. Oil crops, potato and sugar crops, cotton and linen crops, leguminous crops, tobacco, tea, mulberry and other leaf crops all require more potassium. Fruit trees also require more potassium. Different varieties of the same crop have different requirements for potassium, and the requirements for potassium at different growth stages of crops vary significantly. Generally, cereal crops require more potassium during the tillering and jointing stages. Fertilizer combination and potassium fertilizer efficiency, the three elements of nitrogen, phosphorus and potassium promote and restrict each other, so crops require a certain proportion of nitrogen, phosphorus and potassium.
• When the nitrogen and phosphorus content in the soil is low and the amount of nitrogen and phosphorus fertilizer is small, the effect of applying potassium fertilizer is often not obvious. When the amount of nitrogen and phosphorus is increased to a certain level, but the potassium supply level of the soil is low, the application of potassium fertilizer can often increase yields. When the amount of nitrogen fertilizer is high and the soil is seriously deficient in potassium, the effect of combined potassium and nitrogen fertilizers is good. The dosage of nitrogen fertilizer is very high, but when the soil is rich in potassium, the effect of combining the two is not significant.

6. Combined with nitrogen and phosphate fertilizers

• The fertilizer efficiency of potassium fertilizer is related to the supply level of nitrogen and phosphorus. When soil nitrogen and phosphorus supply levels are low, the yield-increasing effect of potassium fertilizer alone is not significant. If nitrogen fertilizer is applied alone or only phosphorus fertilizer is applied without potassium fertilizer, the yield-increasing benefits of nitrogen and phosphorus fertilizers will not be fully utilized. Therefore, attention must be paid to the coordination of nitrogen, phosphorus, and potassium.
• According to the test results conducted on mulberry trees by the Sericulture Research Institute of the Guangdong Academy of Agricultural Sciences, based on the average yield of mulberry leaves picked seven times, compared with no fertilizer application, applying nitrogen fertilizer alone increased the yield of mulberry leaves by 109.5kg per mu, an increase of 36.13%; nitrogen application , phosphorus and potassium fertilizers increased the yield of mulberry leaves by 111.5kg per mu, an increase of 36.79%.
• Many experiments have also shown that within the range of sufficient nitrogen and phosphorus required for crop growth, the effect of potassium fertilizer increases with the increase of nitrogen and phosphorus levels. In the current situation where nitrogen fertilizer is applied in rural areas, the combined application of nitrogen and potassium is particularly important.