What are the effects of potash on rice? When is the best time to apply potassium fertilizer to rice? How much does it cost?

Rice is a kind of food crop which needs a lot of potassium. In recent years, super hybrid rice is being popularized and applied, and hybrid rice has a greater demand for potassium than conventional rice, sometimes as much as 30% to 40% higher. So, what are the effects of potash fertilizer on rice? When is the best time to apply potash fertilizer to rice? How much is it?

The potassium consumption of paddy soil is serious, especially in the acid soil areas of the south where the potassium supply potential is not high, in some high-yield rice production systems, potassium may be deficient, which is very disadvantageous to create high yield. Therefore, in the current development of high-yield and even super-high-yield rice production, appropriate and timely supplement of potash fertilizer is necessary. It should be pointed out here that in order to improve the recycling of potassium in farmland, the input of potassium in chemical fertilizer can be reduced appropriately for rice fields where straw is returned, because 70% of the potassium absorbed by rice in the current season exists in straw. But it is important to apply potassium effectively in rice fields where there is no straw returned to the field.

Physiological effect of potassium on rice: the content of potassium in stems and leaves of rice at different growth stages is about 1.5% Mel 3.5%, and the content in panicle is relatively low, generally less than 0.5% Mel 1%. Potassium almost completely exists as an ion in the plant, and some of it is adsorbed in the protoplasm. Unlike nitrogen and phosphorus, potassium is not a component of protoplasm, fat, cellulose and so on. However, potassium acts as a catalyst in some important physiological metabolism, such as the decomposition and transfer of carbohydrates, which can promote these processes to proceed smoothly. Potassium also contributes to nitrogen metabolism and protein synthesis, so the more nitrogen is applied, the more potassium is needed. Potassium acts as an activator for many important enzymes in plants. Appropriate amount of potassium can increase photosynthesis and carbohydrate content of rice, and thicken the cell wall, thus enhancing the ability of disease resistance and lodging resistance of plants.

The symptoms of potassium deficiency in rice: root development stagnant, easy to produce root rot, the degree of thick green of leaf color edge is similar to that of excessive nitrogen application, but the leaf is relatively short. Severe potassium deficiency was caused by yellowish-brown spots at the tip of the leaf, which gradually extended to the whole leaf, the stem became soft, and the plant height elongation was inhibited. Potassium is highly mobile in plants and can be transferred from old leaves to new leaves, and potassium deficiency occurs first from the lower leaves. When potassium deficiency, starch, cellulose, carbohydrates decreased, rice is in luxuriant shade or lack of light conditions, the growth and development of rice can be improved after the application of potassium fertilizer.

In the fertilization of super-high yield of rice, the application rate of nitrogen fertilizer is generally high, and more attention should be paid to the corresponding supplement of potassium fertilizer in terms of nutritional balance. Because sufficient potassium supply can make the stem of rice plant stout, increase its strength, improve its mechanical properties, not only resist lodging, but also effectively hinder the invasion of bacteria and insect pests, so in the case of large amount of nitrogen fertilizer, if the amount of potassium fertilizer can not keep up with, make the proportion of nitrogen and potassium out of balance, it will cause the problem of more nitrogen and less potassium or obvious lack of potassium. Symptoms of potassium deficiency in paddy fields: for example, stiff seedlings may appear in potassium deficiency at seedling stage; potassium deficiency at jointing stage, shortening of plant internodes, rust spots on lower old leaves, scorched leaf margin due to serious potassium deficiency, rice plant will become soft in structure and accumulation of soluble nitrogen-containing compounds in the body, so that the stress resistance of rice is reduced, the stem of the plant is weak and easy to lodge, the leaves lose water, the harm of diseases and insect pests is serious, and the safety of obtaining high yield is greatly reduced.

When is the best time to apply potash fertilizer to rice? How much is it? It is reported that the relevant agricultural technology departments have carried out research and demonstration on the best application rate and fertilization methods of agricultural potash fertilizer in rice in different seasons. The preliminary results show that the timely topdressing of potash fertilizer after drying the field has a great effect on the increase of rice yield, with an average increase of about 6%. The reasons for increasing yield were analyzed: potassium application could increase the panicle rate of super hybrid rice, reduce the degeneration of tillers, promote tillers into panicles, and increase the number of effective panicles. The seed setting rate was increased to a certain extent, and the 1000-grain weight also tended to increase. As a result, the participants believe that topdressing potassium fertilizer can reduce tillering degradation, and then improve the efficiency of rice tillering, potassium application can also enhance rice grain filling intensity, increase seed setting rate and grain weight, resulting in the increase of rice yield.

In addition, the experimental and demonstration results of how to apply agricultural potassium fertilizer in mechanical direct seeding rice cultivation showed that the appropriate amount of potassium fertilizer was 10 kg K2O per mu, and all fertilizers were applied before transplanting, and then buried under 5 cm soil layer with iron tooth rake. When potassium fertilizer was applied to mechanical direct seeding rice, the yield was 11.6% higher than that without potassium application. The stem thickness of the first, second and third nodes of rice increased, especially the thickness of basal internodes increased significantly, which indicated that the lodging resistance of rice stem was enhanced after potassium application. The effective panicle, the number of filled grains per panicle and the seed setting rate were higher.

In general, the application method of potassium fertilizer can be used as base fertilizer, but in sandy soil or super high-yield cultivation, potassium fertilizer should be divided into base fertilizer and topdressing fertilizer twice; hybrid rice is the peak period of fertilizer absorption from tillering to booting stage, and topdressing is best carried out before heading, so that the plant can maintain a high level of nitrogen and potassium nutrition in the peak growth period, so as to improve the seed setting rate and 1000-grain weight.

Although the amount of nitrogen fertilizer is increasing year by year, while the amount of organic fertilizer is relatively reduced, including straw returning is not common enough, the trend of possible potassium deficiency of rice is increasing year by year in some areas. the phenomenon of potassium deficiency in paddy fields often leads to low seed setting rate and lodging of rice, which is one of the obstacles to achieving the goal of high and stable yield. Therefore, the effect of potash fertilizer on rice is very significant, and the application time and amount of potash fertilizer in rice are also very particular.