High yield of rapeseed must prevent potassium deficiency

At present, the cabbage-type rapeseed widely cultivated in various places, such as Qinyou No.7, Qinyou No.10, Youyan No.7, Zhongyouza No.2, Zhongshuang No.6, Huaza No.4, etc., has a large demand for potassium. It is more than twice as high as cabbage. With the large-scale cultivation of Brassica napus, the phenomenon of potassium deficiency in rapeseed has become more and more common, and many places have become a major obstacle to the high yield of rapeseed. According to a survey by the Agricultural Technology Department of Lujiang City, Hunan Province, the potassium-deficient Brassica napus is generally reduced by 15%-20%.

Potassium deficiency has a large impact

Through investigation, in the area where the soil available potassium content is less than 60ppm, rapeseed is prone to potassium deficiency symptoms. The main manifestations are: in the seedling stage, the leaf flesh fades and yellows, the leaves shrink and thicken, the veins are obviously deepened and the growth is slow; When the potassium is severely deficient, the heart leaves are atrophied and dead, the leaves are bucked and curled at the edge of the leaves, the leaves are uneven, the texture is brittle and hard, and the plants are short, with few branches, fewer pods and more yin. The symptoms of potassium deficiency in rapeseed began to manifest from the old leaves, and then developed to the heart leaf. Finally, the whole plant died and the stalks were broken, which led to reduced yield. Studies have shown that the ratio of nitrogen, phosphorus and potassium in the growth and development of rapeseed is 1:0.4-0.5:0.9-1. It can be seen that the amount of potassium required by rapeseed is almost the same as that of nitrogen.

Potassium supplementation has an outstanding effect

In the area where rapeseed is grown, which soil type rapeseed is prone to potassium deficiency? Generally it is sandy soil and red loam in mountainous or semi-mountainous areas. In addition, the shortage of potassium in rapeseed is most likely to occur in the fields near the mountain stream, the low-yield cold-impregnated fields, the transplanted rapeseed fields that have been planted in the hybrid rice fields for many years, and the fields where the nitrogen fertilizer is applied for a long time. In the soil with potassium deficiency (fast-acting potassium content of 48ppm, 59ppm), 10kg and 15kg of potassium sulphate per acre, whether as base fertilizer or topdressing, have significant yield-increasing effects. The average potassium application rate is not potassium. The control area increased yield by 23% and 34%, respectively.

The effect of potassium application on potassium production is that potassium can promote the operation and accumulation of nutrients in rapeseed, accelerate growth and development, increase plant height, increase branching, and more fruits, not only high rapeseed yield, but also oil content. In the soil with high soil fertility and high potassium content (potable potassium content of 90ppm, 118ppm), there is no obvious potassium deficiency in the cultivation of rapeseed. The effect of applying potassium fertilizer is not obvious.

Reasonable formula for applying potassium fertilizer

When applying potassium fertilizer in various places, formula fertilization should be carried out according to soil census data and soil nutrient rapid test results. Potassium-deficient fields with soil available potassium content below 60ppm, rapeseed with low-yield late rice fields, less soil fertility, and poor soil fertility should be used as key potassium sites.

The amount of potassium fertilizer and the application method are as follows: For the rapeseed which has been deficient in potassium, the potassium fertilizer should be applied once immediately. Generally, 7.5-10 kg of potassium chloride is used per mu, and the shallow ditch is applied near the root of the rapeseed. Cooperate with watering to facilitate root absorption. When there is no chemical potassium fertilizer, 75-100 kg of lumber ash per acre or 150 g of potassium dihydrogen phosphate per acre, 50-60 kg of foliar spray with water, the effect is very good.

In recent years, rapeseed fields with continuous hybrid rice cultivation should be prevented from applying nitrogen fertilizers, and nitrogen, phosphorus and potassium should be applied together, and soil fertilization should be added. It should be used as base fertilizer during transplanting of rapeseed or as fertilizer application during wintering period. Each pot of potassium or potassium sulphate 10 kg left or plant ash 100 kg per acre, can receive significant potassium supplementation, to prevent the symptoms of potassium deficiency.

(Li Cuiying)