How can potato fertilization be tailored to the crop's actual needs?
1. During the seedling stage the plants are small and need little fertilizer; during the tuber formation stage fertilizer demand rises sharply; entering the tuber bulking stage it reaches the maximum demand, then drops sharply again. The uptake of nitrogen, phosphorus and potassium at each growth stage, calculated as a percentage of total nutrient uptake, is as follows: at the seedling stage 17%, 14% and 13% respectively; at the branching stage, when tuber formation begins, 33%, 30% and 28% respectively; at the tuber setting stage, when tubers grow rapidly, 38%, 36% and 44% respectively; at the maturity stage, when starch accumulates, 12%, 20% and 14% respectively. The uptake intensity of nitrogen, phosphorus and potassium is greatest at the branching stage and the tuber setting stage: nitrogen uptake accounts for 72% of the total fertilizer absorbed over the whole growth period, phosphorus for 66% of total uptake and potassium for 72% of total uptake. Therefore, ensuring the supply of nitrogen, phosphorus and potassium during these two periods is extremely important in production.
2. Potato is a potassium-demanding crop: it absorbs the most potassium, followed by nitrogen, and the least phosphorus. Generally, to produce 1 ton of potato tubers, the crop needs to absorb 5 kg of nitrogen, 2 kg of phosphorus and 11 kg of potassium from the soil, that is, a nitrogen-phosphorus-potassium ratio of 1:0.2:2.
3. Farmyard manure is very beneficial to potato growth. Farmyard manure not only contains the three major elements nitrogen, phosphorus and potassium that potatoes need for growth, but also contains the trace elements and beneficial microorganisms potatoes require. Applying organic fertilizer can improve soil structure, build up soil fertility, enhance the soil's ability to retain fertilizer and water, and raise fertilizer and water use efficiency. Under the action of microorganisms, organic matter is mineralized, absorbed and used directly by the crop, and can release a large amount of carbon dioxide, which both enriches the soil and increases soil aeration, creating conditions for high-yielding potato growth.
4. Applying farmyard manure when growing potatoes has the following benefits: it is nutrient-rich with a long residual effect; farmyard manure such as stable manure and compost is a complete fertilizer, and after being applied to the soil, the nitrogen, phosphorus, potassium, iron, zinc and other nutrients released during the decomposition and mineralization of organic matter can directly provide nutrients to potatoes and can also store large amounts of nutrients for the following crop, which is beneficial to the growth and development of the subsequent crop; and it helps improve the physical and chemical properties of the soil.
After farmyard manure is applied to the soil, humification forms humus and humic acid. The vitamins, biotin, enzymes, auxins and other substances in humus can promote crop root development and improve the use of available nutrients in the soil; they promote plant respiration, photosynthesis and various material metabolic processes in the plant, and have a buffering effect that protects plants from toxicity. Humic acid can buffer the range of pH changes in the soil and improve the availability of phosphorus and certain trace elements; it can also regulate water, fertilizer, air and heat in the soil body, helping to ensure good seedling establishment and high yields; and it helps improve potato yield and quality.
Applying farmyard manure to potatoes loosens the topsoil, reduces soil resistance and raises soil temperature, which is conducive to tuber development and bulking, gives uniform tubers and high yields, and facilitates harvesting.