Fertilization of potato

Potato is an extremely popular crop that is a regular part of the diet of many of us. It is a plant rich in numerous vitamins and minerals (being, above all, a valuable source of potassium). It also provides dietary fiber and starch. Potato has relatively high soil and nutrient requirements, so proper fertilization must be applied to achieve high yields.

The recommended dose of nitrogen per hectare for an expected yield of 30 tons of tubers is about 100-120 kg N. Using manure at the optimum rate, the nitrogen dose (at such an expected yield) can be reduced by 25-45%. Various forms of nitrogen such as ammonium, nitrate or amide can be used in potato fertilization. Under early varieties of edible potato, nitrogen can be applied in a single dose before planting. In the cultivation of late varieties of edible potato and in the cultivation of industrial potato, it is recommended to apply nitrogen at two times: about 2/3 of the total dose – just before planting, and the remainder after emergence – before flowering. Applying nitrogen too late can have a negative impact on tuber quality. In determining the nitrogen dose, account should also be taken of the nitrogen brought in before planting together with multicompound fertilizers.
Reasonable use of mineral fertilizers and manure in potato cultivation not only improves soil fertility, but also contributes to its production potential. In order to provide plants with optimal amounts of all necessary mineral elements, it is necessary to use multicompound mineral fertilizers that contain phosphorus, potassium, calcium, magnesium, sulfur and micronutrients.
Unreasonable, or insufficient or excessive fertilization with each of the above-mentioned elements negatively affects not only the yield of the potato, but also its functional characteristics: starch content, quantity and quality of protein, amount of vitamins, especially vitamin C, taste, darkening of the flesh and losses during storage.

The use of only manure or other organic fertilizers under potato cultivation is not sufficient, as they contain too little phosphorus in relation to the plant’s requirements. In addition, potato shows very little ability to utilize phosphorus from compounds that are difficult to solubilize. Insufficient supply of phosphorus to the potato is evidenced by slow plant growth and dark green, bluish coloration of the leaves. In addition, they curl slightly upward, turn brown and die. A potato properly supplied with phosphorus tillers well, blooms strongly, produces an abundant crop of tubers with favorable nutritional, taste and technological characteristics, while thanks to a well-developed skin it stores well during winter.

Potato is a potassium-loving crop due to the special role of potassium in the synthesis of starch and protein. Plants optimally supplied with potassium grow well, are lush, well-leaved, resistant to drought and disease. They produce a high yield of tubers of good consumer and industrial quality. Symptoms of potassium deficiency can be seen in the potato in the form of a withered plant habit, with the plants being small and bushy. Older leaves are unnaturally grayish-green in color, drying up at the tops and edges, curling and drooping. Following potassium deficiency, damaged tubers darken, and darkening of potatoes during cooking is also observed. Excessive potassium fertilization, not balanced by an adequate amount of phosphorus (which can happen when fertilizing only with organic fertilizers) deteriorates the technical quality of the crop and the taste of the tubers. It also promotes losses during storage.

Potato responds favorably to the presence of sulfur in the soil. It has a positive effect on the amount of protein, especially its nutritional value, and also guarantees the good taste of consumption potatoes. Sulfur deficiencies in the potato are most often latent, especially under conditions of excessive nitrogen and potassium fertilization.

Most Polish cultivated soils contain insufficient amounts of magnesium for the potato’s requirements. The deficit of easily plant-available forms of this element is compounded by the use of excessive doses of potassium fertilizers. Under such conditions, stunted growth and withered plant habit are observed. Tissue between the innervation of older leaves turns yellow, then turns brown, dies and sprouts. The edges of the leaves remain green for a long time. The yield of tubers is lower and their biological value is worse than under conditions of optimal magnesium supply.

Potato, like all plants, requires the presence of calcium in the soil for its growth and development. On acidic soils, poor in this element, dying of shoot tops or curling of upper leaves on stems and dying of stolons are observed. Stems break and die before flowering.

The biological value, technological value and taste of potatoes are also eminently positively influenced by micronutrients: boron, zinc, manganese, copper and iron, present in fertilizers produced by Fosfan.