Fertilizer application rates and recommendation for potato and root crops

Foliar fertilizing of potatoes done in time, makes it possible to supply elements necessary for plants in the most critical phases of crop development. Potatoes develop better when nutrients enter the tubers in small portions, but constantly. The fact is that 30-40% of mineral nutrition is obtained from the vegetative mass, which accumulates nitrogen and sulfur from the atmosphere. Thanks to foliar feeding, we can diversify and enrich this process. At the same time, the intensity of nutrients assimilation by the potato root system largely depends on weather conditions and the chemical composition of the soil. Therefore, even on well-fertilized soils, plants may lack some element.

Well-structured, well-drained sandy and medium loamy soils with pH of 5.5 to 7.0 are considered to be the best soils for growing potatoes. However, in practice, potatoes are also grown in soils with a pH of 4.5 to 8.5, but under such conditions, the availability of certain nutrients is sharply reduced or blocked by the soil environment. At a lower pH level, the assimilation of calcium, magnesium and phosphorus deteriorates. As the soil solution reacts with a pH above 7.5, the availability of nutrients, particularly phosphorus, boron, manganese, and zinc, decreases, although high total amounts of these elements may be present in the soil.

The potato vegetation is divided into separate growth phases, and each phase must be taken into account in crop management, because nutrients should be supplied precisely at the moment of their greatest absorption by the plant. For example, the flowering of plants coincides with the stage of the tuber growth, when potassium is very important for the plant.

An optimal fertilization system should provide the plant with nutrients in an accessible form, in the right phase of development, in the right way and in the necessary rates.

Among the macronutrients, potassium and nitrogen are the elements that are used in the largest quantities for the formation of the potato crop, as they are necessary throughout the entire growing season. The need for phosphorus, calcium and magnesium is a bit lower.

Nitrogen is also equally important for the growth of above-ground mass and potato tubers. About 60% of nitrogen is absorbed within 75 days after planting. Therefore, it is especially important to provide the plants with the required level of nitrogen before closing the plants in the row (BBCH 31-39). In order to avoid nitrogen deficiency during cultivation, we recommend using Wonder Leaf Violet fertilizer (N:P:K-30:10:10 + SO3-15, Mo-0.5, w/w %). However, an excessive amount of nitrogen at the beginning of tuber formation can disrupt the flow of nutrients to the tubers and reduce their yield. An excess of nitrogen at the end of the growing season usually reduces the quality of the tubers skin and worsens the potatoes shelf life.

Potassium in the fertilizer Wonder Leaf Red (N:P:K-10:20:30 + B-2, w/w %) plays an important role in the water balance control, stomatal functioning and ion concentration of plant tissues. Potatoes require a large amount of potassium, because its main function is to participate in the sugars transferring from the leaves to the tubers and their transformation into potato starch.

Application of fertilizers: Wonder Leaf Blue (N:P:K-10:53:10 + Zn-2 chelate, w/w %), or Wonder Leaf Mono P 30 (N:P-4:30 + B-0.5, Zn chelate-0.5, amino acids-1, organic acids-4, w/w %) provides phosphorus at the initial stages, namely 4 or more leaves (BBCH 14-19) of plant growth and development. It is important for stimulating the root system, tuber formation, and in the phase of fruit and seed formation to activate the synthesis, transportation and starch accumulation.

Calcium in Wonder Leaf Mono Ca 14 (CaO-14%) fertilizer (a key component of the cell wall) ensures the strength and stability of potato tissue cells. At an optimal level of calcium, tubers are more resistant to bacterial or fungal infections and have better shelf life during storage. Calcium also helps the plant adapt to stress by stimulating signaling reactions in response to adverse factors. It also plays a key role in regulating active potassium transportation for normal stomatal function.

Magnesium plays a main role in photosynthesis. This element is involved in various key stages of sugar and protein production, as well as in the sugars transporting from leaves to tubers in the form of sucrose. Periodic fertilizing of potatoes with magnesium is recommended.

Sulfur is necessary for effective nitrogen assimilationn by plants, which, accordingly, optimizes the entire food chain. At the same time, foliar application of this element on potatoes allows controlling the spread of some diseases in this crop, thus influencing the future yield.

To supply potatoes with magnesium and sulfur, use Wonder Leaf MgS 16-32 (MgO-16, SO3- 32, Mn-0.007 w/w %).

A balanced nutrition strategy must include microelements. The most important microelements for potatoes are boron, copper, manganese and zinc.

Zinc in Wonder Leaf Mono Zn 8 (chelate Zn-8%) as part of enzymes participates in the metabolism of starch and nitrogen, and it is especially important for the synthesis of auxin – the main hormone, controlling the cells and roots growth.

Boron also affects the roots and shoots growth, stimulates pollination, ensures calcium translocation from roots to tubers. Along with potassium and calcium, boron is an important element that ensures the strength of cell walls, significantly affects the quality of tubers and their storage period.

Manganese Wonder Leaf Mono Mn 11 (Mn-11% chelate) affects the content of enzymes activating nitrogen metabolism, energy transportation and fatty acid synthesis. Copper in is a part of enzymes activating carbohydrate and protein metabolism, affecting photosynthesis and protein synthesis.

Treatment of plants with zinc, manganese and copper increases plants resistance to scab, drought and heat.

The system of feeding potatoes with Wonder fertilizers is based on providing the crop with an optimal ratio of macro- and microelements in the most sensitive periods of its development. In potatoes, the phases of germination, row closing, budding and fruit formation are critical in terms of nutrient requirements.

Before planting potatoes, it is recommended to treat seeds with Wonder Leaf Wonder Micro–1.5-2 l/t of planting material to increase the energy of germination and the appearance of favorable seedlings.

Organic and mineral fertilizers

Since the production and application of organic fertilizers has  almost stopped, the soil was depleted of nutrients and microelements — vitamins, necessary for the growth and development of potatoes. Because of this, potato growers increasingly use complex water-soluble fertilizers.

The most effective way of using mineral fertilizers for potatoes is their combined application, which increases the yield, starch content and improves the taste of the tubers.

In order to obtain the maximum efficiency from fertilizers, it is necessary to correctly establish the norms, terms and methods of their application. At the same time, it is necessary to take into account soil and climatic conditions and the level of soil fertility based on agrochemical analysis.

Shortage and excess

Each element of mineral nutrition performs a certain physiological function, so the lack or excess of even one of them affects the plants biochemical composition and appearance. With a sharp violation of mineral nutrition, changes in the structure of individual organs are observed, in particular, in the height of plants, in the color of leaves, the condition of tissues, etc. This is especially important when growing seed potatoes.

Viral and fungal diseases, frost, drought, excessive soil moisture, mechanical damage, etc can cause changes in the external structure of individual organs. Therefore, to determine the causes of non-standard plants growth and development, the possibility of a negative effect of a lack of certain elements of mineral nutrition should be taken into account. Usually, signs of nitrogen, phosphorus, potassium and magnesium deficiency are visible first of all on the lower leaves; calcium, iron, boron, copper — on the top ones.

In field conditions, the nitrogen and potassium deficiency is detected most often on poorly cultivated sod-podzolic soils; phosphorus – on poorly cultivated and acidic; magnesium, iron, zinc, boron – on limed or rich in lime; calcium and molybdenum – on acidic soils.