POTATO CROP GUIDE OF FIELD MANAGEMENT & FERTILIZATION
Jul 08, 2016

The potato ranks as the world's fourth most important food crop, after maize, wheat and rice.Growing potato and getting high yield is a task that requires profound knowledge and expertise. Here are just some of the information for reference :

- Since potatoes are sensitive to the chloride anion, it is essential to use chloride-free fertilizers, which contribute to increased yield and quality.

- Potato growth is classified into five distinct growth phases, and each growth stage has to be considered when managing the crop.

- The highest requirement for potassium is during the bulking up stage of the tubers. The flowering of potato plants indicates the beginning of this morphological stage.

- Adequate control over Nitrogen (N) supply is highly important to obtain high yields of excellent quality potatoes.

- Calcium deficiency interferes with root growth, causes deformation of foliage growth tips, and may result in reduced yields and poor quality.


FERTILIZATION

Nitrogen (N) - Adequate N management is one of the most important factors required to obtain high yields of excellent quality potatoes. An adequate early season N supply is important to support vegetative growth.

Excessive soil N, applied late in the season delays maturity of the tubers and result in poor skin set, which harms the tuber quality and storage properties. Potatoes are a shallow-rooted crop, generally growing on sandy, well-drained soils. These soil conditions frequently make water and N management difficult since nitrate is susceptible to leaching losses. On these sandy soils, it is recommended that potatoes receive split applications of N during the growing season. This involves applying some of the total N requirement prior to planting and applying the remainder during the season with side-dress applications or through the irrigation system. 

The period of highest N demand varies by potato variety and is related to cultivar characteristics, such as root density and time to maturity. Petiole analysis during the growing season is a useful tool, allowing growers to determine the N status of the crop and respond in a timely manner with appropriate nutrients.

Too much ammonium-nitrogen is a disadvantage as it reduces root-zone pH and thereby promotes Rhizoctonia disease. Thus, a careful control of NH4+ concentrations is necessary to minimize ammonium toxicity to potato plants.

Phosphorus (P) - Phosphorus is important for early root and shoot development, providing energy for plant processes such as ion uptake and transport. Roots absorb phosphate ions only when they are dissolved in the soil water. Phosphorus deficiencies can occur even in soils with abundant available P, if drought, low temperatures, or disease interfere with P diffusion to the root, through the soil solution. These deficiencies will result in stunt root development and inadequate function. 

At the tuber initiation stage, an adequate supply of phosphorus ensures that optimum number of tubers is formed. Following the tuber initiation, phosphorus is an essential component for starch synthesis, transport and storage.

Potassium (K) - Potato plants take up large quantities of potassium throughout the growing season. Potassium has an important role in the control of the plant water status and internal ionic concentration of the plant tissues, with a special focus on the stomatal functioning. 

Potatoes require large amounts of soil K, since this nutrient is crucial to metabolic functions such as the movement of sugars from the leaves to the tubers and the transformation of sugar into potato starch. Potassium deficiencies reduce the yield, size, and quality of the potato crop. A lack of adequate soil K is also associated with low specific gravity in potatoes. 

Potassium deficiencies impair the crop’s resistance to diseases and its ability to tolerate stresses such as drought and frost. Applying K fertilizer with a broadcast application prior to planting is most commonly recommended. If the K is band-applied, the rates should be kept below 45 kg K2O/ha to avoid any salt injury to the developing sprouts.

Calcium (Ca) - Calcium is a key component of cell walls, helping to build a strong structure and ensuring cell stability. Calcium-enriched cell walls are more resistant to bacterial or fungal attack. Calcium also helps the plant adapt to stress by influencing the signal chain reaction when stress occurs. It also has a key role in regulating the active transport of potassium for stomatal opening.

Magnesium (Mg) - Magnesium has a central role in photosynthesis, as its atom is present in the centre of each chlorophyll molecule. It is also involved in various key steps of sugar and protein production as well as the transport of sugars in the form of sucrose from the leaves to the tubers. 

Yield increases of up to 10% were obtained in trials in which regular application of magnesium fertilizers has been practiced .

Sulphur (S) - Sulphur reduces the level of common and powdery scab. This effect is related to a reduction in the soil pH where sulphur is applied in its elemental form.


Common nutrient deficiencies - Potato