Background
Growing healthy potatoes and achieving high yields requires a well-timed and balanced potato fertilizer schedule, as potatoes are heavy feeders with significant nutritional demands. A proper fertilization plan should focus on providing the necessary phosphorus and potassium throughout the growth stages, as these elements are crucial for tuber development. Potatoes have a particularly high requirement for potassium, removing up to 1.5 times as much potassium as nitrogen and 3-4 times the amount of phosphate from the soil. Therefore, using potassium sulfate (SOP) instead of potassium chloride (MOP) is recommended for better results. It’s important to tailor the fertilization program based on soil conditions, which can be assessed through semiannual or annual soil testing.
A comprehensive nutrient management plan is essential for optimizing potato growth, as their shallow root system demands a steady supply of nutrients. Regular application of fertilizers high in phosphorus and potassium helps in developing large, healthy tubers. While general guidelines are available, consulting with local agricultural experts is crucial to determining the best fertilization strategy based on your specific field conditions. Proper fertilizer management practices increase the tuber size as well as tuber number.
SIMILAR: Tomato fertilizer Schedule
Potato Fertilizer Schedule at Different Growth Stages
Here are the various growth stages of potatoes when fertilizer should be applied.
Pre-Planting Soil Preparation
Before planting potatoes, apply 15-20 tons of compost per hectare to enhance soil structure and provide slow-release nutrients. It’s essential to conduct a soil test to assess nutrient levels and pH, as potatoes grow best in slightly acidic soils with a pH of 5.0 to 6.0. Organic matter such as compost or well-rotted manure can be added based on the test results. Fresh manure should be avoided near planting time, as its high nutrient levels can damage roots and increase disease susceptibility. Instead, well-rotted compost should be applied around two months before planting to allow nutrients to integrate into the soil. This ensures a steady release of nutrients throughout the growing period, especially for soils with low organic matter.
At Planting: Nitrogen Boost
At planting, potatoes require a moderate amount of nitrogen (N), around 50-80 kg/ha, to support early growth. However, overapplication of nitrogen can lead to excessive leaf growth, delaying tuber development. Balanced fertilization is key, as nitrogen plays a crucial role in increasing the leaf area, which in turn enhances solar radiation interception, contributing to a longer time to flowering, extended physiological maturity, and increased plant height. For optimal yield, potatoes, which are shallow-rooted crops, must absorb 50% of their phosphorus requirement between 15 to 45 days after emergence, ensuring proper root proximity to phosphorus sources.
A mature potato crop producing yields of 25-30 t/ha typically removes about 120-140 kg N/ha. Potatoes have higher nitrogen demands during the first two months when their foliar development is most rapid. However, excessive nitrogen can cause delayed maturity, reduce tuber quality, and sometimes result in lower yields. Ensuring proper phosphorus availability is also essential for tuber growth, requiring soil phosphorus levels to be adequate and close to the root zone. Moreover, at the time of planting apply the following fertilizers
- DAP @ 150 kg per acre.
- Muriate of Potash (MOP) @ 50 kg per acre.
- Magnesium Sulphate @15kg/acre.
- Azotobacter @ 1 kg/ acre mixed with 15 kg compost.
- Phosphorus Solubilizing Bacteria (PSB) @ 1 kg/ acre mixed with 15 kg compost.
Vegetative growth stage (2-4 weeks after planting)
During the vegetative growth phase, potatoes require additional nitrogen to support the development of foliage and stems. A side-dressing of nitrogen is recommended, which plays a key role in photosynthesis, fueling tuber growth later in the season. Ammonium nitrate or urea can be used for a sustained nitrogen release but avoid over-application to prevent delays in tuber formation.
At this stage, the crop experiences rapid growth and increased transpiration rates, with foliage playing a crucial role in nourishing the potato crop. Nitrogen fertilizers are essential in higher quantities during this period, but a balance of ammonium and nitrate forms should be maintained. Excessive ammonium can reduce the pH in the root zone, promoting diseases like Rhizoctonia. Nitrate nitrogen is more beneficial from tuber initiation through the bulking stage.
Tuber Initiation Stage (5-7 weeks after planting)
Phosphorus availability during tuber initiation is vital for ensuring maximum tuber set in potato crops. Foliar applications of phosphorus just before tuber initiation have been shown to increase the total number of tubers, while post-initiation applications enhance tuber size, thereby boosting overall yields. During this stage, the plant’s above-ground parts continue to grow, with photosynthesis providing essential nourishment.
As the plant transitions to tuber initiation, growth slows, and water retention stabilizes. It’s recommended to apply foliar phosphate, such as NPK 0:52:34 at a rate of 3-5 g per liter of water. At around 30-40 days after planting, during tuber initiation, phosphorus and potassium become especially important. Phosphorus is essential for root and shoots development, and its sufficient supply during this period ensures an optimal number of tubers. Given the potato plant’s shallow root system and high demand for phosphorus in the shoots, maintaining high phosphorus levels is critical for healthy and productive growth.
Tuber Bulking Stage (8-10 weeks after planting)
At the tuber bulking stage, nutrient transfer to the underground tubers becomes critical. This phase marks the rapid growth of potato tubers, and the focus should shift from nitrogen to phosphorus and potassium, which enhance tuber quality, size, and disease resistance. Spraying NPK 0:0:50 at 3-5 g per liter of water helps in starch formation and regulates water in the tubers. Fertilizers with high phosphorus and potassium content are essential at this stage, as they promote robust tuber growth.
Additional side-dressing with potassium-rich fertilizers, such as muriate or sulfate of potash, supports tuber development without affecting quality. Calcium applications can help increase tuber size, while magnesium is also needed to ensure proper tuber growth and yield. Potassium plays a crucial role in nutrient transport and carbohydrate movement from leaves to tubers, providing energy for tuber development. It strengthens the plant’s root system and improves resistance to diseases, pests, and environmental stress.
During tuber formation and bulking, the demand for fertilizers and irrigation increases to maximize both tuber quality and quantity. At this stage, water use remains stable, as top growth slows and the plant retains less moisture, emphasizing the importance of nutrient management for optimal tuber production.
Tuber Maturation Stage (10-12 weeks after planting)
As potatoes approach maturity, it’s important to stop adding nitrogen to avoid excessive vine growth and instead focus on maintaining potassium and phosphorus levels. A foliar spray of micronutrients like zinc, boron, and magnesium can support overall plant health and enhance yield by improving tuber size and reducing disorders like hollow hearts and scabs. During the final stages of senescence and tuber ripening, water usage declines due to reduced transpiration and leaf function. As the plants begin to yellow and die back, halt fertilizer applications and concentrate on irrigation management to maintain proper soil moisture for optimal tuber yield and quality.
Critical stages of water requirement In Potato
Maintaining adequate moisture during critical stages of potato growth is essential for optimal yields. Any moisture deficit during these phases can lead to significant yield loss. The first crucial stage is germination (immediately after sowing), where consistent moisture ensures proper sprouting. The second critical phase is tuber initiation (30-35 days after sowing), during which the development of tubers begins, and water stress can negatively impact tuber formation. The third important stage is the tuber bulking phase (45-65 days after sowing), where irrigation is vital for uniform tuber growth. Insufficient moisture during this stage can result in uneven tuber size, leading to a higher proportion of small, irregular tubers and fewer high-quality, marketable ones.
