Incorporating Nutrient Management in Potato Production
Incorporating Nutrient Management in Potato Production
Wesley Haun, Senior Agronomist
Potatoes produced in intensive management environments have high demand for plant nutrients. Producers must strive to enhance plant nutrient availability throughout the growing season. “To optimize fertilizer, use efficiency potato growers need to understand: 1) nutrient uptake patterns and associated sufficiency levels for soil and plant tissue nutrient concentrations, 2) cultural and environmental factors that influence plant nutrient availability, and 3) fertilizer management practices that optimize nutrient use efficiency” (Stark et al. 2004). A basic knowledge of plant physiology will help growers better understand the correlation between growth stages and plant nutrient demands (Figure 1).
Figure 1: Potato growth stages (Image: University of Wisconsin)
Growth Stage I: Sprouts develop from eyes on seed tubers and grow upwards to emerge the soil. Roots begin to develop.
Growth Stage II: Leaves and branch stems develop from above ground nodes along emerged sprouts. Roots and stolons develop at below-ground nodes. Photosynthesis begins.
Growth Stage III: Tubers form at stolon tips but are not yet appreciably enlarging. In most cultivars the end of this stage coincides with early flowering.
Growth Stage IV: Tuber cells expand with the accumulation of water, nutrients, and carbohydrates. Tubers become the dominant site for deposition of carbohydrates and mobile inorganic nutrients.
Growth Stage V: Vines turn yellow and lose leaves, photosynthesis decrease, tuber growth slows, and vines eventually die. Tuber dry matter content reaches a maximum, and tuber skins set at the base of the emerging sprouts.
Plant Nutrient Uptake
An understanding of nutrient uptake requirements enhances nutrient management planning. Potatoes take up approximately 40-50% of their nitrogen (N) and potassium (K) needs and about 30-40% of the phosphorus (P) and sulphur (S) requirements prior to tuber bulking. During the bulking growth stage nutrient uptake increases dramatically and levels out as plant matures (Figure 2). Russet Burbank potatoes with tuber yields of 400–500 cubic 100 weight (cwt) per acre will take up significant amounts of nutrients: N 200-240 lbs/ac, K 280–320 lbs/ac, P 25-35 lbs/ac, S 18-24 lbs/ac. (Stark et al., 2004).
Figure 2: Potato nutrient uptake 3 years average. (Adapted from Stark et al., 2004)
Compaction, hardpans, shallow soils, and soil texture alter plant root growth, resulting in less soil volume from which nutrients can be accessed. Sandy soils have a low cation exchange capacity (CEC) which results in low nutrient holding ability and an increased potential for some nutrient leaching. Soil temperature influences the biological and chemical processes. Root growth is slow at low soil temperature and contributes to limited access to immobile nutrients. Microbial activity is reduced when soil temperature is below 60°F followed by slower nutrient mineralization such as nitrogen and sulphur. Soil pH regulates nutrient availability with optimum levels at 6.5-7.0. Phosphorus and the micronutrients availability decreases as the soil pH increases above 7.0. When soil pH falls below 6.0, phosphorus availability decreases due to interactions with iron and aluminum oxides.
Monitoring Potato Nutrient Demand
Sulphur is often overlooked as a nutrient addition in potato nutrient management programs. If soil sample analyses reveal S levels less than 10 ppm and previous crop history of a given field has had low sulphur levels, it would be wise to apply 30–40 pounds per acre (lbs/ac) of S to enhance the crop’s yield potential. Those sulphur rates could be met with Tiger 90CR® at 33-45 lbs/ac or Tiger XP® at 35–47 lbs/ac. Potatoes tend to respond to Zn and Mn micronutrients with greater yield and/or quality. Table 1 provides the minimal soil test values for selected micronutrients. If your soil test analysis has values less than those shown, additional micronutrients should be included in the nutrient management plan such as Tiger Micronutrients®.
Table 1: Minimal micronutrient soil test values for potato production (Adapted from Stark et al. 2004)
A guideline for plant nutrient application rates should be the soil test analyses and expected yield potential. Yield potential should be an average of last 3-5 crops from each field plus additional 10–15%. A key to efficient potato production is consistent crop monitoring through the growing season. One method of evaluating potato growth is plant tissue collection and analysis. These “tissue” analyses allow evaluating the plant nutrient status throughout the growing season. If needed, immediate corrective actions can be implemented, especially where irrigation is available. Collections should begin approximately four weeks following plant emergence and continue every ten days till about four weeks prior to vine defoliation. The plant part to collect is the petiole at fourth node (Lang et al., 1999). The leaflets should be removed and only submit the petiole from approximately from 30 to 40 plants.
Table 2: Potato petiole nutrient content levels. Adapted from Stark et al., 2004
Table 2 reflects desired nutrient levels in potato petiole analyses. Potatoes with less than 0.15% of sulphur in the petioles should receive 30–40 lbs/ac of sulphur. Foliar deficiency symptoms may be apparent if sulphur levels are below 0.15%. Sulphur is not mobile within the plant and the symptoms are evident in the younger leaves. There will be general yellowing of young leaves in top of plant and lower leaves have normal appearance with dark green color (see top photo). Other test values that are at or below those listed in the “low” column should receive immediate attention.
Nutrient Application
Potatoes have a relatively high nutrient requirement and a small root system (Stark and Love, 2003). When compared to grains and other rotational crops, potato growers commonly apply significantly more fertilizer, unlike other rotational crops that tend to be more nutrient efficient (Hopkins & Stephens, 2007). Various application methods may be employed to field apply plant nutrients. Most nutrients including sulphur (Tiger 90CR, Tiger XP, or Tiger Micronutrients) can be applied in fall or spring broadcast and incorporated into the rooting zone. Other fertilizer application methods commonly used for potatoes include:
1) banding at mark-out or planting,
2) side-dressing after planting,
3) foliar nutrient sprays,
4) injecting liquid fertilizer through the irrigation system (Hopkins et al., 2004)
Banding at mark-out fertilizer is placed 2 to 3 inches to side and below the seed piece. Banding applications at planting are typically placed 1 to 2 inches to side and above the seed piece. Side dressing after planting is a popular application method for nitrogen to enhance plant uptake by timing application with crop demand. Foliar nutrient sprays are utilized to apply low concentration nutrient formulations to treat nutrient deficiencies, especially some micronutrients. Injecting liquid fertilizer through the irrigation system is a method utilized to provide water soluble plant nutrients throughout the growing season. This system has proved very successful with nitrogen applications on sandy soils (Mikkelsen, 2006).
When a potato nutrient plan is implemented, it typically results in greater yield potential. Granted, many factors influence crop yield. A grower’s goal should be to minimize or eliminate those yield-limiting factors they may have control of in a given field. One of those yield limiting factors producers can influence is plant nutrients. Tiger-Sul conducts research projects to evaluate potato yield response to sulphur products. As illustrated in Figure 3, using the grower’s standard fertilizer application with the addition of sulphur with Tiger 90CR resulted in an average increase of 56 cwt. or 10% yield increase as compared to the grower standard fertilizer application without sulphur.
Figure 3: Potato yield response to Tiger 90CR Sulphur. Average of 4 years over 3 locations.
Nutrients taken up by plants are the same irrespective of the nutrient source such as plant or animal residue, soil minerals, manure, or commercial fertilizer. However, there are efficiencies and inefficiencies between the various nutrient sources, and it is important for growers and professional crop advisers to recognize potential situations and incorporate appropriate adjustments. Following the 4Rs for best management practices will facilitate “fine-tuning” management decisions for optimizing potato production. Successful potato production requires progressive integrated management to incorporate knowledge of the crop, influence of climate/weather, soil/water resources, cultural practices that promote optimum growth potential, and the interaction of all these factors that contribute to potato yield and quality.
To learn more, download this an many other Agronomic Technical Bulletins in the Tiger-Sul University, visit the Tiger-Sul website: www.tigersul.com.
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References:
1) Bohl, W.H., S. B. Johnson. (ed) 2010. Commercial Potato Production in North America.
2) Hopkins, B.G. and S.C.Stephens. 2007. Band Placement for Potatoes in Calcareous Soil.
3) Hopkins, B., J.C. Stark, D.T. Westerman, and J.W. Ellsworth. 2004. Nutrient Management Efficiency. University of Idaho.
4) Lang, N.S., R.G. Stevens, R.E. Thornton, and W.L. Pan. 1999. Potato Nutrient Management for Central Washington. Washington State University Extension.
5) Mikkelsen, R.L. 2006. Best Management Practices for Profitable Fertilization of Potatoes. News & Views. Potash & Phosphate Institute
6) Stark, J., D. Westerman, and B. Hopkins. 2004. Nutrient Management Guidelines for Russet Burbank Potatoes. University of Idaho Extension BUL 840.
7) Westerman, D.T., 2006. Nutritional Requirements of Potatoes. American Journal of Potato Research 82:301-307