Contact the Alberta Research Council for details regarding soil sampling procedure and prices:   Alberta Research Council Crop & Plant Management Hwy 16A & 75 Street Vegreville, AB  T9C 1T4 Contacts: Harold Feddema at (780) 632-8238 or Sandi Checkel at (780) 632-8217   Table 3.4-3 List of herticides with potato re-cropping restrictions2.

 

Field Preparation

Written by B. Geisel,  L. Delanoy

Heavy equipment traffic and excessive tillage cause soil compaction, which reduces potato yield and quality (see Soil Compaction in Section 3.4.1 Field Selection). Minimize compaction by reducing the amount of traffic or weight in the field. Do not carry out unnecessarily tillage operations.

Potato producers use a wide range of tillage equipment and techniques to prepare the potato seed bed. The  variation in tillage practices results from the wide range of soil types used in potato production and the variety of tillage implements available for soil preparation. Regardless of the tillage system used, it must meet the following criteria:

• Incorporate trash – A balance must be maintained between incorporating an adequate amount of crop trash to facilitate planting while maintaining sufficient soil trash cover to prevent wind erosion. Crop residue must be incorporated into the soil to allow for trouble free planting. The amount of tillage required to do this will depend upon the soil type, the type of crop preceding potatoes and the ability of the planter to perform properly in crop residues. Tillage should not incorporate so much crop residue that the soil is susceptible to wind  erosion. See Section 3.4.4 Soil Conservation for more details regarding soil erosion.

• Produce good tilth without drying out the soil or producing soil clods - Tillage should produce enough loose soil to allow the planter shoe to  penetrate to the desired depth and to provide the hiller discs with enough loose soil to construct a proper hill over the seed. Tillage that dries out the soil surface will reduce emergence and vigour. Tillage of finer texture soil types (loams) with the wrong implement or at the wrong soil moisture  content will produce clods that remain intact throughout the growing season and into harvest. Soil clods are difficult to separate from the potatoes on the harvester thus reducing efficiency and increasing cost (Figure 3.4-5). Hard dry clods that come into contact with the tubers on the harvester and other handling systems will cause blackspot bruising. For more information on bruise  prevention see Section 3.8.4 Bruise Prevention.

• Herbicide incorporation - Sufficient tillage is required to properly incorporate pre-emergence herbicides. Follow the chemical manufacturers’ instructions regarding the tillage method required for herbicide incorporation.

Figure 3.4-5 Soil clods on conveyor (Courtesy of Gaia Consulting Limited)

 

Field preparation should be performed in as few  operations as possible. Excessive tillage will increase the cost of production, the likelihood of wind erosion and the amount of soil compaction. Below is a short  description of three common tillage methods used on the Prairies.

Conventional

Operations such as deep tillage or discing are performed in the fall and cultivation is performed prior to planting in the spring.

Advantages:

• Inexpensive – Low capital and operating costs
• High capacity – 15-25 acres/hour (6-10 ha/hr) depending upon tractor speed and width of  implement
• Preserves surface trash depending upon number of operations and shovel design

Disadvantages:

• Can produce soil clods, depending upon soil  conditions at the time of tillage

Rotary Power Cultivator

In Manitoba and Saskatchewan, producers growing  potatoes on loam and clay loam soils use conventional tillage (deep tiller or double disc) in the fall. In the spring, a single pass with a rotary power cultivator  prepares the soil before planting (Figure 3.4-6). The rotary cultivator is a power cultivator that stirs the soil laterally rather than mixing the soil vertically like a  rotovator.

Advantages:

• Clod free soil bed
• Preserves surface trash
• Preserves moisture, especially important in  rain-fed production

Disadvantages

• Low capacity – 5-7 acres/hour (2-2.8 ha/hr) with a 20-foot (6 m) implement depending upon soil  conditions and texture
• Costly – High capital and operating expenses
• Poor weed control – has a tendency to transplant rather than destroy weeds

Figure 3.4-6 Rotary power cultivator (Courtesy of Gaia Consulting Limited)

 

Fall Bedding and Reservoir Tillage

A fall bedding and reservoir tillage (diking) implement performs both the tillage and hilling operations. In the fall prior to spring planting of potatoes, the field is tilled with a deep tiller or a double disc. Next, deep subsoil tillage is performed, hills are constructed and reservoir dikes or depressions are formed between the rows (Figures 3.4-7 and 3.4-8). The reservoirs capture water from melting snow and increase soil moisture. In spite of the aggressive fall tillage, surface trash cover is  preserved, reducing the potential for wind erosion. In the spring, the hills are packed with rolling wire baskets to break up soil clods that survive the freezing and thawing cycles over the winter, the hills are reshaped and the reservoirs are removed. The potatoes are planted  directly into the pre-formed hills. After planting, the final hilling is carried out and new reservoirs are formed between the rows.

Advantages:

• High Capacity – 8-11 ac/hr (3-4.5 ha/hr) in fall, 15 ac/hr (6 ha/hr) in spring
• Hills warm up faster in the spring
• Increased water retention
• Reduces run-off and drown-out in low areas as a result of precipitation or irrigation
• More even moisture between high and low areas of the field
• Clod free soil preparation
• Preserves soil trash

Disadvantages:

• Costly – high capital cost
• Requires a large tractor (>300 h.p.) in the fall

Figure 3.4-7 Fall bedding and reservoir tillage implement (Courtesy of Gaia Consulting Limited)

 

Figure 3.4-8 Reservoirs constructed in the fall (Courtesy of Gaia Consulting Limited)

 

Soil Conservation

Written by: B. Geisel, B. Hunt

Soil Erosion

Wind and water erosion resulting in serious soil losses (Figure 3.4-9) can be a problem on the prairies due to a  combination of climate, soil type, growth characteristics of the potato plant and management practices used in  potato production:

• Most potato producing areas, especially southern Alberta, experience high winds when the fields are exposed and vulnerable to erosion.

• Potatoes are usually grown on sand or sandy loam soils, which are susceptible to wind erosion.

• The risk of wind erosion is greater when planting light textured soils to potatoes rather than cereals. Potatoes do not emerge from the soil for 3 weeks after planting and it takes an additional 2 - 3 weeks before there is sufficient vegetative growth to  prevent erosion.

• Tillage, crop rotation and harvest practices used in potato production can leave fields without  adequate crop trash cover for many months of the year. In the fall and spring prior to potatoes, some crop residue must be incorporated into the soil to allow for trouble free planting. Often there is too little trash cover remaining to prevent erosion. The potato harvest is similar to an aggressive tillage operation, which disturbs the soil, leaving little crop residue cover to prevent erosion.

Figure 3.4-9 Soil erosion from a potato field without adequate crop residue cover (Courtesy of Gaia Consulting Limited)

Soil formation is a natural and ongoing process, but if wind erosion is visible, soil losses are greater than the rate of soil formation. One storm that removes a 1/4 inch (7 mm) layer of soil results in the loss of 44 tons per acre (40 tonnes per ha) of top soil and will require at least 10 years to be replenished; assuming no further erosion occurs.

The loss of topsoil through wind erosion reduces yield potential by negatively affecting fertility, physical  structure, tilth, permeability and water holding capacity. In addition, eroded soil from agricultural land can fill ditches reducing the effectiveness of drainage systems. In some jurisdictions, like Alberta, a fine can be imposed if a farmer fails to control erosion, and the expense of cleaning out the drainage or irrigation ditches is the responsibility of the landowner.

The erosion prevention practices listed below are  discussed under three headings:

1. Potato field preparation and planting
2. Potato harvest and post-harvest
3. Long-term strategies

Field Preparation and Planting

In the fall, the combine should be outfitted with a straw and chaff spreader to distribute residue evenly across the field. Additional flailing or harrowing may be necessary to help chop and distribute the crop residue. Even  distribution of the straw allows the farmer to use fewer and less aggressive tillage operations in preparing the field for planting the following spring. Fewer and less aggressive tillage operations preserve more of the trash cover reducing the potential for erosion. Tillage of light textured soils, where it is relatively easy to incorporate crop residues, should be delayed until spring. If fall tillage of a light-textured soil is carried out, it should result in no less than 65% of the ground covered with crop residue (Figure 3.4-10). The amount of residue buried by various tillage implements is shown in Table 3.4-4.

In Alberta, fall bedding and reservoir tillage are  commonly used to prepare fields for planting to potatoes the following spring. The equipment used to form the beds preserves sufficient trash cover to limit erosion. Orienting the beds at right angles to the prevailing winds reduces the impact of wind on soil erosion. The construction of reservoirs between beds prevents soil loss from water erosion caused by snowmelt and heavy spring rains.

Figure 3.4-10 Field with 65% of the soil surface covered with cereal residue (Courtesy of Gaia Consulting Limited).

In the spring, a minimum amount of tillage should be used in preparing the soil so that trash cover is  maintained. The producer should choose tillage methods that incorporate just enough crop residues to allow for trouble free planting, but preserve sufficient cover to  prevent erosion.

Where practical plant potatoes rows at right angles to the prevailing winds to reduce drifting in the spring. In Alberta, rows may be oriented north/south as a method of frost protection. In the north/south orientation, both sides of the hill receive equal amounts of sunlight  maximizing the solar radiation captured during the day.

Strip cropping (alternating strips of potatoes with a crop less prone to erosion) can be planted to reduce the  unsheltered width in erosion-susceptible fields. Crop strips should be perpendicular to the prevailing winds in May. The width of strips will depend on the size of equipment used in cropping and the susceptibility of the soil to wind erosion. Recommended strip widths vary from 76 feet (25 metres) in loamy sands to 305 feet (100 metres) in silty clay loams.

Annual crops such as corn and sunflowers can be used as wind barriers to protect the soil after harvest. Properly spaced annual barriers also trap and evenly distribute snow for effective winter cover. Annual barriers should be planted closer together than tree shelterbelts because they offer less protection. The proper width and distance between annual barriers is shown in Table 3.4-5. Plant the barriers using the seeding rates that would normally be used for crop production.

Harvest

In potato production areas where there are no stones, the potato harvester should be equipped with a vine  shredder, which eliminates the need for tillage to anchor potato vines. Potato vines that are not anchored in the soil can blow off the field and accumulate in ditches, fences and shelterbelts. Shredding provides even  distribution of chopped vine residue improving ground cover and reducing erosion potential (Figure 3.4-11). If the harvester is not equipped with a vine chopper, a  tandem disc or a chisel cultivator equipped with coulters should be used to anchor, but not completely incorporate the vines.

Figure 3.4-11 Shredded potato vines after harvest (Courtesy of Gaia Consulting Limited)

Seeding an annual cereal after the potato harvest will provide good protection from wind erosion until a new crop is established the next season. The success of this method is dependant upon the harvest date and the  growing conditions after harvest. The chances of  establishing a cover crop after September 15th to 20th are poor. The fall cover crop can be seeded by air just prior to harvest or with a conventional seeder just after harvest. The emergence is less even when seeding by air. In Alberta, irrigation may be required to obtain even  emergence of the cover crop. Some farmers choose to use wheat, oats or barley as a cover crop because the crop will winter kill and not interfere with future cropping plans. When choosing an annual cover crop, keep in mind that you will want a crop that germinates and establishes quickly. The malting varieties of barley are well suited to quick establishment. Many farmers will use a higher seeding rate to ensure a good ground cover in the field, i.e. barley at 1.5 bu/acre (62 kg/ha). Others choose to seed fall rye or winter wheat as a cover crop. A  non-selective herbicide is applied the next spring to  control the rye or wheat, or the crop can be left to mature.

Manure applied to the soil surface at 30-40 tons/ac  (70-90 tonnes/ha) will reduce drifting. Researchers have  demonstrated a link between high raw manure applications and an increase in the incidence of common scab, but this affect is rare. The nutrient content of the manure should be taken into account when planning commercial fertilizer applications the following season.

Mulch can provide the same erosion control benefits as a well-established cover crop or well managed crop  stubble. Broadcasting cereal straw with a round bale shredder onto the surface of erosion susceptible areas of the field will reduce wind erosion and add organic  matter. The application of 1 to 3 tons/acre (2 to 6 tonnes/ha) will provide 65% ground cover, which is  sufficient to prevent erosion.

Long-term Erosion Control Strategies

Fields susceptible to wind erosion can benefit from a  systematic planting of shelterbelts. Trees should be planted perpendicular to the prevailing winds that occur in May. The prevailing winds at this time tend to have the highest velocity and fields have the least protective cover. A distance of approximately 660 feet (200 metres) between tree rows is recom-mended. The distance between green ash trees planted in the sheltebelt should be 6 to 8 feet (2.0 to 2.4 m) apart.

In Alberta, there is a growing trend to reduce a soil’s  susceptibility to wind erosion through the build up of organic matter in the soil. The addition of composted manure on an annual basis at rates of 2.5 to 5.5 tons/ac (7 to 12 tonnes/ha) is a safe method of amending the organic matter and reducing the soil’s susceptibility to erosion over time. Planting cereal and forage crops, which  produce large amounts of organic matter, in rotation with potatoes helps reduce soil erosion. Care must be taken when including bean and canola crops in rotation with potatoes, as neither provides much crop residue.

For assistance with soil erosion problems, contact your provincial soil and conservation specialists or Prairie Farm Rehabilitation Administration (PFRA).

Fertility and Fertilizers

Written by: D. Waterer,  J. Heard

Potatoes managed for maximum productivity exert a heavy demand on soil fertility. Significant quantities of  nutrients are removed from the field in the harvested tubers (Table 3.4-6), while additional nutrients are lost through erosion and leaching.

Nitrogen Nutrition and Management

Of all the essential nutrients, nitrogen most often limits potato production. Consequences and symptoms of nitrogen deficiency in the crop are:

• Stunted growth
• Premature death of vines
• Poor yields
• Increased susceptibility to diseases such as early blight and Verticillium wilt
• Likewise there are consequences of excess nitrogen:
• Negative impact on environmental – particularly due to nitrate leaching below the root zone
• Excessive vine growth, which can interfere with harvest
• Delayed tuber set leading to poor yields in regions with a limited growing season.
• More deformed tubers and hollow heart
• Tubers are physiologically immature at harvest, resulting in more harvest damage, poor storability and processing quality
• Low specific gravity

Attention should be paid to nitrogen management because of its influence on crop productivity, quality and the environment. Nitrogen management refers to  placement methods, timing of applications and  assessment of N status as well as N application rates.

 

 

 

 

 

Nitrogen placement and time of application

The relative efficiency of any nitrogen application varies depending on soil moisture, soil temperature, soil type, weed and crop growth. In Table 3.4-7 average efficiency of times and method of N application are compared to spring broadcast, which is given a value of 100.

Table 3.4-7 Average efficiency of times and method of N application

 

Efficiency values are based on nitrogen uptake by plants. Broadcast values assume urea-based nitrogen fertilizers are incorporated to minimize losses through volatilization of ammonia. This incorporation step is critical on soils with a high pH or which contain free lime near the surface, particularly when rainfall is not received following application.

Banding refers to applying fertilizer in-furrow or in bands below and to the side of the seed piece. Banding the N fertilizer restricts contact between the fertilizer and the soil. This delays nitrification of ammonia forms of N  fertilizer, thereby reducing losses of nitrate-N. Banding also reduces loss of N due to contact with crop residues or immobilization.

Excessive rates of banded N can impair sprouting and reduce plant emergence. In-furrow applications of N while seeding, should not exceed 50 lbs N/ac (45 kg N/ha) in the urea form, while no more than 80 lbs N/ac (70 kg N/ha) nitrogen in urea form should be applied as a sideband application. Fertilizer bands established prior to seeding should not be disturbed prior to or during the seeding operation to optimise N efficiency.

Nitrogen losses due to leaching, denitrification, immobilization and weed growth are generally higher for fall-applied than for spring-applied N. These losses are further increased if the N is applied too early in the fall (prior to mid-September) or when soil temperature at the 4" (10 cm) depth is greater than 41°F (5°C). For these reasons, nitrogen should be applied in spring or  in-season. In dry soil, banding N in late fall is as  effective as spring banding.

Nitrogen is relatively mobile in moist soil and therefore need not be applied near the plant to be effectively used. However, surface application or shallow incorporation can result in reduced uptake if the seedbed remains dry  during the early growing season. Nitrogen applied in a band is more effective than surface applications when the soil is dry.

Split applications for nitrogen

Splitting the total N application is an effective strategy to increase fertilizer use efficiency while limiting nitrate leaching. Part of the crop’s total N requirement is supplied prior to planting or is banded at planting. This initial application of N is supplemented with one or more applications of N. The first increment of N is usually applied after tuber initiation. Additional later applications may be used if a petiole nitrate analysis indicates a N deficiency.

Several methods are available for applying N after crop emergence.

• The most common method is top-dressing which involves broadcasting granular fertilizer over the growing crop. Ammonium nitrate is the preferred nitrogen source for top-dressing because it does not require incorporation after application. Urea can be top-dressed, but hilling or irrigation must be used to incorporate the fertilizer shortly after  application. Liquid N can be dribbled onto the hill at the base of the plants, but it also must be  incorporated after application. Care must be taken to avoid contact between the foliage and  liquid N, as it will burn the leaves.

• Nitrogen fertilizers may be banded in the soil to the side of the emerged crop row. Delaying banding increases pruning of the roots and may reduce yields.

• Fertigation, which involves the injection of liquid fertilizer into the irrigation water, can be used to apply N and other nutrients throughout the  growing season. Liquid urea-ammonium nitrate (28%) is the most common source of N injected into irrigation water. Uniformity of N application depends on the uniformity of water application from the irrigation system. Centre pivot and linear irrigation systems provide the most uniform  application of water. Traveling guns and  side-wheel roll systems do not distribute water as uniformly over the field as centre pivots or linear systems because of overlaps between moves. These systems should only be used to apply N fertilizer when the wind is very low and no other N application method is available.

Nitrogen Assessment

Soil testing to a depth of 24 inches in the spring is  critical to planning an effective and efficient N  management program. Post harvest soil samples may help growers to select succeeding crops, which will make maximum use of the residual N after the potato crop.

Commercial soil test laboratories will provide N fertilizer recommendations based upon the nitrate soil test. The recommendations may vary with the soil type, the cultivar, end use of the crop, yield goal, the previous cropping and manuring history of the field. Each provincial soil specialist can also provide rate recommendations based on the soil test results.

Nitrogen management based solely on a soil nitrate test is challenging. In intensively cultivated and irrigated potato fields, mineralization of organic matter may add significant amounts of N. Even in relatively fertile soils, leaching or very high plant demand can cause in-season N deficiencies. The nitrogen demand by the crop during tuber bulking may be 2.5 to 3.5 lbs N/ac/day (2.2 to 3.0 kg N/ha/day). Petiole nitrate sampling allows for in-season monitoring of the crop’s nutrient status. Collect the 4th petiole from 30 – 50 randomly selected plants throughout the field (Figure 3.4-12). Strip the leaflets from the  petiole and keep the sample cool until shipping. Tissue samples are often collected weekly to track changes in nitrate levels, and to plan supplemental fertilizer  applications should levels drop below optimum. Producers should follow laboratory instructions on tissue sampling techniques and interpretation of petiole nitrate results.

Critical petiole nitrate-levels decline as the potato crop develops and matures. Generally, petiole nitrate-N levels at tuber bulking are <10,000 ppm = low, 10,000-15,000 ppm = medium, >15,000 ppm = sufficient. (Figure 3.4-13)

Phosphorus

Soil Availability and Plant Uptake

Soil phosphorus (P) occurs in many forms depending on the pH and chemical composition of the soil. Only a small fraction of the total amount of P present in the soil is actually available to the crop within a given growing season, but the supply of available P is constantly  replenished from soil reservoirs of less available P. Consequently, soil P levels are usually fairly stable over the course of the growing season and do not change much from year to year unless the field has been heavily fertilized. The roots absorb phosphorus ions dissolved in the soil water. Phosphorus deficiencies can occur even in soils with abundant available P if drought, low temperatures or disease interfere with the phosphorus diffusion to the root through the soil solution or  otherwise impair development and function of the roots.

Potato plants require an adequate supply of P throughout the growing season to achieve optimum yields. During the early growth stages, P stimulates the development of a vigorous root system and healthy tops. Plant demand for P peaks at tuber set and then slows during bulking as the nutrient needs of the developing tubers are met by  translocating P from the tops of the plants.

Figure 3.4-12 Diagram showing 4th petiole (Courtesy of Agvise Laboratories)

 

Figure 3.4-13 Target range for petiole nitrate in potato petioles

Phosphorus deficiencies slow growth and reduce yields without producing any obvious changes in the appearance of the crop. Only after P deficiencies have become severe will the crop begin to develop visible signs of P stress - stunted dark green leaves and the edges of the youngest leaves begin to fold downwards. As P deficiencies are difficult to diagnose based on the appearance of the crop, P status should be monitored by tissue testing. Optimum tissue P levels vary from 0.2-0.5%, depending on the crop growth stage (Table 3.4-8).

P Fertilizing Strategies

The P requirements of potatoes are much higher than the P levels typical of most Prairie soils and some type of P  fertilizer program is usually required. Phosphorus application programs should be based on the  recommendations obtained from fall or spring soil tests (Table 3.4-9). As P fertilizers are relatively expensive and the nutrient is immobile in the soil, the objective of the ideal P fertility program is to raise levels of available soil P in the effective root zone to precisely match the   requirements of the crop. Band application of P fertilizer below and to the side of the seed row represents the most efficient means of meeting crop P needs with the minimum amount of P fertilizer. Placing the P fertilizer in a concentrated band adjacent to the developing root system increases the efficiency of fertilizer recovery by the roots while also reducing fixation of the applied P into forms unavailable to the crop. Banding is particularly effective in soils testing low in P or with high P fixing capacity and in situations where growing conditions may interfere with  development of a healthy root system. Broadcast/incorporating P fertilizers prior to planting represents a convenient option in soils requiring only limited P amendment.

Although P is relatively immobile in soil, timely  application of P as a sidedress treatment followed by  irrigation or via fertigation with P may be useful if tissue tests indicate the crop is at risk of a P deficiency. This practice is only recommended when there is risk of a yield limiting nutrient deficiency and there are no other application options available. Excess application of P as either fertilizer or manure is economically and environmentally unsound but has little potential to reduce yield or quality.

Potassium

Soil Availability and Plant Uptake

Potassium (K) is supplied to the crop root through  diffusion over short distances; hence K is also referred to as a relatively immobile nutrient in soils. Much of the K available to the plant is held on exchange sites on clay or  organic matter, which replenishes the soil solution as root uptake of K occurs. Consequently, soil K levels are  usually stable over the course of the growing season and from year to year.

Potatoes require abundant soil K, as this nutrient is  crucial to metabolic functions such as the movement of sugars from the leaves to the tubers and the subsequent transformation of those sugars into starch. Potassium  deficiencies reduce both the yields and quality of the potato crop. Potassium deficiencies impair the crop’s resistance to diseases and its ability to tolerate stresses such as drought and frost. Tubers adequately supplied with K are more resistant to blackspot bruising or after cooking  discoloration, while also experiencing less moisture loss and disease during storage. Potassium deficiencies  typically first show up in the sandier or knoll areas of the field. As K is mobile within the plant, the lower leaves are first to display symptoms of K deficiency - yellowing of the leaves with scorching around the leaf margins. Severely deficient plants may take on a coppery sheen. Small dead spots resembling the lesions produced by fungal disease may form on the leaves. As visible signs of K deficiency only become apparent once the crop is severely stressed, the K status should be monitored by tissue testing. Optimum tissue K levels vary from 2-5 %, depending on the crop growth stage (Table 3.4-8).

K Fertilizing Strategies

Potassium application programs should be based on the recommendations obtained from fall or spring soil tests (Table 3.4-9). As K fertilizers are relatively inexpensive, many growers opt to add a small amount of K fertilizer to potatoes even in K rich soils. Potassium fertilizer (20-40 lbs/ac [18-35 kg/ha]) applied in a band adjacent to the seed row may provide a jump-start to the emerging potato plants. To avoid salt damage to the crop, the total amount of all actual fertilizer nutrients applied as a band should not exceed 100 lbs /ac (88 lbs/ha). Broadcast/incorporating K fertilizers prior to planting represents the preferred approach in soils requiring more substantial K  amendment.

Although K is only moderately mobile in the soil, timely application of KNO3 as a sidedress treatment followed by irrigation or via fertigation may be useful if tissue tests indicate the crop is at risk of a K deficiency. This  practice is only recommended when there is risk of a yield limiting nutrient deficiency and there are no other application options available.

Muriate of potash (KCl 0-0-60) is the least expensive and most readily available form of K fertilizer. There is some evidence that excessive Cl associated with heavy application of KCl may reduce the specific gravity of the potato crop, but this is rarely an issue on the relatively K-rich Prairie soils.

Micronutrients

Although micronutrients (boron, chlorine, copper, iron, manganese molybdenum and zinc) are only required in  relatively small quantities by the potato crop, they are no less important to the health and productivity of the crop than are the other nutrients. Although deficiencies of micronutrients are relatively uncommon in Prairie soils, growers should still have the micronutrient levels in their soil evaluated prior to planting and should confirm the micronutrient status of their crop through tissue testing (Table 3.4-8). The micronutrient needs of the crop may be met through either soil or foliar applications. As  micronutrients are relatively expensive and the margins between adequate and excessive supplies are often  narrow, growers should exercise caution when utilizing these products. Check strips represent a useful tool for confirming the benefits and cost efficiency of any  fertilizer treatment.

Table 3.4-8 Recommended tissue concentrations of  nutrients for potatoes.
Check with your soil testing lab or provincial fertility specialist to obtain values appropriate for your production area, soil type, cultivar, management practices and anticipated end-use of the crop.

Table 3.4-9 General fertilizer recommendations for nitrogen, phosphorus and potassium for irrigated potatoes.
Check with your soil testing lab or provincial fertility specialist to obtain values appropriate for your production area, soil type, cultivar, management practices and anticipated end-use of the crop.

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