Maui County Unversity of Hawaii at Manoa UH Seal Soil Nutrient Management for Maui County College of Tropical Agriculture and Human Resources (CTAHR)
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Fertilizer placement

The placement of nutrients is an important issue in nutrient management because placement strongly influences the subsequent availability of nutrients.

Improper placement can:

  • reduce yield potential
  • result in economic loss

Provided that a soil test indicates a particular nutrient deficiency, considerations of nutrient placement involve:

  • The type of fertilizer being applied
  • Tillage and crop rotation practices
  • Choice of crop
  • Access to necessary equipment
  • Nutrient mobility in the soil
  • Soil characteristics



  • Prior to planting, fertilizers and/or liming materials are applied uniformly over the soil surface.
  • After broadcasting, the fertilizer can be incorporated into the soil through tillage
    • Incorporation usually reduces losses of nitrogen due to volatilization and denitrification from the soil surface.
  • Since phosphorus is an immobile nutrient, broadcasting phosphorus fertilizers is not advantageous. For greater efficiency, phosphorus should be placed closer to the plant roots in bands.
  • Broadcasting provides a way to apply needed micronutrients

Surface Band


  • Prior to planting, fertilizer is applied to the soil surface in a band.
  • After application, the fertilizer can be incorporated into the soil.
  • Under certain conditions, nitrogen availability is increased when applied in a surface band as opposed to broadcasted.

At Planting

  • During planting, fertilizer is applied in a band along the top or side of rows.
  • This can be effective technique for applying immobile nutrients.

Subsurface Band


  • Fertilizer is placed in bands that lie 2 to 8 inches below the soil surface.
  • This can be an effective option for nutrient placement in reduced tillage systems.

At Planting

  • During planting, fertilizer is applied below the soil surface close to the seed row.
  • Often, the fertilizer is placed 1 to 2 inches below (or below and to the side) of the seed row.
  • In cool, wet areas, a “starter application” of fertilizer is placed in a subsurface band to boost seedling growth.

Band application and seedling growth

A major advantage of band application is enhanced seedling growth. Stronger seedlings are less prone to suffer from pests and diseases.

  • To prevent seedling injury, high rates of nitrogen should not be placed near seeds.
  • Banding phosphorus fertilizers near the seed row can increase phosphorus efficiency by reducing the degree of P fixation.
  • Despite an increase in efficiency, phosphorus recovery is typically lower than nitrogen and potassium.
    • While plants typically recover less than 20% of the applied phosphorus, 50 to 75% of applied nitrogen and potassium is generally recoverable.
    • The low rate of phosphorus recovery should not necessarily be considered a drawback, since the build up of P fertility of your soil may be a long term benefit.
  • Banded potassium below or to the side of the seed row typically enhances early seedling growth and reduces the risk of salt damage.
  • Banding potassium is usually a more effective method than broadcasting, although this difference becomes less significant as the rate of applied potassium increases.
NPK and Micronutrient Fertilizers
  • When applying micronutrients with an NPK fertilizer, the fertilizer should be placed a couple inches away from seeds to avoid seedling injury.
Salt damage and the salt index

An important consideration when applying fertilizer bands is the fertilizer’s salt index, which is a measure of the potential salt damage to the plant.

Salt damage

If highly concentrated, dissolved (soluble) salts in the soil solution can have a negative impact on plants. Soluble salts can originate from minerals in the earth and/or heavily applied fertilizers. Soluble salts accumulate in the soil when there are high rates of evaporation and insufficient leaching.

Problems associated with salt damage include:

  • If the concentration of salt in the soil is greater than the salt concentration in plant roots, water will not be absorbed by the plant. Instead, water will leave the plant and enter the soil.
  • High concentrations of soluble salts may also result in elemental toxicities of sodium and chlorine.

Salt index

The fertilizer salt index was developed to classify fertilizers according their potential to cause salt injury to plants.

  • Sodium nitrate is the standard and has an index of 100.
  • Other fertilizers are assigned a salt index value relative to 100, which describes the fertilizer’s potential to cause salt injury as compared to the damage caused by an equal amount of sodium nitrate.
  • A fertilizer with a salt index less than 100 has a lesser potential to cause salt damage in comparison with a fertilizer with a salt index greater than 100.

Click on the web link below to see a table of common fertilizers and their salt indices. This site also presents a simple method for calculating the salt index of any fertilizer using the information provided on the fertilizer bag and the salt index of each component of the fertilizer.


After Planting

  • When topdressing, fertilizers are applied over the soil and plant surface.
  • While topdressing of nitrogen is common in turf and pastures, this method is not recommended for phosphorus and potassium.


After planting

  • When sidedressing, fertilizers are applied in surface or subsurface bands along the side of plant rows.
  • Care must be taken to avoid damage to the crop, especially the plant’s root system.
  • Sidedressing provides a valuable opportunity to split the recommended N into smaller applications and apply N throughout the season.
    • Splitting the total nitrogen application into smaller doses throughout the season can be favorable, especially in coarse soils that have a high nitrate leaching potential.
  • Sidedressing is not effective as an effective method as preplant banding for immobile nutrients since sidedressing does not allow time for these nutrients to become available to plants.

Foliar Applications

  • Foliar fertilizers contain soluble nutrients that are suspended in water.
  • Foliar fertilizer is directly applied to the above ground plant parts.
  • With the exception of certain micronutrients, it is difficult for most plants to absorb sufficient nutrients through their leaves to meet their yield potential.

Foliar application versus soil application

  • When nutrients are obtained from the soil, the nutrients pass first through the root system and then travel through the xylem before reaching plant cells.
  • In contrast, nutrients from foliar fertilizers pass through cracks and/or stomata openings in the cuticle of the leaf and directly enter plant cells.
  • Foliar fertilizers supply plant cells with nutrients more rapidly than the soil. Thus, foliar fertilizers can provide a quick way to correct nutrient deficiencies.
    • However, due to the risk of foliage burn, the rates of nutrients in foliar fertilizers are much smaller (less than 1-2%) and several applications may be necessary.
    • Foliar P fertilizers have a greater risk of causing damage than N and are applied in lower concentrations (less than 0.4-0.5%).
    • Foliar fertilizers are a common way to apply micronutrients since micronutrients are required in much smaller quantities than macronutrients.
  • In high-value horticulture crops, foliar fertilizers may be used in addition to soil nutrients.


  • Fertigation is the application of fertilizers to the soil through an irrigation system, which applies both water and nutrients to plants.
  • It provides an additional way to supply nitrogen, sulfur and potassium.
  • It allows for a high degree of flexibility in nutrient management because nutrients may be applied continually throughout the growth of the crop.
    • Fertigation makes it possible to synchronize nutrient applications with crop demand. This is an effective strategy to prevent luxury consumption of nutrients.
    • Special features in certain fertigation designs allow for the recovery and recycling of irrigation water, which may reduce costs and negative environmental impacts.
    • Fertigation may also reduce losses of nitrogen due to leaching and denitrification.
    • Finally, fertigation may reduce operation costs associated with repeated applications by broadcasting, banding and sidedressing.
  • Successful fertigation requires a well-managed and equipped irrigation system for uniform, maximum efficiency.
  • Applications of phosphorus and anhydrous ammonia are not as common because these nutrients form precipitants if the irrigation water contains Ca, Mg, and HCO3- and clog the irrigation system. Click on the following web link to learn more about fertigation:



  • In warm climates, nitrification occurs readily. As a result, soil ammonium converts quickly to nitrate.
    • Losses of nitrate increase due to nitrate leaching during periods of intense rainfall.
    • Losses of nitrate due to denitrification occur readily in waterlogged soils.
  • To prevent nitrate losses, nitrogen can be applied throughout the season in smaller amounts, rather than applying the total nitrogen at once before the season. This is known as split application.
    • Split applications can be applied as a sidedressing or fertigation.
  • Another way to reduce nitrate losses is to apply fertilizers that contain nitrification and/or urease inhibitors or are slow release.
    • Nitrification and/or urease inhibitors slow the processes of nitrification and urea hydrolysis, respectively.
    • Slow release fertilizers contain a coat of sulfur which must break down before urea is released.


  • During a single season, the availability of phosphorus is limited by P-fixation.
  • To increase the efficiency of phosphorus fertilizers, it is recommended to apply phosphorus before or at planting.
  • In soils with high P-fixing capacity, banding is recommended.
  • Broadcasting is only effective if the P-fixation is low.


  • Like phosphorus, potassium is a relatively immobile nutrient in the soil. As a result, it should be applied before or at planting.
  • Potassium can either be broadcasted or banded.
  • Sidedressing of K is less effective.

Tillage systems

Conventional Tillage

  • The primary purpose of tillage is to loosen the soil.
  • Conventionally, tillage practices involve the use of equipment to break up and overturn the soil surface, while simultaneously incorporating surface residues into the plow layer.
  • In addition to leaving the soil surface relatively free of residues, conventional tillage:
    • aerates the soil
    • decreases compaction of surface soils
    • increases water infiltration in surface soils
    • facilitates proper seed emergence
    • eliminates and/or controls weeds
  • Initial plowing may be followed by secondary tillage operations to remove weeds and further loosen the soil.
  • The most common and oldest tillage practice is moldboard plowing, often using a disk plow.

Soil Tilth

  • Soil tilth is a term used to describe the suitability of a soil toward optimal plant growth.
  • Tilth refers to the workability of the soil, which describes the ability of plant roots to proliferate and for seeds to emerge. It is highly influenced by soil structure, texture, and organic content.
  • A soil with good tilth holds nutrients and water, but is also well drained and aerated.
  • Under natural vegetative conditions, the majority of soils have rapid infiltration, low compaction, good drainage, little soil erosion, and the desired bulk density and water holding capacity. These characteristics describe “good” soil tilth.
  • However, soil tilth can diminish by long term tillage due to increased subsurface soil compaction, reduced in soil organic content, and nutrient degradation.

How workable is your soil?

  • Soil tilth is intimately related to soil aggregation.
  • Soil aggregation often determines the workability of a soil.
  • The soils of Hawaii differ greatly in their degree of aggregation.
    • Some Hawaii soils do not form stable aggregates. And so, as it rains, the aggregates break up and water infiltration declines. Poorly aggregated soils are said to swell when wet and shrink when dry. Subsurface soil compaction is a major concern, especially if these soils are tilled when wet. Over time, plow pans can develop in areas that are compacted by heavy equipment. Soil compaction can ultimately decrease the workability of these soils.
    • Other soils in Hawaii have more stable soil aggregates. An example of a well aggregated soil is a highly weathered soil. In this case, the soil aggregates do not break up as readily when wet. Since these soils are less “sticky,” they are more workable. Thus, the impact of tillage on soil compaction is less.

Organic matter

  • In addition to soil structure, tillage has a large affect on soil organic matter.
  • Since tillage enhances soil aeration, the activity of soil organisms increases. As a result, the rate of decomposition of organic matter speeds up, while the total soil organic matter declines.
  • The management of organic matter is important for soil tilth because organic matter:
    • reduces soil compaction and bulk density
    • increases water holding capacity and infiltration
  • Tillage also directly removes vegetation from the soil surface. This leaves the soil bare and exposed to rain and wind. As a result, soil erosion increases.

Conservation Tillage

  • Conservation tillage is a way to reduce the negative impacts of conventional tillage.
  • In conservation tillage practices, farmers may choose to adopt minimal tillage or no-till practices.
    • In both minimal and no-till practices, there is minimal disturbance of plant residues.
    • In comparison to moldboard plowing, conservation tillage includes practices such as chisel plowing, ridge tillage, and stubble mulching.

Reduced tillage

  • Includes any system that maintains 30% of surface residues.

Chisel plowing

  • A chisel plow disturbs less soil by “stirring” the soil surface. This technique leaves 30% of the soil surface covered with plant residues, while incorporating the remaining 70% into the soil.

Ridge Tillage

  • In ridge tillage, areas between rows are left undisturbed.
  • Thirty percent of the surface residues along the rows remain, while the rest is incorporated into the soil. Crops are then planting along permanent ridges.

Stubble mulching

  • Residues are uniformly distributed onto the field, and the soil is minimally tilled.
  • Much of the incorporated residue remains near soil surface.


  • The soil is left undisturbed. Fifty to one hundred percent of the residue from a previous rotation crop remains on the soil surface.
  • Surface residues:
    • enhance aggregation
    • soil organic matter
    • water infiltration
    • drainage
    • water holding capacity
    • lower soil bulk density
    • soil compaction
  • Minimal tillage enhances the activity and the diversity of soil organisms, which helps to prevent pests and disease problems.
  • Reduced tillage increases total organic matter content in surface layer.
    • Initially, reduced tillage systems may lead to the immobilization of nutrients. In comparison, conventional systems initially encourage the mineralization of incorporated residues, although reducing overall soil organic matter content.
    • However, after initiated, mineralization increases to an even greater level than conventional systems. Since soil amendments are applied to the surface of the soil and not incorporated, they tend to build up in the surface layer.
    • While acidification from organic residues may occur, lime may correct this problem.

Manure Placement

  • Like fertilizers, manures may be broadcasted or placed in surface or subsurface bands.
    • When broadcasting, the manure may either be applied as a solid, liquid, or slurry.
    • When applying manure to subsurface soils, slurry or liquid manure may be injected into subsurface bands.
    • Manures may also be placed in surface bands before and after planting.

Suggested Readings

Nutrient Management Self-Study course:

Fertilizer consumption in Hawaii

Free Publications
Adequate nutrient levels
Obtaining seeds green manure
Wetland taro
Mn toxicity
Organic farming
Production and Handling
Testing N and P
Soil test
Soil amendment
Visual symptoms

For access to other CTAHR Free publications: