Tag: sulfur

16 ESSENTIAL NUTRIENTS IN CROP DEVELOPMENT

Sixteen plant food nutrients are essential for proper crop development. Each is equally important to the plant, yet each is required in vastly different amounts. These differences have led to the grouping of these essential elements into three categories; primary (macro) nutrients, secondary nutrients, and micronutrients.

PRIMARY (MACRO) NUTRIENTS

Primary (macro) nutrients are nitrogen, phosphorus, and potassium. They are the most frequently required in a crop fertilization program. Also, they are need in the greatest total quantity by plants as fertilizer.

NITROGEN

  • Necessary for formation of amino acids, the building blocks of protein
    · Essential for plant cell division, vital for plant growth
    · Directly involved in photosynthesis
    · Necessary component of vitamins
    · Aids in production and use of carbohydrates
    · Affects energy reactions in the plant

PHOSPHORUS

  • Involved in photosynthesis, respiration, energy storage and transfer, cell division, and enlargement
    · Promotes early root formation and growth
    · Improves quality of fruits, vegetables, and grains
    · Vital to seed formation
    · Helps plants survive harsh winter conditions
    · Increases water-use efficiency
    · Hastens maturity

POTASSIUM
· Carbohydrate metabolism and the break down and translocation of starches
· Increases photosynthesis
· Increases water-use efficiency
· Essential to protein synthesis
· Important in fruit formation
· Activates enzymes and controls their reaction rates
· Improves quality of seeds and fruit
· Improves winter hardiness
· Increases disease resistance

SECONDARY NUTRIENTS
The secondary nutrients are calcium, magnesium, and sulphur. For most crops, these three are needed in lesser amounts that the primary nutrients. They are growing in importance in crop fertilization programs due to more stringent clean air standards and efforts to improve the environment.

CALCIUM
· Utilized for Continuous cell division and formation
· Involved in nitrogen metabolism
· Reduces plant respiration
· Aids translocation of photosynthesis from leaves to fruiting organs
· Increases fruit set
· Essential for nut development in peanuts
· Stimulates microbial activity

MAGNESIUM
· Key element of chlorophyll production
· Improves utilization and mobility of phosphorus
· Activator and component of many plant enzymes
· Directly related to grass tetany
· Increases iron utilization in plants
· Influences earliness and uniformity of maturity

SULPHUR
· Integral part of amino acids
· Helps develop enzymes and vitamins
· Promotes nodule formation on legumes
· Aids in seed production
· Necessary in chlorophyll formation (though it isn’t one of the constituents)

MICRONUTRIENTS

The micronutrients are boron, chlorine, cooper, iron, manganese, molybdenum, and zinc. These plant food elements are used in very small amounts, but they are just as important to plant development and profitable crop production as the major nutrients. Especially, they work “behind the scene” as activators of many plant functions.

BORON

  • Essential of germination of pollon grains and growth of pollen tubes
    · Essential for seed and cell wall formation
    · Promotes maturity
    · Necessary for sugar translocation
    · Affects nitrogen and carbohydrate

CHLORINE

  • Not much information about its functions
    · Interferes with P uptake
    · Enhances maturity of small grains on some soils

COPPER

  • Catalyzes several plant processes
    · Major function in photosynthesis
    · Major function in reproductive stages
    · Indirect role in chlorophyll production
    · Increases sugar content
    · Intensifies color
    · Improves flavor of fruits and vegetables

IRON

  • Promotes formation of chlorophyll
    · Acts as an oxygen carrier
    · Reactions involving cell division and growth

MAGANESE

  • Functions as a part of certain enzyme systems
    · Aids in chlorophyll synthesis
    · Increases the availability of P and CA

MOLYBDENUM

  • Required to form the enzyme “nitrate reductas” which reduces nitrates to ammonium in plant
    · Aids in the formation of legume nodules
    · Needed to convert inorganic phosphates to organic forms in the plant

ZINC

  • Aids plant growth hormones and enzyme system
    · Necessary for chlorophyll production
    · Necessary for carbohydrate formation
    · Necessary for starch formation
    · Aids in seed formation

 

In addition to the 13 nutrients listed above, plants require carbon, hydrogen, and oxygen, which are extracted from air and water to make up the bulk of plant weight.

 


Sulfur deficiency

Sulfur deficiency

 

Sulfur (S) is a part of every living cell and is a constituent of two of the 20 amino acids that form proteins. Unlike the other secondary nutrients like calcium and magnesium (which plants take up as cations), S is absorbed primarily as the S042- anion. It can also enter plant leaves from the air as dioxide (SO2) gas.

A chain is only as strong as its weakest link. Often overlooked, sulfur (S) can be that weak link in many soil fertility and plant nutrition programs. As of late, there are several reasons for the increased observance of S deficiencies and increased S needs.

Government regulations now restrict the amount of sulfur dioxide (SO2) that can be returned to the atmosphere from coal-burning furnaces. Most of the S is now removed from natural gas used in home heating and in industry. Also, catalytic converters in new automobiles remove most of the S that was previously returned to the atmosphere when S-containing gasoline was burned in automobiles. In addition, S-free compounds have replaced many of the insecticides and fungicides formerly applied to control insects and diseases in crops. As a result of these government restrictions, less S returns to the soil in rainfall.

Sulfur is supplied to plants from the soil by organic matter and minerals, but it’s often present in insufficient quantities and at inopportune times for the needs of many high-yielding crops. Organic matter ties up most S to the soil, where it remains unavailable to plants until soil bacteria convert it to sulfate (SO4-2) form. That process is known as mineralization.

Just like nitrate nitrogen (N), sulfate moves through the soil and can leach beyond the active root zone in some soils during heavy rainfall or irrigation. Sulfate may move back upward toward the soil surface as water evaporates, except in the sandier, coarse-textured soils that may be void of capillary pores. This mobility of sulfate S makes it difficult to calibrate soil tests and use them as predictive tools for S fertilization needs.

In the field, plants deficient in S show pale green coloring of the younger leaves, although the entire plant can be pale green and stunted in severe cases. Leaves tend to shrivel as the deficiency progresses.

Sulfur, like N, is a constituent of proteins, so deficiency symptoms are similar to those of N. Nitrogen-deficiency symptoms are more severe on older leaves, however, because N is a mobile plant nutrient and moves to new growth. Sulfur, on the other hand, is immobile in the plant, so new growth suffers first when S levels are not adequate to meet the plant’s need. This difference is important in distinguishing between N and S deficiencies, particularly in early stages.

 

 

Symptoms of deficiency can vary across crop species, but similarities exist for how nutrient insufficiency impacts plant tissue color and appearance. Nutrient deficiencies are commonly associated with the physical location on the plant
(i.e., whether the symptoms are primarily observed on older versus newly formed plant tissue), but these symptoms can spread as the severity of the deficiency progresses.

 


Potassium deficiency

Potassium deficiency

Potassium (K) is one of the essential nutrients and is taken up in significant amounts by crops. Potassium is vital to photosynthesis, protein synthesis and many other functions in plants. It’s classified as a macronutrient, as are nitrogen (N) and phosphorus (P). Plants take up K in its ionic form (K+).

While potassium (K) doesn’t constitute any plant structures or compounds, it plays a part in many important regulatory roles in the plant. It’s essential in nearly all processes needed to sustain plant growth and reproduction, including:

  • photosynthesis
  • translocation of photosynthates
  • plant respiration
  • protein synthesis
  • control of ionic balance
  • breakdown of carbohydrates, which provides energy for plant growth
  • regulation of plant stomata and water use
  • activation of plant enzymes
  • disease resistance and recovery
  • turgor
  • stress tolerance, including extreme weather conditions

Perhaps K’s most important function in the plant is that it can activate at least 80 enzymes that regulate the rates of major plant growth reactions. K also influences water-use efficiency. The process of opening and closing of plant leaf pores, called stomates, is regulated by K concentration in the guard cells, which surround the stomates. When stomates open, large quantities of K move from the surrounding cells into the guard cells. As K moves out of the guard cells into surrounding cells, stomates close, therefore K plays a key role in the process plants use to conserve water. Unlike nitrogen (N) and phosphorus (P), the other primary nutrients, K doesn’t form organic compounds in the plant. Its primary function is related to ionic strength of solutions inside plant cells. Potassium plays a key part in increasing yields and controlling disease because it improves a crop’s winter hardiness. It allows crops to get a quicker start in the spring and increases vigor so growth can continue throughout the growing season. Even though the period of K uptake varies with different plants, it’s still vital to maintain adequate K fertility levels in the soil because soil K doesn’t move much, except in sand or organic soils. Unlike N and some other nutrients, K tends to remain where fertilization puts it. When it does move, it’s mainly by diffusion and is always slow. Plants generally absorb the majority of their K at an earlier growth stage than they do N and P. Experiments on K uptake by corn have shown that 70 to 80 percent can absorb by silking time, and 100 percent at three to four weeks after silking. K translocation from the leaves and stems to the grain occurs in much smaller amounts than for P and N. The grain formation period is apparently not a critical one for the supply and uptake of K. Plants deficient in K don’t grow as robustly and are less resistant to drought, excess water, and high and low temperatures. They’re also more vulnerable to pests, diseases and nematode attacks. Potassium is also known as the “quality nutrient” because of its important effects on factors such as size, shape, color, taste, shelf life, fiber quality and other qualitative measurements. Potassium-deficiency symptoms show up in many ways. One of the most common K hunger signs is scorching or firing along leaf margins. Firing first appears on older leaves in most plants, especially grasses. Newer leaves will show hunger signs first on certain plants and under certain conditions. In addition to growing slowly, K-deficient plants’ root systems develop poorly and have weak stalks. Lodging is also common.   Symptoms of deficiency can vary across crop species, but similarities exist for how nutrient insufficiency impacts plant tissue color and appearance. Nutrient deficiencies are commonly associated with the physical location on the plant
(i.e., whether the symptoms are primarily observed on older versus newly formed plant tissue), but these symptoms can spread as the severity of the deficiency progresses.

Iron deficiency

Iron deficiency

Iron (Fe) is essential for crop growth and food production. Plants take up Fe as the ferrous (Fe2+) cation. Iron is a component of many enzymes associated with energy transfer, nitrogen reduction and fixation, and lignin formation.

Iron (Fe) is involved in the production of chlorophyll, and Fe chlorosis is easily recognized on Fe-sensitive crops growing on calcareous soils. Iron also composes many enzymes associated with energy transfer, nitrogen reduction and fixation, and lignin formation. Iron is associated with sulfur in plants to form compounds that catalyze other reactions.

Iron deficiencies are mainly manifested in yellowed leaves that result from low levels of chlorophyll. Leaf yellowing first appears on the younger, upper leaves in interveinal tissues. Severe Fe deficiencies cause leaves to turn completely yellow or almost white, and then brown as leaves die.

Iron deficiencies occur mainly in calcareous (high pH) soils, although some acidic, sandy soils low in organic matter also may be Fe-deficient. Cool, wet weather enhances Fe deficiencies, especially on soils with marginal levels of available Fe. Poorly aerated or highly compacted land also reduces Fe uptake by plants. Uptake of Fe decreases with increased soil pH, and is adversely affected by high levels of available phosphorus, manganese and zinc in the ground.

Since soil applications of most Fe sources are generally ineffective for correcting Fe deficiencies in crops, foliar sprays are the recommended method. The application rate should be high enough to wet the foliage, so spraying a 3 to 4 percent FeSO4 solution at 20 to 40 gallons per acre is typical. Including a sticker-spreader agent in the spray helps improve its adherence to the plant foliage for increased Fe absorption by the plant. Even so, correcting chlorosis may require more than one foliar Fe application.

 

 

Symptoms of deficiency can vary across crop species, but similarities exist for how nutrient insufficiency impacts plant tissue color and appearance. Nutrient deficiencies are commonly associated with the physical location on the plant
(i.e., whether the symptoms are primarily observed on older versus newly formed plant tissue), but these symptoms can spread as the severity of the deficiency progresses.

 

error: Content is protected !!