Concept of Limiting Factors and Cycling of Organic Nutrients

Concept of Limiting Factors; Liebig- Blackman law and Shelford’s Law of Tolerance:

Organism requires essential materials that are necessary for the growth and reproduction are governed by the following rule.

1. Lie big’s “Law” of the minimum:

Under “steady state” condition of the essential material available in amounts most closely approaching the critical minimum needed will tend to be the limiting one. This law of a minimum is less applicable under “transient state” conditions when the amounts, and hence the effects of many constituents are rapidly changing.
Principle developed in agricultural science by Carl Sprengel (1828) and later popularized by Justus von Liebig.
Justus von Liebig (1803-1873) German chemist, the major contributions to agricultural and biological chemistry, known as the “father of the fertilizer industry” for his discovery nitrogen as an essential plant nutrient, and his formulation of the law of the minimum which described the effect of individuals nutrients on crops. Imagine you are building a dog house by using the nails and boards. As long as you have both then you can continue the building. When you run out of nails, you have to stop building. Nails (or rather a lack of nails) are “limiting” of your building process. So you can buy a five-pound box of nails and then return to work.
Inevitably, you will run out of boards next. Even though you still have plenty of nails, you need more boards to continue building. Now, boards are “limiting”. You could call the home store and have an entire semi-truck load of nails brought to your house, but it won’t help the doghouse get built because you need boards. Growth is not controlled by the total amount of resources available, but by the scarcest resources (limiting factor). If the resources which are limited in supply also essential to the establishment of suitable markets, then substitution cannot occur. For example, Isaac Asim noted: We may be able to substitute nuclear power for coal power, and plastics for wood but for phosphorus, there is neither suitable nor replacement. “Life’s Bottleneck”, Fact and Fancy. Plant growth will continue as long as all required factors are present (e.g. light, water, nitrogen, phosphorus, potassium etc.). When one of those factors is depleted, growth stops. Increasing the amount of “limiting” component will allow growth to continue until the component (or another) is depleted. The nutrient most typically “limiting” algae growth in lakes is phosphorus. If phosphorus concentrations can be controlled, then algae can be controlled usually. Sometimes, other nutrients or conditions can limit algae. In Mark Twin Lake, for example, light is the factor that most often limits algae.

2. Shelford’s Law of Tolerance:

The presence and success of an organism depend on the completeness of a complex of conditions. Absence or failure of an organism can be controlled by the qualitative and quantitative deficiency of excess with respect to any one of several factors which may approach the limit of tolerance for that organisms.
V.E. Shelford (1877-1968) American ecologist. The presence and success of an organism depend on the extent to which a complex of conditions are satisfied. The absence or failure of an organism can be controlled by the qualitative and quantitative deficiency of excess or any one of several factors which may approach the limits of tolerance for that organism.

3. Combined Concept of Limiting Factors:

The presence and success of an organism or a group of organisms depend on a complex of the conditions. Any condition which approaches or exceeds the limits of tolerance is said to be the limiting conditions or a limiting factor.
Frederick Frost Blackman (1866-1947) was a British plant physiologist. When a process depends on a number of factors, its rate is limited by the place of the slowest factor.

4. Conditions of Existence as Regulatory Factors:

Light, temperature and water are most important ecological important Environmental factors on land; light, temperature and salinity are the big three in the sea. In fresh water, other factors such as oxygen may be one of major importance.
All these physical conditions of the existence may not only be limiting factors in the detrimental sense but also regulatory factors in the beneficial sense- that adopted organism respond to these factors in such a way that community of organisms achieves the maximum homeostasis possible under the conditions.
Blackman (1912) says that a process is affected by the many factors and rate is controlled by the slowest movement and this is known as a limiting factor.

Cycling of Organic Nutrients:

Heterotrophs and Autotrophs, as well as algae, also require vitamins and other nutrients which they obtain most from their environment. Such organic nutrient ‘cycle’ between organisms and environment like inorganic nutrients, except these, are of biotic rather than abiotic in origin.
The organic nutrients are important for human and other animals. These are found low concentrations in soil, water etc. The only way to measure them by biological essay (bio-essay) using special strains of microorganisms whose growth is proportional to the concentration. Organic nutrients play important role in community metabolism, so they can be limiting. For example, vitamin R_12, although little studied.
The main producers of vitamin B₁₂ are micro-organisms mainly bacteria also the heterotrophic algae either direct producers of vitamin or acting as food for vitamin producing organisms. Bacteria, algae and filter feeders are direct consumers of vitamin absorbing organisms. The non-living particles like clay, inorganic detritus, Organic particles etc. absorb large quantities of vitamin B₁₂ which is supplied to phagotrophic by ingestion. It is not known that these particles fix vitamins is a stable way or are only transitions.
Vitamins concentration varies in different places. It determines the distribution of organisms. Examples, flagellates can survive easily in the regions which survive easily in the regions which lack vitamin as they do not require these.
Thus, the organic nutrient example is vitamins growth promoting hormones can be seen as micro-nutrients which are the limiting and they play role in a regulation, distribution, and succession of the organisms.

References:

E.p., Odum. Fundamentals of Ecology. USA: W.B Saunters Company, n.d.

Jr., Miller G.T. Living in the Environment. Belmont, California, USA: Wadsworth Publishing Company, 2003.