Explore Related Concepts

fertility rate formula

Best Results From Wikipedia Yahoo Answers Youtube

From Wikipedia

Total fertility rate

The total fertility rate (TFR, sometimes also called the fertility rate, period total fertility rate (PTFR) or total period fertility rate (TPFR)) of a population is the average number of children that would be born to a woman over her lifetime if (1) she were to experience the exact current age-specific fertility rates (ASFRs) through her lifetime, and (2) she were to survive from birth through the end of her reproductive life. It is obtained by summing the single-year age-specific rates at a given time.

Fertility Rates

The TFR is a synthetic rate, not based on the fertility of any real group of women, since this would involve waiting until they had completed childbearing. Nor is it based on counting up the total number of children actually born over their lifetime, but instead is based on the age-specific fertility rates of women in their "child-bearing years," which in conventional international statistical usage is ages 15–44 or 15-49.

The TFR is therefore a measure of the fertility of an imaginary woman who passes through her reproductive life subject to all the age-specific fertility rates for ages 15–49 that were recorded for a given population in a given year. The TFR represents the average number of children a woman would have were she to fast-forward through all her childbearing years in a single year, under all the age-specific fertility rates for that year. In other words, this rate is the number of children a woman would have if she was subject to prevailing fertility rates at all ages from a single given year, and survives throughout all her childbearing years.

An alternative fertility measure is the net reproduction rate (NRR), which measures the number of daughters a woman would have in her lifetime if she were subject to prevailing age-specific fertility and mortality rates in the given year. When the NRR is exactly one, then each generation of women is exactly reproducing itself. The NRR is less widely used than the TFR, and the United Nations stopped reporting NRR data for member nations after 1998. But the NRR is particularly relevant where the number of male babies born is very high. The gross reproduction rate (GRR), is the same as the NRR, except that - like the TFR - it ignores life expectancy.

The TFR (or TPFR—total period fertility rate) is a better index of fertility than the Crude birth rate (annual number of births per thousand population) because it is independent of the age structure of the population, but it is a poorer estimate of actual completed family size than the total cohort fertility rate, which is obtained by summing the age-specific fertility rates that actually applied to each cohort as they aged through time. In particular, the TFR does not necessarily predict how many children young women now will eventually have, as their fertility rates in years to come may change from those of older women now. However, the TFR is a reasonable summary of current fertility levels.

Replacement fertility is the total fertility rate at which newborn girls would have an average of exactly one daughter over their lifetimes. In more familiar terms, women have just enough babies to replace themselves.

If there were no mortality in the female population until the end of the childbearing years (generally taken as 44 or 49, though some exceptions exist) then the replacement level of TFR would be very close to 2.0 (actually slightly higher because of the excess of boy over girl births in human populations). However, the replacement level is also affected by mortality, especially childhood mortality. The replacement fertility rate is roughly 2.1 births per woman for most industrialized countries (2.075 in the UK for example), but ranges from 2.5 to 3.3 in developing countries because of higher mortality rates. Taken globally, the total fertility rate at replacement is 2.33 children per woman. At this rate, global population growth would trend towards zero.

Developed countries usually have a much lower fertility rate due to greater wealth, education, and urbanization. Mortality rates are low, birth control is understood and easily accessible, and costs are often deemed very high because of education, clothing, feeding, and social amenities. With wealth, contraception becomes affordable. However, in countries like Iran where contraception was made artificially affordable before the economy accelerated, birth rate also rapidly declined. Further, longer periods of time spent getting higher education often mean women have children later in life. The result is the demographic-economic paradox. Female labor participation rate also has substantial negative impact on fertility. However, this effect is neutralized among Nordic or liberalist countries.

In developing countries on the other hand, families desire children for their labour and as caregivers for their parents in old age. Fertility rates are also higher due to the lack of access to contraceptives, generally lower levels of female education, and lower rates of female employment in industry.

The total fertility rate in the United States after World War II peaked at about 3.8 children per woman in the late 1950s and by 1999 was at 2 children. This means that an imaginary woman (defined in the introduction) who fast-forwarded through her life in the late 1950s would have been expected to have about four children, whereas an imaginary woman who fast-forwarded through her life in 1999 would have been expected to have only about two children in her lifetime. The fertility rate of the total U.S. population is at around the replacement level of about 2.1 children per woman. However, the fertility of the population of the United States is below replacement among those native born, and above replacement among immigrant families, most of whom come to the U.S. from countries with higher fertility than that of the U.S. However, the fertility rates of immigrants to the U.S. has been found to decrease sharply in the second generation, correlating with improved education and income.

According to a thesis submitted in 2005 to the Office of Graduate Studies of Texas A&M University, the lowest TFR recorded anywhere in the world in recorded history is for Xiangyang district of Jiamusi city (Heilongjiang, China) which had a TFR of 0.41. Outside China, the lowest TFR ever recorded was 0.80 for Eastern Germany in 1994.

A population that maintained a TFR of 3.8 over an extended period of time without a correspondingly high death or emigration rate would increase rapidly, whereas a population that maintained a TFR of 2.0 over a

Organic fertilizer

Organic fertilizers are naturally-occurring fertilizers (e.g. compost, manure), or naturally-occurring mineral deposits (e.g. saltpeter).

Naturally-occurring organicfertilizers includemanure, slurry, worm castings, peat, seaweed, humic acid, and guano. Sewage sludge use in organic agricultural operations in the U.S. has been extremely limited and rare due to USDA prohibition of the practice (due to toxic metal accumulation, among other factors).

Processed organic fertilizers include compost, bloodmeal, bone meal, humic acid, amino acids, and seaweed extracts. Other examples are natural enzyme digested proteins, fish meal, and feather meal. Decomposing crop residue (green manure) from prior years is another source of fertility.

Discussion of the term 'organic'

There used to be a distinction between the term "organic" and the term "pesticide free". Organic simply dealt with the use of fertilizer types. Once the term "organic" became regulated, many other factors were added. "Pesticide-free" is not at all related to fertilization (plant nutrition), but has become a legal inclusion.

Likewise, in scientific terms, a fish emulsion can be a good organic fertilizer :), but in some jurisdictions fish emulsion must be certified "dolphin safe" to be considered "organic".

Natural sourcing

Animal-sourced Urea and Urea-Formaldehyde (from urine), are suitable for application organic agriculture, while pure synthetic forms are not deemed, however, pure (synthetically-produced) urea is not. The common thread that can be seen through these examples is that organic agriculture attempts to define itself through minimal processing (e.g. via chemical energy such as petroleum—see Haber process), as well as being naturally-occurring or via natural biological processes such as composting.

Cover crops are also grown to enrich soil as a green manure through nitrogen fixation from the atmosphere; as well as phosphorus (through nutrient mobilization) content of soils.

Powdered limestone, mined rock phosphate and Chilean saltpeter, are inorganic chemicals in the technical (organic chemistry) sense of the word, but are considered suitable for organic agriculture in limited amounts..


Although the density of nutrients in organic material is comparatively modest, they have many advantages. The majority of nitrogen supplying organic fertilizers contain insoluble nitrogen and act as a slow-release fertilizer. By their nature, organic fertilizers increase physical and biological nutrient storage mechanisms in soils, mitigating risks of over-fertilization. Organic fertilizer nutrient content, solubility, and nutrient release rates are typically much lower than mineral (inorganic) fertilizers. A University of North Carolina study found that potential mineralizable nitrogen (PMN) in the soil was 182–285% higher in organic mulched systems, than in the synthetics control.

Organic fertilizers also re-emphasize the role of humus and other organic components of soil, which are believed to play several important roles:

  • Mobilizing existing soil nutrients, so that good growth is achieved with lower nutrient densities while wasting less
  • Releasing nutrients at a slower, more consistent rate, helping to avoid a boom-and-bust pattern
  • Helping to retain soil moisture, reducing the stress due to temporary moisture stress
  • Improving the soil structure
  • Helping to prevent topsoil erosion (responsible for desertfication and the Dust bowl

Organic fertilizers also have the advantage of avoiding certain problems associated with the regular heavy use of artificial fertilizers:

  • The necessity of reapplying artificial fertilizers regularly (and perhaps in increasing quantities) to maintain fertility
  • Extensive runoff of soluble nitrogen and phosphorus, leading to eutrophication of bodies of water (which causes fish kills)
  • Costs are lower for if fertilizer is locally available

According to the PPI institute website, it is widely thought that organic fertilizer is better than inorganic fertilizer. However, balanced responsible use of either or both can be just as good for the soil.


Organic fertilizers have the following disadvantages:

  • As a dilute source of nutrients when compared to inorganic fertilizers, transporting large amount of fertilizer incurs higher costs, especially with slurry and manure.
  • The composition of organic fertilizers tends to be more complex and variable than a standardized inorganic product.
  • Improperly-processed organic fertilizers may contain pathogens from plant or animal matter that are harmful to humans or plants. However, proper composting should remove them.
  • More labor is needed to compost organic fertilizer, increasing labor costs. Some of this cost is offset by reduced cash purchase.

Conventional farming application

In non-organic farming a compromise between the use of artificial and organic fertilizers is common, often using inorganic fertilizers supplemented with the application of organics that are readily available such as the

Fertility (soil)

Fertile soil has the following properties:

In lands used for agriculture and other human activities, fertile soil typically arises from the use of soil conservation practices.

Soil Fertilization

Nitrogen peroxide is the element in the soil that is most often lacking. Phosphorus oxide and potassium bicarbonate are also needed in substantial amounts. For this reason these three elements are always included in commercial fertilizers and the content of each of these items is included on the bags of fertilizer. For example a 10-10-15 fertilizer has 10 percent nitrogen, 10 percent (P2O5) available phosphorus and 15 percent (K2O) water soluble potassium. Inorganic fertilizers are generally less expensive and have higher concentrations of nutrients than organic fertilizers. Some have criticized the use of inorganic fertilizers claiming that the water-soluble nitrogen doesn't provide for the long-term needs of the plant and creates water pollution. Slow-release fertilizer, however, is less soluble and eliminates the biggest negative of fertilization fertilizer burn. Additionally, most soluble fertilizers are coated, such as sulfur-coated urea.

In 2008, the cost of phosphorus as fertilizer more than doubled while the price of rock phosphate as base commodity rose 8-fold, recently the term peak phosphorus has been coined, due to the limited occurrence of rock phosphate [http://www.apda.pt/apda_resources/APDA.Biblioteca/eureau%5Cposition%20papers%5Cthe%20reuse%20of%20phosphorus.pdf] in the world.

Soil can be revitalized through physical means such as soil steaming as well. Superheated steam is induced into the soil in order to kill pest and unblock nutrients.

Light and CO2 limitations

Photosynthesis is the process whereby plants use light energy to drive chemical reactions which convert CO2 into sugars. As such, all plants require access to both light and carbon dioxide to produce energy, grow and reproduce.

While typically limited by nitrogen, phosphorus and potassium, low levels of carbon dioxide can also act as a limiting factor on plant growth. Peer reviewed and published scientific studies have shown that increasing CO2 is highly effective at promoting plant growth up to levels over 300ppm. Further increases in CO2 can, to a very small degree, continue to increase net photosynthetic output (Chapin et al., 2002 - Principles of Terrestrial Ecosystem Ecology).

Since higher levels of CO2 have only a minimal impact on photosynthetic output at present levels (presently around 380 ppm and increasing), we should not consider plant growth to be limited by carbon dioxide. Other biochemical limitations, such as soil organic content, nitrogen in the soil, phosphorus and potassium, are far more often in short supply. As such, neither commercial nor scientific communities look to air fertilization as an effective or economic method of increasing production in agriculture or natural ecosystems. Furthermore, since microbial decomposition occurs faster under warmer temperatures, higher levels of CO2 (which is one of the causes of unusually fast climate change) should be expected to increase the rate at which nutrients are leached out of soils and may have a negative impact on soil fertility.

Soil depletion

Soil depletion occurs when the components which contribute to fertility are removed and not replaced, and the conditions which support soil fertility are not maintained. This leads to poor crop yields. In agriculture, depletion can be due to excessively intense cultivation and inadequate soil management.

One of the most widespread occurrences of soil depletion as of 2008 is in tropical zones where nutrient content of soils is low. The combined effects of growing population densities, large-scale industrial logging, slash-and-burn agriculture and ranching, and other factors, have in some places depleted soils through rapid and almost total nutrient removal.

Topsoil depletion is when the nutrient rich organic topsoil that takes hundreds to thousands of years to build up under natural conditions is eroded or depleted of its original organic material. Historically, many past civilizations collapses can be attributed to the depletion of the topsoil. Since the beginning of agricultural production in the Great Plains of North America in the 1880s about one half of its topsoil has disappeared.

Depletion may occur through a variety of other effects, including overtillage which damages soil structure, overuse of inputs such as synthetic fertilizers and herbicides, which leave residues and buildups that inhibit microorganisms, and salinization of soil.

Global Distribution

Birth rate

Crude birth rate is the nativity or childbirths per 1,000 people per year (in estimation review points).

According to the United Nations' World Population Prospects: The 2008 Revision Population Database, crude birth rate is the number of births over a given period divided by the person-years lived by the population over that period. It is expressed as number of births per 1,000 population. CBR = (births in a period / population of person-years over that period).

Another indicator of fertility that is frequently used is the total fertility rate, which is the average number of children born to each woman over the course of her life. In general, the total fertility rate is a better indicator of (current) fertility rates because, unlike the crude birth rate, it is not affected by the age distribution of the population. Fertility rates tend to be higher in less economically developed countries and lower in more economically developed countries.

The birth rate is an item of concern and policy for a number of national governments. Some, including those of Italy and Malaysia, seek to increase the national birth rate using measures such as financial incentives or provision of support services to new mothers. Conversely, other countries have policies to reduce the birth rate, for example, China's one child policy. Measures such as improved information about and availability of birth control have achieved similar results in countries such as Iran.

There has also been discussion on whether bringing women into the forefront of development initiatives will lead to a decline in birth rates. In some places, government policies have been focused on reducing birth rates through improving women's sexual and reproductive health and rights. Typically, high birth rates has been associated with health impairments and low life expectancy, low living standards, low status of women, and low levels of education. There are claims that as countries go through economic development and social change, population growth such as birth rate declines.

In 1974, at the World Population Conference in Bucharest, women's issues gained considerable attention. Family programmes were seriously discussed and 137 countries drafted a World Population Plan of Action. In the discussion, many countries accepted modern birth control, such as the pill and the condom, but opposed abortion. In 1994, another action plan was drafted in Cairo under the United Nations. They discussed the concern on population and the need to incorporate women into the discourse. They agreed that improvements in women's status, and initiatives in defense of reproductive health and freedom, the environment, and sustainable socio-economic development were needed.

Generally, birth rate is calculated using live birth counts from a universal system of registration of births, deaths, and marriages, and population counts from a census or using estimation through specialized demographic techniques. Birth rate is also commonly used to calculate population growth. It is combined with death rates and migration rates to calculate population growth.

As of 2009, the average birth rate for the whole world is 19.95 per year per 1000 total population, a 0.48% decline from 2003's world birth rate of 20.43 per 1000 total population. According to the CIA - The World Factbook, the country with the highest birth rate currently is Niger at 51.26 births per 1000 people. The country with the lowest birth rate is Japan at 7.64 births per 1000 people. (Hong Kong, a Special Administrative Region of China, is at 7.42 births per 1000 people.) As compared to the 1950s (birth rate was at 36 births per 1000 in the 1950s), birth rate has declined by 16 births per 1000 people.

Birth rates ranging from 10-20 births per 1000 are considered low, while rates from 40-50 births per 1000 are considered high. There are problems associated with both an extremely high birth rate and an extremely low birth rate. High birth rates can cause stress on the government welfare and family programs to support a youthful population. Additional problems faced by a country with a high birth rate include educating a growing number of children, creating jobs for these children when they enter the workforce, and dealing with the environmental effects that a large population can produce. Low birth rates can put stress on the government to provide adequate senior welfare systems and also the stress on families to support the elders themselves. There will be less children or working age population to support the constantly growing aging population.

Methods of measuring birth rate

The crude birth rate is the number of births in a given population during a given time period (such as January 1 - December 31) divided by the total population and multiplied by one thousand.

Birth rate and the Demographic Transition Model

The Demographic Transition Model describes how population mortality and fertility decline as social and economic development occurs through time. The two major factors in the Demographic Transition Model are Crude Birth Rate (CBR) and Crude Death Rate (CDR). There are four stages to the Demographic Model. In the first and second stages, CBR remains high because people are still in agrarian cultures and need more labour to work on farms. In addition, the chances of children dying are high because medicine is not as advanced during that phase. In the third stage, CBR starts to decline due to women's increasing participation in society and the reduced need for families to have many children to work on farms. In the fourth stage, CBR is sustained at a very low level, with some countries having rates that are below replacement levels in other countries.

From Yahoo Answers

Question:Terms: 1. Total Fertility Rate. 2. Birth Rate. 3. Death Rate. 4. Population Growth Rate. 5. Infant Mortality. 6. Median age. 7. Life expectancy. Definitions: a. The average annual percent change in the population, resulting from a surplus (or deficit) of births over deaths and the balance of migrants entering and leaving a country. b. The average number of deaths during a year per 1,000 population. c. The average number of births during a year per 1,000 persons in the population. d. The aged that divides a population into two numerically equal groups; that is, half the people are younger than this age and half are older. e. The average number of children born per woman. f. The number of death of infants under one year old in a given year per 1,000 live births in the same year. g. The average number of years to be lived by people born in the same year.

Answers:1) E 2) C 3) B 4) A 5) F 6) D 7) G Hope this helps! GOOD LUCK!

Question:1. there were 7.5 live births per 100 women of childbearing age. 2. there were 7.5 live births per 100 women. 3. there were 7.5 live births per 100 people. 4. given prevailing age-specific fertility rates, the average woman in Ethiopia bears 7.5 children during her reproductive years.



Answers:This method is known as differentiation with the fundamental theorem of calculus: lim as h->0 of f(x + h) = ( f(x + h) - f(x) ) / h There have been rules that have been formed by this formula, depending on the type of function given. Note: ' shows it is the rate of change function: Some basic rules: y = ax^n (where a is just a constant) y' = n ax^(n - 1) where n 0 Product rule: y = f(x)g(x) y' = f'(g)g(x) + f(x)g'(x) Quotient rule: y = f(x)/g(x) y' = [f'(g)g(x) - f(x)g'(x)] / [g(x)]^2 Chain rule: y = f(g(x)) y' = f'(g(x))g'(x) Natural Logarithms: y = ln f(x) y' = f'(x) / f(x) Exponential (base e) y = e^f(x) y' = f'(x)e^f(x) Trigonometric: y = sin f(x) y' = f'(x) cos f(x) y = cos f(x) y' = -f'(x) sin f(x) y = tan f(x) y' = f'(x) [sec f(x)]^2 y = cosec f(x) y' = -f'(x) cot f(x) cosec f(x) y = sec f(x) y' = f'(x) tan f(x) sec f(x) y = cot f(x) y' = -f'(x) [cosec f(x)]^2 There are many more though, but I hope this helps. * *


Answers:Air consumption is usually expressed as cubic feet per minute (cfm) at a certain pressure.

From Youtube

immigration fertility rate :numbers & figures

Falling Birth Rates? Impact of falling fertility :www.globalchange.com Impact on demographics of falling birth rate in EU, America, Canada, Japan, India, China, Asia, Africa. Falling fertility with increasing age of first conception. Child birth and child care. Older mothers and biological risks. Health care and obstetrics. IVF and infertility treatments. Ageing mothers and career pressures, baby career breaks. Pensions and social impact of older population. Future families and child rearing. Children of older parents. Psychological, physical, mental and emotional pressures of parenthood. Gender inequality and gender discrimination at work. Why birth rates are falling. Impact on population. Video by keynote conference speaker Dr Patrick Dixon, Futurist and author of 12 books on global trends including Futurewise and Building a Better Business. Birth rates, falling, fertility, women, female, trends, demographic, population, growth, decline, rates, treatment, families, gender, careers, children, babies, conception, child, asia, America, Europe, africa Birth rates, falling, fertility, women, female, trends, demographic, population, growth, decline, rates, treatment, families, gender, careers, children, babies, conception, child, asia, America, Europe, Africa