Individual Fertility Research Articles

Montane plant environments in the Fynbos Biome

Environmental data collected at 507 plots on 22 transects, and soil analytical data from 81 of these plots, have been used to describe the plant environments of the mountains in the Fynbos Biome. Two major regional gradients are recognized: a west-east gradient and a coast-interior gradient. Of particular consequence for fynbos-environment studies is the increase in the proportion of fine soil particles from west to east. At least some aspects of soil fertility also increase towards the east. The edaphic changes are paralleled by climatic changes: chiefly a decrease in the severity of summer drought towards the east. On the coast-interior gradient a major non-climatic variable in the gradient is rock cover. High rock cover is a feature of the interior ranges. Soils with organic horizons or with E horizons are a feature on the coastal mountains, but are generally lacking on the interior mountains. The other environmental gradients recognized occur on individual transects and all include edaphic variables. The rockiness-soil depth gradient, on which an increase in rockiness is associated with a decrease in soil depth and usually a decrease in clay content, tends to occur in three situations. Firstly, it is associated with local topographic variation; the shallow, rocky soils being a feature of the steeper slopes. Secondly, it is associated with the aspect gradient; the hot, dry northern aspects having shallow, rocky, less developed soils. Thirdly, it tends to be associated with the altitude-rainfall gradient: shallower soils being found at higher altitudes. It is also at higher altitudes that higher rainfall is found. Variation in oxidizable carbon is chiefly accounted for by the altitude-rainfall gradient. Whereas at a biome-wide level, aspects of soil fertility are related to soil texture, it appears that on individual transects fertility is linked to amounts of plant remains in the soil and to rainfall. Apart from these gradients, which are found on the Table Mountain quartzites, other sources of environmental variation are due to the differences between geological types. The non-quartzitic soils are generally deeper and finer-textured. It is suggested that the nutrient-poor/nutrient-rich distinction must be used with care; at least in the mountains the distinction should not automatically be substituted for the quartzitic/non-quartzitic distinction.

Fertility following reversal of male and female sterilization

It is estimated that 60% of Australian couples will opt for sterilization as a method of birth control. Approximately 0.5 to 1% of all sterilized males and females will request reversal. With tubal occlusion, it appears that the method used to produce occlusion, the occlusion site, the length of viable tube remaining and the time between sterilization and reversal appear to be predictive factors in producing intrauterine pregnancy. With the increasing tendency for sterilization to be performed in younger women, surgeons should consider performing surgery only on the isthmus of the tube, preserving as much undamaged tube as possible and using methods of occlusion other than diathermy to ensure adequate tubal occlusion and yet maintain optimum conditions should reversal be required. Successful pregnancy following vasovasostomy appears to be related primarily to length of time elapsed following vasectomy and to the skill of the surgeon in the use of microsurgical techniques, possibly aided by preservation of nerve supply to the vas. It is doubtful whether the presence of sperm antibodies in serum or semen will affect the return of fertility in most individuals, but further research is required to clarify this.

Determining the Impact of Sex Preferences on Fertility: A Demonstration Study

The stopping rule measure of sex preferences represents a combination of psychological measures of preference and behavioral intentions. This study of 172 college students demonstrates that the stopping rule measure is a useful and practical method of measuring sex preferences. The results further indicate that parity progression ratio measures inherently underestimate the effect of sex preferences on individual fertility because they incorrectly assume that sex preferences (a) are homogeneous within the population and (b) can only act to increase, not to decrease, fertility. Use of the stopping rule measure to predict the possible effects of sex preselection techniques on fertility is also discussed.

Dimorphic incompatibility and gender in Nymphoides indica (Menyanthaceae)

Nymphoides indica (Menyanthaceae) is a distylous, aquatic perennial of pantropical distribution. Controlled field pollinations in a Lower Amazon rice field population demonstrated the presence of a strong self- and intramorph-incompatibility system in the 20 individuals tested. The average seed fertility of short-styled individuals was significantly greater than long-styled individuals, although significant variation among individuals within morphs was also evident. Fertility data obtained from experimental crosses are utilized for developing a new method for the estimation of gender in plants. The potential for gender specialization in N. indica populations and its significance to the evolution of dioecy from distyly in the genus Nymphoides is discussed.

Fertility and Education. What Do We Really Know?

Current research on the relationship between education and fertility is reviewed, and a model relating intervening variables to fertility is developed. The evidence indicates that education may increase or decrease individual fertility. The decrease is greater for the education of women than of men and is greater in urban than in rural areas. However, education is more likely to increase fertility in countries with the lowest level of female literacy. Probably, this increase occurs as a result of improved health, better nutrition, and the abandonment of traditional patterns of lactation and postpartum abstinence, education increases the ability to have live births. In societies with higher average levels of female literacy, education lowers the demand for children by altering perceptions of costs and benefits. In addition, once the biological supply of children exceeds the demand for them, high levels of education enable couples to limit their fertility more efficiently through access to contraceptive knowledge and improved ability to communicate with each other. Several issues require further research. Statistical tables and figues are provided.

Effects of Fertilizers on Slow Rusting in Wheat

Effects of Fertilizers on Slow Rusting in Wheat

Infertility in the Turkey: II. A Description of a Spontaneous Infertility Condition and Its Alleviation by Intramagnal Insemination and Sexual Rest

A spontaneous infertility condition in hens taken from a commercial turkey flock was studied. Forty-eight hens from the original flock of about 2200 were housed in cages to obtain individual fertility records. Thirteen of the 48 hens were sterile upon arrival from the parent flock while five laid eggs which were all fertile. The fertility of other individuals fell between these extremes. Even hens with fertility as low as 9% laid a scattering of fertile eggs after insemination, showing they did store sperm. Reinsemination of the hens with good quality semen did not ameliorate the condition.Insemination in a manner designed to bypass the normal sperm storage glands (i.e. intramagnal AI) increased fertility from less than 10% to over 85%. Hens inseminated in this manner had an average fertility level of 70.6% in the second week after AI and 23.1% in the third.Low fertility hens which underwent a period of sexual rest and ovarian and oviducal regression had high levels of fertility when egg laying resumed. In the 7th and 8th weeks after resumption of lay it appeared that fertility was again declining.

Theoretical and methodological implications of the influence of sex preferences on the fertility attitude-behavior relationship

Data was collected from a sample of 72 volunteers from the University of Colorado introductory psychology subject pool in order to explore the theoretical possibility that measures of preferred family size generate good aggregate but poor individual fertility predictions because they ignore the influence of family sex composition preferences. The average preferred (1st choice) family size of 2.80 for this sample closely matches the average expected value of 2.86 children. Longitudinal studies of fertility intentions sometimes report the proportions of respondents who have exactly the number of children they said they desired at the time of the 1st interview. The expected proportions for this sample again assuming strict adherence to the stopping rules are as follows: 66% of the respondents would have exactly the number of children they desire; 26% would miss their ideal by 1; and 8% would miss their ideal by 2 or more. The maximum correlation between most preferred family size and actual outcomes would be .78. Study results demonstrate that poor attitude-behavior correlations in fertility studies must be partially attributed to the measures of attitude used and to the probabilistic nature of the determinants of fertility behavior as well as to true attitude-behavior inconsistency. The strategy suggested for improving attitude measures is to develop measures which capture the inherent dependence of fertility decisions on probabilistic events.

Fertility Patterns and Trends Among the Old Order Amish

Summary Using statistics from an Amish census, a survey of couples, and a family genealogy, we examine trends in Old Order Amish fertility during this century. We also examine factors which might explain variations in fertility. We find that Amish fertility has remained high and that there is no evidence of a downward trend. Comparisons with Hutterite fertility show that while marital fertility rates are similar for young women, the rates for older Amish women are much lower than those for older Hutterite women. We find some limited evidence of fertility control among women of high parity and among non-farm wives, but most variation in individual fertility is due to physiological factors, some of which appear to be passed from one generation to the next. We find that the main form of population control among the Old Order Amish is apostasy, and that rates of apostasy have been rising. Finally, we examine the family backgrounds of the leavers.

Fertility patterns and trends among the Old Order Amish

Summary Using statistics from an Amish census, a survey of couples, and a family genealogy, we examine trends in Old Order Amish fertility during this century. We also examine factors which might explain variations in fertility. We find that Amish fertility has remained high and that there is no evidence of a downward trend. Comparisons with Hutterite fertility show that while marital fertility rates are similar for young women, the rates for older Amish women are much lower than those for older Hutterite women. We find some limited evidence of fertility control among women of high parity and among non-farm wives, but most variation in individual fertility is due to physiological factors, some of which appear to be passed from one generation to the next. We find that the main form of population control among the Old Order Amish is apostasy, and that rates of apostasy have been rising. Finally, we examine the family backgrounds of the leavers.

On Fertility Policy Research

An understanding of the nature and scope of high-fertility problems and their ties to social change and development policy is essential to fertility policy formation. The current research base for fertility policy is based on 3 components: 1) projection models showing the apparent economic payoffs of lower birth rates; 2) KAP surveys indicating limited knowledge of and access to effective fertility control methods and an actual fertility level above that considered ideal by respondents; and 3) multivariate analyses revealing negative associations between development variables such as education and urbanization and fertility. This knowledge base contains many weaknesses. It neglects details of social organization between the national government and the family or the ways that development programs mesh with local structures and it assumes that fertility decisions are made on the basis of a simple benefit-cost calculus and starts out with a particular policy instrument in mind. A preferable approach would be to begin with the broader development strategy and consider how it incidentally influences the fertility setting (aspects of the local economic institutional and cultural situation governing fertility outcomes) and ways it might be modified to alter that setting to attain the desired fertility effect. This approach involves looking at fertility determinants in terms of decision-making settings. The main research directions flowing from this approach are: 1) institutional analysis of local settings; 2) interpretive analyses of local settings from the point of view of the individuals perceptions; 3) individual modernity and fertility; 4) severances of economic and demographic behavior; 5) mobilization of communities to serve economic and demographic interests; and 6) the study of fertility as a process.

Beyond Economic Man: Economics, Politics, and the Population Problem

In its simplest form, conventional microeconomic theory assumes two decision-making entities-households and firms. Households are presumed to operate rationally, which is interpreted by the postulate, to maximize utility, or satisfaction; and firms are presumed to operate rationally-that is, to maximize profits and to minimize costs. In many situations, however, the theory of maximization does not explain or predict actual behavior: it cannot explain, for example, why individuals vote in a democratic society, or why people join and put a great deal of work into voluntary organizations when there is no remuneration for such efforts, or why some couples do not adopt birth control when it is in their economic interest to do so. To explain such issues requires introduction of psychological and social considerations beyond the scope of traditional economic theory. This paper presents the outlines of a broader approach to microeconomic theory that incorporates modern psychological concepts, considers individuals instead of groups as the basic unit of study, and introduces the concept of individual effort as a variable in behavior and accomplishment of objectives. Some of the implications of this broader theory for individual fertility behavior and for population policy at the national level are explored. There is no intent to proceed from various analytical concepts to detailed population policies as such. Prescription requires the analysis of a

A new perspective on the twentieth-century American fertility swing.

The trend in the American Birthrate of the twentieth century shows the following contrasts: 1) a steady decline during the 1st third; 2) the sharp increase of the baby boom peaking around 1957; and 3) the sharp fertility decline extending to the present. The pattern is the same for both the white and black populations of the country. The 2 most popular demographic theories used to explain fertility swings - the Demographic Transition and Household Economic theories - have the following common defects: 1) they explain cohort fertility in terms of early-established family size goals 2) they fail to recognize the importance of short-term or chance factors in influencing the fertility process and 3) they do not explain subgroup differentiations within the population. A new theory is proposed which postulates that events early in the fertility process affect the later course of the individual fertility behavior. It is hypothesized that the social and economic circumstances present in the life of individuals when they begin their reproductive period will influence the childbearing process. Such factors as the age at first intercourse penalties for premarital pregnancy and the convenience of contraceptive use are considered. The thesis is tested by the swings in general American fertility in the twentieth century and in a specific Philadelphia fertility study. It was found that early establishment of a contraceptive habit plus early reinforcement through lack of pregnancy were responsible for lower total fertility.

Fraternal polyandry and fertility in a high Himalayan valley in Northwest Nepal

The manner in which cultural factors affect fertility has become an important area of anthropological concern. In this article, it will be shown that while fraternal polyandry does not affect individual fertility it does have a significant depressing effect on aggregate fertility and functions, unperceived and unintended, as an important mechanism for reducing population growth.

Social theory and individual fertility behaviour: Some issues of research orientation

Public and official interest in fertility behaviour and its implications issubstantial. The pattern of reproduction in Britain has changed dramatically since the beginning of this century, and the rate of change has accelerated since the early 1960's, with the availability of new means of fertility control and the development of more permissive attitudes towards social and sexual behaviour. At the same time research commitments in the area have also increased. At least part of the purpose of this research has been to understand how and why fertility desires and behaviour alter. In this respect the research efforts have not been particularly successful. Highly sophisticated (and successful) techniques now exist for documenting and monitoring the trends in fertility and in the use of the various techniques for family limitation. Parallel progress has not occurred in the construction of hypotheses which might “explain” these trends. It is this particular area which now merits attention. In the process of correcting the current imbalance we may come to an improved understanding of the behaviour itself, rather than continually improving the means for describing it.

Die Wirkung des Stickstoffs in langsamwirkenden synthetisch‐organischen Stickstoffdüngemitteln oder Mischdüngern mit einer langsamwirkenden Stickstoffkomponente

The effectiveness of nitrogen in slow‐release synthetic‐organic nitrogen fertilizer materials and mixed fertilizers containing a slow‐release nitrogen component.In an incubation trial conducted for a period of 16 weeks at 30°C and 100% R.H. the release of nitrogen was studied from 20 slow‐release nitrogen fertilizers and mixed fertilizers containing a slow‐release nitrogen component on an urea‐aldehyde basis. Amounts equivalent to 500 mg N per kg dry soil were added to a diluvial sandy soil having a pH‐KCl of 5.44 and a moisture content of 55% of the maximum retentive capacity. On the average, 35% of the slow‐release nitrogen was released, 60% of which during the first 4 weeks. The best measure of the amount of N released was the amount of cold‐water soluble N in the fertilizers. The amount of N released exceeded the amount of applied cold‐water soluble N on the average by about 4%, which was also the percentage of released cold‐water insoluble nitrogen.The differences among the individual fertilizers were rather large. In a supplementary trial it was found that the various urea‐aldehyde combinations do not react alike to pH and moisture content of the soil, and that they for that reason can hardly be lumped together with respect to their nitrogen effect. Each of these materials is more or less a special‐purpose fertilizer, and as such less suited as a substitute for the conventional fast‐acting fertilizers in agriculture.

A quantitative evaluation of the comparative value of six fertilizer–nitrogen sources for potatoes

SUMMARYSix fertilizer–nitrogen sources, each at three levels, together with a control of no fertilizer–nitrogen were compared in field trials in two consecutive crop seasons on a sandy soil comparatively deficient in nitrogen at Patna, Bihar. Four mathematical models were fitted to the potato yield data in order to evaluate the relative availability indices of the individual fertilizers. Data collected on final stand and ‘emergence rate’ index (Bartlett) showed that while urea applications gave rise to a comparatively low speed of emergence, with observed shoot injuries, nitrate of soda caused poor final stands. The other fertilizers had no effect on either the final stand or the speed of emergence.Sulphate of ammonia was chosen as the standard fertilizer for the present study. Ammonium sulphate nitrate was as good as or even slightly better, while ammonium chloride and calcium ammonium nitrate were of intermediate efficiency, in that order. Urea and nitrate of soda were decidedly poor as nitrogen sources for potatoes under the conditions of the study. The concurrent Mitscherlich curves model was found to represent the behaviour of these fertilizers with a good measure of fit.The performance of the six fertilizers is discussed in the light of the availability of NH4+ and NO3-, the phytotoxicity of urea and nitrate of soda, and the harmful effects of Cl-. It is concluded that ammonium sulphate nitrate is the best carrier of nitrogen among those studied for potatoes under the conditions set forth.

A multivariate regression analysis of differences in fertility of United States counties.

2 major methods have been used to study correlates of cross-sectional fertility differences: 1) the correlation of various personal characteristics with individual fertility; and 2) the correlation of average characteristics of population aggregates with the average fertility of these aggregates. In the present study 8 independent variables were correlated with 1 measure of fertility. The level of infant mortality has been shown to be associated with fertility. The universe for the present study consisted of 3134 counties (or county equivalents) in the United States. From these a 1-in-5 sample was selected by combining 2 1-in-10 systematic samples each having a different random starting point. 2 variables the proportion of Roman Catholics in the archdiocese or diocese to which the county belongs and the log 10 of the population potential in the county are found to be the most important in accounting for variation in the age-standardized fertility of United States county populations. There is little reason to doubt that these 2 variables are causally influential.

A STUDY ON THE RESPONSES TO NITROGEN, PHOSPHORIC ACID AND POTASH OF RICE VARIETIES

Fertilizer experiments of three rice varieties were made to estimate varietal differences in the responses to the three elements and in their interactions. Significant varietal differences were found not only for the effects on characters of individual fertilizers but also for their interactions. Differences between two years in certain interactions were also significant.

The Effect of Irradiation on Reproduction in Two Strains of Tribolium castaneum Herbst

The effects of x radiation on the reproductive performance of two strains of Tribolium castaneum were measured. The two strains differed in body weight, one strain being two and one-half times as heavy as the other. Females of the heavier strain were more resistant to somatic damage than were females of the light strain. Genetic damage, as measured by a reduction in fertility of irradiated individuals, was not so great in the heavy strain as in the light strain, especially when both parents were irradiated. When only one parent in a mating was irradiated, no sex differences in response to increasing dose were found. When both parents of a mating were treated, since the effective dose was doubled, there was a greater increase in genetic damage than if only one parent were treated. The effect of irradiating both parents can be predicted from the results obtained when only one parent is irradiated. The response curve for somatic damage showed a linear decline at high doses (1000 and 5000 r) but no significant effect at low doses (0 to 800 r). The response curve for genetic damage, as measured by an orthogonal polynomial analysis, was sigmoid in shape with a linearmore » decline at low doses and a curvilinear decline at the high doses. The genetic response curve over all doses can be fitted to a function of the type Y = a + bX + cX/sup 2/, where the different coefficients of X and X/sup 2/ change with the strain. The coefficients also depend on whether one or both parents are treated. The drop in fertility at doses over 5000 r was an average of 66.9% for irradiated foundation adults (summed over mating combinations) and an average of 58.8% for irradiated selected adults, (auth)« less