The Static Theory of the Firm and Three Laws of Plant Growth

Swanson, Earl R.

doi:10.1097/00010694-196305000-00008

Cited by 14 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The two-straight-lines model is attractive because each of its four parameter values is a quantity readily visualized by and of interest to the soil scientist and even the farmer. Economic interpretation of the results could be much simplified; as Swanson (1963) remarks,' Life in the Liebig world is relatively uncomplicated.' In many experiments the rate of increase in yield/kg N changes little over a range of N dressings and so we can meaningfully evaluate a nitrogen efficiency factor.…”

Section: Discussionmentioning

confidence: 99%

Nitrogen requirement of cereals: 1. Response curves

1976

View full text Add to dashboard Cite

Examples of response surfaces for pairs of nutrients and results of 41 multi-level experiments with N only were used to compare the goodness-of-fit of polynomial, inverse polynomial, exponential and intersecting-straight-lines models. Whereas no one model fitted best at every site, many results were well represented by two intersecting straight lines and on average, this model had the least residual mean square. Of 17 experiments with spring barley in south western England the few results best represented by smooth curves were from crops much affected by leaf diseases.Fertilizer response was poorly represented by models without a falling asymptote, like the simple exponential and inverse linear. Study of residuals after fitting the quadratic showed that this widely used model consistently over-estimated both the amount of fertilizer needed for maximum yield and the yield loss when too much fertilizer was given.When fitted to the mean yields of each nitrogen treatment, most models had residual mean squares equal to or less than the error mean square, repeating a result obtained at Rothamsted as early as 1927. We question the validity of some well-known evidence for block and treatment additivity.For 12 experiments in 1970, between-site differences in the parameter values of the two straight lines representing grain yield were related to leaf area at ear emergence.TNTTT? onnrTTO'Nr series of experiments, each experiment testing many levels of one or more nutrients. Instead of estimating Most of the experiments discussed in this and the the effects of individual treatments and their following paper result from important develop-significance, the main object is to determine the ments in experimental methods in the past decade, optimal dressing (or, with several nutrients, their In crop nutrition these changes have resulted optimal combination) and to discover how and why mainly from soil scientists' need to make their fertilizer requirements differ from place to place advice to farmers increasingly precise and at the and from year to year. This paper discusses the form same time less empirical as a result of improved of response curve relating crop yield and fertilizer understanding of plant:soil relationships. Greater input, based mainly on results of multi-level nitroattention has been paid to planning, whereby site gen experiments with cereals, selection is related to soil and husbandry factors likely to influence fertilizer requirements, and there The need f or f resh information on fertilizer response has been more thorough and more uniform recording curves of these and other external factors. The isolatedThe average results of experiments with sugar experiment with few treatments and treatment beet, testing different amounts of N fertilizer, were levels but much replication has been replaced by well fitted by a quadratic response curve, but when

show abstract

Section: Discussionmentioning

confidence: 99%

Nitrogen requirement of cereals: 1. Response curves

1976

View full text Add to dashboard Cite

show abstract

“…For example, Perrin,13 while studying the responses of various Brazilian crops to fertilizer applications, has contrasted the value to farmers of the information obtained from a simple structure based on Liebig's "law" of limiting factors (the "law" as succinctly stated by Swanson 14 says that yields increase at a constant rate with respect to applications of each factor unit until some other factor is limiting), to the information acquired from a multi-input, nonlinear (quadratic) representation commonly favored in much controlled fertilizer response research. Using a set of 28 experiments conducted at various Brazilian sites over a three yr period, Perrin compared farmers' implied ex post net revenues from the two distinct models.…”

Section: Choice Of Modelsmentioning

confidence: 99%

Dose-Response Information and Environmental Damage Assessments: an Economic Perspective

Adams¹,

Crocker²

1982

Journal of the Air Pollution Control Association

View full text Add to dashboard Cite

“…The selection of variables and the specification of the crop yield functional form are always difficult due to the complexity of the yield response (Swanson, 1963; Florax et al, 2002; Anselin et al, 2004). Nistor (2007) reviewed issues specific to the selection of variables and a functional form for drainage response functions.…”

Section: Methodsmentioning

confidence: 99%

The Impact of Drainage Water Management Technology on Corn Yields

et al. 2012

View full text Add to dashboard Cite

Controlled drainage (drainage water management) restricts outflow during periods of the year when equipment operations are not required in the field. This may increase yields as well as reduce the loss of nutrients with negative environmental externalities. An experiment using controlled drainage was investigated and its impact on corn (Zea mays L.) yields was assessed at the field level in Indiana. Specifically, yield monitor data was analyzed across space and time using a geographic information system and spatial panel regression methods. The use of panel data methods controlling simultaneously for spatial and temporal heterogeneity as well as dependence provides precision agriculture researchers with a powerful framework to model crop sensor data across space and time. During the period 2005 to 2009, controlled drainage was found to outperform free‐flow systems by an average of 0.57 to 1.00 Mg ha−1 (5.8–9.8% across the effective range of 0–0.61 m above the water control structure) for the experimental field; however, these aggregate results masked substantial year‐to‐year and within‐field variations.

show abstract

The Static Theory of the Firm and Three Laws of Plant Growth

Cited by 14 publications

References 0 publications

Nitrogen requirement of cereals: 1. Response curves

Nitrogen requirement of cereals: 1. Response curves

Dose-Response Information and Environmental Damage Assessments: an Economic Perspective

The Impact of Drainage Water Management Technology on Corn Yields

Contact Info

Product

Resources

About