Fertilizer production functions for corn and oats; Including an analysis of irrigated and residual response

This study includes predictions of fertilizer production functions for four experiments. The experiments on Clarion and McPaul soils contain predictions of total and marginal yields, isoquants and marginal rates of substitution, isoclines and economic optima. Similar analyses for the other two experiments, conducted on Carrington soil during successive growing seasons, were not warranted because insufficient rainfall limited yield responses. The experiments included in this study were based on partially replicated factorial designs. The experiment with corn on Clarion silt loam in 1954 included nitrogen, phosphorus and potash as variable nutrients. The production function, isoquants and isoclines are represented by equations a, b, c, d, e, f and g. In these equations (and equations listed below), N, P and K denote the pounds per acre of nitrogen, P2O5 and K20, respectively. Isoquant and isocline equations were derived for each pair of nutrients. Hence, there are three of each of these equations. The α in the isocline equations represents a constant price or substitution ratio

Crop response surfaces and economic optima in fertilizer use

The experiments upon which this study is based were designed to allow (1) estimation of the fertliizer-crop production surface and (2) specification of economic optima in level of fertilization and combination of nutrients. Two nutrients were varied on each experiment. The corn experiment, on calcareous Ida silt loam soil, included nine rates each of N and P2O5. Red clover and alfalfa were on Nicollet and Webster loam soils with P2O5 and K2O as the variable nutrients. Each experiment included two replicates of 57 different nutrient combinations - 114 completely randomized observations

Production functions and methods of specifying optimum fertilizer use under various uncertainty conditions for hay

Farmers who use fertilizer on a crop are concerned with at least two uncertainty problems relating to the amount of fertilizer that maximizes profits. Both of these problems arise, in part, from weather, a common underlying cause. First, crop yield is uncertain. Thus, a quantity of fertilizer applied, with the decision made before planting, may not be optimum for the yield actually obtained. Second, at the time of planting, future crop use or price may also be indefinite. The value of hay, for example, may differ according to the method of utilization. Hence, a particular amount of fertilizer applied in the spring may not provide the optimum value product at the end of the season. This study is concerned with the estimation of production functions and the analysis of uncertainty problems as they relate to fertilization of alfalfa with P2O5 and K20. The basic data are taken from an experiment in which three hay cuttings were obtained during the 1952 growing season on Weller silt loam in Van Buren County, Iowa

Fertilizer production functions in relation to weather, location, soil and crop variables

This study is based on several long-term experiments of crop fertilization at three Iowa locations: Howard County, with Clyde and Cresco soils; Hancock County, with acid and calcareous Webster soils; and Wayne County, with Seymour soil. The trials at these widely separated experimental farms included corn and oats fertilized in a 3-year rotation of corn-oats-meadow. The periods of the trials were: Clyde and Cresco soils, 1945-1960; Webster soils, 1954-1960; Seymour soil, 1949-60. Although meadow was not fertilized, residual nutrients from fertilization of the oats nurse crop were expected to affect hay yield. Applied nutrients included only phosphorus and potassium. The objectives of the analysis were: (a) to estimate annual production functions for each crop and compare them with average production functions estimated from the several years of data for the same crops, locations and soil types; (b) to analyze the variability or degree of uncertainty involved in such physical and economic relationships as isoquants, isoclines and profit-maximizing nutrient inputs; (c) to estimate weather indexes and their quantitative relationship to fertilizer response; (d) to estimate generalized production functions that incorporate weather, soil nutrients, location and soil into the production function along with the quantities of K and P applied annually

Production surfaces and economic optima for corn yields with respect to stand and nitrogen levels

This study presents production functions for three experiments on corn in Iowa. It is fourth in a series of studies designed to derive corn response surfaces, yield isoquants and economic optima in fertilizer use.:! It differs from previous studies in that, for the first time, stand (plant population) is included as a variable input along with a plant nutrient (nitrogen). The analysis permits estimation of yield response to stand and to nitrogen as well as to the interaction between stand and nitrogen. Knowledge of this type is relevant, not only for farm recommendations, but also for improved planning of fertilization experiments. The first experiment reported involved stand levels on Shelby loam and was conducted in Ringgold County in 1956. The other two experiments reported were conducted in 1953, with variable stand and nitrogen levels on Marshall and Seymour silt loams, respectively, and were located in Fremont and Wayne counties.3 Each of these experiments included an early and an adapted variety of corn (Iowa 4297 or Iowa 4397 and A.E.S. 801, respectively)

Application of game theory models to decisions on farm practices and resource use

The use of alternative decision models for farmer decision-making under uncertainty is demonstrated in this study. Particular emphasis is given to game theoretic models. These models have previously had little empirical application to farmer decision problems. This study has shown, however, that the models suggest plans which farmers in various problem settings may wish to follow. Research and extension personnel may want to use the models to derive farmer recommendations. Farmers must make decisions in their given, uncertain environment. How are these decisions to be made so that the plans resulting will, as nearly as possible, have the outcomes desired by the farmer? This question expresses the problem this study was designed to investigate. Farmers can follow any of several models specifying how to plan under uncertainty. They may apply the models to their own problems directly or follow recommendations based on the models. Research and extension personnel influence choice of decision models through data and recommendations. Research workers must use some choice mechanism to derive recommendations. Published data may influence choice of decision models, by being suitable for use in only one or a few models. Farmers\u27 abilities to plan rationally may be increased by providing a variety of recommendations based on different decision models giving plans with outcomes desired by farmers. Abilities also may be increased by providing data applicable to several decision models

Genome-wide association analysis of eosinophilic esophagitis provides insight into the tissue specificity of this allergic disease

Eosinophilic esophagitis (EoE) is a chronic inflammatory disorder associated with allergic hypersensitivity to food. We interrogated >1.5 million genetic variants in European EoE cases and subsequently in a multi-site cohort with local and out-of-study control subjects. In addition to replication of the 5q22 locus (meta-analysis p = 1.9×10−16), we identified association at 2p23 (encoding CAPN14, p = 2.5×10−10). CAPN14 was specifically expressed in the esophagus, dynamically upregulated as a function of disease activity and genetic haplotype and after exposure of epithelial cells to IL-13, and located in an epigenetic hotspot modified by IL-13. There was enriched esophageal expression for the genes neighboring the top 208 EoE sequence variants. Multiple allergic sensitization loci were associated with EoE susceptibility (4.8×10−2 < p < 5.1×10−11). We propose a model that elucidates the tissue specific nature of EoE that involves the interplay of allergic sensitization with an EoE-specific, IL-13–inducible esophageal response involving CAPN14

Production functions, isoquants, isoclines and economic optima in corn fertilization for experiments with two and three variable nutrients

This study deals with the basic agronomic and economic relationships of fertilizer use. It is the second in a series of methodological studies designed to predict production surfaces, isoquants, isoclines, marginal products and marginal replacement rates between nutrients when two or more nutrients are used in promoting increased crop yields. These quantities, which are fundamental in obtaining a basic science knowledge of fertilizer-crop relationships, are then used to predict optimum levels of fertilization and optimum ratios of nutrients with profit maximization as the criterion of selection. While the major objectives of the study are of a methodological nature, illustrations are included to show how the basic relationships and principles can be adapted to simple forms for farmer and educational uses. The logical foundations for research of the type reported in this bulletin are reported elsewhere.2 The production functions and economic optima predicted in this study are for corn on three types of soils with two and three nutrients variable in quantity