Variable-rate technology (VRT) has been developed to variablyThe potential for improved profitability due to variapply crop inputs to manage in-field variability. Although growers have able-rate N application depends on identifying areas in begun to adopt VRT, its profitability is uncertain in N management. the field where additional N inputs will increase revenue The objective of this study was to assess the economics of uniform vs. variable-rate N fertilizer application under two N application scenarios on a scale that is greater than the added costs and/or (farmer vs. custom applications). On-farm studies were conducted on identifying areas where reducing N inputs will decrease two continuous corn (Zea mays L.) fields in northeastern Colorado costs on a scale that is greater than potential revenue under furrow and center-pivot irrigation during the 2000 and 2001 reduction correlated with lower grain yield (Snyder et al., growing seasons. The N management strategies were uniform, grid-based, 1999). Therefore, the economic feasibility of variable-rate site-specific management zone-constant yield goal (SSMZ-CYG) and N application is focused on whether increases in gross site-specific management zone-variable yield goal (SSMZ-VYG). "Profit revenue or decreases in N input costs outweigh the added and loss" software was used to analyze the economics of each N cost of technologies or services needed for variable-rate N management strategy and determine which N strategy was most profitapplication ( Ferguson et al., 1999;Thrikawala et al., 1999). Thrikawala et al. (1999) reported that the profitability N fertilizer (6-46%) was used with the SSMZ-VYG N management strategy when compared with uniform N management. Net returns from of variable-rate N application increased above that of the SSMZ-VYG N management strategy were $18.21 to $29.57 ha Ϫ1 uniform N application as area and in-field soil variability more than uniform N management. Results of this study suggest variincreased. However, additional information and appliable-rate N application utilizing site-specific management zones are cation expenses are involved when managing spatial more economically feasible than conventional uniform N application. variability occurring throughout a field. Review of literature suggested that most studies incorporated the information costs (i.e., soil sampling, developing variable-rate
able. Results from three site-years consistently indicated that less total
A Stochastic Dynamic Programming (SDP) model is developed to analyze optimal stocking rates in the face of weather uncertainty and potential climate change projections. The model extends previous work modeling grazing as a predator‐prey relationship. Attention is given to profit maximizing decisions when growing season precipitation is unknown. Comparisons are made across results from a model that utilizes constant growing season precipitation in all years. Results suggest that optimal stocking rates and profitability decrease in climate change scenarios with increased precipitation variability as compared to the historical stochastic weather scenario.
Computers change rapidly, yet the last survey on computer use in agriculture was in 1991. We surveyed Great Plains producers in 1995 and used logit analysis to characterize adopters and non-adopters. About 37% of these producers use computers which is consistent with the general population. We confirmed previous surveys emphasizing the importance of education, age/experience, and other farm characteristics on adoption. However, we also found that education and experience may no longer be a significant influence. Future research and education could focus on when and where computers are most needed, and therefore when adoption is most appropriate.
We develop a dynamic economic model that includes control variables for both nitrogen fertilizer and irrigation water to analyze interseasonal corn production and nitrate leaching in the presence of irrigation system nonuniformity. The economic model is used to estimate profit-maximizing nutrient management plans under varying levels of system uniformity. The model is also used to appraise several policy options that have been proposed in the nitrate leaching literature as a means of regulating water quality. Investments in technology are considered, as well as limits on nitrate leaching, nitrogen fertilizer, and irrigation water. Copyright 1998, Oxford University Press.
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