Mahesh Pandit

Water pollution and income relationships: A seemingly unrelated partially linear analysis

We used a seemingly unrelated partially linear model (SUPLM) to address a potential correlation between pollutants (nitrogen, phosphorous, dissolved oxygen and mercury) in an environmental Kuznets curve study. Simulation studies show that the SUPLM performs well to address potential correlation among pollutants. We find that the relationship between income and pollution follows an inverted U-shaped curve for nitrogen and dissolved oxygen and a cubic shaped curve for mercury. Model specification tests suggest that a SUPLM is better specified compared to a parametric model to study the income-pollution relationship. Results suggest a need to continually assess policy effectiveness of pollution reduction as income increases. This article is protected by copyright. All rights reserved.

IRRIGATION WATER SOURCES AND IRRIGATION APPLICATION METHODS USED BY U.S. NURSERY PRODUCERS

We examine irrigation water sources and irrigation methods used by U.S. nursery plant producers using nested multinomial fractional regression models. We use data collected from the National Nursery Survey (2009) to identify effects of different firm and sales characteristics on the fraction of water sources and irrigation methods used. We find that regions, sales of plants types, farm income, and farm age have significant roles in what water source is used. Given the fraction of alternative water sources used, results indicated that use of computer, annual sales, region, and the number of IPM practices adopted play an important role in the choice of irrigation method. Based on the findings from this study, government can provide subsidies to nursery producers in water deficit regions to adopt drip irrigation method or use recycled water or combination of both. Additionally, encouraging farmers to adopt IPM may enhance the use of drip irrigation and recycled water in nursery plant production.

Market channel selections by US nursery plant producers: a multivariate nonparametric fractional regression analysis

ABSTRACT Availability of market channel alternatives has helped the growth of ornamental plant sales in the United States. To identify the factors affecting the choice and allocation of outputs to different market channels by nursery producers, we first use a mixture of experts model to select clusters of homogenous subpopulations of US nursery producers based on a 2009 National Nursery Survey. The impact of growers’ business characteristics on shares of sales to these channels was estimated using multivariate parametric and nonparametric fractional regression models. Specification tests indicated a nonparametric model was superior to a parametric model in some clusters. Important explanatory variables affecting the sales volume to different channels were sales of plant groups, kinds of contract sales, promotional expenses, and farm size. Results indicated the existence of clear market segmentation of nursery producers in the United States.