Gleaning After Citrus Mechanical Harvesters - Labor Productivity

Canopy and trunk shakers in properly prepared Florida orange groves recover between 85 and 93 percent of the available fruit. Whether a grower should "glean" the remaining fruit depends on if the unit cost of gleaning is less than the on-tree fruit value. Labor productivity of gleaners is an important component in determining the unit cost of gleaning. Previous work by Polopolus and Emerson indicates that worker productivity of orange harvesters averages between 8 and 10 boxes per hour. Their data, however, are restricted to hand crews working in blocks averaging between 300 and 500 boxes per acre. Workers, or gleaners, who follow mechanical harvesting systems have access to far less fruit, perhaps only between 25 and 75 boxes per acre. The objectives of this paper are to test the hypothesis that worker harvest productivity is positively correlated with crop yield, and if true, estimate the overall effect of crop yield on worker productivity. A data set was assembled from 47 Hamlin orange blocks harvested in southwest Florida between 27 November 2007 and 10 January 2008. Each block was characterized by its total production (boxes per acre), the total boxes harvested by either hand crews or mechanical systems, and the average hourly productivity of hand harvesting crews. A linear model of worker productivity as a function of the log-transformed value of fruit availability was estimated by OLS. The estimated parameter coefficient on fruit availability was positive and statistically significant. The model predicts that worker productivity falls from ten to nearly five boxes per hour when fruit availability decreases from 500 to 25 boxes per acre. In order to for all workers to earn at least $8 per hour, the harvesting piece rate must increase from 80-cents for hand harvesters to $1.50 per box for gleaners