Economics of alternative simulated manual asparagus harvesting strategies

Abstract

Asparagus is harvested daily during the production season. The adoption of harvesting strategies less or more frequent than the traditional 24-h strategy has not occurred because of problems in hiring manual labor. A model that predicts daily harvest and the impact of different harvesting strategies was developed. This paper presents a bioeconomic model, capable of predicting daily asparagus harvests, composed by different mathematical functions: emergence, density dynamics, spear growth, diameter, weight, carbohydrates reserve dynamics, and profit. The bioeconomic model was used to simulate yield, number of harvests, profit, and the total cost of harvest for every year in the period 1989–2004. A simulation with the minimum wage harvesting constraint was developed and is labeled as the constrained model. The model was evaluated using data from different locations for four consecutive years in Washington State (USA) asparagus fields. The impact of the minimum wage requirements was estimated in terms of yield and profit for both processed and fresh asparagus. The traditional harvest interval of 24 h was compared to a more frequent (12 h) and a less frequent (48 h) interval. Manual harvest with the interval of 12 h showed the best results in terms of yields and profits for both processed and fresh asparagus. Gains in profits with the actual production conditions in Washington State were US$183.88/ha and US$210.60/ha for processed and fresh product, respectively. The 48-h strategy resulted in decreased yields and profits.