Asparagus yield response to water and nitrogen

Fresh green asparagus (Asparagus officinalis L.) is produced in the Southwest desert regions during a period when it cannot be produced in colder areas. The success of producing optimum yields economically is dependent on the proper applications of water and nitrogen. All water requirements must be met by irrigation since less than 75 mm (3 in.) of annual rainfall occurs in this region. Nitrogen is a critical nutrient that must be applied to obtain maximum yields. Maximum yields of 11.6, 18.6, and 10.0 Mg/ha (9700, 16,700, and 8900 lb/ac) were predicted for asparagus crowns that were 3, 4 and 5 years old, respectively. The amount of water applied to obtain these yields ranged from 270 to 310 cm (106 to 122 in.) and the amount of nitrogen fertilizer applied ranged from 370 to 630 kg/ha (330 to 560 lb/ac). Production functions were developed to predict asparagus yields for water applications that ranged from 50 to 150% of the estimated evapotranspiration and nitrogen applications that ranged from 33 to 167% of the recommended nitrogen rate.