Nitrogen management improves organic asparagus growth and productivity

Abstract

In a 4-year organic field experiment, the influence of increasing nitrogen levels (50, 100, 150, 200 kg N ha-1) supplied from feather meal (13% N) was assessed and asparagus biomass (fern and root) and productivity (yield and quality) determined. Nitrogen treatments were applied after harvest each year and later each year, fern growth was evaluated. Roots were sampled before the initial N applications and again near the end of the study. Increasing N levels up to 150 kg N ha-1 had a significant positive effect on spear yield in each year even though fern growth was not influenced by N level. Root fresh weight accumulation was greater when plants were supplied with N at 150 and 200 kg N ha-1. Soil nutrient analysis showed some buildup in N reserves as N applications levels increased. These finding indicate that improvements in asparagus productivity can be expected when soil nutrient levels and plant N storage improves as a result of supplemental N applications in a low N system. Improvements in asparagus root growth are primarily responsible for these differences.