Application of Controlled Released Fertilizers for Iceberg Lettuce Cultivation
Hsieh M. H. and W. J. Jiang
The purpose of this project was to reduce the impact of labor shortage in iceberg lettuce production for exportation by using controlled released fertilizers. We expected that the fertilization would be reduced from three or four applications to one application during period of iceberg lettuce cultivation. The principal methods include (1) evaluating the efficacy of the controlled released fertilizers through calculated application in winter, (2) estimating the cost and efficacy of the different controlled released fertilizers through the calculated application in spring, and (3) investigating the influence of different types of nitrogen fertilizer on head quality in summer. Results showed that the treatment of controlled released fertilizer through calculated application had significantly increased the head weight and reduced the fertilizer consumption by approximately 51.6%-46.9%-37.9% with N-P2O5-K2O in winter cultivation. In spring cultivation, the treatments of two different brands of controlled released fertilizers also had significantly increased the head weight and reduced the fertilizer consumption by approximately 25.6%-4.7% with N-P2O5. However, the least possible cost of locally produced controlled released fertilizers approximately doubles that of traditional common fertilizers. In summer cultivation, the treatment of controlled released fertilizer without nitrate nitrogen also had significantly increased the head weight compared to a traditional fertilizing treatment that contained nitrate nitrogen and one that did not. In the treatment of controlled released fertilizer without nitrate nitrogen, the leaf weight was significantly higher than the traditional fertilizing treatment without nitrate nitrogen, but significantly less than the traditional fertilizing treatment with nitrate nitrogen. This research had proven that the application of the controlled released fertilizers increased yield as well as soil EC, and decreased the fertilizer consumption. However, the higher cost of the controlled released fertilizers was still the main issue. In the future, the controlled released fertilizers through accurate application should be evaluated more to study whether fertilizer consumption can be reduce more or not. Using increased controlled released fertilizers use can be realized in iceberg lettuce cultivation for exportation and increase the competitiveness of the export vegetable industry.
Key words：Iceberg Lettuce, Controlled Released
Accepted for publication：October 18, 2014