Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/1999
Publication Date: N/A
Interpretive Summary: Restoration of the Florida Everglades is a national priority. As part of this restoration process, there are strict legislative controls on the amount of phosphorus that can be discharged to the natural Everglades from Florida sugarcane farms. Best management practices to meet these requirements cost farmers $153 per ha to install and $9 per ha to maintain. This research compared the use of two soil test procedures for recommending phosphorus fertilizer for sugarcane on organic soils in the Everglades. A new procedure was better at predicting phosphorus fertilizer needs than the historically used procedure. This knowledge will help Florida sugarcane farmers reduce their phosphorus discharge to the Everglades while maintaining optimum yields. In addition, this study summarized several important knowledge gaps regarding sugarcane and phosphorus soil-test calibration in the Everglades. Further research to fill these gaps will further enhance sugarcanes yields and its relationship with the Everglades.
Technical Abstract: To protect habitat in the Everglades, legislation mandates a reduction of at least 25% in the P content of water discharged from the Everglades Agricultural Area (EAA). The objective of this study was to compare two soil-tests for basing P fertilizer recommendations for sugarcane grown on organic soils in the EAA. Three yield characteristics were measured at four field locations with no added P, an often recommended commercial rate of 24 kg P per ha, and 48 kg P per ha for the plant-cane, first-ratoon, and, at three locations, the second-ratoon crop. One group of eight genotypes was planted at two locations, and two other groups of eight genotypes were each planted at one of two other locations. An acetic acid-extractable P soil test predicted yields better than the historically used water-extractable P test. However, unexpected responses in sugar and cane yield characteristics were noted for both P extraction procedures. Further knowledge of the effects of soil pH, factors affecting P mineralization, and sugarcane genotype response to P may explain some of the unexpected results. Accurate P fertilizer recommendations for sugarcane in the EAA are critical to optimize farm profits and the ecologic health of the Everglades.