Further Evidence on the Need of Magnesium for Pineapple in Oxisols

Abstract

Two pineapple experiments were established in Bayamón sandy clay, the most extensively used acid lateritic soil for pineapple growing in Puerto Rico. The experiments were conducted to study the effect of different amounts of magnesium sulfate applied to the soil on yields of pineapples. The influence of magnesium chelate and of foliar sprays on pineapple yields was also studied. The results obtained are briefly summarized as follows: 1. Pineapple plants supplied with magnesium were more vigorous and greener in color than similar plants not receiving this nutrient. 2. Significant heavier fruit yields were obtained from pineapple plants receiving magnesium sulfate at the various rates used as a soil application than from the pineapple plants not receiving this nutrient. 3. Magnesium chelate and magnesium sulfate foliar sprays were also responsible for significantly increasing fruit yields per acre. 4. Highest fruit yields were associated with high nutrient contents of magnesium in the leaves. 5. Highly significant correlations were found between pineapple relative yields and leaf magnesium content at two crop ages. 6. Results indicate that magnesium content of 5- and 9-month old pineapple plants can be used to predict relative crop yields. 7. Capo's new fertilizer-yield equation was used to describe the relation between the application of magnesium sulfate and the yields of pineapples. The equation fitted closely such fertilizer-yield data. 8. The optimum economic magnesium sulfate application for the two pineapple experiments discussed was determined.