Results Of Magnesium Fertilizer Research In Puerto Rico

The results obtained in studies undertaken to determine the influence of magnesium on the yield of various crops of economic importance in Puerto Rico ar-e briefly summarized as follows: 1. Magnesium Lncr-ea aed significantly yields of sweet potatoes when this nutrient wa:s applied to a Lares clay and Sabana Seca sandy clay soils. 2. The application of magnesium sulfate as spray and in the soil relieved grapefruit trees from visual symptoms of deficiency of magnesium. Heavy shedding of the leaves was corrected by using this nutrient. 3. On a highly alkaline soil magnesium applications to the soi.l were not effective in correcting magnes:i.um deficiency in citrus trees. However, magnesium sprays were quite effective in controlling visual syrptoms of magnesium deficiency. 4. There was a significant yield increase of marhetable coffee in favour of magnesium-treated trees. The difference inyield in favour of magnesium-treated trees was equivalent to a 43 percent over the check or untreated trees. 5. Magnesium was responsible for increasing signif:icantly pineapple yields. Highest fruit yields were associated with the highest leaf magnesium content. A significant correlation was found between relative yields and leaf magnesium content. 6. Yields of plantains were increased by 90.9 percent by the application of magnesium. Plantains receiving no magnesium exhibited deficiency symptoms, including yellowing of the older leaves and reduced growth. Foliar composition of the plantains at 7 months predicted their yield response to magnesium. Lowest plantain yields were associated with a leaf magnesium content of 0.15 while h:ighest plantain yields