Occurrence of natural and foliar-fed essential micro-nutrients [Cu, Fe, Mn, Zn] in Sri Lankan tea

The purpose of this study was to understand the natural occurrence of micro nutrients (Zn, Cu, Mn and Fe) in processed black tea in main tea growing regions of Sri Lanka. Made tea samples (BPOF and FBOP) were collected for five months from selected tea estates representing Nuwara Eliya, Westerns, Uda Pusselawa, Uva, Medium-grown and Low-grown regions of Sri Lanka. The results indicated that the Zinc (Zn) content ranges from 22 to 45 pom and the highest Zn content was found in the Western teas. Copper (Cu) content in black tea ranges from 15 to 33 ppm. The highest Cu content was found in Western teas whereas, the lowest amount of Cu was found in Low-grown teas. Manganese (Mn) content in black tea ranges from 153 to 539 ppm. The highest amount of Mn was found in Uva teas and the lowest amount was found in Nuwara Eliya teas. The seasonal variation in Mn content was also observed. Iron (Fe) content in black tea ranges from 54 to 173 ppm. The highest amount of Fe was found in Uda Pusselawa teas and the lowest was found in Medium-grown teas. Nuwara Eliya region teas contain significantly higher amount of Fe compared to Medium-grown teas. This study revealed that Zn, Cu, Mn and Fe content in Black tea is within the standards set by the tea importing countries

Rhizosphere pH and phosphorus forms in an Oxisol cultivated with soybean, brachiaria grass, millet and sorghum

Plants have shown different responses to fertilization with rock phosphate, including responses through alteration of the attributes of rhizospheric soil. The objective of this study was to evaluate soil pH alterations and alterations in the contents of forms of phosphorus in the rhizosphere of soil fertilized with rock phosphate as a result of cultivation of species of plants. An experiment was developed under greenhouse conditions to evaluate alterations in the pH and in the forms of phosphorus in the rhizosphere of an Oxisol fertilized with rock phosphate and cultivated with four species. Treatments consisted of the cultivation of four species of soybean - Glycine max (L.) Merrill, brachiaria grass - Brachiaria brizantha Hochst Stapf, millet - Pennisetum glaucum (L.) R. Brown, and sorghum - Sorghum bicolor (L.) Moench grown in PVC columns filled with soil and divided with a nylon screen (25 µm mesh) to impede root growth in part of the column. After 45 days of cultivation, the soil was divided into the layers of 0-1, 1-2, 2-3, 3-4, 4-5, 5-7, 7-9, and 9-14 mm from the rhizoplane and air dried to determine pH and P contents through Hedley fractionation. In the 1-2 and 2-3 mm layers, soybean cultivation caused an increase in pH when compared to the control treatment (without plants). In the other layers, there were no alterations in pH due to cultivation of plants. The cultivation of millet, brachiaria grass, and sorghum reduced the inorganic P content in the most labile forms only in the 0-1 mm layer from the rhizoplane