Submitted to: Plant Nutrition Colloquium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2000
Publication Date: 8/1/2001
Citation: PARAMASIVAM, S., ALVA, A.K., SAJWAN, K.S., SYVERTSEN, J.P., WHEATON, T.A., TUCKER, D.H. FERTILIZER AND IRRIGATION BEST MANAGEMENT PRACTICES (BMP) FOR OPTIMAL CITRUS PRODUCTION AND WATER QUALITY IN SANDY ENTISOLS OF FLORIDA. PLANT NUTRITION COLLOQUIUM PROCEEDINGS. IN HOST, W.J. et al (eds.), DEVELOPMENTS IN PLANT AND SOIL SCIENCES, KLUWER ACADEMIC PUBLISHERS, pp. 778-779. 2001. Interpretive Summary: Improved management of nutrients and irrigation is critical to increase the nutrient uptake efficiency and to minimize the potential leaching of nitrate form of nitrogen, which is considered as unacceptable at concentrations in excess of 10 mg per liter. Results of a six years field experiment on 25 plus year old Hamlin orange trees (on Cleopatra mandarin rootstock), revealed that optimal N rate for maximum sustained fruit production was 250 Kg N per hectare. At this N rate the nutritional status of the tree was maintained as evident from the spring flush N concentration. Despite the optimal irrigation scheduling, leaching of N accounted for 22 to 34 Kg N per hectare and the nitrate-nitrogen concentration in soil solution in the vadose zone as well as in the surficial groundwater was below the 10 mg per liter standards for drinking water quality.
Technical Abstract: In order to increase efficient use of applied fertilizer by citrus, economically feasible best irrigation and fertilizer management practices (BMPs) are necessary. A six year field study was conducted on a well- drained Tavares fine sand in Highlands County, Florida, USA, to evaluate the effects of N source, placement, and rate (112 to 280 kg/ha/yr) with optimum irrigation management on (i) the fruit yield, quality and leaf nutrient contents of bearing mature (25+year old) 'Hamlin' orange trees on Cleopatra mandarin rootstock and (ii) changes in NO3-N status in soil solution collected from vadose zone below the rootzone and in surficial groundwater. Results of this study indicated that optimum fruit yield could be obtained at about 250 kg N/ha, which supported optimum range of spring flush N concentration. Leaching of NO3-N accounted for only 22 to 34 kg/ha year and the NO3-N concentration in soil solution in the vadose zone and in surficial groundwater remained below 10 mg/L under optimal irrigation and N management conditions used in this study.