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Title: BEST NITROGEN AND IRRIGATION MANAGEMENT PRACTICES FOR CITRUS PRODUCTION IN SANDY SOILS.

Author
item Alva, Ashok
item PARAMASIVAM, S - UNIVERSITY OF FLORIDA
item GRAHAM, W - UNIVERSITY OF FLORIDA
item WHEATON, T - UNIVERSITY OF FLORIDA

Submitted to: Journal of Water Air and Soil Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2002
Publication Date: 6/1/2003
Citation: ALVA, A.K., PARAMASIVAM, S., GRAHAM, W.D., WHEATON, T.A. BEST NITROGEN AND IRRIGATION MANAGEMENT PRACTICES FOR CITRUS PRODUCTION IN SANDY SOILS.. JOURNAL OF WATER AIR AND SOIL POLLUTION, 143:139-154. 2003.

Interpretive Summary: Combination of improved irrigation and nitrogen management is important to minimize nitrate leaching. This study was conducted in five commercial citrus groves to evaluate the impact of best management practices on horticultural responses as well as on groundwater quality in commercial production conditions. Irrigation scheduling was done by using tensiometers at 15 and 30 cm depth and using set points of 10 to 15 cbars. This study successfully showed that in 5 to 8 year-old Valencia orange groves, 59 to 81 Mg per hectare per year fruit production was obtained with only 168 kg N per hectare applied as entirely fertigation with adequate timing and delivery practices. Groundwater nitrate concentrations decreased in a mature grove which received 3 foliar applications of low biuret urea (66 kg N per hectare) and 76 kg N per hectare well timed fertigation for an annual total N of only 142 kg per hectare. This N program did not result in any adverse impact on the tree nutritional statu or fruit production. A comparison of fertigation vs. broadcast application of water soluble granular form with 180 kg N per hectare on mature Valencia groves demonstrated beneficial effects in terms of fruit yield and nutrient status of the trees of fertigation compared to the broadcast application.

Technical Abstract: Combination of improved irrigation and nitrogen management is important to minimize nitrate leaching. This study was conducted in five commercial citrus groves to evaluate the impact of best management practices on horticultural responses as well as on groundwater quality in commercial production conditions. Irrigation scheduling was done by using tensiometers at 15 and 30 cm depth and using set points of 10 to 15 cbars. This study successfully showed that in 5 to 8 year-old Valencia orange groves, 59 to 81 Mg per hectare per year fruit production was obtained with only 168 kg N per hectare applied as entirely fertigation with adequate timing and delivery practices. Groundwater nitrate concentrations decreased in a mature grove which received 3 foliar applications of low biuret urea (66 kg N per hectare) and 76 kg N per hectare well timed fertigation for an annual total N of only 142 kg per hectare. This N program did not result in any adverse impact on the tree nutritional statu or fruit production. A comparison of fertigation vs. broadcast application of water soluble granular form with 180 kg N per hectare on mature Valencia groves demonstrated beneficial effects in terms of fruit yield and nutrient status of the trees of fertigation compared to the broadcast application.