1a.Objectives (from AD-416):
Physiological basis for optimal nitrogen availability in potato rootzone during the growing season to enhance uptake efficiency and optimal partitioning into different plant parts.
1b.Approach (from AD-416):
Field experiments will be conducted using different potato varieties under different irrigation and nitrogen management. The dynamics of nitrogen uptake and partitioning into different plant parts will also be investigated using 15N labeled fertilizer. In addition to evaluation of tuber yield and quality responses to different nitrogen management practices, soil and plant growth parameters will be measured to assist field validation of potato growth simulation model.
With approximately 25,000 acres of winter and spring potatoes, Florida, is an integral part of the supply chain for freshly harvested potatoes in the United States. Potato is the most important spring crop in northeast Florida with a crop value of $135 million in 2007. Per objective 2, BMPs are being developed to increase N-use efficiency for potato production and to reduce nitrogen leaching. The objective of this study was to determine an optimal N-fertilizer rate for commercial chipping potato production. Field experiment was conducted in Hastings, FL. The study was performed on three commercial farms growing potato variety ‘Atlantic.’ In all locations water was supplied through seepage irrigation by pumping water into furrows spaced 60 feet throughout the field, thereby raising the water table to the rootzone. The design was a randomized complete blocks with 4 replicates. Nitrogen rates ranged from 100 to 300 lb N/ac from ammonium nitrate. At emergence, nitrogen was sidedressed at 0, 50, 100 or 150 lb/ac of N from liquid urea ammonium nitrate (UAN). Subsequently, a second sidedress of 50 or 100 lb/ac of N from UAN was applied at the 6-8 inch growth stage. Total and marketable yield, specific gravity, plant dry weights, and nitrogen accumulation in the plants, tubers, leaves/stems were evaluated. Soil nitrogen content was recorded throughout the season. Plant tissues (leaves/stem and tubers) accumulated from 90 to 140 lbN/ac. No difference in potato yield was observed between nitrogen rates at any location. Total marketable potato yield ranged between 250 and 320 cwt/ac. There were no differences in potato yield and tuber specific gravity between N-rate of 50 or 100 lb/ac applied at 6-8 inch growth stage. In two out of three locations, significant increase in tuber specific gravity was achieved with N-fertilizer rate above 100 lbN/ac at the emergence application. The pre-plant N-fertilizer application did not increase soil nitrogen availability at plant emergence, with soil nitrogen content averaging 23 lb/ac which is similar to the soil N content at pre-plant.