ISHS Acta Horticulturae 630: XXVI International Horticultural Congress: Nursery Crops; Development, Evaluation, Production and Use
NUTRIENT UPTAKE, PARTITIONING AND LEACHING LOSSES FROM CONTAINER-NURSERY PRODUCTION SYSTEMS |
| Authors: | A.G. Ristvey, J.D. Lea-Cox, D.S. Ross |
| Keywords: | nutrient budget, nitrogen, N, phosphorus, P, uptake efficiency, Rhododendron, azalea, Ilex cornuta, holly |
| Abstract:
A three-year study was initiated in 1999 to gather long-term data on nitrogen (N) and phosphorus (P) movement from container-nursery operations. The overall objectives of this study were to quantify N and P application, partitioning and leaching losses for Ilex cornuta x regosa var. ‘China Girl’ (holly, a ‘high’ nutrient-use species) and Rhododendron var. ‘Karen’ (azalea, a ‘low’ nutrient-use species), using two irrigation methods (drip vs. overhead sprinkler). Nutrients were applied at industry-recommended rates, with incorporated and top dressed controlled release fertilizer averaging 4.3g N and 6.12g N • plant-1, respectively). Supplemental soluble fertilizer (averaging 2.3g N • plant-1) was applied over the first 14 months of the study period. During this period, irrigation method did not affect N uptake within species, although total runoff was over three times higher (averaging 2.50g N vs. 0.74g N) for sprinkler vs. drip blocks. Plant N-uptake efficiencies during this period were between 17.9 and 24.0% for both species. Total N recoveries (plant, substrate and leachate) were between 24.8 and 45.6% for both species and irrigation methods. In a subsequent 12-week azalea study under controlled greenhouse conditions, plant N-uptake efficiencies averaged 15% for plants fertilized with a similar N / P rate (250 mg N • week-1; 25 mg P • week-1). Large fractions of the total N applied were not accounted for by either study, indicating that, while plant N uptake-efficiencies in container production are very low, there may be significant microbial competition for available N in these systems even over short periods of time. | |
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