Border fertigation: field experiments and a simple model |
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Authors: | E Playán J M Faci |
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Institution: | (1) Department of Genetics and Plant Production, Laboratory for Agronomy and the Environment (DGA-CSIC), Estación Experimental de Aula Dei, CSIC, Apdo. 202, E-50080 Zaragoza, Spain Fax: + 34-976/575620 e-mail: playan@eead.csic.es, ES;(2) Department of Soils and Irrigation, Laboratory for Agronomy and the Environment (DGA-CSIC), Servicio de Investigaciòn Agroalimentaria, DGA, Apdo. 727, E-50080 Zaragoza, Spain, ES |
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Abstract: | Fertilizers are commonly dissolved in border irrigation water. However, there are no available procedures for the proper
design and management of surface fertigation. A series of experiments was conducted to determine the uniformity of fertilizer
application under varying inflow discharges and fertilizer application times in blocked-end borders. Results from the fertigation
evaluations showed that the fertilizer distribution uniformity of the low half (DULH) ranged from 2.9 to 51.6%, while water
DULH ranged from 63.5 to 96.9%. A simplified border fertigation model based on one-dimensional convection was formulated and
applied to the simulation of the experiments. The model was able to explain 43.8% of the variability in the fertilizer DULH.
Application of the model to selected case studies revealed that short-duration applications, such as those resulting from
instantaneous release of fertilizer into the irrigation stream, often produce low uniformities. This is particularly true
for early applications in blocked-end borders and for early and late applications in level basins. In both irrigation systems,
application of fertilizer at a constant rate during the entire irrigation event is frequently the best solution. In the presence
of runoff, the model can be used to find a compromise between fertilizer application uniformity and runoff losses. Finally,
if large deep percolation losses are expected, the model can identify uniform fertigation options based on late applications
of fertilizer.
Received: 8 August 1996 |
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