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Subsurface Drip Irrigation and Fertigation of Broccoli
Author(s) -
Thompson Thomas L.,
Doerge Thomas A.,
Godin Ronald E.
Publication year - 2002
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2002.1780
Subject(s) - fertigation , fertilizer , drip irrigation , environmental science , irrigation , agronomy , growing season , mathematics , hydrology (agriculture) , biology , geotechnical engineering , engineering
Subsurface drip irrigation offers potential for increased water and N fertilizer use efficiency, and decreased groundwater NO 3 pollution. Replicated factorial experiments consisting of four rates of N fertilizer application (60–500 kg ha −1 ) and three target soil water tensions (SWT) (low, medium, and high) were conducted on subsurface drip‐irrigated broccoli ( Brassica olearacea L. Italica ) during three winter growing seasons in southern Arizona. Objectives were to (i) determine effects and interactions of irrigation water and N inputs on net economic return, residual soil NO 3 ‐N, and unaccounted fertilizer N, and (ii) use abstract spatial analysis techniques to simultaneously evaluate agronomic, economic, and environmental production functions during three growing seasons. Spatial analysis was used to identify overlap of acceptable zones of marketable yield, net return, and unaccounted fertilizer N. Acceptable yields and net return were defined as ≥95% of maximum predicted response within the range of the treatments, and acceptable unaccounted fertilizer N was defined as ≤40 kg ha −1 During this study, >95% of maximum net return encompassed N rates of 300 to 500 kg ha −1 , and SWTs of 7 to 25 kPa. There was little accumulation of NO 3 in the top 0.9 m of soil when ≤350 kg N ha −1 were applied. Unaccounted N increased with excessive N and water inputs, and accounted for as much as 46% of N applied. Overlap of acceptable zones of agronomic, economic, and environmental production criteria was achieved in each year. Areas of overlap were bounded by 300 to 325 kg N ha −1 and 8.5 to 12 kPa in 1993–1994, 350 to 500 kg N ha −1 and 11 to 14 kPa in 1994–1995, and 340 to 410 kg N ha −1 and 11 to 24 kPa in 1995–1996.