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Concurrent Evaluation of Agronomic, Economic, and Environmental Aspects of Trickle‐Irrigated Watermelon Production
Author(s) -
Pier J. W.,
Doerge T. A.
Publication year - 1995
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1995.00472425002400010011x
Subject(s) - loam , mathematics , citrullus lanatus , agronomy , environmental science , fertilizer , irrigation , soil water , horticulture , biology , soil science
Abstract Reducing application rates of water and N fertilizers in irrigated cropping systems can lower the potential for N losses, but increases economic risk to producers. A data normalization method and an abstract spatial analysis procedure examined yield, net economic return and unaccounted for N from a subsurface, trickle‐irrigated watermelon [ Citrullus lanatus (Thumb.) Matsum. & Nakai] cropping system in southern Arizona as a function of N and water inputs. Field research was conducted on a Casa Grande sandy loam (fine‐loamy, mixed, hyperthermic Typic Natrargid). A factorial design consisting of four levels of N (60, 216, 315, and 500 kg N ha −1 ) and three average soil water tensions (4, 7, and 17 kPa) resulted in a yield response surface. Watermelon marketable value and costs of water and N inputs were estimated to determine a net return response surface. A N mass balance was calculated by the difference method to estimate post harvest unaccounted for fertilizer N. Predicted maximum marketable yield was 102 Mg ha −1 at 7.2 kPa tension and 336 kg N ha −1 . Predicted maximum net return was $10 819 ha −1 at 10.2 kPa tension and 256 kg applied N ha −1 . Predicted maximum unaccounted for N was 300 kg N ha −1 at 4 kPa tension and 500 kg applied N ha −1 . Normalization and summation of yield, net return and unaccounted for N response variables resulted in a predicted optimum response at 12.6 kPa and 178 kg N ha −1 . The combined response variable was within 95% of this maximum value across the range of 10 to 16 kPa tension and 60 to 300 kg applied N ha −1 . Similarly, spatial analysis of the three response variables indicated 7 to 17 kPa tension and 60 to 315 kg applied N ha −1 would result in yield and net return of >95% of the calculated maxima of marketable yield and net return, while limiting calculated NO 3 − ‐N concentration in soil water draining below the root zone to <10 mg NO − 3 ‐N L −1 . These results suggest that data normalization and abstract spatial analysis are useful in concurrent evaluation of agronomic, economic, and environmental production criteria for subsurface trickle‐irrigated watermelon.