Abstract
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.
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Claims 8
Claim · model-written summary
Predicted maximum watermelon marketable yield was 102 Mg ha −1 at 7.2 kPa and 336 kg N ha −1.
- Taxon
- watermelon
Citrullus lanatuse1 - Treatment
- 336 kg N ha −1e0
- Outcome
- marketable yielde0
- Direction
- maximume0
- Value
- 102 Mg ha −1e0
- Qualifier
- 7.2 kPa tensione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Predicted maximum marketable yield was 102 Mg ha −1 at 7.2 kPa tension and 336 kg N ha −1 .”
e1“watermelon [ Citrullus lanatus (Thumb.) Matsum. & Nakai]”
Claim · model-written summary
Predicted maximum net return was $10 819 ha −1 at 10.2 kPa and 256 kg applied N ha −1.
- Taxon
- watermelonCitrullus lanatuse1
- Treatment
- 256 kg applied N ha −1e0
- Outcome
- net returne0
- Direction
- maximume0
- Value
- $10 819 ha −1e0
- Qualifier
- 10.2 kPa tensione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Predicted maximum net return was $10 819 ha −1 at 10.2 kPa tension and 256 kg applied N ha −1 .”
e1“watermelon [ Citrullus lanatus (Thumb.) Matsum. & Nakai]”
Claim · model-written summary
Predicted maximum unaccounted fertilizer nitrogen was 300 kg N ha −1 at 4 kPa and 500 kg applied N ha −1.
- Taxon
- watermelonCitrullus lanatuse1
- Treatment
- 500 kg applied N ha −1e0
- Outcome
- unaccounted for Ne0
- Direction
- maximume0
- Value
- 300 kg N ha −1e0
- Qualifier
- 4 kPa tensione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Predicted maximum unaccounted for N was 300 kg N ha −1 at 4 kPa tension and 500 kg applied N ha −1 .”
e1“watermelon [ Citrullus lanatus (Thumb.) Matsum. & Nakai]”
Claim · model-written summary
The combined response was optimal at 12.6 kPa and 178 kg N ha −1.
- Taxon
- watermelonCitrullus lanatuse1
- Outcome
- optimum responsee0
- Direction
- optimume0
- Value
- 12.6 kPa and 178 kg N ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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 .”
e1“watermelon [ Citrullus lanatus (Thumb.) Matsum. & Nakai]”
Claim · model-written summary
The combined response stayed within 95% of maximum across 10 to 16 kPa and 60 to 300 kg applied N ha −1.
- Taxon
- watermelonCitrullus lanatuse1
- Outcome
- combined response variablee0
- Value
- 95%e0
- Qualifier
- 10 to 16 kPa tension and 60 to 300 kg applied N ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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 .”
e1“watermelon [ Citrullus lanatus (Thumb.) Matsum. & Nakai]”
Claim · model-written summary
At 7 to 17 kPa and 60 to 315 kg applied N ha −1, predicted yield and net return exceeded 95% of their maxima.
- Taxon
- watermelonCitrullus lanatuse1
- Outcome
- yield and net returne0
- Direction
- >e0
- Value
- >95%e0
- Qualifier
- 7 to 17 kPa tension and 60 to 315 kg applied N ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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”
e1“watermelon [ Citrullus lanatus (Thumb.) Matsum. & Nakai]”
Claim · model-written summary
At 7 to 17 kPa and 60 to 315 kg applied N ha −1, calculated drainage nitrate concentration remained below 10 mg NO − 3 ‐N L −1.
- Taxon
- watermelonCitrullus lanatuse1
- Outcome
- NO 3 − ‐N concentration in soil water draining below the root zonee0
- Direction
- limitinge0
- Value
- <10 mg NO − 3 ‐N L −1e0
- Qualifier
- 7 to 17 kPa tension and 60 to 315 kg applied N ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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 .”
e1“watermelon [ Citrullus lanatus (Thumb.) Matsum. & Nakai]”
Claim · model-written summary
Data normalization and spatial analysis were useful for concurrent evaluation of watermelon production criteria.
- Taxon
- watermelonCitrullus lanatuse0
- Outcome
- useful in concurrent evaluation of agronomic, economic, and environmental production criteriae0
- Comparator
- subsurface trickle‐irrigated watermelone0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“data normalization and abstract spatial analysis are useful in concurrent evaluation of agronomic, economic, and environmental production criteria for subsurface trickle‐irrigated watermelon.”