บทคัดย่องานวิจัย

หมวดหมู่ : ฐานข้อมูลงานวิจัย

Concurrent evaluation of agronomic, economic, and environmental aspects of trickle-irrigated watermelon production.

Pier, J. W.; Doerge, T. A.;

Journal of Environmental Quality Year: 1995 Vol: 24 Issue: 1 Pages: 79-86 Ref: 32 ref.

1995

บทคัดย่อ

Concurrent evaluation of agronomic, economic, and environmental aspects of trickle-irrigated watermelon production.

 

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 cv. Mirage 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 N rates of 60, 216, 315 and 500 kg N/ha and average soil water tensions of 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. An N mass balance was calculated by the difference method to estimate postharvest unaccounted-for fertilizer N. Predicted maximum marketable yield was 102 t/ha at 7.2 kPa tension and 336 kg N/ha.

Predicted maximum net return was $10819/ha at 10.2 kPa tension and 256 kg applied N/ha. Predicted maximum unaccounted-for N was 300 kg N/ha at 4 kPa tension and 500 kg applied N/ha. 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. The combined response variable was within 95% of this maximum value across the range 10-16 kPa tension and 60-300 kg applied N/ha. Similarly, spatial analysis of the 3 response variables indicated 7-17 kPa tension and 60-315 kg applied N/ha would result in yield and net return of >95% of the calculated maxima of marketable yield and net return, while limiting calculated NO3--N concentration in soil water draining below the root zone to <10 mg NO3--N/litre. 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.