6/10/2020 LESA System Provides Uncertain Efficiency Improvements for Alfalfa Irrigation, Sierra Valley, Sierra Valley Irrigation Tests, 2018 – 2019 Bachand & Associates In collaboration with U.C. Cooperative Extension June 2020 1 Contributors, Collaborators and Cooperators • Contributors and Collaborators • Cooperators • Bachand and Associates • Dan Greenwood / Dave Goodwin • Einen Grandi • Kory Burt, B.S. • Yan Liang, Ph.D. • Sandra Bachand, M.S., M.E., P.E. • Philip Bachand, Ph.D. • UC Cooperative Extension • Tom Getts, M.S. 2 1
6/10/2020 Outline • Pivot Systems – LESA vs Standard • Methods and Results • Applied Irrigation Water as Measured by Standard Flow Meters • Irrigation Efficiency • Soil Moisture • Plant Effects • Summary Goal = Provide Defensible, non ‐ biased assessment of pivot technology LESA 3 Center ‐ Pivot Systems Standard (MESA) – Mid ‐ Elevation Spray Application Standard LESA – Low Elevation Spray Application • Nozzle height and spacing roughly half of Standard • Designed to: • Reduce water loss • Increase irrigation uniformity LESA 4 2
6/10/2020 Flow Meter Totals • Installed on center tower LESA 1000 20 Instantaneous Flow 18 • Measures and records Cumulative Depth 800 16 instantaneous & total flow Irrigation Depth (in) 14 Flow (GPM) 600 12 • Telemetric / cloud ‐ based data 10 storage: 400 8 6 • Protected and secure 200 4 • Real ‐ time 2 • Enables quality control measures and 0 0 6/1/2019 7/1/2019 8/1/2019 9/1/2019 10/1/2019 actions for robust data collection Standard • Total irrigation to Field 1000 Partial cutting 20 mid Sept. 18 • Standardized to Field Area 800 16 Irrigation Depth (in) 14 Flow (GPM) 600 12 10 400 8 6 200 4 2 0 0 6/1/2019 7/1/2019 8/1/2019 9/1/2019 10/1/2019 5 Applied Water (Inches) For First Three Cuttings: Flow Meter Totals 12.9 12 Standard Cutting Dates 𝑀𝐹𝑇𝐵 𝑇𝑢𝑒 � 12 𝑗𝑜𝑑ℎ𝑓𝑡 1. 6/13/19 12.9 𝑗𝑜𝑑ℎ𝑓𝑡 � 93% 2. 7/14/19 LESA 3. 8/13/19 6 3
6/10/2020 Irrigation Efficiency Tests • Performed Three replicates on each field for June and July sampling events • Inches Collected: Catch Can Tests • Inches Applied: Nozzle Flow Tests Inches Collected 7 No Nozzle zzle ‐ ap applie lied Depth Depth • Design Characteristics • Different nozzles for LESA & Standard Systems • Design flows increase further from center by span • Valve Characteristics: Measured vs Design Flows • LESA: Measured typically 15 – 30% above Design • Standard: Measured typically 5 – 13% above Design Inches Applied Measured time to fill 1 gallon, 4 tests per nozzle at 3 places in each span 8 4
6/10/2020 Irrigation Application Efficiency (IAE) ������ ��������� = Irrigation ������ ������� Application Efficiency ����� ��� ����� = ������ ����������� ����� Treatment Mean SD N p<0.05 LESA 0.583 0.267 329 Yes Standard 0.761 0.459 327 Yes 9 Irrigation Application Efficiency Summary Mean +/- 95%CI of Standardized Irrigation Efficiency by Span 1.0 • Lots of variance but… 0.8 • IAE relatively similar 0.6 LESA • Across spans (i.e., 3, 5, 7) 0.4 Irrigation Efficiency (in/in) • Across speeds (i.e, 20, 33, 35, 86) 0.2 0.62 0.62 0.50 • Across months (i.e., June, July) 0.0 1.0 • Mean IAE statistically higher for 0.8 Standard vs LESA (0.76 vs. 0.58) 0.6 Standard 0.4 0.2 0.72 0.70 0.87 0.0 3 5 7 Span 10 5
6/10/2020 Soil Moisture Probes at Test Fields • 3 Moisture Probe Sets Per Treatment • Each Set • Replicates • Six probes at six soil depths: • 6” • 12” • 18” • 24” • 36” • 48” • EC, moisture, temperature • Telemetric 11 Results Cutting 2 Cutting 3 Cutting 1 Soil Moisture 12 6
6/10/2020 • Maximum weekly irrigation approx. 2 inches for each system Results • Top soil layers increase moisture in response Soil Moisture – Upper Root Zone 13 • Lower soil layers showing less obvious affect to irrigation… Results • Though LESA field is in greater general decline than Standard field…. • Soil Moisture – Deeper Root Less likely to recover soil moisture and …. • Suggesting more flow to deeper depths under Standard Zone irrigation 14 7
6/10/2020 Available Water in the Root Zone through Cuttings 1 – 3 Similarities between LESA and Standard • Available Water, Average • Similar at deeper depths • Decreases through the year 6.5 5.9 • Similar end value at end of 5.8 5.7 season 3.8 • Available Water, Variance 3.5 1.9 (Distribution) 2.3 • Increases through season • Higher at shallow depths • Similar for both systems 15 Available Water in the Root Zone through Cuttings 1 – 3 Differences between LESA and Standard • Available Water decreased more across LESA system during the season 6.5 5.9 5.8 5.7 • Change in Mean Available Water Decrease at 0 – 2.5 ft 3.8 • LESA = ‐ 1.9 inches 3.5 1.9 • Standard = ‐ 1.2 inches 2.3 • Change in Mean Available Water Decrease at 2.5 – 4 ft • LESA = ‐ 0.8 • Standard = 0.1 16 8
6/10/2020 Crop Yield – Goodwin Ranch • Yield decreases throughout Yield Measurements by Cutting - Goodwin Ranch 1.7 season 1.6 Mean 1.53 Mean +/- SE 1.5 Mean +/- 95%CI • No significant differences 1.4 1.3 between LESA and Standard for 1.2 Alfalfa Yield (dry tons/acre) 1.11 1.1 each cutting 1.0 1.7 1.6 1.5 1.48 1.4 1.3 1.2 1.13 1.1 1.0 1 3 Goodwin Ranch Cutting 17 Crop Yield – Grandi Ranch Yield Measurements by Cutting - Grandi Ranch 2.6 • Yield decreases throughout Mean 2.4 2.32 Mean +/- SE 2.2 Mean +/- 95%CI season 2.0 1.8 • No significant differences 1.60 1.6 1.4 1.33 Alfalfa Yield (dry ton/acre) between LESA and Standard for 1.2 1.0 each cutting 2.6 2.4 2.18 2.2 2.0 1.8 1.56 1.6 1.37 1.4 1.2 1.0 1 2 3 Grandi Ranch Cutting 18 9
6/10/2020 Nutrient Digestible Fiber for Whole Season - Goodwin Ranch 33.0 33.5 34.0 Hay Quality – Goodwin Ranch NDF (%) 34.5 35.09 35.0 35.29 35.5 36.0 36.5 37.0 • Higher quality hay for both LESA and Mean LESA Standard Mean +/- SE Mean +/- 95%CI Treatment Standard systems Total Disgestible Nutrients for Whole Season - Goodwin Ranch • Low NDF 62.0 • High TDN 61.5 60.88 61.0 60.82 • High RFV TDN (%) 60.5 • No significant differences between 60.0 59.5 systems 59.0 Mean LESA Standard Mean +/- SE Mean +/- 95%CI Treatment Relative Feed Value for Whole Season - Goodwin Ranch 186 184 182 180 Overall Quality 1 Irrigation N 178 RFV 176.8 175.9 176 LESA 9 Premium 174 172 Standard 9 Premium 170 168 1 USDA Hay Quality Categorization Mean LESA Standard Mean +/- SE Mean +/- 95%CI Treatment 19 Nutrient Digestible Fiber, Cuttings 1 & 2 - Grandi Ranch 33 34 35.08 35 Hay Quality – Grandi Ranch NDF (%) 36 37 37.77 38 39 40 Mean • Higher quality hay for Standard vs. LESA Standard Mean +/- SE Mean +/- 95%CI Treatment LESA system Total Digestible Nutrients, Cuttings 1 & 2 - Grandi Ranch 62.0 • Low NDF 61.5 61.0 60.72 • High TDN 60.5 TDN (%) 60.0 59.5 59.20 • High RFV 59.0 58.5 58.0 57.5 • Standard significantly higher quality 57.0 Mean LESA Standard Mean +/- SE Mean +/- 95%CI Treatment Relative Feed Value, Cuttings 1 & 2 - Grandi Ranch 190 185 180 176.4 175 Irrigation N Overall Quality 1 170 RFV 165 LESA 6 Good 160.2 160 Standard 6 Premium 155 150 1 USDA Hay Quality Categorization 145 Mean LESA Standard Mean +/- SE Mean +/- 95%CI Treatment 20 10
6/10/2020 Summary comparison of metrics under LESA and Standard Pivot Systems LESA 3 Standard 3 Metric Notes Irrigation Inches 1 Irrigation 12 12.9 LESA used 7% less water Irrigation Efficiency 58% 76% Std had higher IE but greater variance Soil Average Greater annual decline Lower annual decline Similar overall responses to irrigation upper and lower profiles but Moisture greater seasonal decrease for LESA Variance Similar range Similar range Similar variability across time and across locations Operational Flexibilty Lower Higher Std had greater ability to catch up on water deficit but may have greater likelihood of over watering Yield Goodwin Similar 2 Similar 2 Statistically similar averages, variance and trends across cuttings 2 Grandi Similar 2 Similar 2 Statistically similar averages, variance and trends across cuttings 2 Hay Quality Goodwin Similar 2 Similar 2 Statistically similar averages, variance and trends across cuttings 2 Grandi Lower Higher Not statistically different but generally lower quality across all measures Notes 1. 7% less water under LESA. 2. Statistically different for p<0.05 3 Best Similar Worse , Ranking. 21 Summary – Confounding Factors • Operational • Goodwin fields flooded in 2017 and haven’t fully recovered • Pivot speeds were adjusted throughout the study • Full circle systems keep turning (as on LESA field) whereas half circle needs to be manually reversed (as on Standard field) • Affects water distribution, particularly at the end of a run • Environmental • Soil types differed between fields • Shallow groundwater may have affected soil moisture (capillary pressure) • Experimental • One year, one farm 22 11
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