scholarly journals Feasibility of Moderate Deficit Irrigation as a Water Conservation Tool in California’s Low Desert Alfalfa

Agronomy ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1640
Author(s):  
Ali Montazar ◽  
Oli Bachie ◽  
Dennis Corwin ◽  
Daniel Putnam
Keyword(s):  
Soil Moisture ◽  
Irrigation Water ◽  
Water Conservation ◽  
Deficit Irrigation ◽  
Dry Matter ◽  
Yield Reduction ◽  
Dry Matter Yield ◽  
Water Deficits ◽  
Wide Range ◽  
Irrigation Practices

Irrigation management practices that reduce water use with acceptable impacts on yield are important strategies to cope with diminished water supplies and generate new sources of water to transfer for other agricultural uses, and urban and environmental demands. This study was intended to assess the effects of moderate water deficits, with the goal of maintaining robust alfalfa (Medicago sativa L.) yields, while conserving on-farm water. Data collection and analysis were conducted at four commercial fields over an 18-month period in the Palo Verde Valley, California, from 2018–2020. A range of deficit irrigation strategies, applying 12.5–33% less irrigation water than farmers’ normal irrigation practices was evaluated, by eliminating one to three irrigation events during selected summer periods. The cumulative actual evapotranspiration measured using the residual of energy balance method across the experimental sites, ranged between 2,031 mm and 2.202 mm, over a 517-day period. An average of 1.7 and 1.0 Mg ha−1 dry matter yield reduction was observed under 33% and 22% less applied water, respectively, when compared to the farmers’ normal irrigation practice in silty loam soils. The mean dry matter yield decline varied from 0.4 to 0.9 Mg ha−1 in a clay soil and from 0.3 to 1.0 Mg ha−1 in a sandy loam soil, when irrigation water supply was reduced to 12.5% and 25% of normal irrigation levels, respectively. A wide range of conserved water (83 to 314 mm) was achieved following the deficit irrigation strategies. Salinity assessment indicated that salt buildup could be managed with subsequent normal irrigation practices, following deficit irrigations. Continuous soil moisture sensing verified that soil moisture was moderately depleted under deficit irrigation regimes, suggesting that farmers might confidently refill the soil profile following normal practices. Stand density was not affected by these moderate water deficits. The proposed deficit irrigation strategies could provide a reliable amount of water and sustain the economic viability of alfalfa production. However, data from multiple seasons are required to fully understand the effectiveness as a water conservation tool and the long-term impacts on the resilience of agricultural systems.

scholarly journals Effect of Deficit Irrigation on Nitrogen Uptake of Sunflower in the Low Desert Region of California

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2340 ◽  
Author(s):  
Mohamed Galal Eltarabily ◽  
John M. Burke ◽  
Khaled M. Bali
Keyword(s):  
Soil Moisture ◽  
Irrigation Water ◽  
Soil Profile ◽  
Deficit Irrigation ◽  
Crop Production ◽  
N Uptake ◽  
Sprinkler Irrigation ◽  
Growing Season ◽  
Total N ◽  
Irrigation Practices

Nitrogen (N) accounts for more than 80% of the total mineral nutrients absorbed by plants and it is the most widely limiting element for crop production, particularly under water deficit conditions. For a comprehensive understanding of sunflower Helianthus annuus N uptake under deficit irrigation conditions, experimental and numerical simulation studies were conducted for full (100% ETC) and deficit (65% ETC) irrigation practices under the semi-arid conditions of the Imperial Valley, California, USA. Plants were established with overhead sprinkler irrigation before transitioning to subsurface drip irrigation (SDI). Based on pre-plant soil N testing, 39 kg ha−1 of N and 78 kg ha−1 of P were applied as a pre-plant dry fertilizer in the form of monoammonium phosphate (MAP) and an additional application of 33 kg ha−1 of N from urea ammonium nitrate (UAN-32) liquid fertilizer was made during the growing season. Soil samples at 15-cm depth increments to 1.2 m (8 layers, 15 cm each) were collected prior to planting and at three additional time points from two locations each in the full and deficit irrigation treatments. We used HYDRUS/2D for the simulation in this study and the model was calibrated for the soil moisture parameters (θs and θr), the rate constant factors of nitrification (the sensitive parameter) in the liquid and solid states (μw,3, and μs,3). The HYDRUS model predicted cumulative root water uptake fluxes of 533 mm and 337 mm for the 100% ETC and 65% ETC, respectively. The simulated cumulative drainage depths were 23.7 mm and 20.4 mm for the 100% ETC and 65% ETC which represented only 4% and 5% of the applied irrigation water, respectively. The soil wetting profile after SDI irrigation was mostly around emitters for the last four SDI irrigation events, while the maximum values of soil moisture in the top 30 cm of the soil profile were 0.262 cm3 cm−3 and 0.129 cm3 cm−3 for 100% ETC and 65% ETC, respectively. The 16.5 kg ha−1 (NH2)2CO (50% of the total N) that was applied during the growing season was completely hydrolyzed to NH4+ within 7 days of application, while 4.36 mg cm−1 cumulative decay was achieved by the end of the 98-day growing season. We found that 86% of NH4+ (74.25 mg cm−1) was nitrified to NO3− while 14% remained in the top 50 cm of the soil profile. The denitrification and free drainage of NO3− were similar for 100% ETC and 65% ETC, and the maximum nitrate was drained during the sprinkler irrigation period. By the end of the growing season, 30.8 mg cm−1 of nitrate was denitrified to N2 and the reduction of nitrate plant uptake was 17.1% for the deficit irrigation section as compared to the fully irrigated side (19.44 mg cm−1 vs. 16.12 mg cm−1). This reduction in N uptake due to deficit irrigation on sunflower could help farmers conserve resources by reducing the amount of fertilizer required if deficit irrigation practices are implemented due to the limited availability of irrigation water.

scholarly journals Impact of Deficit Irrigation on Shallow Saline Groundwater Contribution and Sunflower Productivity in the Imperial Valley, California

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 571
Author(s):  
Mohamed Galal Eltarabily ◽  
John M. Burke ◽  
Khaled M. Bali
Keyword(s):  
Irrigation Water ◽  
Deficit Irrigation ◽  
Growing Season ◽  
Yield Reduction ◽  
Growth Stages ◽  
Crop Evapotranspiration ◽  
Imperial Valley ◽  
Saline Groundwater ◽  
Irrigation Treatments ◽  
Groundwater Contribution

Yield and production functions of sunflower (Helianthus annuus) were evaluated under full and deficit irrigation practices with the presence of shallow saline groundwater in a semi-arid region in the Imperial Valley of southern California, USA. A growing degree day (GDD) model was utilized to estimate the various growth stages and schedule irrigation events throughout the growing season. The crop was germinated and established using overhead irrigation prior to the use of a subsurface drip irrigation (SDI) system for the remainder of the growing season. Four irrigation treatments were implemented: full irrigation (100% full sunflower crop evapotranspiration, ETC), two reduced irrigation scenarios (95% ETC and 80% ETC), and a deficit irrigation scenario (65% ETC). The salinity of the irrigation water (EC) (Colorado River water) was nearly constant at 1.13 dS·m−1 during the growing season. The depth to groundwater and groundwater salinity (ECGW) were continuously monitored in five 3 m deep observation wells. Depth to groundwater fluctuated slightly under the full and reduced irrigation treatments, but drastically increased under deficit irrigation, particularly toward the end of the growing season. Estimates of ECGW ranged from 7.34 to 12.62 dS·m−1. The distribution of soil electrical conductivity (ECS) and soil matric potential were monitored within the active root zone (120 cm) at selected locations in each of the four treatments. By the end of the experiment, soil salinity (ECS) across soil depths ranged from 1.80 to 6.18 dS·m−1. The estimated groundwater contribution to crop evapotranspiration was 9.03 cm or approximately 16.3% of the ETC of the fully irrigated crop. The relative yields were 91.8%, 82.4%, and 83.5% for the reduced (95% and 80% ETC) and deficit (65% ETC) treatments, respectively, while the production function using applied irrigation water (IW) was: yield = 0.0188 × (IW)2 − 15.504 × IW + 4856.8. Yield reduction in response to water stress was attributed to a significant reduction in both seed weight and the number of seed produced resulting in overall average yields of 2048.9, 1879.9, 1688.1, and 1710.3 kg·ha−1 for the full, both reduced, and deficit treatments, respectively. The yield response factor, ky, was 0.63 with R2 = 0.745 and the irrigation water use efficiencies (IWUE) were 3.70, 3.57, 3.81, and 4.75 kg·ha−1·mm−1 for the full, reduced, and deficit treatments, respectively. Our results indicate that sunflowers can sustain the implemented 35% deficit irrigation with root water uptake from shallow groundwater in arid regions with a less than 20% reduction in yield.

The effects of frequency of defoliation on the yield response of a perennial ryegrass sward to a wide range of nitrogen application rates

1978 ◽  
Vol 90 (3) ◽  
pp. 447-457 ◽  
Author(s):  
D. Reid
Keyword(s):  
Perennial Ryegrass ◽  
Dry Matter ◽  
Total Yield ◽  
Response Surfaces ◽  
Yield Response ◽  
Dry Matter Yield ◽  
Nitrogen Application ◽  
Nitrogen Rate ◽  
Wide Range ◽  
Cutting Frequency

SummaryIn a 3-year experiment on a sward of S. 23 perennial ryegrass 21 rates of nitrogen fertilizer ranging from 0 to 897 kg/ha were applied annually on plots cut three, five or ten times per year. The cutting dates within each frequency were decided on the basis of herbage growth stage. Four-parameter exponential curves fitted to the herbage yield data show that the pattern of response to nitrogen application in the five cuts per year treatment was markedly similar to that reported for a previous experiment (Reid, 1970). Alterations in the cutting frequency affected the pattern of dry-matter yield response to nitrogen, but not that of crude-protein yield response. The combined effects of cutting frequency and nitrogen rate are illustrated by response surfaces fitted to the dry-matter yield results using an extension of the equation for the curves fitted to the individual frequency results. These surfaces show that as the number of cuts per year was increased the total yield and the response to nitrogen decreased, but the response was maintained to an increasingly high nitrogen rate. The practical implications of the results are discussed in relation to intensive grazing managements for dairy cows.

A comparison of the yield responses of four grasses to a wide range of nitrogen application rates

1985 ◽  
Vol 105 (2) ◽  
pp. 381-387 ◽  
Author(s):  
D. Reid
Keyword(s):  
Dry Matter ◽  
Growth Curves ◽  
Yield Response ◽  
Dry Matter Yield ◽  
Meadow Fescue ◽  
Nitrogen Rate ◽  
Yield Data ◽  
Wide Range ◽  
Yield Responses ◽  
Nitrogen Rates

SUMMARYThe yield results are reported for an experiment in which 21 rates of nitrogen fertilizer were applied on pure-sown swards of four grasses, S. 24 and Barvestra perennial ryegrass, S. 37 cocksfoot and S. 53 meadow fescue. Growth curves fitted to the herbage yield data for each grass in each year are presented. On average the total dry-matter yield curves for the two ryegrasses were similar to one another, but showed a slightly smaller response to nitrogen rates below 300 kg/ha than did S. 23 ryegrass in an earlier experiment, and a more rapid decrease in response at higher rates. S. 37 cocksfoot had a similar dry-matter yield response to the ryegrasses at the low nitrogen rates, but the response decreased more rapidly at nitrogen rates over 250 kg/ha. The dry-matter yield response of S. 53 fescue decreased even more rapidly with nitrogen rates over 200 kg/ha. The mean estimates of the optimal nitrogen rate for each of the four grasses, i.e. the nitrogen rate at which the dry-matter response had decreased to 10 kg/kg N, was 380, 372, 357 and 327 kg N/ha for S. 24, Barvestra, S. 37 and S. 53 respectively, compared with 409 kg/ha for S. 23 ryegrass in the earlier experiment.

scholarly journals Estimating irrigation water use over the contiguous United States by combining satellite and reanalysis soil moisture data

2018 ◽  
Author(s):  
Felix Zaussinger ◽  
Wouter Dorigo ◽  
Alexander Gruber ◽  
Angelica Tarpanelli ◽  
Paolo Filippucci ◽  
...  
Keyword(s):  
Water Management ◽  
United States ◽  
Soil Moisture ◽  
Water Use ◽  
Irrigation Water ◽  
Soil Layer ◽  
Data Set ◽  
Soil Moisture Data ◽  
Irrigation Water Use ◽  
Irrigation Practices

Abstract. Effective agricultural water management requires accurate and timely information on the availability and use of irrigation water. However, most existing information on irrigation water use (IWU) lacks the objectivity and spatio-temporal representativeness needed for operational water management and meaningful characterisation of land-climate interactions. Although optical remote sensing has been used to map the area affected by irrigation, it does not physically allow for the estimation of the actual amount of irrigation water applied. On the other hand, microwave observations of the moisture content in the top soil layer are directly influenced by agricultural irrigation practices, and thus potentially allow for the quantitative estimation of IWU. In this study, we combine surface soil moisture retrievals from the spaceborne SMAP, AMSR2, and ASCAT microwave sensors with modelled soil moisture from MERRA-2 reanalysis to derive monthly IWU dynamics over the contiguous United States (CONUS) for the period 2013–2016. The methodology is driven by the assumption that the hydrology formulation of the MERRA-2 model does not account for irrigation, while the remotely sensed soil moisture retrievals do contain an irrigation signal. For many CONUS irrigation hot spots, the estimated spatial irrigation patterns show good agreement with a reference data set on irrigated areas. Moreover, in intensively irrigated areas, the temporal dynamics of observed IWU is meaningful with respect to ancillary data on local irrigation practices. State-aggregated mean IWU volumes derived from the combination of SMAP and MERRA-2 soil moisture show a good correlation with statistically reported state-level irrigation water withdrawals but systematically underestimate them. We argue that this discrepancy can be mainly attributed to the coarse spatial resolution of the employed satellite soil moisture retrievals, which fails to resolve local irrigation practices. Consequently, higher resolution soil moisture data are needed to further enhance the accuracy of IWU mapping.

scholarly journals Estimating irrigation water use over the contiguous United States by combining satellite and reanalysis soil moisture data

2019 ◽  
Vol 23 (2) ◽  
pp. 897-923 ◽  
Author(s):  
Felix Zaussinger ◽  
Wouter Dorigo ◽  
Alexander Gruber ◽  
Angelica Tarpanelli ◽  
Paolo Filippucci ◽  
...  
Keyword(s):  
Water Management ◽  
United States ◽  
Soil Moisture ◽  
Water Use ◽  
Irrigation Water ◽  
Soil Layer ◽  
Data Set ◽  
Soil Moisture Data ◽  
Irrigation Water Use ◽  
Irrigation Practices

Abstract. Effective agricultural water management requires accurate and timely information on the availability and use of irrigation water. However, most existing information on irrigation water use (IWU) lacks the objectivity and spatiotemporal representativeness needed for operational water management and meaningful characterization of land–climate interactions. Although optical remote sensing has been used to map the area affected by irrigation, it does not physically allow for the estimation of the actual amount of irrigation water applied. On the other hand, microwave observations of the moisture content in the top soil layer are directly influenced by agricultural irrigation practices and thus potentially allow for the quantitative estimation of IWU. In this study, we combine surface soil moisture (SM) retrievals from the spaceborne SMAP, AMSR2 and ASCAT microwave sensors with modeled soil moisture from MERRA-2 reanalysis to derive monthly IWU dynamics over the contiguous United States (CONUS) for the period 2013–2016. The methodology is driven by the assumption that the hydrology formulation of the MERRA-2 model does not account for irrigation, while the remotely sensed soil moisture retrievals do contain an irrigation signal. For many CONUS irrigation hot spots, the estimated spatial irrigation patterns show good agreement with a reference data set on irrigated areas. Moreover, in intensively irrigated areas, the temporal dynamics of observed IWU is meaningful with respect to ancillary data on local irrigation practices. State-aggregated mean IWU volumes derived from the combination of SMAP and MERRA-2 soil moisture show a good correlation with statistically reported state-level irrigation water withdrawals (IWW) but systematically underestimate them. We argue that this discrepancy can be mainly attributed to the coarse spatial resolution of the employed satellite soil moisture retrievals, which fails to resolve local irrigation practices. Consequently, higher-resolution soil moisture data are needed to further enhance the accuracy of IWU mapping.

Growth and chemical composition of Townsville lucerne (Stylosanthes humilis). 1. Dry matter yield and nitrogen content in response to superphosphate

1966 ◽  
Vol 6 (21) ◽  
pp. 150 ◽  
Author(s):  
NH Shaw ◽  
CT Gates ◽  
JR Wilson
Keyword(s):  
Nitrogen Content ◽  
Dry Matter ◽  
Nutrient Deficiency ◽  
Dry Weight ◽  
Pot Experiment ◽  
Minor Role ◽  
Dry Matter Yield ◽  
Nutritional Conditions ◽  
Wide Range ◽  
A Minor

In a field experiment on a solodic soil, applications of superphosphate, in the presence of molybdenum, increased the dry matter yield of S. humilis H.B.K. from 2,450 to 5,800 lb an acre, and increased the relative nitrogen content from 2.36 to 3.28 per cent. When this result was examined under more closely controlled conditions in a pot experiment, using the constituent elements of molybdenized superphosphate, it was found that the combination of phosphorus and sulphur produced the greatest dry weight and nitrogen responses. Nevertheless, substantial increases in dry weight of plant tops were obtained with added phosphorus in the absence of sulphur, although the relative nitrogen content of this dry matter was low unless sulphur was also present. There was a small response to molybdenum in this experiment, but calcium played only a minor role. In the pot experiment three replicates were placed in a glasshouse, and one under a light bank in a growth room. Plants grew faster and gave higher dry matter and nitrogen yields under the light bank than in the glasshouse. Attention is drawn to the adaptability that S. humilis displays to a wide range of nutritional conditions, and it is suggested that both the yield and nitrogen content of this legume are probably being limited by nutrient deficiency in most areas of northern Australia where it is being grown.

The effect of rejuvenation of Aspen Parkland ecoregion grass–legume pastures on dry matter yield and forage quality

2000 ◽  
Vol 80 (4) ◽  
pp. 781-791 ◽  
Author(s):  
H. A. Lardner ◽  
S. B. M. Wright ◽  
R. D. H. Cohen ◽  
P. Curry ◽  
L. MacFarlane
Keyword(s):  
Dry Matter ◽  
Forage Quality ◽  
Fertilizer Application ◽  
High Rate ◽  
Dry Matter Yield ◽  
Liquid Form ◽  
Liquid Fertilizer ◽  
Wide Range ◽  
Aspen Parkland ◽  
Split Plot

A 3-yr study was conducted on Black and Gray Wooded soils at five different sites in the Aspen Parkland of Saskatchewan to determine the effect of spiking, burning, mowing, deep-banding (Trt) and applications of N, P, K and S liquid and granular fertilizers (Fert) on dry matter yield (DMY) and forage quality of primarily smooth bromegrass (Bromus inermis Leyss.) and alfalfa (Medicago sativa L.) pastures. Fertilizer application was a liquid form blended to provide 100 kg N ha–1, 45 kg P2O5 ha–1, 23 kg K2O ha–1 and 12 kg S ha–1 in 350 kg of fertilizer ha–1. The experimental design at each site was a randomized complete block in a split-plot arrangement. Main plots were spike, burn, mow, deep-band, deep-band liquid fertilizer and control. The split-plot treatment was granular fertilizer broadcast at 0 and 350 kg ha−1 (providing 100 kg N ha−1, 45 kg P2O5 ha−1, 23 kg K2O ha–1 and 12 kg S ha−1). All treatments were applied in the spring of 1994. Interaction effects of Trt × Yr and Fert × Yr were significant (P < 0.05) indicating a wide range of response to the rejuvenation methods among years. Spiking reduced (P < 0.05) DMY in year 1 at two sites. Deep-banding and mowing increased (P < 0.05) DMY at one site in year 3. Burning increased (P < 0.05) DMY in years 1 and 2 only at the Gray Wooded soil site. In year 1, liquid plus granular fertilizer (200 kg N ha–1) [deep-banded liquid fertilizer (DBLIQ at 100 kg N ha−1) + broadcast fertilizer (+F at 100 kg N ha−1] increased DMY at all sites by 84 to 185% over control plots. This effect carried over (P < 0.05) into year 2 at four sites but not the third and final year. The high rate of N (200 kg N ha−1) of the DBLIQ + F almost doubled (P < 0.05) crude protein content of year 1 forage, 170.3 g kg−1 compared with 96.4 g kg–1 for control. It was concluded that an application of broadcast or liquid fertilizer alone or combined with mechanical treatments will produce a significant effect on herbage yield and quality but only in the short term. Key words: Rejuvenation, fertilizer, spike, burn, deep-band, quality

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