Estimating spatially explicit irrigation water use based on remotely sensed evapotranspiration and modeled root zone soil moisture

Author(s):  
Caijin Zhang ◽  
Di Long
2021 ◽  
Vol 64 (1) ◽  
pp. 287-298
Author(s):  
Ruixiu Sui ◽  
Jonnie Baggard

HighlightsWe developed and evaluated a variable-rate irrigation (VRI) management method for five crop years in the Mississippi Delta.VRI management significantly reduced irrigation water use in comparison with uniform-rate irrigation (URI). There was no significant difference in grain yield and irrigation water productivity between VRI and URI management.Soil apparent electrical conductivity (ECa) was used to delineate irrigation management zones and generate VRI prescriptions.Sensor-measured soil water content was used in irrigation scheduling.Abstract. Variable-rate irrigation (VRI) allows producers to site-specifically apply irrigation water at variable rates within a field to account for the temporal and spatial variability in soil and plant characteristics. Developing practical VRI methods and documenting the benefits of VRI application are critical to accelerate the adoption of VRI technologies. Using apparent soil electrical conductivity (ECa) and soil moisture sensors, a VRI method was developed and evaluated with corn and soybean for five crop years in the Mississippi Delta. Soil ECa of the study fields was mapped and used to delineate VRI management zones and create VRI prescriptions. Irrigation was scheduled using soil volumetric water content measured by soil moisture sensors. A center pivot VRI system was employed to deliver irrigation water according to the VRI prescription. Grain yield, irrigation water use, and irrigation water productivity in the VRI treatment were determined and compared with that in a uniform-rate irrigation (URI) treatment. Results showed that the grain yield and irrigation water productivity between the VRI and URI treatments were not statistically different with both corn and soybean crops. The VRI management significantly reduced the amount of irrigation water by 22% in corn and by 11% in soybean (p = 0.05). Adoption of VRI management could improve irrigation water use efficiency in the Mississippi Delta. Keywords: Soil electrical conductivity, Soil moisture sensor, Variable rate irrigation, Water management.


2020 ◽  
Vol 12 (15) ◽  
pp. 5989 ◽  
Author(s):  
Sisay A. Belay ◽  
Tewodros T. Assefa ◽  
P. V. Vara Prasad ◽  
Petra Schmitter ◽  
Abeyou W. Worqlul ◽  
...  

Smallholder agriculture constitutes the main source of livelihood for the Ethiopian rural community. However, soil degradation and uneven distribution of rainfall have threatened agriculture at present. This study is aimed at investigating the impacts of conservation agriculture on irrigation water use, nutrient availability in the root zone, and crop yield under supplementary irrigation. In this study, conservation agriculture (CA), which includes minimum soil disturbance, grass mulch cover, and crop rotation, was practiced and compared with conventional tillage (CT). We used two years’ (2018 and 2019) experimental data under paired-t design in the production of a local variety green pepper (Capsicum annuum L.). The results showed that CA practices significantly (α = 0.05) reduced irrigation water use (13% to 29%) and runoff (29% to 51%) while it increased percolated water in the root zone (27% to 50%) when compared with CT practices under the supplementary irrigation phase. In addition, CA significantly decreased NO3-N in the leachate (14% to 44%) and in the runoff (about 100%), while PO4-P significantly decreased in the leachate (33% to 50%) and in the runoff (16%) when compared with CT. Similarly, CA decreased the NO3-N load in the leachate and in the runoff, while the PO4-P load increased in the leachate but decreased in the runoff. The yield return that was achieved under CA treatment was 30% higher in 2018 and 10% higher in 2019 when compared with the CT. This research improves our understanding of water and nutrient dynamics in green pepper grown under CA and CT. Use of CA provides opportunities to optimize water use by decreasing irrigation water requirements and optimize nutrient use by decreasing nutrient losses through the runoff and leaching.


2018 ◽  
Author(s):  
Felix Zaussinger ◽  
Wouter Dorigo ◽  
Alexander Gruber ◽  
Angelica Tarpanelli ◽  
Paolo Filippucci ◽  
...  

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.


2019 ◽  
Vol 23 (2) ◽  
pp. 897-923 ◽  
Author(s):  
Felix Zaussinger ◽  
Wouter Dorigo ◽  
Alexander Gruber ◽  
Angelica Tarpanelli ◽  
Paolo Filippucci ◽  
...  

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.


2020 ◽  
Vol 14 (3) ◽  
pp. 393-401
Author(s):  
Germán Eduardo Cely-Reyes ◽  
Karen Victoria Suárez-Parra ◽  
Rosalina González-Forero

The bulb onion is one of the most important agricultural products in Colombia. The productive conditions of the Riego del Alto Chicamocha (Boyaca) district are a regional and national benchmark for this market. The objective of this research was to evaluate four irrigation regimes in terms of production and irrigation water efficiency in bulb onion crops. This trial was in the municipality of Nobsa, village of Dicho (Boyaca). A completely randomized design with four treatments was used: irrigation regime with 150% evapotranspiration (Evt); moisture-based irrigation regime, detected with soil moisture sensors; irrigation regime with 100% Evt; irrigation regime with 60% Evt, along with four repetitions. Starting three weeks after transplant and for 11 weeks (77 days), the polar diameter (cm), equatorial diameter (cm), root length (cm), leaf length (cm), SPAD units, stomatal conductance and irrigation water use efficiency were determined. The irrigation regime with 100% Evt had the best performance in terms of the polar and equatorial diameters and the root and leaf lengths, which were reflected in the fresh weight at harvest. The irrigation regime with soil moisture values obtained from remote sensors, with lower amounts of applied water, had better values for the transformation of water to fresh mass, with 13.64 kg mm-1.


Author(s):  
R.J. Paton ◽  
P.B. Greenwood

Pasture production and irrigation water-use efficiencies were measured for 3 irrigation regimes on a Mackenzie shallow, stony soil in the Mackenzie Basin near Omarama. Irrigating at 25% was the most efficient of three irrigation frequencies maintained over the 198 1-1986 period (irrigated at O%, 25%, and 50% plant-available water capacity). Less frequent irrigation resulted in lower pasture yields due to increased water stress, while more frequent watering resulted in a 55% drainage loss of irrigation water below the root zone. At 1.16 t DIvUha per irrigation, the increase in pasture yield with irrigation at 25% was higher than most increases achieved in existing irrigation schemes in Central Otago and mid Canterbury. Over 6 years, this treatment required 4-7 irrigations annually and, on average, produced 6.0 t DM/ha more than did dryland pasture. The water-use efficiencies achieved in the border-strip irrigation system used were generally greater than expected for highly permeable stony soils where large drainage losses of irrigation water below the root zone are common. This was the result of reduced soil water transmission rates after compaction by heavy machinery during border strip* preparation. That effect of compaction was persistent, and had not diminished 9 years after initial pasture and irrigation development, as structural improvement of this soil is slow, even under irrigation. Keywords: high country pasture, irrigation, Mackenzie Basin


2019 ◽  
Vol 11 (11) ◽  
pp. 3670-3690 ◽  
Author(s):  
R. Abolafia‐Rosenzweig ◽  
B. Livneh ◽  
E.E. Small ◽  
S.V. Kumar

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