Field evaluation of a water use model for potatoes

1998 ◽  
Vol 78 (3) ◽  
pp. 441-448 ◽  
Author(s):  
C. F. Shaykewich ◽  
G. H. B. Ash ◽  
R. L. Raddatz ◽  
D. J. Tomasiewicz
Keyword(s):  
Water Use ◽  
Field Data ◽  
Root Zone ◽  
Growth Parameters ◽  
Solanum Tuberosum L ◽  
Ground Cover ◽  
Field Evaluation ◽  
Irrigation Scheduling ◽  
Crop Growth ◽  
Rooting Depth

A water use model for potatoes (Solanum tuberosum L.) was calibrated and tested. The model requires phenological relationships for estimating emergence, degree of crop cover and rooting depth. These weather-driven crop growth functions were previously calibrated using field data from 1994 and 1995. In this paper, the model was tested using field data from the 1996 growing season at two locations. The 1996 crop growth parameters were estimated fairly accurately. This contributed to reasonably accurate (average bias <3 mm, root mean square error <15 mm) root zone available soil water estimates by the model. Thus, the model could be used in irrigation scheduling. Key words: Evapotranspiration, rooting depth, ground cover

scholarly journals Scheduling Irrigations for Carrots

HortScience ◽  
1990 ◽  
Vol 25 (6) ◽  
pp. 641-644 ◽  
Author(s):  
E. Gordon Kruse ◽  
James E. Ells ◽  
Ann E. McSay
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Root Zone ◽  
Agricultural Research ◽  
Irrigation Schedule ◽  
High Water ◽  
Irrigation Scheduling ◽  
Rooting Depth ◽  
Use Efficiency ◽  
Crop Coefficients

A 3-year irrigation scheduling study on carrots (Daucus carota L.) was conducted at the Colorado State Univ. Horticulture Research Center near Fort Collins to determine the irrigation schedule that produced the best combination of high water use efficiency and marketable yields with the least amount of water and fewest irrigations. This study used an irrigation scheduling program developed by the U.S. Department of Agriculture/Agricultural Research Service with crop coefficients calculated for carrots. Maximum carrot production and water use efficiency were obtained when the scheduling program simulated a 30-cm rooting depth at planting, increasing linearly to 60 cm in 75 days. Best yields and water use efficiency were attained by irrigating whenever 40% of the available water in the root zone had been depleted. The computer program for irrigation scheduling is available on diskette from the authors.

scholarly journals Cotton Irrigation Scheduling Using a Crop Growth Model and FAO-56 Methods: Field and Simulation Studies

2017 ◽  
Vol 60 (6) ◽  
pp. 2023-2039 ◽  
Author(s):  
Kelly R. Thorp ◽  
Douglas J. Hunsaker ◽  
Kevin F. Bronson ◽  
Pedro Andrade-Sanchez ◽  
Edward M. Barnes
Keyword(s):  
Soil Moisture ◽  
Water Use ◽  
Root Zone ◽  
Crop Coefficient ◽  
Irrigation Scheduling ◽  
Crop Growth ◽  
Statistical Testing ◽  
Fine Tuning ◽  
Cotton Yield ◽  
Post Hoc

Abstract. Crop growth simulation models can address a variety of agricultural problems, but their use to directly assist in-season irrigation management decisions is less common. Confidence in model reliability can be increased if models are shown to provide improved in-season management recommendations, which are explicitly tested in the field. The objective of this study was to compare the CSM-CROPGRO-Cotton model (with recently updated ET routines) to a well-tested FAO-56 irrigation scheduling spreadsheet by (1) using both tools to schedule cotton irrigation during 2014 and 2015 in central Arizona and (2) conducting a post-hoc simulation study to further compare outputs from these tools. Two replications of each irrigation scheduling treatment and a water-stressed treatment were established on a 2.6 ha field. Irrigation schedules were developed on a weekly basis and administered via an overhead lateral-move sprinkler irrigation system. Neutron moisture meters were used weekly to estimate soil moisture status and crop water use, and destructive plant samples were routinely collected to estimate cotton leaf area index (LAI) and canopy weight. Cotton yield was estimated using two mechanical cotton pickers with differing capabilities: (1) a two-row picker that facilitated manual collection of yield samples from 32 m2 areas and (2) a four-row picker equipped with a sensor-based cotton yield monitoring system. In addition to statistical testing of field data via mixed models, the data were used for post-hoc reparameterization and fine-tuning of the irrigation scheduling tools. Post-hoc simulations were conducted to compare measured and simulated evapotranspiration, crop coefficients, root zone soil moisture depletion, cotton growth metrics, and yield for each irrigation treatment. While total seasonal irrigation amounts were similar among the two scheduling tools, the crop model recommended more water during anthesis and less during the early season, which led to higher cotton fiber yield in both seasons (p &lt; 0.05). The tools calculated cumulative evapotranspiration similarly, with root mean squared errors (RMSEs) less than 13%; however, FAO-56 crop coefficient (Kc) plots demonstrated subtle differences in daily evapotranspiration calculations. Root zone soil moisture depletion was better calculated by CSM-CROPGRO-Cotton, perhaps due to its more complex soil profile simulation; however, RMSEs for depletion always exceeded 20% for both tools and reached 149% for the FAO-56 spreadsheet in 2014. CSM-CROPGRO-Cotton simulated cotton LAI, canopy weight, canopy height, and yield with RMSEs less than 21%, while the FAO-56 spreadsheet had no capability for such outputs. Through field verification and thorough post-hoc data analysis, the results demonstrated that the CSM-CROPGRO-Cotton model with updated FAO-56 ET routines could match or exceed the accuracy and capability of an FAO-56 spreadsheet tool for cotton water use calculations and irrigation scheduling. Keywords: Cottonseed, Crop coefficient, Decision support, Depletion, Evapotranspiration, Fiber, Management, Simulation, Soil moisture, Yield.

Use of geographic information systems and remote sensing as automated tool for variable rate irrigation prescriptions

2019 ◽  
Author(s):  
◽  
Anh Thi Tuan Nguyen
Keyword(s):  
Remote Sensing ◽  
Real Time ◽  
Regression Models ◽  
Field Data ◽  
Irrigation Management ◽  
Irrigation Scheduling ◽  
Crop Growth ◽  
Variable Rate ◽  
Water Application ◽  
Center Pivot

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Economic as well as water shortage pressure on agricultural use of water has placed added emphasis on efficient irrigation management. Center pivot technology has made great improvement with variable rate irrigation (VRI) technology to vary water application spatially and temporally to maximize the economic and environmental return. Proper management of VRI systems depends on correctly matching the pivot application to specific field temporal and areal conditions. There is need for a tool to accurately and inexpensively define dynamic management zones, to sense within-field variability in real time, and control variable rate water application so that producers are more willing to adopt and utilize the advantages of VRI systems. This study included tests of the center pivot system uniformity performance in 2014 at Delta Research Center in Portageville, MO. The goal of this research was to develop MOPivot software with an algorithm to determine unique management areas under center pivot systems based on system design and limitations. The MOPivot tool automates prescriptions for VRI center pivot based on non-uniform water needs while avoiding potential runoff and deep percolation. The software was validated for use in real-time irrigation management in 2018 for VRI control system of a Valley 8000 center pivot planted to corn. The water balance model was used to manage irrigation scheduling. Field data, together with soil moisture sensor measurement of soil water content, were used to develop the regression model of remote sensing-based crop coefficient (Kc). Remote sensing vegetation index in conjunction with GDD and crop growth stages in regression models showed high correlation with Kc. Validation of those regression models was done using Centralia, MO, field data in 2016. The MOPivot successfully created prescriptions to match system capacity of the management zone based on system limitations for center pivot management. Along with GIS data sources, MOPivot effectively provides readily available graphical prescription maps, which can be edited and directly uploaded to a center pivot control panel. The modeled Kc compared well with FAO Kc. By combining GDD and crop growth in the models, these models would account for local weather conditions and stage of crop during growing season as time index in estimating Kc. These models with Fraction of growth (FrG) and cumulative growing degree days (cGDD) had a higher coefficient of efficiency, higher Nash-Sutcliffe coefficient of efficiency and higher Willmott index of agreement. Future work should include improvement in the MOPivot software with different crops and aerial remote sensing imagery to generate dynamic prescriptions during the season to support irrigation scheduling for real-time monitoring of field conditions.

scholarly journals Geophysical Quantification of Water Percolation Quotient in an Alluvial Agricultural Soil

2017 ◽  
Vol 9 (12) ◽  
pp. 54
Author(s):  
Florence Cassel ◽  
Shankar Sharma
Keyword(s):  
Water Use ◽  
Management Practices ◽  
Distribution Patterns ◽  
Water Shortage ◽  
Irrigation Scheduling ◽  
Crop Growth ◽  
Irrigated Agriculture ◽  
Irrigation Planning ◽  
Water Percolation ◽  
Geophysical Surveys

Efficient water use planning is crucial for the sustainability of irrigated agriculture in California, where alluvial geological materials with indigenous salts impinge on crop growth. To facilitate irrigation scheduling and cultivation planning, it is necessary to determine water percolation quotients (WPQ) required for removal of excess salts from the rhizosphere. In order to estimate real-time WPQ, we conducted electromagnetic geophysical surveys at a saline farmland followed by stochastic computations. Results showed a wide variability in salinity that reached 16 dS m-1 in some locations. About 95% of the surveyed samples surpassed 2 dS m-1. Despite spatially dependent asymmetric variability and skewness (-0.13 to 1.90), the WPQ distribution patterns were consistently quantified with low errors (< 0.06). The sensor responses in the fields reached 100% cumulative frequency at a threshold of 13.6 dS m-1. Up to 49% of WPQ data ranged from 0.1 to 0.2. The WPQ decreased with increasing salinity and the zones with low quotient values represented areas where plant growth could be impaired. High WPQ levels demarcated zones with potential solute dissolution and dispersion. Overall, evaluation of WPQ can benefit irrigation planning and crop management practices while enhancing water use efficiency for agricultural production in farms that have been affected by drought and water shortage, and crop growth can be sustained at WPQ level that maintains salts below the crop tolerance threshold.

Soil Water Measurement as Basis to Optimize Irrigation Scheduling: A Review

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 553f-554
Author(s):  
A.K. Alva ◽  
A. Fares
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Real Time ◽  
Soil Water Content ◽  
Root Zone ◽  
Soil Water Potential ◽  
Irrigation Scheduling ◽  
Rooting Depth ◽  
The Impact

Supplemental irrigation is often necessary for high economic returns for most cropping conditions even in humid areas. As irrigation costs continue to increase more efforts should be exerted to minimize these costs. Real time estimation and/or measurement of available soil water content in the crop root zone is one of the several methods used to help growers in making the right decision regarding timing and quantity of irrigation. The gravimetric method of soil water content determination is laborious and doesn't suite for frequent sampling from the same location because it requires destructive soil sampling. Tensiometers, which measure soil water potential that can be converted into soil water content using soil moisture release curves, have been used for irrigation scheduling. However, in extreme sandy soils the working interval of tensiometer is reduced, hence it may be difficult to detect small changes in soil moisture content. Capacitance probes which operate on the principle of apparent dielectric constant of the soil-water-air mixture are extremely sensitive to small changes in the soil water content at short time intervals. These probes can be placed at various depths within and below the effective rooting depth for a real time monitoring of the water content. Based on this continuous monitoring of the soil water content, irrigation is scheduled to replenish the water deficit within the rooting depth while leaching below the root zone is minimized. These are important management practices aimed to increase irrigation efficiency, and nutrient uptake efficiency for optimal crop production, while minimizing the impact of agricultural non-point source pollutants on the groundwater quality.

scholarly journals Model parameters of four important vegetable crops for improved water use and yield estimation

Water SA ◽  
2018 ◽  
Vol 44 (4 October) ◽  
Author(s):  
JT Vahrmeijer ◽  
JG Annandale ◽  
JM Steyn ◽  
KL Bristow
Keyword(s):  
Water Use ◽  
Growth Parameters ◽  
Water Productivity ◽  
Resource Planning ◽  
Crop Growth ◽  
Climatic Conditions ◽  
Model Parameters ◽  
Vegetable Production ◽  
Vegetable Crops ◽  
Wide Range

High-value vegetable crops are typically grown under irrigation to reduce production risk. For water resource planning it is essential to be able to accurately estimate water use of irrigated crops under a wide range of climatic conditions. Crop water use models provide a means to make water use and yield estimates, but need crop- and even cultivar-specific parameters. There is generally a lack of crop-specific model parameters for some important commercially grown vegetable crops, especially parameters determined over both summer and winter seasons. The experimental site used in this study was on the Steenkoppies Aquifer, a catchment under stress and an important vegetable production area in South Africa. Crop-specific growth parameters and water use for 4 selected high-value vegetable crops (beetroot, cabbage, carrots and broccoli) were measured over multiple seasons (two summers and one winter). These were used to parameterise the Soil Water Balance (SWB) generic crop growth model for both summer and winter seasons. In seasons where the same cultivar was planted, a single set of model parameters could be used to successfully simulate crop growth and water use. Results show that the amount of irrigation water required is dependent on season and rainfall, with broccoli having the lowest (1.8–2.7 kg m−3) and beetroot the highest (12.2–23.4 kg m−3) water productivity (WPFM), defined as fresh mass of marketable product per unit water consumed. The root crops had a greater harvest index (HIDM) than cabbage and broccoli. The parameters obtained expand the current database of SWB crop growth parameters for vegetables and can be used in a wide range of mechanistic simulation models to improve water management at field and catchment levels.

Partial Root Zone Drying Application in the Propagation of Vegetable in Northern Nigeria

2011 ◽  
Vol 367 ◽  
pp. 831-838
Author(s):  
Olufemi P. Abimbola ◽  
Temitayo A. Ewemoje
Keyword(s):  
Root System ◽  
Water Use ◽  
Root Zone ◽  
Growth Parameters ◽  
Experimental Period ◽  
Water Requirement ◽  
Crop Water Requirement ◽  
Control Treatment ◽  
Yield Reduction ◽  
Crop Water

This study compares the response of Amaranthus candatus vegetable to root-to-shoot signals of soil drying and assesses applicability of the use of partial root zone drying (PRD) technique in increasing water-use efficiency. From a completely block randomized design, seeds were grown on three plots with each having three replicates. Three treatments were compared: half of the root system watered and half droughted by delivering 50% less crop water requirement (CWR) per irrigation depicted as 50%PRD; both halves of the root system received water application of 50% less crop water requirement per irrigation (50%CWR); while in the control treatment, both halves received 100% crop water requirement (100%CWR). The wetted and dried sides of the root system of 50%PRD were alternated on a 7-day cycle throughout experimental period. Effects of the differences in water-use on growth parameters, such as plant height, stem girth; number of leaves and leaf area were examined. Weights at harvest and root-to-shoot ratios were also compared. Drying half of the root system caused marked declines in all growth parameters in 50%CWR but only slight declines in 50%PRD. Since the main effect of water stress on Amaranthus is yield reduction, achieving better yields requires an optimum water supply from planting until ripening. Average edible wet weights (yields) of the 50%PRD and 50%CWR water applications when compared with the control were 81% and 25% respectively. The higher yield in 50%PRD may be attributed to high stomata sensitivity to drought signaling, as indicated by relatively low root to shoot ratio of 0.33. This lower ratio for 50%PRD treatment, compared to 50%CWR and 100%CWR with 0.40 and 0.66 values, was an indication of healthier and more profitable plants in 50%PRD because the decrease came from a greater shoot size.

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