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Solid set canopy delivery systems (SSCDS) are fixed spray systems that consist of a network of permanently plumbed emitters in high-density tree-fruit orchard canopies. Most of the previously configured SSCDS worked on the principle of hydraulic spray delivery (HSD), which may not be suitable for large-scale installation due to the drop in operating pressure caused by frictional losses in the spray lines. Therefore, a pneumatic spray delivery (PSD) based SSCDS was developed in this study for potentially achieving uniform spray application at all locations along the spray lines. A reservoir subsystem was developed to contain a precisely metered amount of spray liquid. Once filled, compressed air pushed through the spray lines can pressurize the reservoir to help deliver uniform spray into the canopy through emitters. In this study, HSD and PSD systems of 91 m set length were installed in a high-density apple orchard. Both systems were evaluated for variations in operating pressure, spray output, and spray performance. Spray performance was quantified during the middle (BBCH 75) and late (BBCH 85) apple (cv. WA-38 on tall spindle architecture) crop growth stages. Deposition and coverage in three canopy zones and on both sides of leaves were evaluated using Mylar cards and water-sensitive papers (WSP) as samplers, respectively. The Mylar cards and WSP were respectively analyzed using fluorometry and image processing. Statistically similar operating pressure (p > 0.05) was observed for the HSD and PSD systems at 3 m (286.1 and 284.1 kPa, respectively), 33 m (268.4 and 270.5 kPa), 60 m (260.6 and 268.9 kPa), and 87 m (255.3 and 257.9 kPa) from the row inlet. Despite the operating pressure drop, the PSD system had uniform spray output along the 91 m spray line. Compared to the HSD system, about 4%, 3%, 5%, and 20% higher spray output was delivered with the PSD system at 3, 33, 60, and 87 m, respectively, along the spray line. Overall, the PSD system had significantly higher mean spray deposition (p < 0.01) compared to the HSD system during the middle (521 and 382 ng cm-2, respectively) and late (631 and 409 ng cm-2, respectively) growth stages. The PSD system also had numerically higher spray deposition compared to the HSD system for all the canopy zones and on either side of leaf surfaces. Spray coverage trends were similar to deposition; however, the differences were not significant. Overall, the PSD-based SSCDS shows potential for large-scale installation, with additional refinements, for uniform spray applications in high-density apple orchards. [ABSTRACT FROM AUTHOR]

A solid set canopy delivery system (SSCDS) has the potential to be an efficient spraying technique because it minimizes chemical drift and allows timely spray applications even under adverse field conditions. A conventional SSCDS, working as a hydraulic spraying system, is controlled manually. Such operation makes it labor and time intensive for spray application in larger orchards. Therefore, a new hardware and software design was implemented in this project for fieldlevel automation of a conventional SSCDS. An electronic control system (ECS) and a spray control unit (SCU) were developed and integrated with an improvised conventional SSCDS. A graphical user interface (GUI) was developed to provide user inputs to the ECS for valve actuation-based decision making. The SCU consisted of a microcontroller, a relay board, and a radio frequency (RF) module assisting in actuation of the solenoid valves in the desired sequence with commands from the ECS. Integrated RF trans-receiver modules facilitated closed-loop wireless communication between the ECS and SCU. This technical note elaborates on the successful integration of the hardware and software to achieve SSCDS automation and functionality, as well as the performance evaluation in a vineyard. The results confirmed the envisioned triggering sequence and solenoid valve actuation for different operating stages of the SSCDS over 120 m loop length. Moreover, the automated SSCDS had no significant differences in spray volume or pressure along the loop up to 82 m. Overall, the proposed integration will aid in automating SSCDS-based spray operation for larger orchards. To validate such a setup, further studies are planned for a centrally located control station and spraying several adjacent plots at a time. [ABSTRACT FROM AUTHOR]

The use of modeling in an agricultural context under cold climates is challenging because of processes such as freezing, thawing, and snowmelt, which have significant effects on field hydrology. DRAINMOD is one of the most widely used models for design and performance evaluation of drainage systems and has routines that represent cold-region hydrological processes. The objectives of this research were to validate DRAINMOD simulations of water table depth and drainage outflow under conditions prevailing in the Canadian Prairies and to use this model to evaluate the design criteria usually adopted in Manitoba. The dataset from one growing season was used to calibrate the model for water table depth and drainage outflow. Two additional growing seasons of data were used for validation. One year of data was used for model warm-up prior to the calibration year. The Nash-Sutcliffe modeling efficiency (EF) ranged from 0.79 to 0.95 for water table and from 0.60 to 0.70 for drainage outflow simulations. The normalized percent error (NPE) ranged from 3.9% to 14.5% for drainage simulations, while the mean absolute error (MAE) ranged from 4.8 to 9.3 cm for water table simulations. Evaluation of drainage designs suggested for Manitoba using a 20-year dataset indicated that the design criteria generally adopted in this province (i.e., 0.9 m depth and 15 m spacing) need not be widely used across different soil types. For the sandy loam soils used in this study, a maximum drain spacing of 40 m could be used without significant yield losses. Simulated yields were found to be more sensitive to excess moisture conditions at the beginning of the growing season. [ABSTRACT FROM AUTHOR]

Subsurface drainage is used for removing excess water in poorly drained agricultural lands. The performance of subsurface drainage systems varies depending on the soil, crop, and climatic factors. Field evaluation of drainage systems under different field conditions can be costly and time-consuming, necessitating the use of computer models for the design and the evaluation of long-term performance. DRAINMOD is a widely used model for simulating shallow groundwater hydrology in poorly or artificially drained farmlands. The objective of this study was to evaluate DRAINMOD for simulating the hydrology and potato (Solanum tuberosum) crop yield under cold climatic conditions. Data were obtained from a field study that was conducted during 2010 to 2012 in southern Manitoba in a fine sandy loam soil. DRAINMOD calibration and validation were done using data from subsurface-drained plots with drain spacing of 15 m and average drain depth of 1.06 m. Daily subsurface drainage flow, weather parameters, irrigation rate, and water table depth were measured onsite. Subsurface drainage and water table depth were the main variables that were evaluated with DRAINMOD simulations. In general, DRAINMOD predictions of subsurface drainage flow and water table depth were in good agreement with observed values on a daily basis. Statistical parameters showed that DRAINMOD predictions of daily water table depth were more accurate than model predictions of daily drainage flow. The Nash-Sutcliffe modeling efficiency values were in the range of 0.69 to 0.76 for drainage flow and 0.57 to 0.94 for water table depth. The mean absolute error was between 70 and 134 mm for water table depth predictions and between 0.42 and 0.44 mm for drainage flow predictions. The root mean square error was 0.77 to 1.14 mm for drainage flow and 83 to 147 mm for water table depth. DRAINMOD overpredicted potato yield by up to 1%. Based on the results, it is concluded that DRAINMOD predictions of the shallow groundwater hydrology under cold climate were satisfactory. [ABSTRACT FROM AUTHOR]

Subsurface drainage is used for removing excess water from agricultural lands to improve productivity, although it can cause water quality problems downstream. Agricultural drainage is identified as one of the contributing factors to Lake Winnipeg's nutrient enrichment and subsequent water quality deterioration. It has been suggested that controlled drainage in the Lake Winnipeg watershed could be a potential best management practice (BMP). The objective of the study was to evaluate the flow and nutrient export through subsurface drainage by comparing free drainage with overhead irrigation (FDIR) and controlled drainage with subirrigation (CDSI) under potato crop. The experiment was carried out in southern Manitoba in a potato field with sandy loam soil using the same irrigation water source. Subsurface drainage was installed in 2009 at an average design depth of 0.9 m. Controlled drainage was accomplished by using drainage control structures at drainage outlets. Subirrigation was carried out by pumping water back through the subsurface drainage network. Drainage flow, nutrient export, and weather parameters were monitored during the growing seasons of 2010 and 2011. On average, controlled drainage reduced the flow volume by 91% in 2010 and 54% in 2011 compared to free drainage. The drainage volume from FDIR plots ranged from 13% to 53% of the rainfall received, while for CDSI plots it varied from 0% to 8%. In both years, average nitrate concentrations were lower in CDSI compared to FDIR plots. However, average phosphate concentrations were lower in 2010 and higher in 2011 under CDSI compared to FDIR. Compared to FDIR plots, average nitrate-N export from CDSI plots was reduced by 98% in 2010 and 67% in 2011. Average phosphate export was reduced by 94% in 2010; however, in 2011, it was 15% higher than FDIR. The majority of the export happened during the period dominated by heavy drainage outflow, which coincided with spring snowmelt. The nutrient export reduction by CDSI is attributed mainly to the drainage volume reduction by controlled drainage. [ABSTRACT FROM AUTHOR]

High fertilizer inputs and uncontrolled subsurface drainage can result in the export of nutrients from farmland, leading to negative environmental impacts. Controlled drainage can be an effective best management practice to minimize the export of nutrients. However, information about controlled drainage in the Canadian Prairies is scarce. The objective of this study was to compare free drainage with overhead irrigation (FDIR) to controlled drainage with subirrigation (CDSI) in terms of nitrogen, phosphorus, and salt exports from corn fields in the Canadian Prairies. The irrigation water had low concentrations of nitrate (≤0.2 mg L-1) and orthophosphate (<0.1 mg L-1) and low electrical conductivity (0.55 dS m-1), which were assumed to have low influence on the export of nutrients and salts. In 2010, the exports of NO3-N (138 kg ha-1), PO4-P (0.6 kg ha-1), and salts (2.34 Mg ha-1) from the FDIR treatment during the growing season were significantly larger (p < 0.05) than exports from the CDSI treatment, which were 0.07 kg ha-1, 0.08 kg ha-1, and 0.41 Mg ha-1, respectively. This comparison did not include the drainage outflow arising from spring snowmelt due to delays in the installation of monitoring equipment. In 2011, which included the drainage outflow due to spring snowmelt events, the exports of NO3-N (36 kg ha-1), PO4-P (0.27 kg ha-1), and salts (1.1 Mg ha-1) from FDIR were significantly larger (p < 0.05) than the exports from CDSI, which were 10 kg ha-1, 0.08 kg ha-1, and 0.39 Mg ha-1, respectively. Therefore, controlled drainage with subirrigation (CDSI) showed significant reductions in export of NO3-N (71%), PO4-P (69%), and salts (64%) compared to free drainage with overhead irrigation (FDIR). This study shows the advantage of controlled drainage over free drainage in reducing the export of nutrients and salts. [ABSTRACT FROM AUTHOR]

The time domain reflectometry (TDR) method measures soil water content by measuring the dielectric permittivity of the soil using the travel time of an electromagnetic step pulse through a waveguide embedded in the soil. When installing TDR probes at deeper depths, retrieval and re-use is not easy. This study investigated the performance of a multilevel TDR probe created by embedding the waveguide on the outside wall ofa PVC pipe and running the coaxial cable through the interior of the pipe as a way to protect the cable. The length of the stainless steel rod at the center of the probe was 0.06 m, and the stainless steel rod forming the outer loop was 0.063 m long. The rods were embedded in a groove made on one end of the wall of a 0.2 m section of PVC pipe. The ends of the stainless steel rods were directed through the wall to protrude inside the pipe and soldered to the coaxial cable. Fifteen sets of probes were built and tested Several such sections of PVC pipe can be connected in series to create a multilevel probe, which will protect the cables from damage during installation and removal. The reusable multilevel TDR probes were tested in the laboratory and compared with the weighing method. The fitted straight line from the regression analysis between TDR θvv and weighing method θv resulted in good correlation, with R² of 0.89 and 0.97, respectively, for the first and second laboratory experiments. The field experiment gave an R² of 0.51 where it was difficult to maintain good soil contact. This multilevel probe is cost-effective, reusable, and can measure soil water content at many different depths. [ABSTRACT FROM AUTHOR]

In Canada, the Province of Manitoba is the second largest potato producer after Prince Edward Island. Potato is a moisture-sensitive crop, and excess or inadequate soil water content can adversely affect the yield and quality. Potato in Manitoba experiences periods of excess as well as insufficient water content within the soil profile during the growing season. The objective of this study was to compare the effect of four different water management treatments on potato yield in a fine sandy loam soil in southern Manitoba: controlled drainage with subirrigation (CDSI), free drainage with overhead irrigation (FDIR), no drainage with overhead irrigation (NDIR), and no drainage with no irrigation (NDNI). In November 2009, tile drains were installed at a depth of 0.9 m. CDSI was done through drainage control structures with a target water table depth of 0.6 m. Overhead irrigation was done using a traveling gun. Groundwater level drainage discharge, and potato yield data were collected during the 2010 and 2011 growing seasons. In 2010, potato yield was not found to be significantly different between the treatments due to the large variability between the replicates. However, in 2011, potato yield from the FDIR treatment was significantly higher compared to NDNI and CDSI (p <0.05). The NDNI treatment yield was significantly lower (p < 0.05) than the other three treatments. When compared with NDNI, the other treatments showed a yield increase of 15% to 32%. Maintaining adequate soil moisture by overhead irrigation was most effective for increasing potato yield when rainfall is inadequate. [ABSTRACT FROM AUTHOR]

Subsurface drains are commonly used in humid regions to deal with high water tables. However, corn (Zea mays L.) could benefit from subsurface drainage even under semi-arid conditions where high-intensity rainfall causes the water table to rise within the root zone for short periods. In southern Manitoba, seasonally high water tables with high salinity have led to salinization of the root zone, making subsurface drainage an attractive option to increase yields. The objective of this research was to evaluate agronomic performance of corn under water table management using subirrigation and tile drainage. Four treatments were tested in this experiment: (1) controlled drainage with subirrigation (CDSI), (2) no drainage with overhead irrigation (NDIR), (3) free drainage with overhead irrigation (FDIR), and (4) no drainage with no irrigation (NDNI) as control. The impacts of these treatments on crop performance, measured by yield, kernel quality, plant biomass, and plant height, were evaluated over two growing seasons. In the first year, which was 57% wetter than the 30-year average, yields were 8.48 (NDNI), 10.36 (NDIR), 10.10 (FDIR), and 9.22(CDSI) Mg ha-1 with only the mean yield difference for the NDIR and the CDSI treatments being statistically significant (p = 0.014). In the second year, which was 16% drier than normal, yields were 9.25 (NDNI), 10.47 (NDIR), 11.28 (FDIR), and 9.49 (CDSI) Mg ha-1 with no statistically significant differences in yield. [ABSTRACT FROM AUTHOR]