Central Nova Scotia Research Articles

Evaluation of dichlobenil for hair fescue (Festuca filiformis Pourr.) management in wild blueberry (Vaccinium angustifolium Ait.)

AbstractHair fescue is an economically destructive, tuft‐forming weed common in wild blueberry fields. The current management of hair fescue is almost completely reliant on pronamide (3,5‐dichloro‐N‐[2‐methylbut‐3‐yn‐2‐yl]benzamide) herbicide with few other products demonstrating effectiveness. Dichlobenil (2,6‐dichlorobenzonitrile) is a group 29 herbicide registered for use in wild blueberry; however, it has seen limited use because of its high product cost of over CAD 1800 ha−1 and limited research on the effect of varying application rates. Treatments (dichlobenil at 4400, 5700, and 7000 g a.i. ha−1, pronamide at 2240 g a.i. ha−1, and a nontreated control) were applied during the 2020 autumn prior to wild blueberry stem emergence in the nonbearing year (2021). Each treatment was replicated five times per field across three fields in central Nova Scotia. Dichlobenil at 4400, 5700, and 7000 g a.i. ha−1 reduced 2021 (nonbearing year) living tuft density by 59%, 71%, and 83%, respectively, and provided residual control in 2022 (bearing year) with densities reduced by 59%, 69%, and 78%, respectively. Comparatively, pronamide reduced 2021 and 2022 living tuft density by 95% and 91%. Reductions in living tuft density resulted in yield increases of 62%, 57%, and 94% in plots treated with dichlobenil at 4400, 5700, and 7000 g a.i. ha−1, respectively, and 73% for plots treated with pronamide. Results demonstrate that dichlobenil is an effective herbicide for managing hair fescue in wild blueberry. The potential for the selection of herbicide‐resistant biotypes to industry standard pronamide could be prolonged with integrated dichlobenil applications.

Climate, fire disturbance regime, and vegetation response of the past 2500 years for central Nova Scotia

AbstractThe interaction between climate change and disturbances affects forest composition and dynamics, but most of our empirical knowledge comes from short‐term studies of the past century. Pollen and charcoal analyses of lake sediment cores retrieved from three sites in Nova Scotia were used to produce a landscape‐level analysis of long‐term forest cover dynamics and fire disturbances of the past ~2500 years. The present‐day forests had been established by that time, although a long‐term increase in Picea at the expense of northern hardwoods was seen at all sites, consistent with other pollen records found across New England and Eastern Canada. The driving influences of forest change prior to European settlement were a combination of climate and disturbance, acting on site characteristics of each region. Fires were relatively infrequent in this region and did not have a major impact on the evolution of the forests of central Nova Scotia. Changes in the relative abundances of the tree taxa occurred in response to long‐term cooling during the past 3000 years and century‐scale climate variability such as the Little Ice Age (ce 1450–1850) and Medieval Warm Period (ce 800–1300). The impact of climate variability on the fire regime depends on the landscape and vegetation type. “Borealization” of the Acadian Forest, noted during the period of European colonization, has been occurring for millennia.

Machine vision system for real-time debris detection on mechanical wild blueberry harvesters

Improving fruit quality is important to wild blueberry producers. Plant debris like leaves and stems caused a reduction in fruit quality during mechanical harvesting. A debris detection system was developed using two Logitech C920 webcam cameras mounted before and after the blower fan on a commercial mechanical wild blueberry harvester. Images were collected from two commercially managed wild blueberry fields located in central Nova Scotia to develop a dataset of 1000 images. Two convolutional neural networks (CNNs), YOLOv3 and YOLOv3-SPP, were used and compared for performance analysis. The CNNs were trained using no augmented images, images with five augmentations (sharpening, brightness, contrast, gamma correction, and saturation), and images with five augmentations that were more heavily weighted towards gamma. Four different computer hardware packages (Hewlett-Packard, Shuttle XPC, Jetson TX2, and GPU-based Desktop) were used to determine the appropriate hardware and CNN model combination for real-time performance. YOLOv3 and YOLOv3-SPP were trained to mAP scores of 72.87 and 74.38% using the dataset with more gamma-augmented images. This was an improvement over the dataset with no augmentation (67.75; 68.49%) and equally numbered augmentations (71.26%; 73.03%). YOLOv3-SPP combined with an Intel® Core™ i9-7900X CPU and Nvidia GeForce RTX™ 2080 Ti GPU in a desktop computer achieved the fastest detection rate of 33.30 ms. The detection speed on all other hardware configurations exceeded 33.30 ms, indicating that a powerful desktop GPU is required for real-time performance of this task. With adequate processing hardware, the developed technology could be integrated into a control system to automatically adjust brushes based on conveyor information from mechanical wild blueberry harvesters to make cleaning berries easier and enhance fruit quality.

Modeling of total and active organic carbon dynamics in agricultural soil using digital soil mapping: a case study from Central Nova Scotia

Monitoring the changes in soil organic carbon (SOC) pools is critical for sustainable soil and agricultural management. This case study models total and active organic carbon dynamics (2015/2016 to 2019/2020) using digital soil mapping (DSM) techniques. Model predictors include topographic variables generated from light detection and ranging data; soil and vegetation indices derived from Landsat satellite images; and soil and crop inventory information from Agriculture and Agri-Food Canada to predict total organic carbon (TOC) and permanganate oxidizable carbon (POXc) at the 0–15 cm depth increment for a 37 km2 study area in Truro, Nova Scotia. Quantile Regression Forest and stochastic Gradient Boosting Model were utilized for prediction. Although both models performed equally well for predicting TOC and POXc, the accuracy of TOC predictions (e.g., concordance correlation coefficient (CCC) = 0.67) was better than POXc predictions (e.g., CCC = 0.53). The Landsat variables and crop inventory were dominant predictors, while topographic variables across the relatively homogeneous terrain had relatively little influence. During the study period, changes in POXc were predicted across 98% of the study area, with a mean absolute loss of 5.77 (±11.48) mg/kg/year, and in TOC on 27% of the area, with a mean absolute loss of 0.15 (±0.09) g/kg/year. While the annual crop fields observed the highest loss of TOC and POXc, the decline in pasture–grassland–forage fields was relatively low. The study reinforced the effectiveness of DSM for modeling multiple SOC pools at the farm to landscape scales.

Controls on Barite Mineralization in a Major Intracontinental Shear Zone: Carboniferous of the Cobequid Highlands, Nova Scotia

Prominent veins of late Carboniferous barite, associated with fluorite and calcite, outcrop close to older granite plutons along an intracontinental shear zone that was active throughout the Carboniferous in southeastern Canada. Some barite is stratigraphically constrained to younger than 315 Ma and final mineralization is constrained by a published Rb–Sr isochron of 300 ± 6 Ma. Barite occurrences in the Carboniferous basins of central Nova Scotia, 50 km to the south, are synchronous with or post-date ankerite-siderite-magnetite-pyrolusite and Pb-Zn mineralization, which was facilitated by fluid interaction with thick evaporites. This study aims to determine controls on the distribution of barite in the shear zone, from field relationships, vein petrography and isotope geochemistry of minerals. The isotope chemistry of shear zone barite is similar to that occurring in Pb-Zn-Mn-Ba mineralization to the south, suggesting a common origin. Veins of barite, associated with fluorite, represent the youngest and regionally coolest phase of a 70 Ma history of Carboniferous mineralized veins along the Minas Fault Zone. Their prominence close to granite plutons reflects brittle deformation of the deeply-rooted granites in a complexly deforming fault zone, but the origin of abundant F remains uncertain.

Dung analysis of the East Milford mastodons: dietary and environmental reconstructions from central Nova Scotia at ∼75 ka years BP

To reconstruct a mastodon diet and provide a snapshot view of environmental conditions in eastern Canada prior to the onset of the Wisconsinan glaciation, we analysed the faunal and floral components of dung associated with juvenile mastodon remains from East Milford, Nova Scotia, dated to 74.9 ± 5.0 ka cal BP. The diverse assemblage of pollen, non-pollen palynomorphs, plant macrofossils, and macroinvertebrate remains in the dung suggests that the mastodons lived in a spruce-dominated mixed coniferous–deciduous forest with a strong boreal aspect interspersed with wetlands rich in charophytes, sedges, cattails, bulrushes, and bryophytes. The abundance of spruce needles and birch samaras in the dung sample is consistent with an inferred browsing behaviour, having been reported for other mammutid species previously. The limited diversity and near-absence of coprophilous fungi, such as Sporormiella, in the dung could have an impact on understanding the influence of feeding strategies on the presence of coprophilous taxa in sedimentary records, and thus interpretations of megafaunal abundance. The dung also yielded the earliest known Canadian remains of the bark beetle Polygraphus cf. rufipennis, gemmulae of the freshwater sponge Eunapius cf. fragilis, and loricae of the rotifer Keratella cochlearis.

An investigation into the potential of Gabor wavelet features for scene classification in wild blueberry fields

A Gabor wavelets based technique was investigated as a potential tool for scene classification (into one of bare patch, plant, or weed) for its ultimate utility in site-specific application of agrochemicals in wild blueberry fields.Images were gathered from five sites located in central Nova Scotia, Canada. Gabor wavelet features extracted from these images were used to classify scenes according to visually determined classes using step-wise linear discriminant analysis.For individual fields, classification accuracy attained ranged between 87.9% and 98.3%; selected Gabor features ranged between 27 and 72; contextual accuracy for herbicide ranged between 67.5% and 96.7%, and contextual accuracy for fertilizer ranged between 63.6% and 97.1%. The pooled scenes yielded a classification accuracy of 81.4%, and contextual accuracy figures of 61.1% and 73.1% for herbicide and fertilizer, respectively, with selected Gabor features of 36.Calibrations based on LDA coefficients from the pooled scenes could help avoid the need to re-calibrate for each field, whereas those based on individual field LDA coefficients could improve accuracy, hence enable saving on expensive agrochemicals.

Occurrence and origin of groundwater methane in the Stellarton Basin, Nova Scotia, Canada

Groundwater methane (CH4) in areas of fossil fuel development has been a recent focus of study as high CH4 concentrations pose water quality concerns and potential explosive hazards. In 2013, a provincial study in Nova Scotia identified areas with elevated groundwater CH4. However, due to limited data, the specific sources and local distribution of CH4 in those areas remain unknown. In this study, we examined the Stellarton Basin in central Nova Scotia, Canada, a region with an abundance of coal formations, numerous abandoned coal mines, and an active open pit coal mine. Methane was detected in 94% of water samples that were sampled from 45 private water wells. Six water wells exceeded the 28 mg/L hazard mitigation threshold with CH4 levels of up to 72.7 mg/L. The δ13CCH4 (−85.5 to −48.5‰) and the δ2HCH4 (−280 to −88‰) indicated that >95% of samples had CH4 of microbial origin. However, the detection of ethane (C2H6) up to 2.97 mg/L and propane (C3H8) up to 0.008 mg/L, as well as the δ13CC2H6 values (−30.1 to −15.6‰) suggested a mixture of microbial CH4 with trace thermogenic gas, likely migrated from Stellarton coals (δ13CC2H6 of −27.6 to −15.35‰). A mobile greenhouse gas analyzer survey was conducted within the perimeter of residences and off-gassing from taps had atmospheric CH4 measurements as high as 66 ppmv. This study integrates multiple sampling and monitoring methods to investigate groundwater CH4 in a coal-bearing region. The findings advance the understanding of the origin and occurrence of CH4 in complex groundwater systems. The data acquired in this study may be used as a pre-drill baseline for groundwater CH4 concentrations and origins should coal-bed methane operations in Nova Scotia proceed in the future.

Real-Time Detection of Strawberry Powdery Mildew Disease Using a Mobile Machine Vision System

Strawberry cropping system relies heavily on proper disease management to maintain high crop yield. Powdery mildew, caused by Sphaerotheca macularis (Wall. Ex Fries) is one of the major leaf diseases in strawberry which can cause significant yield losses up to 70%. Field scouts manually walk beside strawberry fields and visually observe the plants to monitor for powdery mildew disease infection each week during summer months which is a laborious and time-consuming endeavor. The objective of this research was to increase the efficiency of field scouting by automatically detecting powdery mildew disease in strawberry fields by using a real-time machine vision system. A global positioning system, two cameras, a custom image processing program, and a ruggedized laptop computer were utilized for development of the disease detection system. The custom image processing program was developed using color co-occurrence matrix-based texture analysis along with artificial neural network technique to process and classify continuously acquired image data simultaneously. Three commercial strawberry field sites in central Nova Scotia were used to evaluate the performance of the developed system. A total of 36 strawberry rows (~1.06 ha) were tested within three fields and powdery mildew detected points were measured manually followed by automatic detection system. The manually detected points were compared with automatically detected points to ensure the accuracy of the developed system. Results of regression and scatter plots revealed that the system was able to detect disease having mean absolute error values of 4.00, 3.42, and 2.83 per row and root mean square error values of 4.12, 3.71, and 3.00 per row in field site-I, field site-II, and field site-III, respectively. The slight deviation in performance was likely caused by high wind speeds (>8 km h−1), leaf overlapping, leaf angle, and presence of spider mite disease during field testing.

Optimising the parameters influencing performance and weed (goldenrod) identification accuracy of colour co-occurrence matrices

Wild blueberry crop yields are dependent on heavy agrochemical applications to control weeds competing with the crop. Goldenrod is a creeping herbaceous perennial weed that occurred in 90% of wild blueberry fields surveyed in Nova Scotia. A colour co-occurrence matrices (CCMs) based algorithm can be used for spot-application of herbicide on goldenrod within wild blueberry fields. The objective of this study was to analyse the effect of different parameters on computational complexity and goldenrod identification accuracy of CCMs in wild blueberry cropping system. An image acquisition graphical user interface (GUI) and CCMs based textural analysis algorithm were developed in Microsoft Visual® C# programming language. The GUI was used to acquire 2244 area of interest images along with a set of 2244 full frame images from two different wild blueberry fields in central Nova Scotia, Canada. Six image intensity levels, seven image sizes, and three CCMs were used to for the study. The results indicated that intensity levels and image size significantly influenced the computational requirements of CCMs. Images with 256 or 128 intensity levels could be used as these levels correctly classified 94% and 89% of test observations respectively. The processing times were increased from 535 μs to 10,650 μs and 9864 μs to 63,750 μs as the intensity increased from 8 to 256 levels and image size increased from 16 × 16 to 1024 × 1024 pixels, respectively. The time required for textural feature extraction was not statistically significant for different image sizes used in this study. Overall, the results indicated that intensity levels of 128 or 256, a unit image size of 128 × 128 pixels, and saturation colour plane alone or in combination with hue can help to minimise the processing burden without compromising the classification accuracy for real-time applications.

Machine vision smart sprayer for spot-application of agrochemical in wild blueberry fields

An essential part of the wild blueberry cropping system is the proper management of agrochemical inputs including herbicides, fungicides and insecticides. A machine vision system was developed and mounted on the rear sprayer boom 0.18 m in front of the sprayer nozzles capable of targeting the agrochemical application on an as-needed basis. The three-point hitch mounted sprayer featured 27 nozzles over a 13.7 m boom width and a storage tank capacity of 1135 l. Nine digital color cameras continually take images in real-time while computer software processes the images in 0.15 s to determine the target locations where the nozzles open and spray at speeds up to 1.77 m s−1. Two wild blueberry fields in central Nova Scotia were selected for smart sprayer performance testing with spot-application (SA) of agrochemical as compared to control and uniform application techniques. Chateau® herbicide was applied in a field with an infestation of hair cap moss. Spray droplet comparison showed moss patches were properly targeted using the smart sprayer. SA provided the same coverage performance as compared to uniform on the moss targets with herbicide application savings of 78.5% using the smart sprayer. Harvestable yield results were similar for all application tracks. TruPhos Magnesium and ZincMax foliar fertilizers were tank mixed with Bravo® and Proline® fungicides and applied to compare the difference of SA, control and uniform application. Results showed SA of foliar fertilizer and fungicide led to less premature leaf drop and increased the blueberry stem height, number of branches, stem diameter and fruit buds. SA of foliar fertilizer and fungicide also increased the percent of healthy wild blueberry plants by 57.8% and the harvestable yield by 137.8%. Fungicide application savings using the smart sprayer for SA were 11.6%.

Late Holocene Records of Changing Moisture Regime from Wetlands in Southwestern Nova Scotia, Canada: Implications for Wetland Conservation and Restoration

An understanding of the morphological stability and succession of open water and wetland ecosystems in Nova Scotia is a priority for informing the conservation management of critical habitats for a complex of nationally listed, rare, disjunct wetland species. Baltzer Bog and Big Meadow Bog in southwestern Nova Scotia contain stratigraphic records of late Holocene moisture variability. Baltzer Bog is a shrub bog that formed in an elevated, enclosed kettle basin. Excavated sections exposed by peat mining revealed 2 distinct wood-rich horizons that are located above a well-developed soil and wood horizon that yielded a radiocarbon-dated age of 3260 cal. BP from an upright stump. The overlying wood-rich horizons were dated at 1640 and 1045 cal. BP and were overlain by Sphagnum species transitions indicative of increasing wetness. At Big Meadow Bog, a thin wood mat in Sphagnum at 90 cm depth was dated at 1760 cal. BP. These records are broadly correlative with pollen and stratigraphic data from Pleasant River Fen in central Nova Scotia that indicate periods of high and low productivity and a fluctuating water table from 1950 cal. BP until present. Though other high-resolution paleoclimate records from the region indicate that the late Holocene was a time of increasing precipitation and cooler air temperatures, these wetland records demonstrate that in Nova Scotia this time period was characterized by rapid variations in effective moisture and that significant and sustained dry periods likely occurred. This record of late Holocene moisture variability and its influence on habitat structure serves to better establish the potential for long-term residency of threatened and endangered species at wetland sites.

A real-time ultrasonic system to measure wild blueberry plant height during harvesting

Spatial variations in wild blueberry plant height pose a serious challenge for the operator to maintain the optimum harvester picking head height. Harvester head adjustment based on plant height increases harvestable fruit yield and quality while preventing plant pulling. An advanced Ultrasonic Plant Height Measurement System II (UPHMS II) was developed and incorporated into a commercial mechanical harvester. The developed system consisted of three ultrasonic sensors covering the width of the harvester head, a real-time kinematics global positioning system (RTK-GPS), custom built software, and a rugged computer. The custom software acquired and processed the ultrasonic sensing data in real-time during mechanical harvesting. Four wild blueberry fields were selected in central Nova Scotia to evaluate the performance of the developed system. Forty eight experimental plots were randomly constructed within four fields and wild blueberry plant heights were recorded manually prior to harvest. The UPHMS II was tested and evaluated to estimate plant height. The manual plant height measurements were compared with ultrasonically sensed data to ensure the accuracy of the developed system. A previous system (UPHMS I) comprising of one ultrasonic sensor was also tested and evaluated. Results of regression and scatter plots revealed that the UPHMS II was able to sense plant height in real-time more accurately with root mean square error (RMSE) of 1.7 cm when compared with the UPHMS I (RMSE = 5.7 cm). The UPHMS II equipped with three sensors covered the complete width of the harvester (0.91 m), which showed higher accuracy compared to the UPHMS I.

The thermal structure of the central Nova Scotia Slope (eastern Canada): seafloor heat flow and thermal maturation models

The thermal history and maturation potential of the central Scotian Slope is constrained using a combination of 47 recently acquired seafloor heat flow measurements, two-dimensional (2D) seismic reflection data, available well data, simple lithospheric rift models, and thermal and petroleum systems modelling. Consistent heat flow values of 41–46 mW·m−2 were measured seaward of the salt diapiric province and across the slope away from the influence of salt structures. Significant but highly variable increases in heat flow were measured for stations overlying salt diapiric structures, reaching values upwards of 72 mW·m−2. Simple models of conductive heat transfer with static salt geometries constrained from reflection profiles indicate that two of the four models fit the data, whereas two indicate much higher values suggestive of additional, convective effects. Dynamic 2D thermal models were developed to incorporate the effects of lithospheric rifting, crustal stretching, and radiogenic heat production in the sediment and basement. These models help constrain the hydrocarbon maturation potential of the central Scotian Slope, where deep borehole data are lacking. Our results suggest that a potential Late Jurassic source rock interval rests primarily within the late oil window and that salt structures act primarily to reduce maturation in the adjacent deep sediment layers.

Supplementary Light Source Development for Camera-Based Smart Spraying in Low Light Conditions

Abstract. High wind constraints during day time agrochemical spraying has pushed the wild blueberry producers to apply agrochemicals during the early morning, evening or after dark, to avoid drift problems due to low wind conditions. The objective of this study was to develop an artificial light source system combined with a smart sprayer comprising of a digital camera-based sensing system to allow cameras to detect target areas (weed, plant or bare soil) in real-time for accurate application of agrochemicals in low light conditions. After testing and evaluation of different light sources, a rugged light source system equipped with polystyrene diffuser sheets was constructed to provide an even distribution of light across the entire 12.2 m machine vision sensor boom. Distribution of artificial light underneath the sensing boom at zero ambient light was examined by recording the light intensity at 0.15 m spacing on the ground under the camera boom using a lux meter. Results of light distribution revealed that the Magnafire ® 70 W high intensity discharge (HID) lights provided wide angle of even light illumination, high intensity and rugged construction. A wild blueberry field was selected in central Nova Scotia, Canada, and a test track was made to evaluate the performance of the artificial light source system to apply agrochemicals on a spot-specific basis under low natural light conditions. A real-time kinematics-global positioning system (RTK-GPS) was used to map the boundary of the test track, selected bare soil areas, weed areas and wild blueberry plant areas in the field. Water sensitive papers (WSPs) were placed at randomly selected locations, the smart sprayer was operated under low light conditions, and the percent area coverage (PAC) was calculated. The mean PAC from WSP located in bare soil, weeds and blueberry spots in the track was 5.19%, 27.53%, and 1.74%, respectively. PAC of the WSPs placed in bare soil and blueberry patches were 22.34% and 25.79% lower than in weed patches, respectively. Results reported that the custom developed artificial light source system was accurate enough to detect targets in low light conditions. Additionally, spot-spacing only in weed areas resulted in 65% of chemical saving.

Transformations revealed through food studies

This issue brings us food-related research and perspectives from across Canada, from Nunavut and the Northwest Territories to central Alberta, Kenora (Ontario), and Nova Scotia. A common thread weaves throughout this work: one of transformative change—either already in progress or still needed—among individuals, communities, and food systems.

Effect of Split Variable Rate Fertilization on Wild Blueberry Plant Growth and Berry Yield

Abstract. Traditionally, wild blueberry growers apply fertilizer uniformly without considering the substantial variation in soil characteristics, topographic features, and berry yield. Occurrence of heavy rainfall events, gentle to severe topography along with high proportion of bare spots and weed patches emphasize the need for variable rate split (VRS) fertilization. The VRS fertilization has a potential to improve fertilizer use efficiency and reduce environmental impacts. Two commercial wild blueberry fields were selected in central Nova Scotia. Fields were divided into three sections [VRS section, uniform rate split (URS) section, and uniform rate (UR) section]. Fertilization was performed by following the global positioning system (GPS) guided prescription map. Soil samples and plant growth parameters were collected during the vegetative year and berry yield samples were collected during the crop year. The experimental design used for this study was split-plot design and the analysis of all collected data were performed using SAS (SAS, 2010) at 5% level of significance. Plant density and plant height were non-significantly different under all slope zones of VRS, URS, and UR treatment sections. Plants in URS and UR sections were taller than VRS sections in low lying areas. Although there were non-significant differences for berry yield in all slope zones of VRS, URS, and UR fertilizer treatments, the mean berry yield was higher in VRS section as compared to the other sections. Significant correlations were observed between soil properties and plant growth parameters under all treatment sections. The VRS fertilization saved 39% and 42% fertilizer in Cooper (field-1) and North River (field-2) fields, respectively. Based on the results of this study, it can be concluded that the VRS fertilization in wild blueberry fields could reduce fertilizer usage without affecting the crop productivity.

Improved Growth and Harvestable Yield through Optimization of Fertilizer Rates of Soil-applied Nitrogen, Phosphorus, and Potassium in Wild Blueberry (Vaccinium angustifolium Ait.)

The study examined the main and interactive effects of soil-applied fertilizers [nitrogen (N), phosphorus (P), and potassium (K)] from a 12-year (six production cycles) field experiment conducted at Kemptown, Nova Scotia (Canada). It also recommends the optimum rate for improved growth and harvestable yield of wild blueberry (Vaccinium angustifolium Ait.). The fertilizers were applied in a single application at the onset of shoot emergence in early spring of each sprout year at rates of 0, 12, 30, 48, and 60 kg·ha−1 N using urea (2000 only) or ammonium sulfate, 0, 18, 45, 78, and 90 kg·ha−1 P using triple super phosphate, 0, 12, 30, 48, and 60 kg·ha−1 K using potassium chloride. Response surface analysis of the data indicated that 35 kg·ha−1 N, 40 kg·ha−1 P, and 30 kg·ha−1 K were optimum for fruit production and maintaining stem lengths <20 cm, and resulted in an average of 54% more floral buds, 25% more berries per stem, and 13% greater yield than previous recommend rates of 20 kg·ha−1 N, 10 kg·ha−1 P, and 15 kg·ha−1 K. The higher fertilizers rates cost an extra $80/ha but increased net profits by $490/ha. Findings of this study could contribute toward better farm profitability in areas with similar growing conditions. They also suggest that modifications to existing fertilizer rates be made for Central Nova Scotia wild blueberry.

Estimation of the rootzone depth above a gravel layer (in wild blueberry fields) using electromagnetic induction method

Wild blueberry (Vaccinium angustifolium Ait.) fields in the north east Canada are naturally grown in a course textured thin layer of soil and below this layer is a soilless layer of gravel. The root zone depth of this crop varies from 10 to 15 cm. Investigating the depth to the gravel layer below the course textured soil is advantageous, as it affects the water holding capacity of the root zone. Water and nutrient management are the two primary determinants of crop yield and the amount of leaching. The objective of this study was to estimate the depth to the gravel layer using DualEM-2 instrument. A C++ program written in Visual Studio 2010 was used to develop mathematical models for estimating the depth to the gravel layer from the outputs of DualEM-2 sensor. Two wild blueberry fields were selected in central Nova Scotia, Canada to evaluate the performance of DualEM-2 instrument in estimating the rootzone depth above the gravel layer. The mid points of squares created by grid lines were used as the sampling points at each experimental site. The actual depth to the interface was measured manually at selected grid points (n = 50). The apparent ground conductivity (ECa) values of DualEM-2 were recorded and the depth to the interface was estimated for the same sampling points within the selected fields. The fruit yield samples were also collected from the same grid points to identify the impact of the depth to the gravel layer on crop yield. After calibrations, comprehensive surveys were conducted and the actual and estimated depths to the interface were established. The interpolated maps of fruit yield, and the actual (zin) and estimated ( $$ {\text{z}}_{\text{in}}^{*} $$ ) depths to the interface were created in ArcGIS 10 software. Results indicated that the zin was significantly correlated with $$ {\text{z}}_{\text{in}}^{*} $$ for the North River (R 2 = 0.73; RMSE = 0.27 m) and the Carmel (R 2 = 0.45; RMSE = 0.20 m) sites. Results revealed that the areas with shallow depth to the gravel layer were low yielding, indicating that the variation in the depth to the gravel layer can have an impact on crop productivity. Non-destructive estimations of the depth to the gravel layer can be used to develop erosion control strategies, which will result in an increased crop production.

Effect of Split Variable Rate Fertilizationon Ammonia Volatilization in Wild Blueberry Cropping System

<abstract><title><italic>Abstract. </italic></title> Currently, fertilizer is applied uniformly in wild blueberry (Vaccinium angustifolium. Ait) fields, once in a two year production cycle, without considering substantial variation in soil/plant characteristics, topographic features, and fruit yield. The heavy rainfall, gentle to severe topography with high proportion of bare spots, and weed patches in wild blueberry fields emphasizes the need for variable rate split (VRS) fertilization to avoid environmental contamination. Two commercial wild blueberry fields were selected in central Nova Scotia to examine the impact of VRS fertilization on ammonia volatilization losses. Management zones (MZs) were delineated based on slope variation within the selected fields (steep slope (Zone-1), moderate slope (Zone-2), and low slope areas (Zone-3)). The fields were divided into two sections (VRS section and uniform rate (UR) section). Global positioning system (GPS) guided prescription maps based on slope variation were generated in ArcGIS 10 software to apply fertilizer in both fields. In VRS section, fertilizer was applied three times with commercial variable rate (VR) fertilizer spreader in Zone-1, Zone-2, and Zone-3 with fertilization rates of 66, 50, 33, and kg ha^-1, respectively. Single uniform grower’s fertilizer rate (200 kg ha^-1) was applied in UR sections of the selected fields for comparison. The ammonia volatilization trials were established under VRS and UR fertilized sections of the selected fields immediately following the fertilization. The ammonia volatilization samples were collected after each fertilization in VRS sections and once in UR sections. The samples were analyzed for ammonium nitrogen (NH₄⁺-N) concentrations. Leaf samples were collected in third week of July at tip-dieback stage and analyzed for leaf nutrient concentrations. The results of repeated measure analysis of variance showed ammonia volatilization losses were significantly (p < 0.05) lower in VRS sections as compared to uniformly fertilized sections of the selected fields. Secondly, the study found that the leaf nutrient concentrations were not reduced using VRS fertilization. Results of this study also indicated that the VRS fertilization improved the nitrogen use efficiency and reduced the ammonia volatilization in wild blueberry fields.