Central Nova Scotia Research Articles

Impact of Variable Rate Fertilization on Nutrients Losses in Surface Runofffor Wild Blueberry Fields

Abstract. Wild blueberry producers apply agrochemicals uniformly without considering substantial variation in soil properties and topographic features that may affect fruit yield within a field and pollute environment. A wild blueberry field was selected in central Nova Scotia, Canada to evaluate the impact of variable rate (VR) fertilization on nutrient losses in surface runoff, from steep slope to low lying areas, and crop productivity. The field was divided into three subfields (Field 1, Field 2, and Field 3) under three management zones (Zone 1, Z1; Zone 2, Z2; and Zone 3, Z3). The runoff plots were installed to collect surface runoff samples from different zones of the field. Three fertilizer (NPK: 16.5 – 34.5 – 4.5, respectively) rates (200,150, and 100 kg ha -1 for Z1, Z2, Z3, respectively) were applied in runoff plots of VR treatment using fertilizer spreader. Uniform fertilizer rate of 200 kg ha -1 for comparison was applied in runoff plots of uniform application (UA) treatment. No fertilizer was applied in runoff plots of control treatment. The surface runoff samples were collected after every heavy rainfall event and analyzed for total phosphorus (TP), dissolved reactive phosphorus (DRP), particulate phosphorus (PP), and inorganic nitrogen concentrations. The VR treatment significantly (p≤0.05) decreased TP, DRP, PP, and inorganic nitrogen losses in surface runoff as compared to UA. Plant growth parameters and fruit yield were also collected from runoff plots. Plants in UA treatment were taller than VR treatment in low lying areas. Numbers of buds per stem were significantly affected by fertilizer treatments. The fruit yield in VR treatment was non-significantly different than UA treatment. The VR fertilizer application used 40% less fertilizer than standard UA of fertilizer. The VR fertilization could reduce nutrients loading in surface runoff from wild blueberry fields. The runoff plots could be used to accurately determine the surface runoff from small-scale runoff plots. However, the construction of runoff plots and data collection at field scale is laborious and time consuming.

Impact of Variable Rate Fertilization on Wild Blueberry Plant Growth and Fruit Yield

Abstract. Variable rate (VR) fertilizer application has the potential to improve fertilizer use efficiency, reduce cost of production, and reduce environmental impacts. Two wild blueberry fields were selected in central Nova Scotia to examine the effect of VR fertilization on plant growth and fruit yield as compared to uniform fertilization. The field boundaries, weeds, and bare spots were mapped using real-time kinematics global positioning system (RTK-GPS). The variation in slope was mapped and management zones were delineated. Both fields were divided into two sections (VR and uniform). The GPS-guided prescription maps were generated in ArcGIS 9.3 for VR treatment sections. Three fertilization rates 200, 150, and 100 kg ha -1 were applied in Z1, Z2, and Z3, respectively, with a VR fertilizer spreader. The bare spots and weeds were mapped and classified as a separate class in the prescription maps and zero rate was allocated. For comparison, growers uniform fertilizer rate of 200 kg ha -1 was applied in uniform treatment section of both fields. Soil samples were taken from selected sampling points from each field before and after the fertilization, and soil properties and levels of soil nutrients were determined. Plant growth parameters and fruit yield were also collected from selected points in each field. Plants in uniform treatment sections were taller than VR treatment sections in low lying areas. Plant density, number of branches, and number of buds were non-significantly affected with fertilizer treatments. Plant growth parameters were significantly correlated with soil properties and soil nutrients in both VR and uniform treatments. The fruit yields in VR treatment sections were non-significantly different than uniform treatment section, although mean fruit yield was higher in VR section. VR fertilization saved 39% and 41% fertilizer in Fields 1 and 2, respectively. Results of this study suggested that VR fertilization could increase fruit yield and reduce fertilizer usage in wild blueberry fields.

Performance evaluation of multiple ground based sensors mounted on a commercial wild blueberry harvester to sense plant height, fruit yield and topographic features in real-time

Site-specific crop management can increase profitability and reduce environmental risks of wild blueberry crop having large spatial variation in soil/plant characteristics and topographic features which may affect fruit yield. An integrated automated system comprising of an ultrasonic sensor, a digital color camera, a slope sensor, a real-time kinematics GPS (RTK-GPS), custom software and ruggedized computer was developed. The system was incorporated onto a commercial wild blueberry harvester, to measure plant height, fruit yield, slope and elevation simultaneously while harvesting. Two wild blueberry fields were selected in central Nova Scotia, Canada to evaluate the performance of the system. Field boundaries, bare spots, weeds and grass patches were mapped with a RTK-GPS prior to start the experiment.Linear regression was used to calibrate the actual fruit yield with the percentage of blue pixels (R2=0.91–0.92; P<0.001; n=40) using a 0.91×0.70m quadrat at selected points from both fields. The output voltage of the ultrasonic sensor was significantly correlated with manually measured plant height (R2=0.94; P<0.001; n=13). Comprehensive surveys were conducted in both fields to measure plant height, fruit yield, slope and elevation rapidly in real-time at the same time of harvest. The maps for the measured parameters were developed in ArcGIS 10. Maps showed substantial variability in measured parameters across the fields, suggesting more fruit yield and lower plant height in low lying areas (mild slope) and vice versa. A negative relationship among fruit yield and plant height and the results of zonal statistics in ArcGIS 10 also supported the results identified by the maps. Overall, the results of calibration and mapping indicated that the developed system was an accurate, reliable and efficient to map plant height, fruit yield, slope and elevation in real-time. This information can be used to develop site-specific fertilization, based on easily measured field parameters, to optimize productivity while minimizing the environmental impacts.

Concordance of N bio-indicators: Dandelion and earthworms in a rotational pasture

Earthworms are important soil metabionts indicative of N enrichment in pastures. A rotational pasture in central Nova Scotia was tested for earthworms using chemical extraction followed by excavation and hand sorting in 28 paired micro plots placed in areas with low versus high proportion of the N indicator plant species dandelion (Taraxacum officinale). Species richness was low with five earthworm species of the Lumbricidae recovered in the following order of abundance: Lumbricus rubellus, Lumbricus terrestris, Aporrectodea turgida, Aporrectodea tuberculata, and Aporrectodea trapezoides. All species occurred at high constancy except the rare A. trapezoides. The inventory revealed spatial differentiation of earthworm abundance and community structure at the field level. High proportion of dandelion reduced pasture sward biomass while abundance of L. rubellus and A. tuberculata significantly (p<0.05) increased with a concomitant increase in epigeic earthworm dominance at the expense of the anecic L. terrestris. Thus, low cost and non-destructive floristic surveys of N indicators, such as dandelion, allow for concordant inferences about the environmental impact of intensive cow pasture on earthworms and ecosystem function. High earthworm counts may run contrary to the notion of ecological integrity depending on specific earthworm abundances. Reduced earthworm benefits due to any de-intensification of rotational pasture must be assessed against increased risks of N-leaching in intensive pastures with high proportion of dandelion.

Modelling the effects of climate change and timber harvest on the forests of central Nova Scotia, Canada

Understanding the range of possible climate change impacts on forests and the interactions between them is vital to sustainable forest management. We examine whether the combined influence of climate change and timber harvest will affect tree species distribution and productivity beyond predictions based on climate alone. We used the landscape disturbance model LANDIS-II to simulate two climate and two harvest scenarios in 14,000 ha of managed watersheds. The elevated temperature led to a decline in the abundance of boreal species and a substantial increase in some temperate and pioneer species. Importantly, the interaction of climate change and timber harvest yielded changes in the distribution of some species that would not be expected based on climate alone. Conversely, some late-successional species exhibited resistance to climate-driven changes in their distribution. Climate change caused an increase in forest productivity when harvest was simulated, but a decrease in no-harvest scenarios. A time lag in forest response was likely responsible for this decrease in the absence of widespread mortality. The finding that disturbance may drive the range expansion of early-successional broadleaved species and cause a decline of red spruce has implications for forest community associations, as well as for forest management where conifers are favoured for pulp production.

Growing Degree-day Models for Predicting Lowbush Blueberry (Vaccinium angustifolium Ait.) Ramet Emergence, Tip Dieback, and Flowering in Nova Scotia, Canada

Experiments were established to evaluate the suitability of growing degree-day (GDD, Tbase = 0 °C) models for predicting emergence, tip dieback, and flowering of lowbush blueberry ramets in Nova Scotia, Canada. Data for model development were collected from quadrats established in several non-bearing and bearing blueberry fields throughout the dominant blueberry production areas in northern and central Nova Scotia. Blueberry ramets emerged between 222 and 265 GDD (6 May to 14 May) and reached 90% emergence between 619 and 917 GDD (7 June to 5 July). Emergence continued to slowly increase until late summer or early fall. Tip dieback began between 598 and 792 GDD (14 June to 21 June) and duration of this phase depended on whether late-emerging ramets developed to tip dieback. A four-parameter Weibull and a three-parameter Gompertz equation adequately explained cumulative blueberry ramet emergence and cumulative ramets at tip dieback as functions of GDD in the non-bearing year, respectively. The four-parameter Weibull function also explained the relationship between cumulative flowering ramets and GDD in the bearing year. Flowering ramets were first observed between 376 and 409 GDD (19 May to 30 May) in the bearing year. Model predictions for initiation of emergence, tip dieback, and flowering were 243, 692, and 389 GDD, respectively. Models were validated with independent data sets collected throughout northern and central Nova Scotia. The relationship between the percentage of open flowers on individual ramets and GDD in the bearing year was well described by a Gaussian model at two sites with a predicted peak number of open flowers between 552 and 565 GDD.

Systematic variations in basement morphology and rifting geometry along the Nova Scotia and Morocco conjugate margins

Abstract The Nova Scotia and Morocco margins formed within a transition between volcanic margins to the south and non-volcanic margins to the north. We present deep seismic profiles to document the nature of this transition. Profiles on the Nova Scotia margin show two major transitions. The first transition represents a sharp reduction in syn-rift volcanism coincident with major changes in the East Coast Magnetic Anomaly and with the southern limit of the Slope Diapiric Province. The second transition represents a further restriction in syn- and post-rift volcanism leading to exposure of serpentinized mantle or the creation of highly tectonized oceanic crust. This transition is marked by highly extended and faulted continental crustal blocks. Revised plate reconstructions show similar transitions along the Moroccan margin. The southern transition occurs at a major change in the West Africa Coast Magnetic Anomaly and the southern limit of the Morocco Salt Basin. The second transition occurs at a major basement high (Tafelney Plateau), which is considered a high relief accommodation zone and contains highly extended faulted crustal blocks similar to those in a conjugate position off central Nova Scotia. This transition marks a major change in rifting asymmetry and separates the margins into two fundamentally distinct segments.

An automated yield monitoring system II for commercial wild blueberry double-head harvester

Wild blueberry fruit yield maps could be used to generate prescription maps for site-specific application of fertilizer to improve crop productivity. An automated yield monitoring system II (AYMS II) consisting of two μEye color cameras, real time kinematics-global positioning system, custom software, and a ruggedized laptop computer was developed and mounted on a Specialized Farm Motorized Vehicle (SFMV) for real-time fruit yield mapping. Custom software was developed in C++ programming language to acquire and process image in real-time from both cameras and store the percentage of blue pixels in ruggedized laptop computer. Two wild blueberry fields were selected in central Nova Scotia to evaluate the performance of the AYMS II for fruit yield mapping. Calibration was carried out at 20 randomly selected data points in each field. The ripe fruit was hand-harvested out of a 2.0 × 0.7 m quadrat at each selected point and camera images were also taken from the same points to calculate the percentage of blue pixels (fraction of blue pixels in the image). Linear regression analysis was performed to calibrate the actual fruit yield with the percentage of blue pixels. Real-time yield mapping was carried out with AYMS II. The estimated yield along with geo-referenced coordinates was imported into ArcGIS 9.3 software for detailed mapping. The AYMS II, hardware and software performed well to estimate wild blueberry fruit yield. The linear regression results showed highly significant relationship between the percentage of blue pixels and actual fruit yield in field 1 and field 2. The correlation between actual and predicted fruit yield (validation, using the equation from field 2) in field 1 and field 2 (validation, using the equation from field 1) was also highly significant. Maps developed in ArcGIS 9.3 showed substantial variability in fruit yield in both fields. The bare spots were coincided with no or low yielding areas in the fields. The viable AYMS II will be incorporated into wild blueberry harvester. This information obtained from AYMS II could be used to implement site-specific management practices within the blueberry fields to optimize productivity while minimizing the environmental impact of farming operations.

Exploring adaptation to climate change in the forests of central Nova Scotia, Canada

The threat of climate change is now recognized as an imminent issue at the forefront of the forest sector. Incorporating adaptation to climate change into forest management will be vital in the continual and sustainable provision of forest ecosystem services. The objective of this study is to investigate climate change adaptation in forest management using the landscape disturbance model LANDIS-II. The study area was comprised of 14,000 ha of forested watersheds in central Nova Scotia, Canada, managed by Halifax Water, the municipal water utility. Simulated climate change adaptation was directed towards three components of timber harvesting: the canopy-opening size of harvests, the age of harvested trees within a stand, and the species composition of harvested trees within a stand. These three adaptation treatments were simulated singly and in combination with each other in the modeling experiment. The timber supply was found to benefit from climate change in the absence of any adaptation treatment, though there was a loss of target tree species and old growth forest. In the age treatment, all trees in a harvested stand at or below the age of sexual maturity were exempt from harvesting. This was done to promote more-rapid succession to climax forest communities typical of the study area. It was the most effective in maintaining the timber supply, but least effective in promoting resistance to climate change at the prescribed harvest intensity. In the composition treatment, individual tree species were selected for harvest based on their response to climate change in previous research and on management values at Halifax Water to progressively facilitate forest transition under the altered climate. This proved the most effective treatment for maximizing forest age and old-growth area and for promoting stands composed of climatically suited target species. The size treatment was aimed towards building stand complexity and resilience to climate change, and was the most influential treatment on the response of timber supply, forest age, and forest composition to timber harvest when it was combined with other treatments. The combination of all three adaptation treatments yielded an adequate representation of target species and old forest without overly diminishing the timber supply, and was therefore the most effective in minimizing the trade-offs between management values and objectives. These findings support a diverse and multi-faceted approach to climate change adaptation.

Development of prototype automated variable rate sprayer for real-time spot-application of agrochemicals in wild blueberry fields

An automated prototype variable rate (VR) sprayer was developed for control of 8 individual nozzles on a 6.1 m sprayer boom for in-season, site-specific application of agrochemicals on weeds. The sprayer boom was divided into 8 sections and mounted behind an all-terrain vehicle (ATV) at 76.2 cm above the ground. The variable-rate control system consisted of 8 ultrasonic sensors (one per spray section) mounted on a separate boom in front of the ATV, DICKEY-john Land Manager II controller and flow valve, solenoid valves and an 8-channel variable rate controller interfaced to a Pocket PC (PPC) using wireless Bluetooth ® radio with Windows Mobile ® compatible software. This type of VR sprayer does not use prescription maps, but relies on sensors to provide real-time weed detection information which is used to dispense correct agrochemical rates for the weeds. The sprayer can be used for in-season, spot application (SA) of agrochemicals by activating specific boom sections where the weeds have been detected. Two wild blueberry fields have been selected in central Nova Scotia to evaluate the accuracy of the VR sprayer. Water sensitive papers (targets) were stapled to weeds randomly selected in two tracks of each field. The papers were orientated parallel to the ground. The percent area coverage (PAC) of the sprayed targets with both SA and uniform application was calculated by an imaging system. Non significance of the t-test for uniform versus SA targets PAC indicated that there was no significant bias in the SA and that the SA was accurate. The PAC with both applications ranged from 10.01% to 81.22% and from 5.39% to 72.67% in field 1 and field 2, respectively. Weed heights at selected points were measured and related with percent area coverage to examine the sprayer performance for spray application. Linear regression analysis showed that weed heights were significantly correlated ( R 2 ranged from 0.60 to 0.75) with percent area coverage of the targets in selected fields with both applications. It is proposed that herbicide should be applied at early stage of weed growth (weed height ranged from 35 cm to 55 cm and plant height ranged from 12 cm to 30 cm) for appropriate application with these specific VR sprayer arrangements. Based on these results, the VR sprayer was efficient and accurate enough for spot-application of agrochemicals usage in wild blueberry fields.

General stratigraphic framework of the Quaternary in Eastern Canada

In eastern Canada, inter-glacial and interstadial deposits have been reported from Nova Scotia and Québec, but in the other provinces only Wisconsinan deposits. In Nova Scotia, pollen from some organic deposits buried beneath one or more tills, indicates a warm, interglacial climate — presumably the Sangamon Interglacial Interval. Other buried organic deposits, in contrast, indicate a cool, boreal forest environment. As radiocarbon analyses have given 'greater than' dates the deposits are considered to be early Wisconsinan. The interval is tentatively correlated with the St. Pierre Interstadial of Québec. The only known mid-Wisconsinan deposit is at Salmon River on St. Mary's Bay, in southwestern Nova Scotia, where the marine shells have been dated at 38,600,4C years. Elsewhere in both coastal and interior Nova Scotia multiple till sections suggest a more or less continuous ice cover through-out the Wisconsinan. In central Nova Scotia, however, red tills have been considered late-Wisconsinan. In Québec, there is a very limited, but nevertheless important, record of the Sangamon Interglacial Interval. Compact clayey rhythmites in the Harricana River Basin, close to James Bay, appear to correlate with the lacustrine member of the Missinaibi Formation farther west in Ontario. In southern Québec, there is another indication of interglacial deposits for the oldest sediments exposed in the Sherbrooke region and in the Upper Chaudière River Valley beneath the lowest of three Wisconsinan tills. These deposits were weathered and cemented prior to deposition of the oldest till. As the gravels contain pebbles of Laurentian Shield gneiss there obviously was a pre-Sangamon glaciation. These two areas contain the most complete stratigraphie record of the Wisconsinan yet established in Québec.

Volcanic ash in the Lower Cretaceous Chaswood Formation of Nova Scotia: source and implicationsGeological Survey of Canada Contribution 20100082.

Lignites and coals, because of their low sedimentation rates of terrigenous detritus, may preserve a record of volcanic ash fall. Lignite from the Lower Cretaceous Chaswood Formation in central Nova Scotia was studied to identify whether any volcanic ash is present and can be correlated to known Early Cretaceous volcanism in southeastern Canada and adjacent New England. The bulk mineralogy and geochemistry of lignite and lignitic mudstones was determined by X-ray diffraction and whole-rock geochemical analysis of ashed samples; selected samples were examined by electron microprobe and scanning electron microscope. Much of the terrigenous component of some lignites consists of detrital sediments. In some lignites, distinctive rare earth element patterns are due to leaching from monazite and concentration in organic matter. Some lignites, however, lack illite and (or) quartz indicative of detrital sources, but show unusual abundance of stable high-field-strength elements such as Nb, Ta, and Hf, suggesting a volcanic source. Wood or charcoal fragments appear mineralized and diagenetic talc is present. Most of any ash component has been altered to kaolinite. Bulk composition of original ash ranges from basaltic to rhyolitic and matches chemically with subalkaline volcanic rocks on the SW Grand Banks and Orpheus graben. Coeval volcanic rocks on the U.S. continental margin and the New England–Quebec igneous province are more alkaline. Altered ash in lignite in the lower member of the Chaswood Formation correlates with Neocomian volcanism on the SW Grand Banks; and in the middle and upper members with Aptian–Albian volcanism in Orpheus graben.

Associations of Risk of Depression with Sexual Risk Taking among Adolescents in Nova Scotia High Schools

Several interrelated factors, including depression, influence adolescents' chances of risky sexual behaviour. We examined the relation between depression and sexual risk-taking behaviours in adolescents after accounting for the effects of other variables. We surveyed male (n = 1120) and female (n = 1177) adolescents at 4 high schools in central Nova Scotia, measuring factors known to be associated with sexual risk taking. Risk of depression was assessed using the Center for Epidemiologic Studies Depression Scale. Outcomes were self-reported sexual behaviours. We used logistic regression to assess associations of multiple factors with sexual risk taking. In univariate analyses, risk of depression was associated with 3 risk-taking behaviours for females (being sexually active, having unplanned sex when using substances, and not using effective contraception at last intercourse) and 2 for males (having unplanned sex when using substances and having more than 1 partner in the previous year). In full multivariate models, risk of depression in females remained significantly associated with unplanned sex and nonuse of effective contraception at last intercourse, but was no longer associated with being sexually active. For males, both associations remained significant. Risk of depression is consistently and independently associated with adolescent sexual risk behaviours after adjusting for other variables. Health care providers working with teenagers should screen for risky sexual behaviours and sexually transmitted infections if depression is apparent in their patients.

Sediment sources and dispersion as revealed by single-grain 40Ar/39Ar ages of detrital muscovite from Carboniferous and Cretaceous rocks in mainland Nova ScotiaGeological Survey of Canada contribution 20090289.

Single-grain ages of detrital muscovite from 15 sand(stone) samples from the Lower Carboniferous Horton Group and the Lower Cretaceous Chaswood Formation of central Nova Scotia were used to infer the nature of the Early Carboniferous unroofing of the Meguma terrane and the reworking of Carboniferous rocks in the Early Cretaceous. In the western Windsor Basin, a sample from the oldest Horton Group rocks yielded ages principally between ca. 400 and 380 Ma, suggesting that most of the muscovite present came from the metamorphic rocks of the Meguma terrane but was variably reset by the intrusion of the South Mountain Batholith at ca. 380 Ma. Other samples in this part of the basin show partial post-depositional resetting. Younger Horton Group metamorphic rocks in the eastern Windsor Basin contain many grains with ages of ca. 370–360 Ma, suggesting derivation from the central core of the South Mountain Batholith or the Musquodoboit Pluton. Horton Group sandstones from the western part of the St. Marys Basin contain muscovite derived from the Liscomb Complex along with metamorphic muscovite variably reset by the intrusion of this complex. In general, our data suggest predominant northward dispersion of muscovite from the Meguma terrane to the Horton Group and a lack of axial transport along the Horton grabens through central Nova Scotia, a pattern compatible with tectonic models in which the Meguma terrane is ramped over the Avalon terrane. Muscovite ages obtained for the Chaswood Formation compare well with those from the Horton Group rocks in the western St. Marys Basin. These rocks may have been exposed to rapid erosion by reactivation of the Cobequid–Chedabucto fault zone in the Early Cretaceous and the resulting sediments were perhaps transported to depositional sites along northeast-trending faults. Unlike the detrital monazites in these rocks, there is no evidence that any of the detrital muscovites came from distal sources outside the Meguma terrane.

An Automated Cost-effective System for Real-time Slope Mapping in Commercial Wild Blueberry Fields

The development of site-specific agriculture has increased the need for knowledge regarding within-field variability in factors such as soil/plant characteristics and topography that influence wild blueberry (Vaccinium angustifolium) production. Surface soil properties are the first type of information most frequently used by blueberry producers in developing management plans. Topographic features are not yet routinely used to guide within-field management. The majority of blueberry fields in eastern Canada have gentle to severe topography. An automated slope measurement and mapping system (SMMS) consisting of low-cost accelerometers used as tilt sensors, differential global positioning system (DGPS), and laptop and custom software was developed. The SMMS was mounted on an all-terrain vehicle for real-time slope measurement and mapping. Six commercial wild blueberry fields were surveyed in central Nova Scotia to evaluate the performance of SMMS. The automatically sensed slopes (SS) were also compared with manually measured slopes (MS) at 20 randomly selected points in each field to examine the accuracy of SMMS. The SMMS measured slope reliably in the selected fields with root mean square error ranging from 0.12 to 0.56 degrees and correlations of SS with MS of R2 = 0.95 to 0.99. The selected fields had substantial variation in slope (ranging from 0.8 to 31.0 degrees). Therefore, the use of low-cost and reliable accelerometers with a DGPS is a better option than expensive real-time kinematic DGPS for developing cost-effective SMMS to quantify and map slopes (real-time) for planning site-specific management practices in commercial fields. The SS maps or real-time SMMS could also be used to adjust vehicle speed at particularly steep slopes.

Detecting Bare Spots in Wild Blueberry Fields Using Digital Color Photography

Wild blueberry fields are developed from native stands on deforested land by removing competing vegetation. The majority of fields are situated in naturally acidic and non-fertile soils that have high proportions of bare spots, weed patches, and gentle to severe topography. Producers presently apply agrochemicals uniformly without considering bare spots. The unnecessary or over-application of agrochemicals in bare spots may increase cost of production and environmental pollution. An automated cost-effective machine vision system using digital color photography was developed and tested to detect and map bare spots for site-specific application of agrochemicals within wild blueberry fields. The experiment was conducted at a 4-ha wild blueberry field in central Nova Scotia. The machine vision system consisting of a digital color camera, differential global positioning system, and notebook computer was mounted on a specialized farm vehicle. Custom software for grabbing and processing color images was developed in Delphi 5.0 and C++ programming languages. The images taken by the digital camera were stored in the notebook computer automatically and then processed in red, green, and blue (RGB), and hue, saturation, and value (HSV) color spaces to detect bare spots in real-time within blueberry fields. The best results were achieved in hue image color space with 99% accuracy and a processing speed of 661 ms per image. The results indicated that bare spots could be identified and mapped with this cost-effective digital photography technique in wild blueberry fields. This information is useful for site-specific application, and has the potential to reduce agrochemical usage and associated environmental impacts in the wild blueberry production system.

Automated, Low-Cost Yield Mapping of Wild Blueberry Fruit

The presence of weeds, bare spots, and variation in fruit yield within wild blueberry fields emphasizes the need for yield mapping for site-specific application of agrochemicals. An automated yield monitoring system (AYMS) consisting of a digital color camera, differential global positioning system, custom software, and a ruggedized laptop computer was developed and mounted on a specially designed Farm Motorized Vehicle (FMV) for real-time fruit yield mapping. Two wild blueberry fields were selected in central Nova Scotia to evaluate the performance of the AYMS. Calibration was carried out at 38 randomly selected data points, 19 in each field. The ripe fruit was hand-harvested out of a 0.5- 0.5-m quadrant at each selected point and camera images were also taken from the same points to calculate the blue pixel ratio (fraction of blue pixels in the image). Linear regression was used to calibrate the actual fruit yield with percentage blue pixels. Real-time yield mapping was carried out with AYMS. Custom software was developed to acquire and process the images in real-time, and store the blue pixel ratio. The estimated yield per image along with geo-referenced coordinates was imported into ArcView 3.2 GIS software for mapping.

The roles of pedogenesis and diagenesis in clay mineral assemblages: Lower Cretaceous fluvial mudrocks, Nova Scotia, Canada

Clay mineral assemblages in alluvial mudrocks are important for paleoclimatic interpretation and for understanding burial diagenetic cementation in sandstones, but it is commonly difficult to unravel the relative importance of source weathering, pedogenesis and diagenesis in their origin. The clay mineral assemblages in fluvial overbank mudrocks from the Lower Cretaceous Chaswood Formation in central Nova Scotia, investigated by X-ray diffraction analysis of the < 2 µm fraction of 45 samples, include kaolinite, illite, vermiculite, and mixed layer kaolinite/expandable clay and mica/vermiculite. The assemblages vary with depositional facies. Wetland organic-rich mudrocks have large amounts of amorphous material and kaolinite is the dominant clay mineral. In the eastern part of the basin, where overbank mudrocks were episodically uplifted by syn-sedimentary strike-slip faulting, cumulate ultisol and alfisol paleosols are common. In the ultisols, hematite is enriched and kaolinite increases at the expense of illite in the B horizon. Alfisols contain more illite and vermiculite and the B horizon is enriched in goethite. In the western part of the basin, where thin sandstones with abundant diagenetic kaolinite cement are interbedded with the mudrocks, the distinctive clay mineral assemblage of mica/vermiculite mixed layer, vermiculite with 15.5 Å peak, and kaolinite/expandable mixed layer clay with a 17.7 Å peak is interpreted to result from bacterially-mediated oxidation of organic matter below the paleo-water table during early burial diagenesis. Deeper burial diagenesis may lead to slightly higher kaolinite crystallinity. Volcanic ash appears to alter to kaolinite/expandable mixed layer clay with a 7.9 Å peak. Comparison with the continuously subsiding and rapidly accumulated Wessex Formation of southern England, formed at a similar paleolatitude, shows the strong role of pedogenic processes and early diagenesis by meteoric water in development of clay mineral assemblages in the locally tectonically uplifted Chaswood Formation.

Estimation of Wild Blueberry Fruit Yield Using Digital Color Photography

The wild blueberry industry of North America may benefit significantly from precision agriculture technology. Currently, crop management practices are implemented on an average basis without considering the substantial variation in soil properties, bare spots, topographic features, and fruit yield in blueberry fields. Yield maps along with fertility, weed, and topographic maps can be used to generate prescription maps for site-specific application of agrochemicals (e.g., fertilizer or pesticide). Two wild blueberry fields in central Nova Scotia were selected to evaluate a photographic method for fruit yield estimation. A 10-megapixel 24-bit digital color camera was mounted on a tripod and pointed downwards to take photographs of the blueberry crop from a height of approximately 1 m. At harvest time, blueberry crop images were collected in each field at 30 different sample locations displaying a range in yield. Actual fruit yield was sampled from the same locations by hand-harvesting out of a 0.5 0.5 m quadrat using a commercial blueberry rake. Custom image processing software was developed to count the blue pixels of ripe fruit in the quadrat region of each image and express it as a percentage of total quadrat pixels. Linear regression was used to calibrate the fruit yield with percentage blue pixels separately in each field, and then the calibration equation of field 1 was used to predict fruit yield in field 2 for validation of the method. Percentage blue pixels correlated highly significantly with hand-harvested fruit yield in field 1 (R2 = 0.98; P < 0.001; n = 30) and field 2 (R2 = 0.99; P < 0.001; n = 30). The correlation between actual and predicted fruit yield in field 2 (validation) was also highly significant (R2 = 0.99; P < 0.001; n = 30; RMSE = 277 kg/ha). Non-significance of the t-test for actual versus predicted yield indicated that there was no significant bias in the yield estimation and that the predicted yield was accurate. Based on these results, an automated yield monitoring system consisting of a digital camera, computer, and DGPS will be developed and incorporated into a harvester to monitor and map blueberry fruit yield in real time.

Carbon storage in a chronosequence of red spruce (Picea rubens) forests in central Nova Scotia, Canada

Red spruce ( Picea rubens Sarg.) forests are an ecologically and economically important forest type in eastern Canada. We quantified the carbon (C) stocks of natural red spruce dominated stands in central Nova Scotia. Twenty-four stands over a 140 year chronosequence were sampled. Within each stand, major C pools including above- and below-ground tree biomass, shrub and herb vegetation, dead organic matter, and upper (0–10 cm) mineral soil were measured. A nonlinear four-parameter logistic function was fitted to the total site C stock data to describe the change in total ecosystem C storage over time. Total site C storage increased throughout stand development in a general sigmoidal pattern, increasing from 94.4 Mg C·ha–1in the youngest age-class to a maximum of 247.0 Mg C·ha–1in the 81- to 100-year-old age-class, then decreasing in the oldest age-classes. Carbon pools of live vegetation, standing dead trees, and downed woody debris displayed recognizable changes in C storage throughout stand development, conforming to some of the fundamental ideas on forest stand dynamics. Overall, above- and below-ground tree biomass had the greatest influence on total site C storage dynamics. These results are likely to be integrated into further forest management plans and generalized in other contexts to evaluate carbon stocks at the regional scale.