Aitazaz A. Farooque

Response of Wild Blueberry Yield to Spatial Variability of Soil Properties

Abstract Crop management practices within wild blueberry fields are implemented uniformly, with inadequate attention being given to substantial variations in soil properties and fruit yield. These variations emphasize the need for precise and site-specific crop management based on proper characterization and quantification of spatial soil variability. The objective of this research was to characterize and quantify the spatial patterns of variability in soil properties and fruit yield. A grid pattern of sampling points was established at each experimental site to collect soil and fruit yield samples during 2009 to 2010 at North River and Carmal sites, Nova Scotia, Canada. The soil samples were collected from 0- to 15-cm depth at each grid point. These soil samples were analyzed for soil organic matter, pH, texture, electrical conductivity, and inorganic nitrogen (N). The volumetric moisture content (&thetas;v) was recorded at each grid point using time domain reflectometry. Ground conductivity readings were also recorded using dual EM conductivity meter at same selected grid points. Fruit yield was mapped using calibrated digital color photography during the crop year. The coefficient of variation of the soil properties and fruit yield suggested moderate to high variability (coefficient of variation >15%) except for soil pH. The results of correlation analysis indicated that the values for inorganic N, soil organic matter, electrical conductivity, clay, and &thetas;v were generally higher in high-yielding areas and vice versa. The trend was opposite for sand and silt content, which were higher in low-yielding areas. Most of the soil properties had a large spatial variation with semivariogram range of 20 to 50 m and varied greatly within field. Kriged maps of soil properties and fruit yield also showed substantial variation within field. Characterization of spatial soil variability in wild blueberry fields would assist in planning future soil sampling in new fields showing soil and/or yield variability. The selection of soil sampling should be based on the sampling interval suggested by the variogram range (<20 m). Proper soil sampling can help in identifying yield-limiting soil properties and develop prescription maps for site-specific nutrient management to ameliorate unproductive areas and reduce environmental contamination.

Impact of Variable Rate Fertilization on Subsurface Water Contamination in Wild Blueberry Cropping System

Abstract. Wild blueberry fields have gentle to severe topography with high proportion of bare spots, and weed patches emphasizing the need for variable rate (VR) fertilization. To evaluate the impact of VR fertilization on subsurface water contamination, two wild blueberry fields were selected in Nova Scotia, Canada. The field boundaries, weeds and bare spots were mapped using real-time kinematics global positioning system. The variation in slope was mapped and management zones i.e. steep slope (Zone-1), moderate slope (Zone-2) and low lying areas (Zone-3) were delineated. Both fields were divided into two halves (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 Zone-1, Zone-2 and Zone-3, respectively, with a VR fertilizer spreader. The bare spots/weeds were classified as a separate class in the prescription maps and no fertilizer was applied in those areas. For comparison, the uniform fertilizer rate of 200 kg ha -1 used by growers was applied in uniform treatment sections of the selected fields. Subsurface water samples were collected after every heavy rainfall (>20 mm) from 36 suction lysimeters placed in each field with 18 lysimeters in each treatment. The subsurface water samples were analyzed for nitrate nitrogen (NO 3 — N), and ammonium nitrogen (NH 4 + -N) concentrations under VR and uniform fertilization. Leaf samples were collected from both VR and uniform treatments and were analyzed for leaf nutrient concentrations. The results of this study suggested significantly lower NO 3 — N and NH 4 + -N loading from subsurface water samples leaving the root zone in moderate and low lying areas for VR treatment as compared to uniform treatment. The nitrogen, phosphorus, and potassium nutrient levels in leaves were found to be higher than the recommended ranges for uniform treatment as compare to VR treatment suggesting the excess uptake by plants in uniform treatment which may result in more vegetative growth and lower yield. The results indicated that VR fertilization based slope can increase input use efficiency, farm profitability and reduce subsurface water contamination.

Ecological impacts of the N-viro biosolids land-application for wild blueberry (Vaccinium angustifolium. Ait) production in Nova Scotia

Land application of biosolids from processed sewage sludge may deteriorate soil, water, and plants. We investigated the impact of the N-Viro biosolids land-application on the quality of the soil water that moved through Orthic Humo-Ferric Podzols soil of Nova Scotia (NS) at the Wild Blueberry Research Institute, Debert, NS Canada. In addition, the response of major soilproperties and crop yield was also studied. Wild blueberry (Vaccinium angustifolium. Ait) was grown under irrigated and rainfed conditions in 2008 and 2009. Four experimental treatments including (i) NI: N-Viro irrigated, (ii) NR: N-Viro rainfed, (iii) FI: inorganic fertilizer irrigated, and (iv) FR: inorganic fertilizer rainfed (control) were replicated 4 times under randomized complete block design. Soil samples were collected at the end of each year and analyzed for changes in cation exchange capacity (CEC), soil organic matter (SOM), and pH.Soil water samples were collected four times during the study period from the suction cup lysimeters installed within and below crop root zone at 20 and 40 cm depths, respectively. The samples were analyzed for a range of water quality parameters including conductance, hardness, pH, macro- and micronutrients, and the infectious pathogens Escherichia coli (E. coli) and salmonella. Berries were harvested for fruit yield estimates. Irrigation significantly increased CEC during 2008 and the soil pH decreased from 4.93 (2008) to 4.79 (2009). There were significant influences of irrigation, fertilizer, and their interaction, in some cases, on most of the soil water quality parameters except on the infectious bacteria. No presence of E. coli or salmonella were observed in soil and water samples, reflecting the absence of these bacteria in biosolids used in this experiment. Nutrient concentration in the soil water samples collected from the four treatments were higher in the sequence NI > NR > FI > FR. The irrigation treatment had significant effect on the unripe fruit yield. We conclude that the comparable performance of N-Viro biosolids and the increasing prices of inorganic fertilizers would compel farmers to use economically available N-Viro biosolids that, coupled with the supplemental irrigation, did not deteriorate the studied soil properties, soil water quality, and the wild blueberry yield during this experiment.

Performance Evaluation of a Prototype Variable Rate Sprayer for Spot – Specific Application of Bravo® Fungicide in Wild Blueberry

Wild blueberry yields are highly dependent on fungicides to control floral blight (monilinia and botrytis) and leaf diseases (septoria and rust). Growers apply fungicides uniformly without considering the significant bare spots (30-50% of the total field area). The repeated and excessive use of agrochemicals in bare spots has resulted in an increased cost of production. The over use of the fungicides is harmful to the environment and can contaminate surface and ground water. The proper targeting of fungicide on only foliage has the potential to save a substantial amount of chemical. Therefore, a significant need of an affordable variable rate sprayer for spot application of fungicide is needed for wild blueberry production. The objective of this study was to determine the performance of a prototype variable rate sprayer for spot application of Bravo® fungicide in wild blueberry fields. The 6.1 meter VR sprayer was mounted on a all-terrain vehicle. Color cameras were used to detect bare soil areas in wild blueberry fields. Eighteen 6.1 meter wide test plots were selected in a wild blueberry field and the bare soil areas were mapped using RTK-DGPS. Three application rates (uniform, variable and control) were selected at random for each plot. Digital color images were taken at 6 randomly selected locations in each of the 18 plots. Each image was analyzed to calculate green ratio for determining effect of Bravo® on wild blueberries. The application tracks were statistically compared with reference to the control tracks. Water sensitive paper was also placed in randomly selected locations for analysis purposes. The results can be used to determine the performance of applying fungicide on site-specific bases using a variable rate sprayer.

Mapping Water Table Depths using Electromagnetic Induction Methods to Develop Variable Rate Technologies

Most of the agricultural fields are generally irrigated or drained uniformly without considering the variation in water table depths (WTD). Investigating these depths is important for scheduling irrigation, drainage system designs and water balance models. The objective of this study was to estimate the WTD using electromagnetic induction (EMI) method. Thirty observation wells were installed to calibrate the DualEM-2 for predicting the WTD within a soybean and a pasture field in central Nova Scotia, respectively. The horizontal co-planar (HCP) geometry, perpendicular co-planar (PRP) geometry and WTD were recorded simultaneously from each well for three consecutive days after every significant rainfall. Comprehensive surveys were conducted in selected fields to measure ground conductivity with DualEM-2 and a differential global positioning system (DGPS). The HCP component of the DualEM-2 was better than PRP component for estimating WTD because of its greater sensing depth. The preliminary results showed significant correlations between the actual WTD and HCP measured with DualEM-2 in both fields. The regression equation was utilized to predict WTD from ground conductivity survey data (BEEC: R2 ranged from 0.76 to 0.93; p-value<0.01, Boulden: R2 ranged from 0.69 to 0.85; p-value<0.01).The predicted WTD maps were generated in ArcGIS 9.3 software. This information could also be used for measuring the depletion of WTD, site-specific irrigation and drainage design with time after the application of irrigation or rainfall.

Biochar: a sustainable solution for solid waste management in agro-processing industries

ABSTRACT Agro-processing is a major industry in Canada. The processing of an agricultural product generates an enormous amount of water and solid waste. Appropriate management of these waste streams has become a challenging issue. The present study proposes a concept of circular bio-economy whereby solid waste from one agro-processing industry is used as a feedstock for producing biochar, which is then used in another agro-processing industry for wastewater treatment. The biochar after wastewater treatment can be used for agricultural soil applications. This article describes a study on the pyrolysis of oilcakes from crambe and meadowfoam seeds. The pyrolysis of oilcakes obtained from crambe and meadowfoam seeds is conducted in a furnace-heated reactor at 450 °C and 550 °C and the properties of char, oil and gas are studied. The biochar is then used for wastewater treatment. This article discusses the results.

Effect of split fertilization on subsurface water quality in wild blueberry fields

Abstract. The majority of wild blueberry ( Ait.) fields are situated in acidic soils, having poor water holding capacities, weed patches, gentle to severe topography, and substantial proportion of bare spots, which emphasize the need for variable rate split (VRS) fertilization. Two commercial wild blueberry sites were selected in Nova Scotia, Canada to evaluate the impact of VRS fertilization on subsurface water contamination. The sites were divided into three sections [VRS section, uniform rate split (URS) section, and uniform rate (UR) section]. Prescription maps were generated with ArcGIS 10.1 software based on slope variation for VRS fertilization. Fertilization was performed based on the prescription maps using variable rate (VR) spreader. Fifty-four lysimeters were installed in VRS, URS, and UR treatment sections to collect subsurface water samples. Subsurface water samples were collected after every heavy rainfall event (>15 mm), and were analyzed for nitrate nitrogen (NO 3 - -N) and ammonium nitrogen (NH 4 + -N) concentrations. Leaf samples were collected from each fertilizer treatment and analyzed for macro and micro nutrients. Results suggested that the VRS treatment significantly decreased (p 3 - -N and NH 4 + -N concentrations in subsurface water samples when compared to URS and UR treatments. Overall for the Cooper site, mean NO 3 - -N leaching under the VRS treatment section were 45% and 47% lower as compared to the URS and UR treatment sections, respectively. However, mean values of NH 4 + -N concentration under the VRS treatment section of the North River site were 38% and 45% lower as compared to the URS and UR treatment sections, respectively. Results revealed that the VRS treatment did not have any negative effect on leaf nutrient concentrations. The VRS fertilization saved almost 40% in this study. Results demonstrated that the VRS fertilization in wild blueberry fields can increase fertilizer use efficiency and reduce water contamination via subsurface leaching.

An on-the-go ultrasonic plant height measurement system (UPHMS II) in the wild blueberry cropping system

Abstract. Wild blueberry ( Vaccinium angustifolium Ait.) is a perennial rhizomatous low shrub and mostly mechanically harvested. The operator of the harvester needs to maintain the optimum height of harvester‘s head according to the plant height for better yield and quality while decreasing plant pulling. An ultrasonic on-the-go plant height measurement system (UPHMS II) was developed and compared with previous height measurement system (UPHMS I). A real-time kinematics differential global positioning system (RTK-GPS), a custom program and a ruggedized computer and both plant height sensing system were mounted on a commercial mechanical harvester for real-time plant height measurement during harvesting. A custom program was developed to acquire and process ultrasonic sensing data in real-time from both UPHMS I and UPHMS II simultaneously. Two wild blueberry fields were selected in central Nova Scotia to evaluate the performance of both UPHMS I and UPHMS II. Manually measured plant height values from 24 plots were compared with real-time measured values of two systems. UPHMS II performed better to predict wild blueberry plant height with higher accuracy than UPHMS I. The RMSE of the sensed height of UPHMS I and UPHMS II were 6.4 cm and 1.6 cm, respectively. UPHMS II can be an economic option to control wild blueberry harvester head automatically to increase harvester and operator‘s efficiency. Real-time and accurate sensing of plant height is the first step toward the automation of the wild blueberry harvester. Refinements for the optimum head height according to the plant height is required for future studies.

PREDICTIVE MODEL FOR WILD BLUEBERRY FRUIT LOSSES DURING HARVESTING

Abstract. Wild blueberries are one of the most important fruit crops of Canada, producing more than 50% of the world’s production. Understanding and predicting the relationships between the machine operating parameters, fruit losses, topographic features and crop characteristics can aid in better berry recovery during mechanical harvesting. This paper suggested a modeling approach for prediction of fruit losses during harvesting using artificial neural network (ANN) and multiple regression (MR) techniques. Four wild blueberry fields were selected and completely randomized factorial (3 x 3) experiments were constructed at each site. One hundred sixty two plots (0.91 x 3 m) were made at each site, in the path of operating harvester. The total fruit yield, total losses were collected from each plot within selected fields. The harvester was operated at specific levels of ground speed (1.20, 1.60 and 2.00 km h-1) and head rotational speed (26, 28 and 30 rpm). The readings of slope, plant height, and fruit zone were also recorded from each plot. The collected data were normalized, and 70% of the data were utilized for training, and 30% for validation of the developed models using ANN and MR techniques. The developed models were validated internally and externally and the best performing model was identified based on mean square error (MSE), root mean square error (RMSE), coefficient of efficiency (CE) and coefficient of determination (R2). Results of scatter plot among the RMSE and epoch suggested that an epoch size of 15000 was appropriate to process fruit losses using ANN approach. Results revealed that the prediction accuracy of the MR models was lower (R2 = 0.46; RMSE = 0.14) than the ANN model (R2 = 0.84; RMSE = 0.075) for training dataset, which might be due to the non-linear nature of the data. Results reported that the ANN model predicted fruit losses with higher (R2 = 0.63; RMSE = 0.11) accuracy when compared with MR model (R2 = 0.37; RMSE = 0.15) for external validation dataset. Overall, the results of the study suggested that the ANN model was able to predict fruit losses accurately and reliably as functions of fruit yield, crop and machine variables. This study will help to identify the factors responsible for fruit losses and to suggest optimal harvesting scenarios to improve berry picking efficiency and recovery.

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.