Browsing by Author "Grafton MCE"

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    A review of practices in precision application of granular fertilisers
    Grafton MCE; Yule I; Manning M; Nelson, W
    There is an implicit assumption in cited literature on precision agriculture (PA) that spreading of fertiliser is performed perfectly in the field leading to uniform application, this is not true. Variation can be large and often the actual performance of spreading equipment used has never been measured or verified. In various countries around the world there are quality assurance (QA) systems designed to achieve a prescribed level of performance. Even within these QA schemes limited testing is undertaken and always under perfect or near perfect conditions. The test methods are designed to establish an acceptable bout width which meets an acceptable evenness of spread if driven accurately. The test does not take into account wind conditions (except for requiring less than 15kmhr-1 for testing), humidity, slope, terrain or the instrumentation to maintain the desired bout width. This paper examines the effect of the farm environment and the physical characteristics of fertilisers on the spread patterns of fertilisers in the field. Fertilisers with heterogeneous particle size distributions proved to have more robust spread patterns under field conditions than those with homogeneous particle size distributions.
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    Ballistic modeling and pattern testing to prevent separation of New Zealand fertilizer products
    (American Society of Agricultural and Biological Engineers, 18/06/2015) Grafton MCE; Yule IJ; Robertson BG; Chok SM; Manning MJ
    In recent years twin disc centrifugal spreaders have become larger with some manufacturers claiming to be able to spread fertilizer products as far as 60 m. To achieve wider spread widths, the fertilizer particle exit velocity off the disc has increased, as a result the ballistic qualities of the product becomes more critical. This case study uses data-mined information from Ravensdown Fertiliser Co-op Ltd, a major fertilizer supplier. This article examines and researches products used by arable and grassland farmers and studies the effect of changes in product characteristics on spread bout width from these newer spreaders. Ballistic modeling, based on particle density, size, and shape was used to test the distance fertilizer particles travel at various velocities. Fertilizer particle velocities were measured by high speed photometry using both common fertilizers and common spreaders found in New Zealand. Spreading equipment was pattern tested using the New Zealand Spreadmark method. Ballistic modeling of particles proved appropriate in ideal conditions. Fertilizer manufacturers believe that spreader operators often fail to take account of physical characteristics of products being spread and target the widest bout width possible. This can lead to an in-field Coefficient of Variation (CV) which is much greater than 15% and leads to sub-optimal utilization of fertilizer, where variations in particle size distribution occur. Similar situations have been experienced when spreading fertilizer blends; where blends previously spread successfully, at narrower bout widths now separate. Ballistic models could provide bout width recommendations for products and blends, for a range of applicators and reduce crop striping.
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    Establishing a risk profile for New Zealand pastoral farms
    (Versita, 22/09/2017) Grafton MCE; Manning MJ
    In this paper, the risk profile of two pastoral production systems in New Zealand are examined. All farmers must manage and mitigate a multitude of risks. Traditionally, a farm budget is solely undertaken to satisfy a lending institution. Limited variance analysis takes place, usually for output prices and inputs such as: interest rates, energy costs, and fertiliser. The authors of this paper use “@Risk”, a risk profiling plug-in tool for Microsoft Excel to demonstrate how farm budgets can be more relevant to farmers. Many risk factors that affect farm financial performance, such as climate and commodity prices, are not controlled by the farmer. Wet summers help hill country sheep and beef pastoral farmers, as more grass growth occurs, which thereby reduces the cost of production and increases revenue, as more stock is finished. Whereas in drought years income falls as stock must be sold prior to finishing, in severe droughts capital stock may also be sold. Input costs also rise as pasture weed invasion occurs; health issues such as rye grass staggers may also add cost. Monte Carlo simulations on model farm budgets for a North Island sheep and beef property and a Canterbury dairy farm help demonstrate the risk profile of each farm type.
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    FEASIBILITY STUDY, EXTENDING THE SWATH WIDTH OF TOPDRESSING AIRCRAFT TO REDUCE STRIPING OF FERTILISER MIXES
    (Massey University, ) Brown HA; Grafton MCE; Davies CE; Currie, LD; Christensen, CL
    Fertiliser mixes of magnesium oxide coated urea and super phosphate require high application rates 250kg/ha - 500kg/ha. These rates are inclined to clog spreaders reducing their efficiency and compromising operational safety. As a result, the current spreader design is, not fitted for these rates. The swath width from a Cresco 08-600 without a spreader is only 12m wide, meaning many passes are required to cover a field. The mixture also tends to segregate which leads to striping. A new method of spreading fertilizer, which provides a wider swath width and an even distribution, is required. This method must be able to meet the CAA requirements for topdressing safety, minimise segregation in fertiliser mixtures and preferably should be applicable to most bulk fertilizers in common use; the method must not add any significant weight to the aircraft that would decrease its operating capacity. The feasibility of developing a means of initiating spreading of bulk fertilisers from topdressing aircraft hoppers from regions outside of the influence of the prop wash are investigated. If feasible, the system should be able to apply fertiliser across a 40m swath width at the target application rate, in a single pass. This would reduce flight time and improve the distribution pattern leading to reduced operating costs and higher crop yield. This preliminary report suggests that it is mathematically possible to widen the swath width of the Cresco 08-600 to 40m at an application rate of 350kg/ha by means of a screw conveyor transporting and evenly releasing fertiliser along the length of the wing up until the dihedral is reached. The next stage in this project will be to design the screw conveyor system and test it on the ground to see its limitations and potential safety concerns.
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    Geostatistical determination of soil noise and soil phosphorus spatial variability
    (Elsevier Masson, 28/09/2017) Kaul TMC; Grafton MCE
    This research studies the effect of stratifying soil samples to try and find a suitable depth to establish a geospatial relationship for a practical soil sampling grid in New Zealand hill country. Cores were collected from 200 predetermined sites in grids at two trial sites at “Patitapu” hill country farm in theWairarapa, New Zealand. Trial 1 was a 200 m 100 m grid located in a gently undulating paddock. Trial 2 was a 220 m 80 m grid located on a moderately sloped paddock. Each grid had cores taken at intervals of 5 m, 10 m, or 20 m. Core sites were mapped out prior to going into the field; these points were found using a Leica Geo Systems GS15 (real time kinematic GPS) and marked with pigtail pegs and spray-paint on the ground. Cores were taken using a 50 mm-diameter soil core sampler. Cores were cut into three sections according to depth: A—0–30 mm, B—30–75 mm, and C—75–150 mm. Olsen P lab results were obtained for half of the total 1400 samples due to financial constraints. The results indicate that there was a significant decrease in variability from Section A to Section B for both trials. Section B and C for Trial 1 had similar variability, whereas there was another significant drop in variability from Section B to C in Trial 2. Measuring samples below the top 3 cm appeared to effectively reduce noise when sampled from 3 to 15 cm. However, measuring from 7.5 cm to 15 cm on the slope in Trial 2 reduced variability so much that all results were almost identical, which may mean that there is no measurable representation of plant available P. The reduction in noise by removing the top 3 cm of soil samples is significant for improving current soil nutrient testing methods by allowing better geospatial predictions for whole paddock soil nutrient variability mapping
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    Identifying grass species using hyperspectral sensing
    (Fertilizer and Lime Research Centre, ) Cushnahan T; Yule IJ; Pullanagari RR; Grafton MCE; Currie, L; Singh, R
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    Measuring the spread patterns of spreaders under normal field conditions compared to test conditions
    (Fertilizer and Lime Research Centre, 1/06/2016) Grafton MCE; Acebes DI; Yule IJ; Willis LA; Currie, L; Singh, R
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    The ballistics of separation of fertiliser blends at wide bout widths
    (28/02/2014) Grafton MCE; Yule IJ; Currie, LD; Christensen, CL
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    Understanding soil phosphorus variability with depth for the improvement of current soil sampling methods
    (7/02/2017) Kaul TM; Grafton MCE; Hedley MJ; Yule IJ
    Noise in soil test results can be reduced by measuring phosphorus below the top 3cm of soil from ground level. This is significant for improving current soil nutrient testing methods by allowing better geospatial predictions for whole paddock soil nutrient variability mapping for use in precision fertilizer application. In this study 200 cores were collected from predetermined grids at two trial sites at „Patitapu‟ hill country farm in the Wairarapa. The sites were selected according to accessibility and slope- Trial 1 was a 200m x 100m grid located in a gently undulating paddock. Trial 2 was a 220m x 80m grid located on a moderate to steeply sloped paddock. Each grid had cores taken at intervals of 5m, 10m and 20m. Core sites were mapped out on a Landsat 8 image (NASA) of the Trial sites using ArcGIS 10.2 (ESRI, Redlands Ca.) prior to going into the field; these were then marked out using a LEICA (real time kinematic GPS), pigtails and spray-paint on the ground. Cores were taken using a 30mm diameter soil core sampler. Trial 1 cores were cut into four sections according to depth: A – 0-30mm, B – 30mm-75mm, C- 75mm-150mm, and D- >150mm. Trial 2 cores were cut into three sections: A – 0-30mm, B – 30mm-75mm, C- 75mm-150mm. Olsen P lab results were collected for 120 of the 400 soil cores. These results were analyzed to compare the spatial variability of each depth. The results indicate that there is a significant decrease in variability from section A to section B for both trials. Section B and C for trial 1 have similar variability, whereas there is another significant drop in variability from section B to C in trial 2. Measuring samples below the top 3cm appears to effectively reduce noise, however measuring below 7.5cm for a steeply sloped paddock such as trial 2 may reduce variability too much as to no longer be representative of plant available P, and therefore misrepresenting the overall variability of soil P across a paddock or farm.