Three-dimensional scanning of soil surface and furrow profiles using a portable and affordable unit

Soil surface and furrow profiles in soil dynamics research and applications are usually measured using manual profile meters and laser-based scanners. Manual profile meters are laborious to use, and laser-based scanners could be expensive and not portable. An approach was developed for measuring soil surface and furrow profiles using a portable and affordable 3D scanner. The developed approach was validated by using the 3D scanner to measure the width and depth of a V-groove (with known dimensions) created in three types of soils (coarse sand, Black Vertosol and Red Ferrosol) at different soil water contents moulded in a soil box. Average error of ±1.83% was found for all the three soil types and soil water contents. Results from the 3D scanner were also validated in the field by comparison to profiles measured with a pinned profile meter. In terms of percentage difference in readings, the 3D scanner results showed 16, 5 and 4% greater furrow width, ridge height and cross-sectional area, respectively, and 1% less furrow backfill. These differences were partly due to profile meter pins digging into loose soil and limitation with accurate width measurement. Data acquisition and processing with the 3D scanner unit were significantly faster than with the pinned profile meter. In general, it could be concluded that the developed methodology has the level of accuracy required for soil surface and furrow profile measurements. Furthermore, this approach is a cost-effective alternative to using laser-based scanners

Farm resource use as influenced by diverse cropping systems in the Australian Northern cropping zone

Many farming systems in Australia are underperforming. For example, a recent analysis showed that only about 29% of current crop sequences in the northern grains region of Australia are achieving 80% of their water-limited yield potential (Hochman et al., 2014). This is compounded by tight profit margins and changing climate and market conditions. Available evidence also suggests that between 2013 and 2018, the cost of consumable inputs, such as fertiliser, has increased by 5.7% (ABARES, 2018). Also, over the past five years, the cost of agricultural machinery in Australia has increased by 13.4% (ABS, 2018). However, several farming system component analyses and simulations have predominantly focused on the impact of biophysical processes on farming system performance, including soil quality, water use efficiency, dynamics of nitrogen, crop yields, and disease and nematodes effects of farming practices at the paddock scale. While biophysical optimisation of the farming system may be possible to improve the efficiency of most farming systems, key elements that are often ignored is how the intensity and diversity of different cropping systems impact on whole-farm factors, such as labour and machinery resources. Far from being obvious, these input resources are critical because they modify farm productivity and profitability in the short and long term. Moreover, a consideration of these factors is crucial because they can influence the adoption of farm innovations. The central objective of this study is to examine farm resource constraints with a focus on machinery, labour requirements and fuel requirements as influenced by diverse crop rotations in the northern grain-growing region of Australia. Our analysis is based on three steps. First, we simulated different crop rotations over 112 years (i.e., 1900-2012) of historical climate records using the Agricultural Production Simulator (APSIM). These crop rotations were identified following focus group meetings with leading farmers and advisors throughout the northern cropping zone of Australia. Second, we obtained information on machinery and labour parameters from existing literature, local technical guides and through a consultation process with farm advisers and growers (N = 26 farmers). Finally, we combined the APSIM generated outputs with the machinery and labour data to comprehensively determine how different crop rotations affect labour and machinery requirements within the farming system using analysis of variance. Results showed that the low-intensity systems required 46% less labour per ha than the higher-intensive systems, while the less diverse systems required about 33% less labour per ha than the more diverse systems. Planting and spraying operations respectively represent about 27% and 37% of total fieldwork requirements. Also, the labour required per ha is less in bigger farms compared to smaller farms, which may be explained by the larger machines used by these larger farms. For all sequences considered, peak labour periods fell in July, October to November, while non-peak period is August to September and December to January, corresponding with the periods in which most farm production activities occur. We conclude that Diversified crop rotation systems had significant effect on labour and machinery requirements and differed significantly among rotations (P < 0.05). Also, diverse rotations may create higher labour demand and peak periods that might, in some cases, limit the adoption of diversified crop rotations in some farm businesses, suggesting that labour efficiency can be an important consideration in farming systems research and analysis. These findings will be explored further as part of the on-going development of a bio-economic modelling to explore the trade-offs and synergies between system performance objectives and impacts of innovations options at the whole-farm level

A new frame-based calibration method for extended octagonal ring transducers

An extended octagonal ring transducer (EORT) is a simple, single, and compact biaxial force measuring transducer, which is ideal for soil force measurement in tillage tool research. Calibration of EORTs is needed to ascertain their sensitivities and to determine an accurate calibration equation to convert voltage output to force measurement. Typically, calibration of EORTs involves the use of universal tensile testing machines, hydraulic systems and large gravitational loads (hanging weights) to apply loads. In this study, a simple calibration frame that enables application of non-gravitational loads was evaluated and used to hold and calibrate an EORT through both uniaxial and biaxial loading. The frame was suitable for both uniaxial and biaxial application of offset coincident force up to 3000 N and centered perpendicular force up to 1500 N. The EORT exhibited a strong linear relationship (R2 ≥ 0.9998) between applied forces and voltage outputs, low hysteresis errors (≤0.4%), and low cross-sensitivities (3.61% and 1.6% for coincident and perpendicular forces, respectively). Calibration equations developed from the primary bridge output data or from the biaxial loading data using the frame produced good force predictions, which also improved when taking into account the impacts of cross-sensitivity. The results confirmed that this calibration approach can integrate the interactions of output cross-sensitivity to deliver more accurate force prediction. Coefficients of determination of the relationships between applied and predicted forces were 0.9993 to 0.9996 and 0.9877 to 0.9984 for coincident and perpendicular forces, respectively. This calibration frame presents potential for safely applying large, non-gravitational loads in a contained and portable manner and its concept can easily be adapted to suit the scale of the transducer

Determination of discrete element model parameters for a cohesive soil and validation through narrow point opener performance analysis

The discrete element method (DEM) is a powerful tool that can be used to predict soil disturbance and soil cutting forces to assist design optimisation of soil cutting tools. In this study, DEM input parameters were calibrated to model a cohesive soil (Black Vertosol of southern Queensland, Australia) using the hysteretic spring contact model, coupled with linear cohesion model, and nominal particle radius of 5 mm. DEM simulations were validated using experimental results for the effects of opener rake angle and cutting edge chamfer, and bentleg opener shank offset on no-tillage narrow point opener performance. Overall, DEM results closely agreed with experimental results and exhibited similar trends. By using particle displacement analysis to predict loosened furrow boundary, most predictions of furrow parameters namely furrow cross-sectional area, furrow width, and critical depth had relative errors ranging from 1 % to 19 %. Lateral soil throw was predicted with relative errors of 0.2 %–9 %, except for the straight opener with 45° rake angle (-32 %). Ridge height was over predicted in all cases due to larger DEM particles than actual soil particles used. Relative errors of 20 %, 22 %, -31 %, and -5 % in draught were recorded for the straight openers with 90° (blunt), 90° (chamfered), and 45° rake angles, and the bentleg opener, respectively. These results show that DEM and the input parameters determined to model the cohesive soil of this study can be used to reliably assess furrow opener performance

No-tillage furrow opener performance: a review of tool geometry, settings and interactions with soil and crop residue

The primary features of an effective and efficient furrow opener include controlled soil disturbance and low draught and vertical force requirements. When integrated in a no-tillage seeding system, furrow openers should also have the ability to assist, and not hinder, the functions of seeding system components – such as maintaining adequate surface residue distribution, accurate and uniform placement of seeds and fertiliser, and regular inter-plant spacing. This review highlights how these goals are affected by opener type, geometry and settings, and soil and residue conditions. Typically, tine openers cause greater soil disturbance than disc openers whereas disc openers are likely to cause residue hairpinning. Winged tine openers reduce residue interference with seed placement and support greater lateral seed spread. Inverted-T openers can achieve subsurface soil shattering, which helps conserve moisture and provides good seed–soil contact. A tine opener with concave cutting edge reduces soil disturbance relative to straight and convex cutting edges. Increasing rake angle, tine width and operating depth increase degree of soil disturbance and draught requirement. Increasing forward speed reduces residue interference with sowing but might decrease the accuracy and uniformity of depth and separation of seed and fertiliser placement. Relative to common openers, bentleg openers have lower draught and penetration force requirements while combining minimal lateral soil throw with high furrow backfill, even at speeds of up to 16 km h–1. The performance of bentleg openers need to be evaluated under residue conditions and in cohesive and adhesive soils. Recommendations for future research are presented

Evaluation of bentleg and straight narrow point openers in cohesive soil

The bentleg opener was developed to overcome the high soil disturbance caused by straight narrow point openers, with the original evaluation conducted on sandy soils. A bentleg furrow opener was compared to narrow point openers with varying rake angles (45° and 90°) and cutting edge cross-sections (blunt, and single- and double-side chamfers) for soil disturbance, tillage forces, and soil aggregate break down in Black Vertosol (Vertisol in the USDA Soil Taxonomy), a highly cohesive soil relative to sandy soils used previously. Whereas the 45° rake angle caused greater soil disturbance, produced larger soil aggregates, and reduced draught and vertical force requirements, all openers with 90° rake angle (blunt and chamfered openers) had a shallow critical depth (44–46 mm) and caused smearing. Contrary to previous findings in sandy soil, both single and double side chamfering of opener cutting edge had no significant effect on soil movement, furrow width, and furrow cross-sectional area. However, greater soil movement was observed on the chamfered side of the single-side chamfered opener than the non-chamfered side. The chamfers significantly reduced draught and vertical forces and produced smaller soil aggregates. The bentleg opener loosened soil to the furrow bottom but caused the least soil movement out of the furrow and formed a ridge in the middle of the furrow, which resulted in the highest furrow backfill. It also encountered a downward vertical force which assisted penetration and had a greater proportion of aggregates within the optimum range (1.18 and 9.5 mm). The bentleg opener, thus, shows potential for improved seed covering and satisfactory performance at operating speeds above 8 km h−1

Analysis of effects of operating speed and depth on bentleg opener performance in cohesive soil using the discrete element method

High operating speeds are desirable, different seeding depths are required, and low soil disturbance is necessary for sowing in no-tillage farming. The effects of operating speed (8–16 km h−1) and depth (60–120 mm) on bentleg opener (four variations) performance were analysed in comparison to straight openers in a virtual soil bin using the discrete element method (DEM). Generally, increasing operating depth and speed resulted in increased soil disturbance and reaction forces. However, the bentleg openers loosened furrows down to the furrow bottom and caused less lateral soil throw at all operating depths and speeds. Bentleg openers, particularly without foot, increased furrow width by lower magnitudes compared with straight openers as operating speed was increased. The greatest lateral soil throw beyond furrow banks recorded for the bentleg openers at operating speed and depth of 16 km h−1 and 60 mm were less than the least for the straight openers, except for the footless bentleg with forward raked side leg. Backward raked side leg had the lowest impact on lateral soil throw and spill over distance with increasing operating speed. Increasing operating speed shifted the main ridge created by the bentleg openers above the furrow’s centre outward to the left. Furrow backfill of 97–100% was achieved with the bentleg openers. Bentleg openers with 45° foot rake angle required the lowest draught and vertical forces. Backward raked side leg resulted in the highest draught force among the bentleg openers and the greatest vertical (penetration) force among all the opener

Analysis of effect of bentleg opener geometry on performance in cohesive soil using the discrete element method

Bentleg furrow openers can significantly reduce soil disturbance and reaction forces relative to conventional narrow point openers used in no-tillage farming. The effect of bentleg opener geometry on soil disturbance and reaction forces in a cohesive soil was assessed in a virtual soil bin using the discrete element method. Soil disturbance and reaction forces at an operating depth and a speed of 100 mm and 8 km h−1, were shown to be minimised by using (1) a shank lateral offset of 70 mm, (2) a side leg bend angle that ensures the elbow, which is the transition between the side leg and vertical shank, is not located below the soil surface, (3) an arched instead of angled elbow, (4) a cutting edge chamfer angle as low as practical, and (5) tine thickness as small as practical. Furrow size was found to be more dependent on shank lateral offset and side leg bend angle than side leg forward angle. Though side leg forward angles >90° reduce particle displacement and will work better in fields with stones and roots, they also considerably increase draught and penetration resistance. A low rake angled foot minimises soil reaction forces and drives soil loosening. Reducing foot height and interaction of the vertical shank with soil particles minimises surface soil displacement. These results have expanded the understanding of bentleg opener mechanics and are in close agreement with those reported for sandy soils. Therefore, similar criteria can be followed to optimise bentleg opener design for different soil types

Evaluation of NEXEN™ stabilized nitrogen applied to overhead irrigated cotton (Gossypium hirsutum L.)

This study was conducted to determine the agronomic feasibility of using NEXENTM (urea treated with the urease inhibitor N-(N-butyl) thiophosphoric triamide) for surface of nitrogen (N) fertilizer in irrigated cotton, particularly, for in-crop season N applications. Field experiments were established on a cotton farm in southern Queensland (Australia) during the 2015-2016 season. Fertilizers were applied at N rates equivalent to 0 (control), and 140, 200 (farm practice) and 260 kg ha-1, respectively, to provide a ±30% range of the standard rate used for the commercial crop. The fertilizer was applied on the surface, incorporated or a combination of both pre-plant incorporation and surface application in-crop. Results showed that there was no fertilizer type or nitrogen rate effect above an application rate of 140 kg ha-1 N. This was consistent with analyses of cottonseed N from fertilizer-treated crop, which suggested that the crop was over-supplied with N above that rate. Given these results, the use of NEXENTM appears to be a promising alternative for (overhead) irrigated cotton, for both pre-plant and in-crop season application of N. Although commonly used in the Australian cotton industry, techniques such as ‘water-run‘ urea are considered as low efficiency because of the associated environmental losses of N. Surface application of nBTPT-treated urea with conventional twin discs fertilizer spreaders may enable for improved field operating efficiency and reduced cost of fertilizer application compared with other methods or fertilizer types that require soil incorporation. Our estimates indicated that operating costs may be reduced from approximately AUD16 per ha to AUD5 per ha (AUD1 ≈ USD0.75) when fertilizer is surface-applied compared with soil incorporation, because of lower energy requirements (draft) and labor (operating width, forward speed), with further savings achieved through improved timeliness. This alternative requires investigation to determine the potential risk of N losses through gaseous evolution (volatilization, N2/N2O), particularly in furrow irrigated systems

Supplemental information for "Performance Evaluation of Jerusalem Artichoke Digging Tool in Cohesive Soil Using Discrete Element Method"

The data includes additional figures and tables referenced in the manuscript. </p