Mechanized Harvesting Operations Research Articles

New Progress in Intelligent Picking: Online Detection of Apple Maturity and Fruit Diameter Based on Machine Vision

In the realm of automated apple picking operations, the real-time monitoring of apple maturity and diameter characteristics is of paramount importance. Given the constraints associated with feature detection of apples in automated harvesting, this study proposes a machine vision-based methodology for the accurate identification of Fuji apples’ maturity and diameter. Firstly, maturity level detection employed an improved YOLOv5s object detection model. The feature fusion section of the YOLOv5s network was optimized by introducing the cross-level partial network module VoVGSCSP and lightweight convolution GSConv. This optimization aimed to improve the model’s multiscale feature information fusion ability while accelerating inference speed and reducing parameter count. Within the enhanced feature fusion network, a dual attention mechanism combining channel and spatial attention (GAM) was introduced to refine the color and texture feature information of apples and to increase spatial position feature weights. In terms of diameter determination, the contours of apples are obtained by integrating the dual features of color and depth images within the target boxes acquired using the maturity detection model. Subsequently, the actual area of the apple contour is determined by calculating the conversion relationship between pixel area and real area at the current depth value, thereby obtaining the diameter of the apples. Experimental results showed that the improved YOLOv5s model achieved an average maturity level detection precision of 98.7%. Particularly noteworthy was the detection accuracy for low maturity apples, reaching 97.4%, surpassing Faster R-CNN, Mask R-CNN, YOLOv7, and YOLOv5s models by 6.6%, 5.5%, 10.1%, and 11.0% with a real-time detection frame rate of 155 FPS. Diameter detection achieved a success rate of 93.3% with a real-time detection frame rate of 56 FPS and an average diameter deviation of 0.878 mm for 10 apple targets across three trials. Finally, the proposed method achieved an average precision of 98.7% for online detection of apple maturity level and 93.3% for fruit diameter features. The overall real-time inference speed was approximately 56 frames per second. These findings indicated that the method met the requirements of real-time mechanical harvesting operations, offering practical importance for the advancement of the apple industry.

Sugarcane Row Gaps Assessment over Successive Burned and Unburned Annual Harvests

Mechanized harvesting operations promote a series of benefits to sugarcane production but are also a cultivation step responsible for developing a series of problems for the soil and the plants due to plant mechanical damage, resulting in a decline in production over successive cycles due to row gaps emergence. The objective of this study was to evaluate the impact of burned and unburned harvesting systems on the occurrence of sugarcane row gaps over annual harvests. For this study, a burned and an unburned area were selected. The row gap number and length (sum of gaps, m) were measured after the sugarcane planting and plant-cane cultivation stages and after the first, second, and third sugarcane ratoon harvests. The results revealed that there was no difference in the number and length of row gaps between the burned and unburned harvesting systems. However, the row gap number and length considerably increased after the second harvest in both treatments (burned and unburned). The row gap number and length were close to 5 and 1–5 m at the planting and plant-cane cultivation stages and increased to around 60 and 70 m as the harvest progressed, respectively, in burned and unburned harvesting. Our results suggest that row gaps in sugarcane fields are independent of the burned or unburned sugarcane harvesting system but increase as the number of harvests increases.

Experimental Study of a 4HLB-4 Half-Feed Four-Row Peanut Combine Harvester

In order to improve the operational performance of the self-developed 4HLB-4 half-feed four-row peanut combine harvester, single-factor and multifactor field tests were conducted on key operational parameters affecting the quality of harvesting. The response surface methodology was used to study the effects of the forward speed, clamping height, peanut picking roller rotational speed, and cleaning sieve vibrational frequency on the loss rate and impurity rate. A response surface regression model of the loss rate and impurity rate was constructed. A multi-objective integrated optimization was carried out for each factor. The results showed that, in terms of the order of significance, the influence of each factor on the impurity rate was as follows: cleaning sieve vibrational frequency > clamping height > forward speed > peanut picking roller rotational speed. The order of significance of the influence of each factor on the loss rate was as follows: peanut picking roller rotational speed > forward speed > clamping height > cleaning sieve vibrational frequency. The optimal combination of parameters was a forward speed of 0.85 m/s, clamping height of 190 mm, peanut picking roller rotational speed of 550 rpm, and cleaning sieve vibrational frequency of 590 cpm. Under these conditions, the impurity rate of 2.62% and the loss rate of 2.05% were obtained, which effectively reduced the impurity rate and loss rate and met the quality requirements of Chinese peanut mechanized harvesting operations. The results of this study can provide a basis for the improvement and optimization of the 4HLB-4 half-feed four-row peanut combine harvester and the optimization of its operating parameters.

Study on path planning of mechanized harvesting of ratoon rice in the first season based on the capacitated arc routing problem model.

The stubble crushing caused by the harvester during the first season of ratoon rice harvesting will directly affect the grain yield of the ratoon season. In this work, a harvester path planning method for quadrilateral fields to address the harvester driving path problem of the first season of ratoon rice mechanized harvesting is proposed. This research first analyzes the operational characteristics and requirements of ratoon rice first-season mechanized harvesting, and then models the mechanized harvesting process of ratoon rice in the first season as a capacitated arc routing problem (CARP) considering the fact that the harvester cannot complete the full-coverage harvesting operation at one time due to the limitation of grain bin volume. The genetic algorithm (GA) with strong global search capability is used to solve it, and the selection and variation links of the algorithm are improved. The path planning method proposed in this article can dynamically find the optimal harvester travel route according to the specific conditions of the field and the parameters of harvester implements. The simulation test shows that the CARP method performs better in terms of harvesting path length and crushed area compared to the conventional rectangular detour and foldback reciprocating harvesting paths. The degree of optimization of this method is influenced by various factors such as the width of the cutting table, the turning radius of the harvester, and the size of the grain bin capacity. This research provides a more efficient and flexible path planning method to improve the efficiency of ratoon rice first-season mechanized harvesting operations and optimize the harvester's operating path, which can well meet the operational requirements.

Depth-to-water maps as predictors of rut severity in fully mechanized harvesting operations

ABSTRACT The preservation of the functionality of forest soil is a key aspect in planning mechanized harvesting operations. Therefore, knowledge and information about stand and soil characteristics are vital to the planning process. In this respect, depth-to-water (DTW) maps were reviewed with regard to their potential use as a prediction tool for wheel ruts. To test the applicability of open source DTW maps for prediction of rutting, the ground surface conditions of 20 clear-cut sites were recorded post harvesting, using an unmanned aerial vehicle (UAV). In total, 80 km of machine tracks were categorized by the severity of occurring rut-formations to investigate whether: i) operators intuitively avoid areas with low DTW values, ii) a correlation exists between decreasing DTW values and increasing rut severity, and iii) DTW maps can serve as reliable decision-making tool in minimizing the environmental effects of big machinery deployment. While the machine operators did not have access to these predictions (DTW maps) during the operations, there was no visual evidence that driving through these areas was actively avoided, resulting in a higher density of severe rutting within areas with DTW values <1 m. A logistic regression analysis confirmed that the probability of severe rutting rapidly increases with decreasing DTW values. However, significant differences between sites exist which might be attributed to a series of other factors such as soil type, weather conditions, number of passes and load capacity. Monitoring these factors is hence highly recommended in any further follow-up studies on soil trafficability.

Spatio-temporal prediction of soil moisture and soil strength by depth-to-water maps

The utilization of detailed digital terrain models entails an enhanced basis for supporting sustainable forest management, including the reduction of soil impacts through predictions of site trafficability during mechanized harvesting operations. Since wet soils are prone to traffic-induced damages, soil moisture is incorporated into several systems for spatial predictions of trafficability. Yet, only few systems consider temporal dynamics of soil moisture, impeding the accuracy and practical value of predictions. The depth-to-water (DTW) algorithm calculates a cartographic index which indicates wet areas. Temporal dynamics of soil moisture are simulated by different DTW map-scenarios derived from set flow initiation areas (FIA). However, the concept of simulating seasonal moisture conditions by DTW map-scenarios was not analyzed so far. Therefore, we conducted field campaigns at six study sites across Europe, capturing time-series of soil moisture and soil strength along several transects which crossed predicted wet areas. Assuming overall dry conditions (FIA = 4.00 ha), DTW predicted 20% of measuring points to be wet. When a FIA of 1.00 ha (moist conditions) or 0.25 ha (wet conditions) were applied, DTW predicted 29% or 58% of points to be wet, respectively. De facto, 82% of moisture measurements were predicted correctly by the map-scenario for overall dry conditions – with 44% of wet measurements deviating from predictions made. The prediction of soil strength was less successful, with 66% of low values occurring on areas where DTW indicated dryer soils and subsequently a sufficient trafficability. The condition-specific usage of different map-scenarios did not improve the accuracy of predictions, as compared to static map-scenarios, chosen for each site. We assume that site-specific and non-linear hydrological processes compromise the generalized assumptions of simulating overall moisture conditions by different FIA.

Effect of Heavy Machine Traffic on Soil CO2 Concentration and Efflux in a Pinus koraiensis Thinning Stand

Mechanized timber harvesting is cost efficient and highly productive. However, mechanized harvesting operations are often associated with several environmental problems, including soil compaction and disturbance. Soil compaction impedes air circulation between the soil and atmosphere, which in turn results in increased concentrations of CO2 within soil pores. In this study, we investigated the impact of forest machine traffic on soil conditions to determine soil CO2 efflux (Fc), and soil CO2 concentrations (Sc). Field measurements included soil bulk density (BD), soil temperature (ST), soil water content (SWC), Fc, and Sc over a 3-year period at a specific thinning operation site (Hwacheon-gun) in the Gangwon Province of Korea. To assess the soil impacts associated with machine traffic, we established four machine-treatment plots (MT) characterized by different geographical and traffic conditions. The results revealed that BD, Sc, and SWC increased significantly on the disturbed track areas (p &lt; 0.05). Furthermore, reduced soil Fc values were measured on the soil-compacted (machine disturbed) tracks in comparison with undisturbed (control) areas. Variations in BD, SWC, and Sc were significantly different among the four MT plots. Additionally, in comparison with undisturbed areas, lower Fc and higher Sc values were obtained in compacted areas with high soil temperatures.

Characteristics of Agricultural Dust Emissions from Harvesting Operations: Case Study of a Whole-Feed Peanut Combine

The rapid development of peanut mechanization has increased the amount of dust expelled from peanut mechanized operations, which degrades the air quality and endangers the health of agricultural workers. Therefore, the purpose of this study is to figure out the characteristics of dust emission from mechanized peanut harvesting. To this end, the particulate matters of diameters ≤ 2.5 μm and ≤10 μm and the total suspended particles were sampled in real time during peanut harvesting in Henan Province, China, and the airborne particle concentrations and particle size distributions were measured. The dust particles discharged during the mechanized peanut harvesting were concentrated within the 2~30 µm size range. When the wind speed was reduced below the settling velocity of the largest particles, the more massive particles were carried in the downwind. The amount of free silica in the dust samples was determined by X-ray diffraction analysis. Both the total dust and free silica concentrations exceeded the occupational exposure and threshold limits. To improve the characteristics of dust emission, the microstructure and dispersion of the dust were also investigated. Reducing the agricultural operations during periods of high wind speed, low crop-moisture content, and low air humidity is recommended for reducing the dust exposure of workers. The results will provide guidance and technical support for reducing the dust emissions of mechanized harvesting operations, improving air quality, and reducing the health hazards to operators.

Productivity Analysis of Modified Farm Tractors in Forwarding Industrial Wood Products

Public demands for forest products and services have been increasing gradually in many countries all over the world. Among the forest products, mostly round woods are produced in Turkey due to high economic value. On the other hand, there is a significant increase in demand for industrial woods in the domestic market in recent years. The reason behind this increase is the need of domestic companies in the wood-based panel industry for a large amount of wood raw material. . Farm tractors are the most widely used forest machinery in the extraction of industrial wood in Turkey. Farm tractors can be effectively used in mechanized harvesting operations after receiving some modifications and additional attachments. The modified farm tractors are affordable machinery for small logging contractors since their initial purchasing costs and hourly operating costs are quite low comparing with the forest harvesting equipment (i.e. skidder, forwarder, cable yarder). In this study, productivity of a modified farm tractor was analyzed during forwarding of industrial wood products. The study was implemented in Pinus nigra stand located in (?) the city of Afyonkarahisar in Turkey. In the study, the effects of forwarding distance on productivity were evaluated using statistical analysis. The results indicated that the most time-consuming work stage was unloading the truck and piling the wood products at the landing area, followed by ( in terms of time-consumption) collecting woods and loading the tractor at the stump. The average productivity of the forwarding operation was 6.06 stere/h (stere is the amount of wood pile with the height, width, and depth of one meter). It was also found that the productivity of the forwarding was significantly affected by the forwarding distance.

Modelling the effect of some operational parameters on grain loss in mechanised rice harvesting: a case study in Malaysian paddy fields

Excessive grain loss is still a persistence problem in mechanised rice harvesting using combine harvester in Malaysian paddy fields. Therefore, this study was conducted to develop a model for predicting the effect of some operational parameters on grain loss during mechanised harvesting operation. Three operational parameters that always associated with grain loss were measured through direct field measurements on the daily harvesting operations in the sampled rice granaries. The measured parameters included field speed of combine harvester, grain moisture, and soil moisture contents. Regression and correlation analyses were employed to develop the model estimation. The results of the predictive model exposed the fitted model with a strong relationship between associated variables and established the measured parameters to determine the grain loss. The findings would be beneficial in assisting the rice farmers to predict grain loss during harvesting and minimise excessive grain loss in mechanised harvesting operations in Malaysia.

EVALUATION OF ASSORTMENTS CONSIDERING DIFFERENT STUMP AND PRE-BUCKING DISC HEIGHTS IN MECHANIZED HARVESTING OPERATIONS OF A Pinus taeda L. FOREST

This study aimed to evaluate assortments by adopting distinct stump heights and pre-bucking disc heights in the mechanized harvesting operations of a Pinus taeda L. forest, which is owned by a company located in Campo Belo do Sul (SC). To that end, the simulation of six scenarios was carried out after the forest’s clear-cutting. The scenario 1 includes the company's specifications. Scenario 2 includes the real situation, that is, the measurements made in sample units installed on the field and scenario 3 includes stump heights of 10 cm and pre-bucking disc heights of 5 cm. In the other scenarios, stump and pre-bucking disc heights with values higher than the ones specified by the company were included. Then, using a taper function, we calculated the assortments in tons per hectare (t ha-1) and monetary value per hectare (R$ ha-1), considering the price of wood with bark (R$ t-1) for each assortment. Results show that Scenario 1 presented a larger amount of wood, however, Scenario 3 represented higher revenue due to the higher wood quantity of the value-added assortments. On the other hand, Scenario 6 presented the lowest amount of wood comparing to the others, and Scenario 2 presented the lowest economic return. All things considered, the company performs its activities below what is planned, but with production higher than the other evaluated scenarios. Regarding the economic return, the other scenarios are more feasible than Scenario 2, which shows that the company needs to seek process improvements with the implementation of another scenario that could bring better results.

Soil compaction on traffic lane due to soil tillage and sugarcane mechanical harvesting operations

Mechanical sugarcane harvesting increases soil compaction due to the intense traffic of agricultural machinery, reducing longevity of sugarcane crops. In order to mitigate the harmful effects caused by agricultural traffic on the soil structure in sugarcane fields, this study evaluated impacts of mechanical sugarcane harvesting on traffic lane under two soil tillage systems based on load bearing capacity models. The experiment was carried out in the region of Piracicaba, state of Sao Paulo, Brazil, on a Rhodic Nitisol, under conventional tillage (CT) and deep strip-tillage (DST). For CT soil tillage was applied to the entire area with a heavy disk harrow, at operating depths from 0.20 to 0.30 m followed by a leveling harrow at a depth of 0.15 m. For DST, soil tillage was performed in part of the area at a depth of 0.80 m, forming strip beds for sugarcane planting, while the traffic lanes were not disturbed. Undisturbed soil samples from traffic lanes were used in the uniaxial compression test to quantify preconsolidation pressure and to model the soil load bearing capacity. The surface layer (0.00-0.10 m) was most susceptible to compaction, regardless of the tillage system (CT or DST) used. In the DST, the traffic lane maintained the previous soil stress history and presented higher load bearing capacity (LBC) than the traffic lane in the CT. As in CT the soil was tilled, the stress history was discontinued. This larger LBC in DTS minimized the impacts of the sugarcane harvest. Under CT, additional soil compaction due to mechanical sugarcane harvesting in the traffic lane was observed after the second sugarcane harvest. There was a reduction in load bearing capacity from 165 kPa to 68 kPa under CT and from 230 kPa to 108 kPa under DST, from the first to the second harvest at surface layer. Water content at mechanical harvesting was the most relevant factor to maximize impacts on the soil structure in traffic lanes, for both tillage systems.

Assessment of Broad-Leaved Forest Stand Management

There are many broad-leaved forests in Japan that were formerly managed for charcoal production, which have been abandoned for decades. Appropriate thinning can revitalize these forests if the cost balance of the management is positive. Two critical elements are the construction of spur roads to facilitate mechanized harvesting operations and management planning that considers stand properties such as the growing stock, species, and tree size distribution. We surveyed three abandoned former broad-leaved coppice stands; one coastal, one cool temperate and one warm temperate. The stock in all three stands exceeded 300 m3 ha-1, two- to three-fold the official forest registry data estimates. The dominant species in terms of tree numbers are Castanopsis sieboldii, Pieris japonica, and Quercus glauca. Medium-sized trees involve those well suited for firewood, i.e., Quercus acuta, Quercus glauca, Quercus serrata, etc. Each plot contained a few large trees that potentially have a high market value, e.g., Cinnamomum camphora, Zelkova serrata, Abies firma, etc. The average income from harvested trees was estimated to be 10200 JPY (Japanese Yen) m-3, whereas the thinning costs would be 3200 to 5400 JPY m-3, with the additional spur road construction costs. The management cost balance of a broad-leaved stand in a 60 year rotation was evaluated with both Net Present Value (NPV) (for interest rates of 1, 2, 3, and 4%) and Internal Rate of Return (IRR). This balance was compared with that of a typical plantation stand of Japanese cedar (Cryptomeria japonica) and of a fast-growing plantation stand of Chinese fir (Cunninghamia lanceolata). The estimated NPVs were largest for the fast-growing plantation stand, second largest for the typical plantation stand, and lowest for the broad-leaved stand with a NPV interest rate of 1 + %. However, the IRR of the broad-leaved stand was the highest, followed by that of the fast-growing plantation stand, while the IRR of the typical plantation stand was the lowest. This order was the same for NPVs assuming higher interest rates. 1 JPY=0.0086 € on April 29, 2019.

Steep terrain forest operations – challenges, technology development, current implementation, and future opportunities

ABSTRACTWhile modern fully mechanized ground-based systems are a default option for safe and productive harvesting, they have always been limited by terrain factors such as slope, soil strength, and roughness. There is a limit with regard to the physical feasibility of operating machines on steep slopes because both the weight and also the force from the momentum created during traction loss can affect stability. A huge interest to improve traction of harvesting machines when operating on steep slopes is arising. One way to improve traction and stability on steep slopes is through assisting harvesting machines by winch and cable to anchor locations such as tree stumps or stationary equipment. This technology offers potential for improving the safety, productivity, and efficiency of a harvesting operation, as well as for improving machine mobility and reducing soil disturbance through the reduction of slip. With the exponential development of such technology, an integrated approach must be developed for conducting productive and injury-free mechanical harvesting operations on steep slopes that draws on the skills and accountabilities of the working team. Beyond a certain physical threshold, the only feasible and achievable solution providing some “intelligent behavior” to machines and systems would be the role of mechatronics application. One of the most relevant points could be the possibility to introduce the concept of “teleoperation” using unmanned ground vehicles. Combining teleoperation with winch-assist technology would provide a platform for extending the range of ground-based equipment to previously infeasible terrain conditions.

Productivity of a single-grip harvester in a beech dominated stand: a case-study under Bavarian conditions

ABSTRACTForest conversion from spruce dominated forests to close-to-nature stands with considerable proportion of deciduous tree species is of high importance in Germany. During mechanized harvesting operations, the complex tree architecture and high wood density of deciduous tree species, in particular of beech, pose a challenge during the processing phase. Usually more powerful machinery is required than for softwood stands of comparable age and tree dimensions. This pilot-study assessed the productivity of a TimberPro 620-E single-grip harvester with a LogMax 7000C harvesting head in a mature mixed-wood stand located in southern Germany. A total of 82 trees previously inventoried were harvested using one of two silvicultural treatments (clear-cut or selective-cut). A conventional time and motion study was performed using a hand-held computer on the selected trees that were harvested. Results demonstrated considerable differences in percent distribution of the harvesting related work cycle elements between the two tested silvicultural treatments, particularly with machine movement. Based on single-tree recovered volume estimations, average harvesting productivity during the clear-cut was 31% higher for spruce compared to beech trees. During the selective-cut, average harvesting productivity was 33.9 m3/PMH0 for spruce compared to 23.4 m3/PMH0 for beech, thus indicating a 45% higher productivity in spruce recorded during the pilot study.

Efficacy of leaf litter mulch to mitigate runoff and sediment yield following mechanized operations in the Hyrcanian mixed forests

Following ground-based skidding operations, understory vegetation and litter layer are commonly damaged or displaced by the movement of machines and timber on the machine operating trails, thus leaving the area vulnerable to increased runoff flow and sediment yield. One of the interim options available to suppress runoff and soil loss is the application of litter mulch directly after mechanized harvesting operations. The goal of the study is to assess the effects of broadleaves litter mulch on runoff and sediment yield immediately after rainfall events on a severely compacted skid trail in a mixed forest in Hyrcanian forests, northern Iran. The study included six treatments (undisturbed area, untreated trail, and four levels of litter rate; 0.42, 0.81, 1.31, and 1.69 kg m2 referred to as LR1, LR2, LR3, LR4, respectively) and two levels of trail gradient (10% and 20%), replicated in three plots (7 m long × 1 m width). The highest runoff values of 1.54 and 1.33 mm were measured at trail gradients of 20 and 10% for the untreated trail, respectively. The litter mulch application resulted in runoff decreasing by 49%, 67%, 75%, and 79% in the LR1, LR2, LR3, and LR4 treatments, respectively. The highest values of runoff coefficient were measured in the untreated trail (U; 4.6%), followed by LR1 > LR2 > LR3 ≈ LR4 treatments. Sediment yield in the untreated treatment was 7.32 g m−2 on the 10% gradient trail and 6.15 g m−2 on the 20% trail gradient. Sediment yield values in the LR1, LR2, LR3, and LR4 treatments were decreased by 76%, 85%, 90%, and 93%, respectively, compared to the untreated treatment. By increasing the litter rate, runoff and sediment yield responses significantly decreased as the rainfall increased. The net differences between the tested litter rates and the runoff and sediment yield reductions were higher with increasing rainfall intensity.

Application of Terrestrial Laser Scanner to Evaluate the Influence of Root Collar Geometry on Stump Height after Mechanized Forest Operations

The height of tree stumps following mechanized forest operations can be influenced by machine-, tree-, terrain-, and operator-related characteristics. High stumps may pose different economic and technical disadvantages. Aside from a reduction in product recovery (often associated with sawlog potential), leaving high stumps can complicate future entries if smaller equipment with low ground clearance is used, particularly in the case where new machine operating trails are required. The objective of this exploratory study was to examine if correlations existed between the height of tree stumps following mechanized harvesting and the shape of the above-ground root collar, stump diameter, and distance to the machine operating trail. In total, 202 sample stumps of Norway spruce (Picea abies (L.) Karst.) and the surrounding terrain were scanned with a terrestrial laser scanner. The collected data was processed into a 3D-model and then analyzed. Stump height was compared with different characteristics such as stump diameter at the cut surface, distance to the machine operating trail, number of visible root flares per stump, and the root collar. The number of root flares per stump had a positive influence on stump diameter and height, showing a general trend of increasing diameter and height with the increasing number of root flares. Root angles also had an influence on the stump diameter. The diameter of a stump and the shape of the root collar at the cut surface together had a significant effect on stump height and the model reported explained half of the variation of stump heights. Taken together, these findings suggest that other factors than the ones studied can also contribute in influencing stump height during mechanized harvesting operations. Further investigations, including pre- and post-harvest scans of trees selected for removal, are warranted.

Corn Residue Particle Size Affects Soil Surface Properties

Core Ideas Corn harvesting practices generate characteristic residue particle size distributions. Corn residue particle size influences its composition and decomposition. Residue particle composition and decomposition influence soil properties, i.e., soil C and N. Mechanical harvesting operations affect soil properties via residue size distributions. Field operations may differentially influence crop residue size distributions, altering residue decomposition rates and soil carbon (C) and nitrogen (N) dynamics. In a laboratory microcosm study modeling corn residue distributions observed in a no‐till cropping system, microbial respiration was initially (first 30 d) inversely proportional to residue particle size across four size classes. Subsequently (30–60 d), respiration in the smallest particle size decreased in relation to the larger size classes. Residue particle size significantly increased soil C levels, with the smallest sizes producing the longest‐lasting effects (150 d). Smaller residue size classes initially (30 d) immobilized more soil N compared with larger size classes; however, at 150 d, the smaller size classes had mobilized increasing amounts of N while the larger size classes had progressively immobilized more N. We conclude that crop residue management operations changed characteristic residue size distributions that moderate decomposition activities and result in unique soil C and N dynamics, possibly influencing soil properties, including nutrient availability.

Safety Optimized Shift-Scheduling System based on Wireless Vibration Monitoring for Mechanical Harvesting Operations

Safety Optimized Shift-Scheduling System based on Wireless Vibration Monitoring for Mechanical Harvesting Operations

The impact of log surface damage caused by harvester Eucalyptus debarking on pulp value recovery

Mechanised harvesting operations are growing in popularity in South Africa, as motor-manual and manual harvesting operations pose significant health and safety risks to workers. Potential damage inflicted by single-grip harvester feed rollers and delimbing knives on the log surface during debranching and debarking of eucalypts may affect chip size distributions during chip production. Chip size is important as it influences pulp quality and recovery in the kraft pulping process. The study investigated the influence of two mechanised debarking treatments in eucalypts (three feed roller passes and five feed roller passes along the stem surface) with feed-roller-induced log surface damage on pulp value recovery. The two mechanised treatments were compared against chips produced from manually debarked logs with no surface damage. In addition, the effect of two log drying periods (one week and two weeks) and three log classes (base, middle and top logs) on chip quality were also analysed. An economic evaluation was conducted to quantify potential recoverable pulp value losses associated with debarking treatments and log drying periods. Logs subject to manual debarking produced significantly less undesired sized chips than both three-pass and five-pass mechanically debarked logs and therefore had significantly greater pulp value recovery. Mechanically debarked logs had a projected pulp value recovery of R62, R86 and R123 less per bone dry tonne of chips produced from base, middle and top logs, respectively, when compared with manually debarked logs with no log surface damage after a one-week log drying period. Mechanically debarked logs also had a projected pulp value recovery of R77, R40 and R59 less per bone dry tonne of chips produced from base, middle and top logs, respectively, when compared with manually debarked logs with no log surface damage after a two-week log drying period. Logs dried for two weeks also produced significantly less under-sized chips than chips produced from one-week-dried logs and therefore had greater pulp value recovery. However, two-week-dried logs produced wood chips with significantly more over-thick chips than logs dried for one week. The volume of undesirable-sized chips produced during chipping increased with decreasing log size.