Straw Length Research Articles

Effect of Straw Length, Stubble Height and Rotary Speed on Residue Incorporation by Rotary Tillage in Intensive Rice–Wheat Rotation System

High-yielding agriculture in an intensive rice–wheat rotation system leads to plenty of residues left in the field after harvest, which is detrimental to seeding operation, seed germination, and early plant growth. Some residue thus needs to be incorporated into the soil. Providing the relationship between tillage operations and residue incorporation and establishing a mathematical model play important roles in residue management and the design of tillage machinery. In order to obtain detailed data on the interaction between residue incorporation and tillage operations, a multifunctional field-testing bench with precise parameter control was developed to assess residue incorporation characteristics of rotary tillage, and we investigated the effects of straw length, stubble height and rotary speed on residue incorporation. Three experimental factors affecting residue incorporation performance were studied, i.e., six lengths of straw (30–150 mm), four heights of stubble (50–200 mm), and three rotary speeds (240–320 rpm). Chopped straw and stubble with certain sizes were prepared for the test, and we measured the burying rate and distribution uniformity of residue after rotary tillage. The results indicated that straw length, stubble height, and rotary speed all impact residue incorporation quality. The burying rate and distribution uniformity of residue decreased with the increase in straw length and stubble height; a lower rotary speed parameter buried less residue and distributed it with worse uniformity than a higher one. It is suggested that farmers determine the straw length and stubble height at the stage of harvest according to the required burying rate and distribution uniformity of residue.

Protein content and HvNAM alleles in Nordic barley (Hordeum vulgare) during a century of breeding

BackgroundBarley has been bred for more than a century in the Nordic countries, with dramatic improvements of yield traits. In this study we investigate if this has come at the cost of lower grain protein and micronutrient (iron, zinc) content, by analysing 80 accessions representing four different improvement stages. We further re-sequenced the two grain protein content associated genes HvNAM-1 and HvNAM-2 in full and performed expression analyses of the same genes to search for genetic associations with nutrient content.ResultsWe found higher thousand grain weight in barley landraces and in accessions from the late improvement group compared to accessions from the mid of the twentieth century. Straw length was much reduced in late stage accessions. No significant temporal decrease in grain protein, iron or zinc content during twentieth century Nordic crop improvement could be detected. Out of the 80 accessions only two deviant HvNAM-1 sequences were found, represented by one accession each. These do not appear to be correlated to grain protein content. The sequence of HvNAM-2 was invariable in all accessions and no correlations between expression levels of HvNAM-1 and HvNAM-2 and with grain protein content was found.ConclusionsIn contrast to studies in wheat, where a strong negative correlation between straw length and grain protein and micronutrient content has been found, we do not see this relationship in Nordic barley. The last 60 years of breeding has reduced straw length but, contrary to expectations, not protein and micronutrient content. Variation in grain protein and micronutrient content was found among the Nordic barley accessions, but it is not explained by variation of HvNAM genes. This means that HvNAM is an unexploited source of genetic variation for nutrient content in Nordic barley.

Experimental Investigation on Environmentally Sustainable Cement Composites Based on Wheat Straw and Perlite.

Environmentally sustainable cement mortars containing wheat straw (Southern Italy, Apulia region) of different length and dosage and perlite beads as aggregates were prepared and characterised by rheological, thermal, acoustic, mechanical, optical and microstructural tests. A complete replacement of the conventional sand was carried out. Composites with bare straw (S), perlite (P), and with a mixture of inorganic and organic aggregates (P/S), were characterised and compared with the properties of conventional sand mortar. It was observed that the straw fresh composites showed a decrease in workability with fibre length decrease and with increase in straw volume, while the conglomerates with bare perlite, and with the aggregate mixture, showed similar consistency to the control. The thermal insulation of the straw mortars was extremely high compared to the sand reference (85–90%), as was the acoustic absorption, especially in the 500–1000 Hz range. These results were attributed to the high porosity of these composites and showed enhancement of these properties with decrease in straw length and increase in straw volume. The bare perlite sample showed the lowest thermal insulation and acoustic absorption, being less porous than the former composites, while intermediate values were obtained with the P/S samples. The mechanical performance of the straw composites increased with length of the fibres and decreased with fibre dosage. The addition of expanded perlite to the mixture produced mortars with an improvement in mechanical strength and negligible modification of thermal properties. Straw mortars showed discrete cracks after failure, without separation of the two parts of the specimens, due to the aggregate tensile strength which influenced the impact compression tests. Preliminary observations of the stability of the mortars showed that, more than one year from preparation, the conglomerates did not show detectable signs of degradation.

A novel method for measuring and evaluating spatial distribution of straw incorporated by rotary tillage

AbstractStraw incorporation after tillage plays an essential role in soil organic matter and fertility. Despite the importance of understanding the effect of tillage on straw distribution in the soil, an accurate method to measure and evaluate the spatial distribution of straw has not been developed. In this work, we proposed a method for quantifying straw distribution in soil following tillage. The approach uses a straw spatial coordinate digitizer, Pro/Engineer drawing software, and MATLAB visualization software. Straw of four different lengths was mixed into soil by a rotary tillage. Results indicated that the uniformity of straw spatial distribution decreased with the increase of straw length. T50 (50‐mm straw length) had the greatest uniformity. As a result, it is recommended that straw be cut to 50 mm or shorter. This work offers a new insight into the quantitative analysis of straw spatial distribution in soil.

Power Consumption Analysis and Experimental Study on the Kneading and Cutting Process of Licorice Stem in Horizontal Total Mixed Ration Mixer

Aiming at the problems of high-power consumption and insufficient kneading and cutting of roughage in the total mixed ration mixer. In this paper, licorice stems were taken as experimental objects, the horizontal twin-shaft TMR mixer was used to carry out the experimental study. It should be as brief as possible and concise. Through the kneading and cutting process power analysis, determine the influencing factors of kneading and cutting power consumption. The auger speed, processing time and blade type were taken as experimental factors, with standard straw length rate and power consumption as indicators, Box–Behnken test with three factors and three levels was carried out, analysis of variance was performed on the test results, the results show that the significant effect of each factor on the standard grass length is processing time, blade type and auger speed in descending order. The significance of the influence on power consumption from large to small is auger speed, processing time and blade type. The response surface analysis and parameter optimization were carried out, the results show that the auger speed is 20 r/min, the processing time is 29 min, and the blade type is quincunx blade. At this time, the standard straw length was 82.634%; Power consumption 4525.815 kJ, TMR mixer performance reached the best. The results can provide a theoretical basis for the subsequent research and development of TMR mixer.

Machine learning tensile strength and impact toughness of wheat straw reinforced composites

The wheat straw reinforced composite is considered as a “green composite” as it utilizes biodegradable and recyclable food waste materials as reinforcing materials. Mechanical properties, such as tensile strength and impact toughness, are greatly dependent on the composite content and processing parameters. While compression molding is one of popular methods to fabricate the wheat straw/polypropylene composite, experimental trials to achieve targeted mechanical properties can be time-consuming and expensive. In this work, we develop the Gaussian process regression model to present the relationship among the fiber content, processing parameters of the compression molding, and mechanical performance of wheat straw reinforced polypropylene composites. The model achieves a correlation coefficient of 99.13% (95.68%), a root mean square error of 0.0857 (0.4369), and a mean absolute error of 0.0693 (0.3265) for tensile strength (impact toughness). The models are simple and fast to implement, produce predictions with high accuracy, and thus might be considered as efficient tools for mechanical property estimations. Should data become available, the model may be extended to include other descriptors, such as the wheat straw length, size distribution, and chemical treatment parameters.

Performance test and process parameter optimization of 9FF type square bale straw crusher

In order to solve the problem of low productivity, unqualified segment length and high energy consumption during the process of crushing square bale straw caused by improper operation parameters, a 9FF square bale straw crusher was developed. In this study, by taking maize straw as the test material, the feeding speed, spindle speed of the crushing device and the state of the crushing device were taken as influence factors, and standard straw length rate, productivity per net working hour (hereinafter referred to as NWH) and energy consumption per ton of product as test indicators, the influence of the factors on the indicators were studied, and tests were carried out on the process of square bale straw crushing. By adopting the single factor test on the effect of the feeding speed, the spindle speed of the crushing device and the state of the crushing device on the test indicators, the suitable range of each factor was determined, respectively. Using the orthogonal test method, range method, variance method and comprehensive balance method, the experiment analyzed the significance of the influence of the three factors on various indicators and the order of priority. The test results showed that: the feeding speed was 5 m/min, spindle speed was 3000 r/min, and the state of the crushing device was a mixing cutter hammer, which was the best parameter combination (A1B1C1) for the processing technology of the square bale forage crusher. The standard straw length rate was 93.7%, and the productivity per NWH was 2.80 t/h, with energy consumption per ton of 4.72 kW•h/t, in which the standard straw length rate and productivity per NWH reached optimal values, and the energy consumption per ton of product was slightly higher than the optimal value in the experiment. The research results can provide a reference for the optimal design of the special crusher for square bale straw. Keywords: square bale, straw crusher, crushing, working parameter optimization, performance test DOI: 10.25165/j.ijabe.20211403.5970 Citation: Zhang J, Feng B, Guo L, Kong L Z, Zhao C, Yu X Z, et al. Performance test and process parameter optimization of 9FF type square bale straw crusher. Int J Agric & Biol Eng, 2021; 14(3): 232–240.

Sustainable application of rice husk and rice straw in cellular concrete composites

This study seeks to evaluate the effect of incorporating rice husk and rice straw as a sealing material, and to evaluate the mechanical, acoustic, thermal, and durability properties of the cellular concrete that will be used. A sustainable use option for rice culture waste is provided and detailed in this paper. This study seeks to improve the thermoacoustic performance of cellular concrete using only rice husk by adding rice straw. The introduction of straw reduced the compressive strength by about 15% and increased the three-point bending strength. Sound absorption increased when adding rice straw, and the sound insulation values were statistically similar. With respect to the thermal analysis, the thermal conductivity was directly proportional to the straw length. In general, the best formulation was S-15%-3, which contained 15% rice straw at 3 cm. Specimens were submitted to wetting-and-drying cycles to evaluate durability, leading to increased compressive strength, which also increased with longer curing times. Furthermore, the cycles led to a reduction in the three-point bending strength while the thermal conductivity remained similar.

Complete feed versus concentrate and straw fed separately: Effect of feeding method on eating and sorting behavior, rumen acidosis, and digestibility in crossbred Angus bulls fed high-concentrate diets

The aim of this study was to evaluate the effect of feeding method on eating and sorting behavior, rumen acidosis, and apparent total tract digestibility of crossbred Angus bulls fed a high-concentrate diet. Twenty-one Angus beef bulls (497 ± 7.7 kg of initial BW, and 324 ± 3.0 d of age) were housed individually and fed ad libitum. Three experimental treatments were tested: complete feed of pellet and chopped straw in a single feeder (TMR), pellet and chopped straw fed separately in two feeders (SS); pellet and long unprocessed straw fed separately in two feeders (LS). Feed consumption, fecal and bloat scoring were recorded daily. Every 2 wk TMR sorting, eating behavior, general activity, social and oral behaviors, and BW were recorded. At days 14 and 35 apparent total tract digestibility during one week was measured. At days 28 and 42 rumen samples were collected via rumenocentesis to measure rumen pH and determine ruminal volatile fatty acids (VFA) concentrations. At the study end (day 57) animals at slaughterhouse liver and rumen wall color and lesions were recorded by a macroscopic inspection. No differences among treatments in total DMI, and fecal and bloat scoring were observed. The straw to concentrate ratio was smaller in the SS and LS treatments (8–92) than in the TMR (15–85), and sorting analyses indicated that TMR bulls refused large particles (> 4 mm) and small particles (< 1.5 mm). TMR bulls spent less time eating (P < 0.01) and tended to perform more self-grooming (P = 0.06), oral non-nutritive behaviors (P < 0.01) and stereotypes (P < 0.01) than bulls fed straw separately. Animals fed TMR had a greater (P < 0.01) pH than SS and LS, however rumen pH was above 5.6 in all treatments and rumen wall lesions did not differ among treatments. Feeding TMR increased (P < 0.05) the rumen acetate to propionate ratio. Bulls fed LS had greater total apparent DM (P < 0.05) and CP digestibility (P < 0.01), but no differences among treatments were observed in starch digestibility. In conclusion, even if straw to concentrate ratio and NDF intake was smaller in the SS and LS treatments than in the TMR, feeding pellet and straw separately, independently of straw length, did not predispose animals to suffer rumen acidosis as indicated by rumen pH, feed consumption, animal behavior, fecal and bloat scoring and rumen wall macroscopic evaluation.

Performance test and process parameter optimization of 9FF type square bale straw crusher

In order to solve the problem of low productivity, unqualified segment length and high energy consumption during the process of crushing square bale straw caused by improper operation parameters, a 9FF square bale straw crusher was developed. In this study, by taking maize straw as the test material, the feeding speed, spindle speed of the crushing device and the state of the crushing device were taken as influence factors, and standard straw length rate, productivity per net working hour (hereinafter referred to as NWH) and energy consumption per ton of product as test indicators, the influence of the factors on the indicators were studied, and tests were carried out on the process of square bale straw crushing. By adopting the single factor test on the effect of the feeding speed, the spindle speed of the crushing device and the state of the crushing device on the test indicators, the suitable range of each factor was determined, respectively. Using the orthogonal test method, range method, variance method and comprehensive balance method, the experiment analyzed the significance of the influence of the three factors on various indicators and the order of priority. The test results showed that: the feeding speed was 5 m/min, spindle speed was 3000 r/min, and the state of the crushing device was a mixing cutter hammer, which was the best parameter combination (A1B1C1) for the processing technology of the square bale forage crusher. The standard straw length rate was 93.7%, and the productivity per NWH was 2.80 t/h, with energy consumption per ton of 4.72 kW•h/t, in which the standard straw length rate and productivity per NWH reached optimal values, and the energy consumption per ton of product was slightly higher than the optimal value in the experiment. The research results can provide a reference for the optimal design of the special crusher for square bale straw. Keywords: square bale, straw crusher, crushing, working parameter optimization, performance test DOI: 10.25165/j.ijabe.20211403.5970 Citation: Zhang J, Feng B, Guo L, Kong L Z, Zhao C, Yu X Z, et al. Performance test and process parameter optimization of 9FF type square bale straw crusher. Int J Agric & Biol Eng, 2021; 14(3): 232–240.

The history of the breeding work on winter durum wheat development: results, problems, prospects

The current paper has considered the results of sixty years of breeding work on winter durum wheat development, a new grain crop for the steppe arid conditions of the Don area. This breeding period was represented by five stages, each of them was characterized by the solution of various problems, by the development of methods for obtaining and using the initial material and, on its basis, varieties being urgent for the definite period. Throughout the history of breeding work there were developed 32 winter turgid and durum wheat varieties, 21 of which were zoned or included into the State List, 16 were protected by patents, 6 were studied at the SVT. There have been presented the study results of the varieties of different breeding stages according to their main economically valuable traits and properties, obtained in the trial ‘History of the breeding work’ with green manure fallow in 2015–2019. There have been identified their positive advantages and disadvantages in the breding process. Significant progress has been achieved in changing plant architectonics by reducing straw length on 39.3–45.2 cm, increasing the resistance to lodging on 1.3–1.4 points, improving the agrocenosis on 300–400 heads per m 2 , and increasing the harvesting index from 26.1 to 41.1%. Productivity due to productive breeding for 60 years increased on 3.37 t/ha or 66.3%, and the productivity potential of the modern short-stemmed varieties reached 10 t/ha and more. There has been found out that productivity improvement during breeding positively affected on adaptive properties (winter resistance, drought resistance, resistance to brown and yellow rust, powdery mildew) and the indices grain and pasta quality. There have also been indicated the problematic areas which require further intensive work not only in breeding, but also in a wider distribution of the winter durum wheat varieties in agricultural production.

Effects of length and application rate of rice straw mulch on surface runoff and soil loss under laboratory simulated rainfall

Forest land affected by deforestation yields high soil and water losses. Suitable management practices need to be found that can reduce these losses and achieve ecological and hydrological sustainability of the deforested areas. Mulch has been found to be effective in reducing soil losses; straw mulch is easy to apply, contributes soil organic matter, and is efficient since the day of application. However, the complex effects of rice straw mulch with different application rates and lengths on surface runoff and soil loss have not been clarified in depth. The current paper evaluates the efficiency of rice straw mulch in reducing the hydrological response of a silty clay loam soil under high intensity and low frequency rainfall events (tap water with total depth of 49 mm and intensity of 98 mm/h) simulated in the laboratory. Surface runoff and soil loss at three lengths of the straw (10, 30, and 200 mm) and three application rates (1, 2, and 3 Mg/ha) were measured in 50 cm (width) × 100 cm (length) × 10 cm (depth) plots with disturbed soil samples (aggregate soil size < 4 mm) collected in a deforested area. Bare soil was used as control experiment. Runoff volume and erosion were significantly (at p < 0.05) lower in mulched soils compared to control plots. These reductions were ascribed to the water absorption capacity of the rice straw and the protection cover of the mulch layer. The minimum runoff was observed for a mulch layer of 3 Mg/ha of straw with a length of 200 mm. The lowest soil losses were found with straw length of 10 mm. The models developed predict runoff and erosion based on simple linear functions of mulch application rate and length, and can be used for a suitable hydrological management of soil. It is concluded that, thanks to rice straw mulch used as an organic soil conditioner, soil erosion and surface runoff are significantly (at p < 0.05) reduced, and the mulch protection contributes to reduce the risk of soil degradation. Further research is, however, needed to analyze the upscaling of the hydrological effects of mulching from the plot to the hillslope scale.

Effect of Nettle (Urtica dioca L.) density on fiber yield and quality in a natural ecosystem under East Mediterranean conditions

Nettle (Urtica dioica L.), a new industrial crop, has been cultivated since the 12th century for its fibers. This study was conducted to specify the optimal density of plants in order to move from wild harvest to nettle cultivation. For the present study, sampling was performed in 21 different fields throughout Greece, during October 2018. The effect of nine different plant densities on several agronomic (plants height, leaf area and dry matter) and fiber quality (straw length, fiber percentage, yield, extension at break, strength, length, diameter) characteristics was determined. The higher fiber yield occurred at the lower density (4 plants m2), while the higher fiber diameter observed at the highest density (12 plants m2). Comparisons were performed at the 5% level of significance (p ≤ 0.05). According to our results, there have been negative correlations between plant density and certain agronomic and quality characteristics such as plant height and fiber length, hence the optimal density is about seven plants per m2.

Design and Test of Double-Cutterbar Structure on Wide Header for Main Crop Rice Harvesting

Harvesting main crop rice with a wide header at a required height can increase its ratoon crop yield by decreasing the stubble rolling rate. However, an increased harvest width brings in more input material in a specific time, causing the size enlargement or working speed slowdown of harvesters. To solve this issue, a double-cutterbar structure was proposed. To provide a design baseline for the structure, the cutterbar configuration methods based on rice plant deformation were developed and verified, stalk shearing tests were conducted, and a double-cutterbar prototype was fabricated and tested. The results indicated that the methods developed for the configuration of the upper and lower cutterbars could considerably implement their functions of lowering the straw-grain ratio and keeping stubble height as required. The shearing tests indicated that the bevel angle significantly influenced the total shearing energy on each cutting point in Internode 2 and 3 (p &lt; 0.05) due to the increased stalk cross sectional area. The stubble rolling rate, panicle straw length and stubble height of the developed harvester were 26.9 %, 125 ± 80 mm and 332 ± 22 mm, respectively, which could meet the requirements of main crop rice harvesting. The outcomes indicated the functionality and practicability of the double-cutterbar structure developed based on rice plant deformation and shearing properties.

A high-strength lightweight concrete made using straw

This experimental work aims to develop an eco-lightweight concrete with excellent mechanical and thermophysical properties using straw. Thus, this paper considers the use of a formulation of an ultrahigh-performance concrete based on dune sand, with the introduction of up to 20 kg/m3of straw. The study investigates the mechanical and thermophysical properties of the obtained high-strength lightweight concrete and examines the effects of the straw length. The results show that, depending on the amount of straw used, a decrease of up to 33% of density and 60% of thermal conductivity is noted. Moreover, despite increasing the straw content, which reduces the mechanical strength of the concrete, interesting strength values are noted; for instance, values varying from 42 to 59 MPa in compressive strength and from 3·2 to 5·3 MPa in flexural strength for 2 cm of straw length are obtained.

Anaerobic co-digestion: a sustainable approach to food processing organic waste management

Anaerobic digestion is a promising technology to control pollution and recover energy from organic matter. In this study, batch experiments were conducted to investigate methane yields of seven organic wastes from a food processing company and dairy manure (DM) from a tie-stall barn having two straw lengths (2 cm and 10 cm) at 52 °C. This was followed by anaerobic co-digestion of all organic wastes with DM in bench experiments. The results indicated that the highest methane yield was observed in lipid-rich waste (basil sauce, 0.47 L/gVS) followed by carbohydrate-rich wastes (pumpkin processing residue, 0.21 L/gVS); the lowest yield was obtained from tomato leaves and stems (0.09 L/gVS). Furthermore, the methane yield from DM was about 0.18 L/gVS, irrespective of the straw length. Anaerobic co-digestion of food processing residues with DM demonstrated a 41% increase in methane yield (0.24 L/gVS), as compared to DM alone (0.17 L/gVS), while the milling of both organic wastes and DM did not affect methane yields. Thus, integration of anaerobic co-digestion in food processing residue management is a sustainable approach that guarantees a closed-loop flowing economy and makes food processing environmentally friendly.

Design and Parameter Optimization of Spiral-Dragon Type Straw Chopping Test Rig

In order to address the problems of large chop length, high energy consumption and poor chopping effect that were associated with a horizontal total mixed rations (TMR) mixer, a straw chopping device was designed; further, its structure and working principle were analyzed. In this study, wheat straw was chosen as the test object. The number of processing times, number of fixed blades, cutting speed, number of tooth plates and the inclined angle of the box were considered as the test factors. The standard straw length rate and average power were used as evaluation indices for conducting the orthogonal rotation combination experiment with five factors and five levels of quadratic regression. The experimental results denoted that the order of influencing factors on the standard straw length rate can be given as follows: the number of processing times, number of fixed blades, cutting speed, number of tooth plates and inclined angle of the box. The order of the influence of each factor on the average power can be given as follows: the cutting speed, number of fixed blades and number of tooth plates. Further, the optimum structural and working parameters of the device can be determined as follows: linear cutting speed of 17-20 m/min, box inclined angle of 70°-80°, 20-23 fixed blades, 5-6 processing times and 4-7 tooth plates. Under such a circumstance, the standard straw length rate reached up to 70.5%-77.4% and the average power was low at 5.8-7 kW. The results can be used as reference for designing a chopping device for a TMR mixer. Keywords: total mixed rations, straw, chopping device, parameter optimization DOI: 10.25165/j.ijabe.20201301.4927 Citation: Ma P B, Li L Q, Wen B Q, Xue Y H, Kan Z, Li J B. Design and parameter optimization of spiral-dragon type straw chopping test rig. Int J Agric & Biol Eng, 2020; 13(1): 47–56.

Design and parameter optimization of spiral-dragon type straw chopping test rig

In order to address the problems of large chop length, high energy consumption and poor chopping effect that were associated with a horizontal total mixed rations (TMR) mixer, a straw chopping device was designed; further, its structure and working principle were analyzed. In this study, wheat straw was chosen as the test object. The number of processing times, number of fixed blades, cutting speed, number of tooth plates and the inclined angle of the box were considered as the test factors. The standard straw length rate and average power were used as evaluation indices for conducting the orthogonal rotation combination experiment with five factors and five levels of quadratic regression. The experimental results denoted that the order of influencing factors on the standard straw length rate can be given as follows: the number of processing times, number of fixed blades, cutting speed, number of tooth plates and inclined angle of the box. The order of the influence of each factor on the average power can be given as follows: the cutting speed, number of fixed blades and number of tooth plates. Further, the optimum structural and working parameters of the device can be determined as follows: linear cutting speed of 17-20 m/min, box inclined angle of 70°-80°, 20-23 fixed blades, 5-6 processing times and 4-7 tooth plates. Under such a circumstance, the standard straw length rate reached up to 70.5%-77.4% and the average power was low at 5.8-7 kW. The results can be used as reference for designing a chopping device for a TMR mixer. Keywords: total mixed rations, straw, chopping device, parameter optimization DOI: 10.25165/j.ijabe.20201301.4927 Citation: Ma P B, Li L Q, Wen B Q, Xue Y H, Kan Z, Li J B. Design and parameter optimization of spiral-dragon type straw chopping test rig. Int J Agric & Biol Eng, 2020; 13(1): 47–56.

Evaluation of straw spatial distribution after straw incorporation into soil for different tillage tools

Straw incorporation into the soil can effectively solve the problem of extra harvested crop residues on the surface. However, due to the lack of research on the spatial distribution effects of straw in the soil after incorporation, it is difficult to evaluate the actual straw incorporation effects of tillage tools. In this study, straw incorporation experiments were conducted via three types of tillage tools in rice stubble fields: a traditional rotary tiller (TR), a straw rotary burying and returning machine (SR) developed by our research group, and a subsoiling + straw rotary burying and returning machine (SSR). The same operating parameters, such as working speed and tillage depth, were used in the experiments. The spatial distribution of straw after tillage tool operation was measured and compared by a measuring device developed for straw three-dimensional coordinates. The results showed that after TR operation, the cutting effect on the straw was poor; more straw was left on the surface and less straw was buried into the lower layer of the tillage depth compared to SR and SSR; the average length of straw in the divided cells was small; and there were many cells without straw. Compared with that of TR, the straw average length of SR and SSR decreased by 48.2% and 52.7%, respectively. Only a small amount of straw remained on the surface. The proportion of straw in the lower layer of the tillage depth increased by 154.9% and 214.1%, the average straw length in cells increased by 114.9% and 98.6%, and the number of cells without straw decreased by 40.2% and 36.0%, respectively. On the whole, SR and SSR had more advantages for straw cutting and straw incorporation into the soil, and SSR could bury more straw into the soil of the lower layer. Therefore, for fields with excessive residue concerns, the SSR was the most desirable tillage tool.

Experimental tests of Bertrand’s question and the Duhem–Quine problem

In this paper we report on an experimental test of Bertrand’s question on the probability to find a random chord drawn inside a unit-radius circle with length greater than . In an experiment performed by tossing straws onto a circle, we confirm a theoretical prediction that the answer depends on the ratio of the circle diameter, 2R, to the straw length, L, and that the special case, which follows from rotational and translation invariance using integral geometry, is only obtained in the experimentally unattainable limit of infinite straw length, . In addition, we observe a systematic discrepancy in the limit, , where a large number of events are rejected. We conclude that the experimental test of Bertrand’s paradox provides a good illustration of the Duhem–Quine problem: that hypothesis testing is always conditional on a bundle of real auxiliary assumptions.