F. Kumhála

The impact of topography on soil properties and yield and the effects of weather conditions

Quantitative knowledge of the factors and interactions affecting yield is essential for site-specific crop management. One of the factors that frequently affects yield is topography. The aims of this study were to compare elevation data obtained from a combine harvester yield monitor and a hand RTK-GPS, and to evaluate the relationships between the spatial variation of cereal yield, selected crop nutrient concentration and topographic attributes derived from the two sources of elevation data. Simple models of elevation, slope and flow accumulation were created from the data of an experimental field in the Czech Republic, and the relations between yield and soil nitrogen and organic carbon contents and topography were determined over a four-year period. The models of elevation, slope and flow accumulation were compared with the yield, and soil nitrogen and organic carbon contents during the growing seasons of 2004, 2005, 2006 and 2007 in relation to total precipitation and temperature. The relationship between yield and topographic attributes was evaluated with the help of geostatistical methods. The results of correlation analysis among the variables were evaluated statistically by forward stepwise linear regression. No significant differences between elevation data from the combine harvester yield monitor and RTK-GPS were found. There was a significant relation between yield and crop nutrient concentration with topography. The correlation coefficients between flow accumulation and yield were weak for the wetter years and strong for the drier years.

Procedures of soil farming allowing reduction of compaction

Evaluation of new technologies using guidance systems is very important and can help producers with choosing the right equipment for their applications. Without using satellite navigation during field operations, there is a tendency for passes to overlap. That results in waste of fuel and pesticides, longer working times and also environmental damage. When utilising satellite guidance for field operations, there is a close connection with controlled traffic farming (CTF) as well. CTF is currently a quite quickly developing farming system based on fixed layout of machinery passes across a field. Tracks precisely set out for a machine’s tyres in the field could be a tool for minimising soil compaction risk which is another threat to the environment. The purpose of this paper was to evaluate the accuracy of currently available guidance systems for agricultural machines. Real pass-to-pass errors (omissions and overlaps) in a field were measured. Consequently, comparison between observed guidance systems was made regarding final working accuracy. Further, intensity of machinery passes, percentage of wheeled area and repeated passes in fields were monitored. These measurements were made in fields under real operating conditions using a conventional tillage system with ploughing and also a conservation tillage system, both systems with randomly organized traffic. Finally, the same parameters were monitored in fields where fixed machinery tracks were used for all operations and passes but only under a conservation tillage system. Pass-to-pass accuracy was measured for the evaluation of different guidance systems. Size of missed areas or overlaps was evaluated statistically. Concerning intensity of machinery passes and total field area affected by machinery passes, the following facts were found out. The experiments with randomized traffic showed a significant difference of the parameters mentioned above between a conventional tillage system with ploughing and a conservation tillage system. Wheeled area was 86 and 64%, respectively which proves benefits of conservation tillage. The experiments with a fixed track system showed that the total run-over area by machinery tyres decreased even more (up to 31%) in comparison to randomized traffic in a field (only fields under conservation tillage system were monitored and evaluated). The following statements based on our results can be made. The navigation and therefore possibility for better accuracy of machinery passes in fields together with permanent machinery tracks utilization could help with soil condition improvement and also energy savings which would result from that. The CTF system will help with further development of a system for soil compaction protection which is currently a real necessity.

Laboratory Measurement of Mowing Machine Material Feed Rate

The main objective of this research was to evaluate two possibilities of material feed rate measurement of modern mowing machines equipped with conditioner. The machines are commonly used for harvest of grasses (Lolium multiflorum, Dactylus glomerata, Phleum pratense, etc.), clover (Trifolium pratense, etc.), alfalfa (Medicago sativa) etc.A mowing machine with finger conditioner was equipped with an electronic measuring unit for the purpose of our measurements. The mowing machines conditioner shaft was supplied with strain gauges placed on a torque-meter and with a RPM optical sensor counter. Together with torque-meter the mowing machine was equipped with a curved impact plate mounted on the machines material output.It was decided to arrange a laboratory measurement to obtain information about the dependence of conditioner power input and signals from the impact plate on material mass flow. A mixture of grass and alfalfa was used for our measurement.The measurements carried out proved that a very good linear relationship existed between the conditioners power input, output frequency of the apparatus measuring impact force by means of the impact plate, and material feed rate through the mowing machine. The calculated coefficients of correlation were about 0.95. It is possible to differentiate a material feed rate difference of 0.5kg s−1 using both methods. This accuracy should be sufficient for practical utilisation such as creating yield maps.

Segmented Capacitance Sensor with Partially Released Inactive Segments

Abstract Material throughput measurement is important for many applications, for example yield maps creation or control of mass flow in stationary lines. Quite perspective can be the capacitive throughput method. Segmented capacitance sensor (SCS) is discussed in this paper. SCS is a compromise between simple capacitive throughput sensors and electrical capacitance tomography sensors. The SCS variant with partially released inactive segments is presented. The mathematical model of SCS was created and verified by measurements. A good correspondence between measured and computed values was found and it can be stated that the proposed mathematical model was verified. During measurement the voltage values on the inactive segments were monitored as well. On the basis of the measurement there was found that these values are significantly influenced by material distribution.

Sensitivity analysis of key operating parameters of combine harvesters

Kavka M., Mimra M., Kumhála F. (2016): Sensitivity analysis of key operating parameters of combine harvesters. Res. Agr. Eng., 62: 113–121. The sensitivity analysis of key operating parameters on the average annual sub-profit in a group of three combine harvesters operating in companies providing agricultural services were analysed. Based on the results of the cost analysis, the following key operating parameters with the greatest influence on the costs were identified: the purchase price of the machine, the price of fuel, maintenance costs, personnel costs and annual performance. These parameters were used in the sensitivity analysis to investigate their effect on unit costs. Changing the above-mentioned parameters is calculated within ± 30% from their mean value. To perform a sensitivity analysis of the average annual sub-profit of combine harvesters, the unit price of mechanized work was additionally used. The results showed that greatest impact on both the average annual earnings of combines operation and on the changes in unit cost was those of the annual performance of the combine harvester, combine harvester purchase price and the cost of fuel. On the other hand, maintenance and personnel costs had a smaller influence concerning these changes of parameters.

Influence of Overall Straw Management on Next Crop Germination, Growth and Final Yield when Using Conservation Tillage Technologies

For the purpose of simulation of straw and chaff distribution quality across working width of a combine harvester after its passage, different straw management variants with even and uneven plant remains placement were established. It has to be stated in advance that all measurement were carried out under normal field conditions under conventional machinery operation which is commonly used in practice. The influence of non-even distribution of plant residues and their excessive amount placed on the field surface after harvest on next plant germination, growth and yield was observed.

Parallel Plate Mass Flow Sensor for Forage Crops and Sugar Beet

Measurements described in this paper were realized in order to find out whether there is some relationship between mass flow of plant material passing through a parallel plate capacitive sensor and its output signal. This possibility of mass flow determination could be useful for the aim of forage crops or sugar beet yield maps creation. A parallel plate capacitive throughput sensor was designed for that purpose. The capacitive sensor and the whole oscillating circuit were driven at 27 MHz frequency. The laboratory set-up consisted of a conveyer belt, carrying a measured quantity of material into sensor, equipped with an electronic measurement apparatus. Material passed through the sensor between its plates. Laboratory tests were carried out with forage crops and with sugar beet. Resulting coefficients of determination ranged from R2=0.95 to 0.97 for forage crops and around R2=0.98 for sugar beet. It was possible to conclude from our measurement that forage and sugar beet mass flow determination by means of the parallel plate capacitive sensor is a promising way. The results showed a strong linear relationship between the feed rates of plant material passing through the sensor and tested measuring capacitive sensor circuit output signal.

Capacitance Sensor for Forage Mass Determination

Non-contacting methods for material properties determination and crop yield determination are the best solution especially for rough conditions in agriculture, however, it requires reliable and durable sensors as a source of primary data. The capacitance sensor based technique can be used for forage material mass determination in order to utilize obtained data for yield maps creation.