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Abstract: A simple and robust monodroplet generator was constructed for drop-on-demand application of aqueous solutions of pesticides to crop plants and weeds. A short current impulse regulated the opening of a solenoid valve, allowing pressurised nitrogen gas to flow into a liquid chamber. Once a jet is released from the nozzle, one single droplet is detached, and the remaining part is retracted back into the cylinder as the excess gas is exhausted. The effects of the impulse width, pressure, diameter of the orifice, and the surface tension of the liquids as influenced by adjuvants were evaluated in terms of droplet diameter and generation potentiality. In general, increasing the impulse width and orifice diameter led to an increase in the droplet diameter. In contrast, increased pressure and reduced surface tension of the liquid led to a decreased diameter, although the effect was observed only at lower impulse widths and larger orifice diameters. With an optimum adjustment, we were able to generate monodroplets with diameters ranging from 533 to 1819 μm, although the range could be varied easily by changing the parameters. [Copyright &y& Elsevier]

A direct injection system (DIS) for pesticide injection at all nozzles was set up in order to ascertain its ability to be cleaned. Under laboratory conditions, the system was contaminated with a safe-to-use salty polyvinylpyrrolidone-water solution as a test pesticide and then cleaned in two steps: (1) reclaiming the test pesticide by pushing it back into the pesticide tank using pressurized air (pre-cleaning) and (2) rinsing the contaminated part of the hydraulic system with water. Tests on a 3 m wide test bench included gravimetric and conductivity measurements to determine the amount of residues in the test section and test pesticide concentrations in the rinsing water. Mechanical action inside the test section was varied by (1) increasing the air pressure for pre-cleaning, (2) increasing the rinsing water pressure, and (3) employing pulsed water-airflow. Initial test pesticide concentrations in the rinsing water could be as high as 25%, which is more than in common spray mixes and requires further dilution. While continuous rinsing at higher pressures saved up to 10% of the water, rinsing the test section with pulsed water led to water savings of more than 50%. Rinsing turned out to be a time-consuming procedure, as it took almost 10 min for test pesticide concentrations in the rinsing water to approach 0%. [ABSTRACT FROM AUTHOR]

To investigate the root-soil anchorage strength, a pull-out test is often needed. Because of vegetation diversity and site-specific conditions, each species has its special pattern in the development of root systems. Therefore, there is a desire to provide an appropriate technique that can be adapted to different species, in this study, a penetrometer with minor modification is proposed for the pull-out test. In addition, two types of clamps were designed. To assess the feasibility in the field, four species were tested: maize (Zea mays L.), sunflower (Helianthus annuus L.), sugar beet (Beta vulgaris L) and fat-hen (Chenopodium album). Furthermore, two indices were verified: the peak value of pull-out force, and the work of a complete pull-out course. The statistical results showed that both the shoot heights and stem diameters of maize and sunflower (single-branched plants) were significantly correlated with the peak value of pull-out force (0.871 ≥ R² ≥ 0.798). Alternatively, the work of the pull-out course was suitable for fat-hen (multi-branched plant) in relation to the root dry mass (R² = 0.791). For sugar beet, a weak correlation (R² = 0.371) was observed, and the reason is interpreted. In addition, the failure rate of uprooting each species by each clamp is presented. In general, the proposed technique could be regarded as an effective tool in ecological and agricultural investigations. [ABSTRACT FROM AUTHOR]

Direct injection systems have been developed in recent years to enhance the feasibility of this technology for site-specific on-field pesticide application, to reduce environmental pollution, and to ensure operator's safety and comfort. The injection of concentrated pesticides downstream of the water tank demands additional features for mixture homogenization. To evaluate the system's mixing properties, a decolorization method and a new sensor for mixture quality measurement at the nozzle were developed and tested. Results showed that the sensor and the method described in this work were adequate for determining the homogeneity If the mixture during injection. Different mixing chamber settings were tested with and without a KMS static mixer. The results indicated the necessity of a mixing device for direct injection systems with short lag times. For a static mixer, the impacts of the mixer position, mixer length, additive viscosity, and mixing ratio were tested. The 12 L/D KMS static mixer was found to be an optimal device for the mixing process in the nozzle with additive concentrations of up to 0.3%. The mixing time can be reduced to 40.2 ms in this case. In the case of non-Optimal positioning of the mixer or mixing at lower concentrations, the mixer length should be extended to achieve the same mixing result. [ABSTRACT FROM AUTHOR]

The objective of this research was to develop a yield monitoring system primarily for sugar beets by applying ultra-wideband (UWB) radar technology. Like radar systems used in geological engineering, these devices acquire data via electromagnetic waves. The basic idea was to use such data to identify sugar beets in agricultural soils, which would provide non-invasive in-soil detection of sugar beets Or order to enable counting of individual sugar beets and determination of single sugar beet root mass. Further goals were to enhance the methods and procedures of the UWB radar technology for other applications in agriculture, as a general goal, and to define applicability restrictions of the system for sugar beet and other root crops. In the first phase of the research, laboratory experiments were used to develop, test, and consequently improve the data acquisition and processing procedures. In this first phase, the feasibility of detecting sugar beets in soil in laboratory conditions using the reflected energy with a simple threshold approach was confirmed. In the second phase, the potential detectability and size estimation of sugar beets based on the distribution and consistency of backscattered energy amounts obtained in field conditions was researched. Based on the data recorded in field conditions, visual detectability was above 90%, with good correlations between sugar beet positions and energy peak positions. The best correlations between mass of sugar beets and the amounts of backscattered energy exceeded 80%. [ABSTRACT FROM AUTHOR]