Watermark, Tensiometer and Time Domain Reflectometry (TDR) are commonly used soil water sensors in irrigation practice whose performance depends on soil type, depth and growing conditions. Here, the results of sensor performance evaluation in different soil depths as well as the field and laboratory testing in silty clay loamy soil are presented. Gravimetric soil moisture samples were taken from sensor installation depths (10, 20, 30 and 45 cm) and used as reference Soil Water Content (SWC). The measurements varied significantly (p < 0.05) across the monitoring depths. On average across the soil depths, there was a strong negative linear relationship between Watermark (r = −0.91) and TDR (r = 0.94), and a moderate negative (r = −0.75) linear relationship between SWC and Tensiometer. In general, Watermark and Tensiometer measured SWC with great accuracy in the range of readily available water, generated larger Mean Difference (MD) than TDR and overestimated SWC, while TDR underestimated SWC. Overall, laboratory testing reduced the root mean square error (RMSE, Watermark = 1.2, Tensiometer = 2.6, TDR = 1.9) and Mean Average Error (MAE, Watermark = 0.9, Tensiometer = 2.04. TDR = 1.04) for all tested sensors.

The paper presents a review of different sensory systems for trees’ characterization and detection in permanent crops and the detection of plant health status in crop conditions for the purpose of applying the variable application rate. The use of new technologies enables the use of variable inputs in production with the aim of increasing the economic profit and reducing the negative impact on the environment. World trends increasingly emphasize the use of various sensor systems to achieve precision agriculture and apply the following: ultrasonic sensors for the detection of permanent crops; LIDAR (optical) sensors for treetop detection and characterization; infrared sensors with similar characteristics of optical sensors, but with very low cost prices and N - sensors for variable nitric fertilization. The daily development of sensor systems applied in agricultural production improves the performance and quality of the machines they are installed on. With a more intensive use of sensors in agricultural mechanization, their price becomes more acceptable for widespread use by achieving high quality work with respect to the ecological principles of sustainable production.

The research results of the spraying technical factors' impact on ground and air drift, and the deposit on the treetop in cherry orchards, are presented in the paper. Two different spraying systems (classical and sensory system) are investigated, Agromehanika AGP 200 ENU sprayer being used. The research is conducted according to ISO standard 22866 (Plant Protection Equipment-Drift Measurement Methods in Field Conditions). The impact of spraying norm as factor A (A1-250 l/ha; A2-200 l/ha); the nozzle type as factor B (B1-Lechler TR 8002 C; B2-Lechler ITR 8002 C) and the fan air velocity as factor C (C1-18 m/s; C2-12 m/s) are examined by the variance analysis. To spray and evaluate the drift, Tartazine organic dye solution with 4% concentration is used. The filter papers, used as collectors, according to the specified ISO standard, are placed directly in the spraying zone. The sampled filter papers are washed out with 10 ml of deionised water under laboratory conditions. After washing, the colour intensity, i.e., the solution wavelength , is read by a spectrophotometer (Varian Cary 50 UV-Visible). Different drift intensity (ground and air drift) and treetop deposits are realized by the usage of various treatments of technical spraying factors and various spraying systems. Unlike the ground and air drifts, the deposit within the treetop does not show statistically significant change by using a sensory spraying system, i.e. by using a selective application.

This paper represents the results of the research of generated noise levels measured in three different years (2010, 2013, and 2015), in accordance with the proscribed norms HRN ISO 6394, HRN ISO 6396 and HRN ISO 5131. The research was conducted on test sites of Belje d.d. company. The measurement was carried out on three tractors of the FENDT model 410 with the aim of determining the increase of generated noise relative to the time the tractors spent in exploitation. The obtained results showed that none of the tractors produced a higher level of noise than the permitted 90 dB. The main hypothesis of this experiment is that, exploitation-wise, tractors with a greater number of work hours will produce more noise than the ones with a smaller number of work hours.

The paper depicts sensors in precision agriculture. It encompasses the most significant and frequently used sensors in agriculture. Furthermore, the paper explains the main sensor types according to their design, the recorded range of electromagnetic spectrum, as well as the way of detection, recording, measuring, and representation of the detected energy. The development of remote research has provided deeper understanding of remote sensors and their advantages. The sensors installed on soil testing equipment, fertilizing and crop protection machinery, as well as crop picking machinery have been analyzed relative to precision farming. The paper depicts widely known sensors OptRx, ISARIA and VRT technology. The results of the paper assess the data collected by sensors and processed in order to produce maps for agrotechnical operations. The application of maps decreases the employment of human resources, heightens the capacity of data collection, increases the precision of agricultural activities, and finally results in decreasing the cost of final products. The technological progress over the past decade has enabled the development of technology with variable application standards (VRT) that, according to current needs, enables input optimization.