UAV-spray application in vineyards: Flight modes and spray system adjustment effects on canopy deposit, coverage, and off-target losses.

Improvements in the spray application of plant protection products enhance agricultural sustainability by reducing environmental contamination, but by increasing food quality and human safety. Currently, Unmanned Aerial Vehicles (UAVs) are raising interest in spray applications in 3D crops. However, operational configurations of UAV-spray systems need further investigation to maximise the deposition in the canopy and minimise the off-target losses. Our experimental research focused on investigating the effects on the canopy spray deposition and coverage due to different UAV-spray system configurations. Twelve configurations were tested under field conditions in an experimental vineyard (cv. Barbera), derived from the combination of different UAV flight modes (band and broadcast spray applications), nozzle types (conventional and air inclusion), and UAV cruise speeds (1 and 3 m s-1). Also, the best treatment, among those tested, by using the UAV-spray system and a traditional airblast sprayer were compared. The data was analysed by testing the effects of the three operational parameters and their two- and three-way interactions by means of linear mixed models. The results indicated that the flight mode deeply affects spray application efficiency. Compared to the broadcast spray modes, the band spray mode was able to increase the average canopy deposition from 0.052 to 0.161 µL cm-2 (+ 309 %) and reduce the average ground losses from 0.544 to 0.246 µL cm-2 (- 54 %). The conventional airblast sprayer, operated at a low spray application rate, showed higher canopy coverage and lower ground losses in comparison to the best UAV-spray system configuration.

Developing strategies to reduce spray drift in pneumatic spraying in vineyards: Assessment of the parameters affecting droplet size in pneumatic spraying.

Pneumatic sprayers are widely used in vineyards due to their very fine droplet size, which makes the drift risk to become an important problem to be considered. The aim of this study was to assess the effect of the spout diameter at the release point on the spray droplet size and uniformity achieved for different liquid flow rates (LFR) and air flow rates (AFR). A test bench was developed to simulate a real pneumatic sprayer under laboratory conditions, and it was empirically adjusted to match the air pressure conditions as closely as possible to real working conditions. Two positions of insertion of the liquid hose, the conventional position (CP) and an alternative position (AP), were tested for three LFRs, 1.00, 1.64, and 2.67Lmin-1, and four AFRs, 0.280, 0.312, 0.345, and 0.376m3s-1. The air speed decrease between the two insertion points of the liquid hose was measured. A Malvern SprayTec® instrument was used to measure the droplet size, and the D50, D10, and D90 parameter values were obtained. The relative SPAN factor (RSF) was also calculated. A model to predict variations in D50 was fitted using the aforementioned parameters. The results show that variations in the diameter of the spout significantly change the droplet size, producing a mean increase of 59.45% in D50 and similar increases in D10 and D90. The model developed to predict variations in D50 has a very high degree of accuracy (R2=0.945). The relative decrease in the air speed along the spout did not present significant differences for the different airflow rates tested. The results of the study show that the droplet size produced in pneumatic spraying can be modified easily by varying the air spout dimensions. This should be taken into account by manufacturers from a design point of view.

Batch and continuous biogas production arising from feed varying in rice straw volumes following pre-treatment with extrusion.

This paper studies the synergistic effects on biogas production obtained when different feedstocks are co-digested with varying proportions of rice straw and explores their behavior at the laboratory scale in continuously stirred digesters. Evaluative measures included methane production, volatile solids degradation, ash accumulation, and extrusion effectiveness. The effect of extrusion on the production of energy was also investigated. Results indicated that continuous stirred digesters fed with substrates composed of 10% or 30% of ensiled rice straw (on total FM) produced 146.1 and 140.0lNCH4kgDM(-1)day(-1), respectively. When extrusion was employed, organic matter degradation was promoted and methane production was significantly raised-by as much as 16%. For the feeds containing 10% rice straw, the increase in obtained energy was higher than the energy needed for the extrusion, but the energy balance was close to zero when the percentage of rice straw was the 30% of the feed.

Decision support tools for environmentally safe use of pesticides.

Prevention of environmental risk due to pesticide application is demanded by EU legislation regarding water and crop protection issues. The pesticide users are required to take responsibility for the environmental consequences of applications. Therefore they need to make responsible decisions at both strategic and tactical level. The first one is a long term decision on selection of equipment, and the other applies to decisions on use of equipment in actual meteorological and environmental situation at any time when treatment is needed. In order to assist the user to make proper decisions the decision support tools were developed in form of web-based applications: EOS - Environmentally Optimised Sprayer; DET--Drift Evaluation Tool. EOS performs evaluation of the sprayer in terms of its risk mitigation potential based on the technical solutions present on the sprayer and selected by the user. EOS has been designed as a stepwise structured questionnaire, divided in sections representing different sources of pollution, i.e. RISK AREAS (step 1): Inside contamination; outside contamination; Filling; Spray Loss (Drift); Remnants. Within each RISK AREA there were identified PROBLEMS (step 2) to be solved by different TECHNOLOGIES (step 3), evaluated in different ASPECTS (step 4) when the user selects TECHNICAL SOLUTION (step 5) used on the sprayer. The items of steps 1-4 were assigned weights (%) and the items of TECHNICAL SOLUTIONs were scored from 0 to 10 (10 = best in class). This stepwise approach and valuation of items allows for calculating the effective score of each individual TECHNICAL SOLUTION in terms of its risk mitigation potential. The sum of these individual scores related to the final score of environmentally optimised sprayer gives the evaluated sprayer's EOS index (%) expressing the environmental value of the sprayer. DET performs evaluation of drift risk in actual situation, and proposes measures to mitigate this risk, helping the operator to make better tactical decisions. It consists of three sections: (I) SPRAY APPLICATION SITE; (II) METEO and FIELD CONDITIONS; (III) DRIFT RISK MITIGATION. Within the sections (I) and (II) the user makes selection of options defining the distance between application site and sensitive areas, as well as weather and field/crop conditions. The selected items describe the actual and objective situation, for which DET calculates the Drift Risk Value [%] followed by appropriate recommendation. In section (III) the user can simulate and check the effect of drift mitigation measures by selecting one of the classified spray drift reduction technologies or key application parameters affecting risk of drift. Based on the user's selection the tool appropriately modifies the Drift Risk Value and gives the final recommendation. Simple and practical EOS and DET tools are meant to be used by pesticide users and advisors as they also have educative and awareness raising value.

The effect of particle size and thermal pre-treatment on the methane yield of four agricultural by-products.

One way to optimize methane production in anaerobic digestion plants is to substitute ligno-cellulosic by-products for crops traditionally used as energy sources. However, using these by-products requires introduction of a pre-treatment system to minimize energy input and maximize energy output for an improved net energy equation. In this study, four agricultural byproducts (wheat, barley, rice straw and maize stalks) underwent various mechanical and thermal treatments prior to anaerobic digestion including particle size reduction to 5.0, 2.0, 0.5, and 0.2 cm and heat application to 90 °C and 120 °C. Mechanical pre-treatment increased byproduct methane yields more than 80%; thermal pre-treatment improved yields more than 60% for wheat and barley straw. Pre-treating wheat straw improved methane yields most, regardless of whether the method was thermal or mechanical. An electric net energy balance was also completed to analyze the feasibility of the pre-treatments according to input and output of energy.

Residual biogas potential from the storage tanks of non-separated digestate and digested liquid fraction.

Biogas plants daily produce enormous volumes of digestate that can be handled in its raw form or after mechanical separation. In Italy, effluents are usually stored within aboveground, uncovered tanks, which make them potential emitters of biogas into the atmosphere. The purpose of this study was to estimate the amount of biogas emitted to the atmosphere during the storage phase of non-separated digestate and digested liquid fraction. The trials were performed at two northwest Italy 1 MWel. biogas plants. A floating system for the residual biogas recovery, and a set of three wind tunnels for NH3 emission measurement were used. The experiment demonstrated significant loss to the atmosphere for each of the gases; specifically, on average, 19.5 and 7.90 N m3 biogas MWhel.(-1) were emitted daily from the storage tanks of non-separated digestate and digested liquid fraction, respectively.

Thermal pre-treatment of solid fraction from mechanically-separated raw and digested slurry to increase methane yield.

Anaerobic digestion plants rely on large-capacity storage tanks to manage the agronomic utilisation of the digestate. As a consequence, many Italian A.D. plants have introduced mechanical separation of the digested slurry to simplify process requirements. This study evaluated the possibility of reusing mechanically-separated solid fraction as a further biomass input anaerobic digestion plants. The effects of storage and thermal pre-treatment on digested solid fraction were assessed through biogas and methane yield measures, and then compared to the yields associated with undigested solid fraction of raw pig slurry. The specific CH4 yields of digested solid fractions ranged between 71.4 and 156.9 lN/kg VS, whereas the biogas yield from undigested solid fractions was 78.7 lN/kg VS. Solid fraction storage showed no significant effect on specific CH4 yields in any of the examined samples. However, in the case of the undigested solid fraction, thermal pre-treatment proved to be an effective method to increase CH4.

The methane yield of digestate: effect of organic loading rate, hydraulic retention time, and plant feeding.

In biogas plants, huge volumes of digestate are produced daily and stored in uncovered tanks, which leak methane into the atmosphere and cause negative environmental impacts. To better understand the effect that different operating parameters of anaerobic digestion plants have on digestate residual methane yield, four digestate samples collected from plants with very different operations were analysed in batch reactors. Their methane yields were very heterogeneous and varied between 2.88 and 37.63 NL/kgVS. The methane yield was shown to be highly influenced by the A.D. plant Organic Loading Rate and by feedstock quality; hydraulic retention time had only limited effects.

Evaluation of the biogas productivity potential of some Italian agro-industrial biomasses.

Batch trials were carried out to asses the biogas productivity potential of rice and barley straw, grape stalks, grape marcs, maize drying up residues, tomato skins and seeds, and whey. Trials were carried out in 2l glass digesters kept in a thermostate controlled room at 40 degrees C for 40days. The most productive biomasses, in terms of specific methane yield, were the whey and the maize drying up residues. Their specific methane yields were 501 and 317l(N) CH(4) *kgSV(-1), respectively. Barley and rice straw gave a specific methane yield of 229 and 195l(N) *kgVS(-1). Similar result was also obtained from tomato skins and seeds. Grape stalks and grape marcs produced lowest amounts of specific methane, respectively, 98 and 116l(N) CH(4) *kgSV(-1). According to trial results and considering the availability of examined biomasses in Italy, it is possible to estimate their total energetic potential close to a value of 21,900TJ *year(-1). This energetic potential value is equal to that obtainable from the anaerobic digestion of about 6.5 million tons of maize silage.

Advanced spraying techniques in fruit growing--the ISAFRUIT project--towards safer and better quality of fruit.

In 2006 the project ISAFRUIT (www.isafruit.org)--"Increasing fruit consumption through a trans disciplinary approach leading to high quality produce from environmentally safe, sustainable methods"--was launched within the 6th Framework Program of the EC. Within the project's work package ECOFRUIT (WP 5.1 - Safe European fruit from a healthy environment) a Crop Adapted Spray Application (CASA) system is developed. This system is developed to ensure efficient and safe spray application in orchards according to actual needs and with respect to the environment. The system consists of three components: 1. Crop Identification System (CIS), 2. Environmentally Dependent Application System (EDAS), and 3. Crop Health Sensor (CHS). A sprayer prototype able to automatically adapt spray and air distribution according to the characteristics of the target, to the level of crop disease and to the environmental conditions is under development.

Improved recycling of livestock slurries on maize by means of a modular tanker and spreader.

Slurry spreading represents a critical component of the waste management strategy since it influences the nutrients' availability for the crops. The Italian Regulation in force sets severe limits to the slurry application to land. These limits--and the necessity to optimise the slurry fertilising value--require to operate with the correct application rate and with a sufficient spreading uniformity. An innovative slurry spreader able to optimise the reuse of this by-product as an agronomic resource whilst respecting the national regulation has been tested under practical conditions. The agronomic trials showed that the controlled recycling--performed with the innovative slurry spreader--gave no statistically different grain yields from those obtained with the chemical fertilisation. The ammonia emissions recorded after the slurry injection were the 16% of those recorded after the band application.