The analysis of technical suitability of the equipment for application of plant protection products in Southeastern Slovenia

Technical testing of the equipment for the application of plant protection products (PPP) was performed in Southeastern Slovenia in the period from 2004 to 2013. The technical conditions of boom or orchard sprayers was examined in details and the following parts were checked: drive, anti-drip valves, nozzles, filters, pipes and tubes, manometers, all valves, pressure regulators, agitator, pump, liquid discharge, spray solution reservoir and spray boom or fan system. The analysis revealed a poor condition of most devices in the initial years. However, technical suitability improved drastically until 2013. Technical condition was not directly related to the region of inspection although the lowest number of defective sprayers was recorded in the Posavje region. This can be linked to higher frequency of use and maintenance of the sprayers in this region as it stands out as the area with larger farms. Occasional technical disorders of the equipment can be recorded each year. It is therefore essential to continue with regular technical inspection to ensure optimal and accurate functioning of the sprayers.


INTRODUCTION
Devices used for the application of plant protection products (PPP) are machines, which enable uniform application of PPP to the plant surface.Devices usually utilize water to dissolve and apply PPP and can be categorized as sprayers and air assisted sprayers (Mrhar, 1997).Phytopharmaceutical products, which are applied via sprayers, destroy, suppress, control or deter harmful organisms and prevent their negative effect on plant growth and development or storage of plant products (Blažič, 2009).
Technical flawless of the spraying equipment is crucial for optimal distribution of PPP.The quality of the sprayer is important but it does not guarantee good results if the device is not properly managed and maintained.Up-to-date development of spraying equipment and its technical assistance and inspection are generally focused to ensure accurate PPP application (exact dosage, uniform distribution) and ameliorate other factors (such as working speed) (Roettele et al., 2011).Sprayers must provide exact application and uniform dosage of PPP during the entire lifespan of the device.To ensure their proper functioning, sprayers must be regularly tested and potential technical faults eliminated (Ganzelmeier, 2004a).SIST EN 13790-1 (2004) and SIST EN 13790-2 (2004) standards were implemented in EU member states in order to unify the technical demands for testing of the devices for PPP application.The purpose of the standards is to ensure comparable testing conditions throughout the EU.Their contents can be summarized into the following significant points (Ganzelmeier, 2004b): (1) unification of different procedures, findings and technical demands, previously implemented in specific EU member states; (2) methodology and technical requirements are based on successful practices, previously implemented in specific EU member states; (3) high technical level is ensured with minimum time and funding; (4) EU member states are obliged to accept and implement new standards and withdraw old standards; (5) standards represent the basis for the unification of technical testing in the EU and serve as potential interactive tool in the future; (6) standards set technical requirements but do not regulate the decisions of specific EU member states.
In case of Poland, technical testing of the devices for the application of PPP started in 1995 and became mandatory in 1999.Holownicki et al. (2004) reported similar national standards to that of SIST EN 13790-1 (2004) and SIST EN 13790-2 (2004) prior to their implementation.However, several parts of the spraying equipment were tested according to a less strict methodology, which frequently only included visual assessment.
Norway began technical testing of spraying equipment in 1990 (boom sprayers) and in 1995 (air assisted sprayers) on a voluntary level.The testing became mandatory for all devices in 2000.Although national technical tests were very sophisticated, slight changes were made after the implementation of SIST EN 17390-1 (2004) and SIST EN 13790-2 (2004) (Bjugstad et al., 2004) standards.
Italy started voluntary testing of air assisted sprayers in the Bolzano region as far back as in 1980.Oddly, technical testing of spraying devices has not been performed in several other regions to this day.In 2004, only 9 of 20 Italian regions had developed a system for technical testing.Some technical testing stations were established in 1996 -1999 but most were founded in 2002-2004(Balsari et al., 2004)).Up to now, 120 testing stations are active in Italy but the testing is only mandatory in Tuscany region.Most technical tests are performed by private institutions.Public testing stations are mostly focused on voluntary testing and experimental testing of the spraying equipment (Balsari et al., 2004).
Germany implemented technical testing practices of spraying devices in late 1960 (boom sprayers) and in the middle of 1980 (air assisted sprayers) on a voluntary level.About 1000 testing stations are located in Germany today, which cover 2000 different locations.Testing became mandatory in 1993 and until then approximately 30.000 devices were tested each year.Today, as many as 63.000 sprayers are tested yearly (Osteroth, 2004).
In Slovenia, technical testing of spraying equipment was already defined in 1994 Plant Health Act (Zakon o zdravstvenem …, 1994).Tests have been performed for the last two decades and the aim of the present paper is to present the testing results to a broader scientific community.The effects and results of the testing are discussed and strategies for their improvement suggested.

MATERIALS AND METHODS
Experimental data include the records of technical testing from 2004 until 2013.Inspections were performed at 86 different locations in Southeastern Slovenia, encompassing Agricultural advisory services Trebnje, Novo Mesto, Metlika, Črnomelj, Krško, Sevnica and Brežice.The research covers the area from Trebnje, Bela krajina, Novo Mesto, Škocjan, Šentjernej, Kostanjevica na Krki, Krško, Brežice to Bizeljsko.Micro locations (testing stations) varied each year (according to the suggestions of local communities) but this did not affect the groups of spraying devices subjected to inspection.
Technical testing was performed according to Rules on terms and procedures, which must be met by all authorized supervisory companies for regular inspection of PPP application devices (Pravilnik o pogojih …, 2000, Pravilnik o spremembi pravilnika …, 2002, Pravilnik o spremembah in dopolnitvi …, 2005).The details on technical inspection are specified in aforementioned Rules on terms and procedures.

Data analysis
Data were statistically analyzed in program R, version 3.0.2.Regression models-linear mixed models were used to interpret the correlation between the year and rate of faults.The level of risk was 5 %.

Technical condition of all spraying devices
Technical condition of spraying devices varied according to the year of inspection.Data is presented in Table 1.

Technical condition of boom sprayers
Data on boom sprayer technical testing is presented in Table 2.We assumed that the share of defected boom sprayers decreased during the 10-year period.Data analysis was performed on several segments of the boom sprayer.The negative value of the coefficient suggests that the defects on boom sprayers decreased in the examined period.Figure 3 depicts the decrease of share of devices with defects in all segments of boom sprayers in the period from 2004 to 2013.Some differences were minor but the condition of several segments was significantly improved.

Technical condition of air assisted sprayers
Differences in technical conditions of air assisted sprayers are reported in Table 4.  Data were statistically analyzed and a decrease of defected air assisted sprayers was expected in the 10year period.
Analysis was performed on several segments of air assisted sprayers.The negative value of the coefficient denotes a decrease of defects in air assisted sprayers during the examined period.The share of defects on all segments of air assisted sprayers decreased in the period from 2004 to 2013.The only exceptions were defects on the air blower, which increased slightly from 2009 to 2012.

Technical condition linked to the region of the technical testing
The locations for technical testing were not the same each year and therefore, the area was divided into seven units, each corresponding to the jurisdiction of a single

Technical condition of all spraying devices
As anticipated, technical condition of all spraying devices (boom sprayers and air assisted sprayers) increased during the examined time period.
Although technical inspection of PPP spraying devices in Slovenia began two decades ago, it only became mandatory in 2002.The initial technical condition of spraying devices was therefore poor, which can be ascribed to the general non-attendance at testing prior to 2002.Only environmentally conscious individuals and larger farmers tested their sprayers on a regular basis as they were aware of the importance of proper functioning of the devices.The latter are only effective in distribution of PPP if their technical condition is optimal.Frequently, leakage, poor distribution of the liquid solution and inadequate dosing (output) were recorded at testing, which resulted in reduced quality of application and economic loss.Every deviation from standard functioning of the sprayer inevitably leads to inefficient use of PPP.
Sadly, it seems that many farmers were not concerned with inferior performance of their sprayers as they only cultivate small areas of land and are thus satisfied with reduced performance -functioning of the devices.Small-scale farmers only require minor quantities of PPP and do not regard plant protection as a major economic cost of farming.This can be linked to a great number of defects on sprayers in the initial years of technical testing, i.e. in 2004 and 2005.Later, farmers were obliged to test their spraying equipment by law and a qualified mechanic serviced their devices on site.Many minor defects were corrected and users were simultaneously educated on a proper use and maintenance of the spraying equipment.
The results of this practice came to sight in the following years as the number of defects on sprayers greatly reduced.This proves the importance of regular technical testing for improved condition of spraying equipment in Slovenia.
However, defects can be recorded each year and it is therefore essential to proceed with technical testing of PPP sprayers in the future.Spraying devices have a limited lifespan and technical performance of every sprayer is reduced in time.For example, defected sprayers from the period of 2004-2008 were once in immaculate condition but because of their use and/or poor maintenance flaws occurred.That is why sprayers must be tested on a yearly basis to limit the use of faulty equipment on Slovenian farms and uncover hidden defects on the equipment such as inferior transversal distribution of spraying solution.

Technical condition of boom sprayers
As expected, technical condition of boom sprayers greatly improved in the experimental period.Many defects were recorded on different segments of boom sprayers in 2004 and 2005 and their number was reduced in later years.

Technical condition of air assisted sprayers
As in boom sprayers, technical condition of air assisted sprayers improved dramatically from 2004 to 2013.Most defects were similarly recorded in 2004 and 2005 and a superior condition of these devices was recorded in later years.

Technical condition linked to the region of the technical testing
Locations were grouped according to the jurisdiction of Agricultural advisory services and three main regions were formed based on geographical similarities of the area.We assumed that the technical condition of spraying devices is not defined by region and the hypothesis was confirmed.No significant differences were detected among the three regions.Nevertheless, smaller share of defected sprayers was recorded in the Posavje region which can be ascribed to several factors.Many large farms are active in this region and consequently, the farmers possess newer and better equipment for PPP application.The spraying devices are less prone to develop any defects and are also regularly serviced.Experiences show, that small-scale farmers frequently use defected sprayers on their land.

Figure 1 :
Figure 1: Share of defected devices in a particular year (data on boom sprayers and air assisted sprayers merged) Slika 1: Delež okvarjenih naprav za obe vrsti naprav v posameznem letu

Table 1 :
Data on inspected devices (data on boom sprayers and air assisted sprayers merged) in a particular year

Table 2 :
Data on inspected boom sprayers in a particular year

Table 3 :
Results of data analysis using the linear mixed model for several boom sprayer segments Preglednica 3: Rezultati linearnega mešanega modela na podatkih za posamezne sklopeškropilnice

Table 4 :
Data on inspected air assisted sprayers in a particular year

Table 5 :
Results of the linear mixed model analysing data of several air assisted sprayer segments The devices are old and poorly maintained but the farmers cannot afford new mechanization due to nonfavorable economic calculation based on limited land use.The other reason for superior results of the Posavje region may be linked to better technical support of Agricultural advisory services and education on the importance of proper PPP use in this area.These practices should be inspected in detail and implemented in other areas.