Influence of mobile technical means on soil of Tartu county

Uurimustöös tutvustatakse Tartumaa mulla peamisi parameetreid ning uuritakse, milline on kirjeldatud põllumulla füüsikalis-mehaanikaline seisund peale kündmist ning peale mobiilsete tehniliste vahendite kasutamist. Üheks läbivaks probleemiks kogu töös on põllumulla tihenemine mobiilse tehnilise vahendi toimel. Uurimustöös tehakse nii laborkatseid kui põldkatseid, mille andmeid hiljem töödeldakse ning graafiliselt esitatakse. Nii laborkatsete kui põldkatsete puhul kasutatakse põhiliselt mulla tihendajat, normaalpingete lugejat ning elektroonilist penetromeetrit. Lisaks andmete kogumisele pakutakse välja laborkatseseadme edasiarendamiseks välja uus lahendus. Selleks esitatakse katseseadmele nõuded, määratakse normatiivid, tehakse morfoloogiline analüüs, projekteeritakse eskiismudel ning tehakse riskianalüüs. Laborkatsetel saadi tulemused kombineerides erineva tihkusega mullasilindreid ning penetromeetromeetriga mõõtes. Katsetulemusi analüüsides leiti, et heleda mulla tulemusi ei saa värvikaardi koostamisel kasutada, kuid tumeda mulla tulemused võeti arvesse, kuna need ühtisid kõige enam ka põldkatse tulemustega. Põldkatsetel kasutati uudset metoodikat, kus mõõtmisi tehti nii risti jäljega, kui piki jälge, et saada võimalikult palju katsetulemusi ning varieeruvust. Idee seisneb selles, et sellise meetodi abil saab koostada pealmise horisondi kaardi, millelt on visuaalselt näha tihenenud ning kobedad alad. Võttes kokku põldkatse tulemused, võib öelda, et kerge traktor tihendas suhteliselt võrdväärselt mulda võrreldes raske traktoriga. Andmete töötlemisel pakutakse välja uudne lahendus, mille abil saab mulla pealmist horisonti visualiseerida ning hinnata. Visualiseerimiseks kasutatakse kahte värvivahemikku, kus helerohelisest tumeroheliseni (0...0,65 MPa) on taimedele sobilik kasvuvahemik, tumerohelisest punaseni (0,7...1,15 MPa) on ebasobiva tihkusega muld ning erkpunane (1,2 MPa ning üle selle) on kriitiline.This paper shows primary properties of soils in Tartu county. It researches the physical and mechanical condition of soil after ploughing it and after the use of mobile technical means. One of the main topics in this paper is compaction of soil during the impact of technical devices. The tests are done in laboratory as well as on field and the results are processed and delivered in graphs. Soil compactor, device for measuring pressure and electronic penetrologger are used in laboratory tests. Electronic penetrologger is also used in field tests to research the soil compaction in different circumstances. In addition to collecting data a new solution for developping a laboratory testing device is given. Therefore, requirements for testing device are presented, standards are appointed, morphological analysis is conducted, a model is engineered and risk analysis is given. The results in laboratory testing were received combining cylinders with different density and measuring with a penetrologger. A good overview of two different colors of soil resulted the tests although many of them did not give results. After analysing the data it was clear that the results of light soil cannot be taken into account. On the other hand, the results of darker soil coincided with the results of the field tests, therefore, were taken into account. A new method was used in field testing: soil density was measured across the track as well as along the track to get as many data as possible. The idea of this method is to draw a chart of upper horizon which shows visually compacted and mellow areas of the soil. In conclusion of field testing, a lightweight tractor compacted the soil relatively equally as a heavy tractor. A new solution is given to visualize and estimate the soil’s upper horizon. Two ranges of colors are used to visualize: light green to dark green (0…0,65 MPa) is a proper density for the plants to grow, dark green to red (0,7…1,15 MPa) is not suitable for growing plants and bright red (1,2 MPa and more) means this soil is in a critical state