# Variation in Crop Yield Depending on the Tractor Tire Contact Area and Clay Loam Soil Moisture
## 3 Results
The contact area of the tractor tires with the soil had a significant influence on the number of productive stems of spring wheat and barley. In the treatment of the dry soil plot, the number of productive stems of spring wheat and barley was lower compared to their number in the wet soil variant. It was found that the biomass of spring wheat and field peas per square meter measured lower in the A2 and A3 plots than in the A4 and A5. Agricultural machinery with commonly used wheeled chassis significantly impacts germination, which can lead to reduced crop yields [25]. In less damaged soils rutted by double wheels, grain yield was higher compared to the control plot, considering the plant growth period. [PERSON] et al. [7] determined that wheat grain yield was significantly reduced by soil compaction. In the first harvest year, maximum wheat grain yield (395.7 g\(\cdot\)m\({}^{-2}\)) was obtained from T1 (no compaction), which progressively decreased to the  
Figure 10: The germination of spring barley dependence on tire contact area. minimum (278.9 g\(\cdot\)m\({}^{-2}\)) from T4 (six passes). A similar trend of grain yield was observed in the second harvest year when the maximum grain yield (432.6 g\(\cdot\)m\({}^{-2}\)) was recorded for T1 (control) and the minimum (323.0 g\(\cdot\)m\({}^{-2}\)) from T4 (six passes). It was established that from compacted soil, wheat grain yield was lower than control for both years [7]. The results of our research investigated the compaction of a single pass, on the basis that tractors do not make multiple passes during sowing, but rather a single pass showed that the yield of spring wheat and peas negatively responds to the soil compaction under displacement by tractor slippage. Yield losses were approximately like stated by [PERSON] et al. [7]. However, the lowest yields were obtained for peas in an uncompacted plot, which was coarse, cloddy soil. It was determined that there were no meaningful differences in grain yield mass between options when the soil was rutted at different tire pressures. However, significant differences were observed between options when the soil was rutted by single versus double wheels. Dry weather conditions led to fluctuations and common losses in grain yields, which are summarized and presented in the graphs. Soil compaction with double wheels had a positive effect on grain yield. Figure 12 illustrates field pea yield results (t\(\cdot\)ha\({}^{-1}\)) as influenced by varying tractor tire contact areas (A) under two soil moisture conditions. Under dry soil conditions, the highest yield was observed at A5--2.75 t\(\cdot\)ha\({}^{-1}\), which was approximately 9.5% higher compared to the non-compacted control plot A1--2.51 t\(\cdot\)ha\({}^{-1}\). However, intermediate tire contact areas A2 and A3 resulted in decreased yields compared to A1, by 9.6% and 3.2%, respectively. Under wet soil conditions, increasing the tire contact area led to progressively higher yields. The highest yield was also achieved at the largest tire contact area, A5--3.0 t\(\cdot\)ha\({}^{-1}\), representing a substantial yield increase of 8.6% compared to the control plot, A1--2.76 t\(\cdot\)ha\({}^{-1}\). The smallest contact area (A2) showed a 7.3% yield loss compared to the control under wet soil conditions. Figure 13 illustrates barley yield results (t\(\cdot\)ha\({}^{-1}\)) as influenced by varying tractor tire contact areas (A) under two soil moisture conditions. Under dry soil conditions, the highest yield was observed at A5--3.75 t\(\cdot\)ha\({}^{-1}\), which was approximately 8.38% higher compared to the non-compacted control plot A1--3.46 t\(\cdot\)ha\({}^{-1}\). However, intermediate tire contact areas A2 and A3 resulted in decreased yields compared to A1, by 9.83% and 6.07%, respectively. In contrast, under wet soil conditions, increasing the tire contact area led to progressively higher yields. The highest yield was also achieved at the largest tire contact  
Figure 11: The germination of spring wheat dependence on tire contact area.