# Variation in Crop Yield Depending on the Tractor Tire Contact Area and Clay Loam Soil Moisture
## 3 Results
Well-structured soil helps maintain a balanced air-water ratio [25]. In heavy loamy soils, creating a suitable seedbed can be challenging, as the soil tends to form clouds that dry out quickly, leading to moisture loss at the seed depth. In unprepared soil, seeds struggle to germinate, resulting in sparse crops and empty spaces often colonized by weeds. Compressing the soil can increase and maintain soil moisture under dry conditions. However, uncompacted soil at a depth of 0-5 cm retained more moisture compared to soil with single-wheel drive at nominal tire pressure. In other words, when single wheels slipped approximately 30%, the soil was extensively dug up and dried. As climate conditions shift towards dryness, it becomes evident that seeds do not germinate as well as they should in tractor tracks. It was observed that the seed germination rate was higher in treatments with wet soil compared to those with dry soil. The soil water in the layers beneath the seedbed serves as a primary moisture reserve for successful seed emergence during dry post-sowing periods. Large seeds of field peas require more water for emergence than cereal grains. Figure 9 illustrates the cumulative effect of tractor tire contact area on field pea germination (plants per m\({}^{2}\)) under two distinct soil moisture conditions. In both soil conditions, germination increases with larger tire contact areas. This suggests that increased tire contact may improve germination, making it crucial to preserve the moisture of the upper seedbed layer. Increasing from A2 to A5 in dry soil, germination was about 19%; on wet soil was better by 11%. Peas that germinated later, across all contact areas, emerging only after rain, caused unripped peas at harvest. Figure 10 illustrates the cumulative effect of tractor tire contact area on barley germination (plants per m\({}^{2}\)) under two distinct soil moisture conditions. Under dry soil conditions,  
Figure 9: The germination of field pea dependence on tire contact area. barley germination ranged from 376.02 plants\(\cdot\)m\({}^{-2}\) (control, A1) to 406.67 plants\(\cdot\)m\({}^{-2}\) (largest contact area, A5), showing an 8.2% increase in germination seedling density. Incremental increases in tire contact area consistently resulted in increased germination of barley compared to the non-compacted control. In wet soil conditions, barley germination increased more noticeably, rising from 388.67 plants\(\cdot\)m\({}^{-2}\) in the control (A1) to 408.62 plants\(\cdot\)m\({}^{-2}\) at A5. A steady upward trend was observed as the tire contact area increased, resulting in improved barley germination, particularly noticeable in wetter soil conditions. Figure 11 presents spring wheat germination results (plants\(\cdot\)m\({}^{-2}\)) depending on tractor tire contact area (A) under two soil moisture conditions. The control plot without tractor compaction (A1) served as a reference for comparison. Adjustments in tire contact area were achieved by altering tire air pressure and adding dual wheels. The tire contact area rose from A1 (397.89 plants\(\cdot\)m\({}^{-2}\)) to a maximum at A5 (419.77 plants\(\cdot\)m\({}^{-2}\)), representing a 5.2% increase in wheat germination under dry soil conditions. As tire contact area increased in moist soil circumstances, germination improved progressively and peaked at A5 (434.89 plants\(\cdot\)m\({}^{-2}\)), a 6.3% increase over the control (A1, 408.98 plants\(\cdot\)m\({}^{-2}\)). Germination was 2.6% higher than in the control plot, even at the least adjusted contact area (A2). These findings underscore the positive impact of improved seed contact on germination rates, particularly in wet soil conditions, by showing that increasing tractor tire contact area consistently improves wheat germination. Crop productivity relies on favorable moisture conditions after sowing; a good start of sprout germination accompanies later during the whole growing period as a result of soil compaction level.