Agricultural Engineering Practice Exam 2025 – The All-in-One Guide to Master Your Certification!

The primary factor influencing the penetration of a disc plough in soil is the position of the gangs relative to each other. When one gang is higher than the other, it can create an imbalance that affects how the plough engages with the soil. This uneven setup can lead to inadequate soil penetration, as the depth of cut is directly influenced by the alignment of the discs. A properly aligned plough, where both gangs are uniform, allows for optimal penetration and effective soil turnover.

The other options reference different elements that may impact performance but are not fundamental factors influencing penetration. For instance, while the speed of the plough is important, it is not the primary aspect affecting how deeply the discs penetrate. Disc spacing is critical for effective soil displacement and residue management but remains secondary to the alignment of the gangs. Similarly, the gang scraper's position affects soil flow and quality of furrow but is also not a primary factor in penetration depth. Thus, the correct choice focuses on the crucial role of gang alignment in the performance of a disc plough.