Ploughing, often referred to as tilling, is an ancient agricultural practice that involves mechanically turning over or breaking up the upper layer of soil to prepare it for planting. This process has been a fundamental part of farming since the earliest civilizations. While historically powered by humans and draft animals, modern agriculture uses powerful tractors and sophisticated implements. The basic function of manipulating the soil remains unchanged: creating an environment that promotes successful crop establishment and growth.
The Primary Goals of Soil Tillage
Farmers primarily plough to achieve a series of physical and biological objectives that foster a good growing environment for their crops. The foremost goal is preparing a suitable seedbed, or “tilth,” by loosening compacted soil and creating a soft, crumbly texture. This fine structure ensures good seed-to-soil contact for rapid and uniform germination. The loosened soil also breaks up dense layers, allowing for better air circulation and water movement into the soil profile.
The turning action of ploughing incorporates old crop residue and surface organic matter into deeper soil layers. This mixing helps distribute nutrients throughout the root zone and promotes residue decomposition. Ploughing also controls weeds by physically uprooting and burying them, disrupting their life cycle. Furthermore, exposing the soil can help manage certain soil-borne pests and diseases by disturbing their habitats.
Methods and Tools of Soil Turning
The act of ploughing is performed by different types of implements, each designed to achieve a specific level and style of soil disturbance.
Moldboard Ploughing
The traditional and most intensive tool is the moldboard plough, which uses large, curved surfaces to cut, lift, and completely invert the soil slice. This inversion is highly effective at burying all crop residue and weeds, leaving a clean, bare soil surface. Moldboard ploughing typically reaches depths of 10 to 20 inches and is the method most associated with conventional deep tillage.
Chisel Ploughing
A different approach is utilized by the chisel plough, which employs narrow shanks to penetrate and fracture the soil without fully turning it over. Its primary function is to loosen compacted subsurface layers, often operating at depths of 8 to 12 inches. This method leaves a significant portion of the crop residue on the surface, creating vertical channels for water infiltration and root growth, helping to alleviate compaction layers.
Comparing Conventional Ploughing to Conservation Tillage
Conventional deep ploughing, particularly with the moldboard plough, leaves the soil fully exposed, which has significant ecological consequences. The intense physical turning breaks down the soil’s natural structure, making it highly vulnerable to erosion by wind and water. Bare soil increases surface runoff, carrying away nutrient-rich topsoil and accelerating the decomposition of organic matter, which releases stored carbon into the atmosphere.
Conservation tillage, including minimal tillage and no-till farming, represents a modern response to these trade-offs. This alternative system focuses on minimizing soil disturbance by avoiding deep inversion. Conservation methods aim to leave at least 30% of the previous crop’s residue on the surface, acting as a protective layer. This residue cover dramatically reduces soil erosion, improves water infiltration, and helps the soil retain moisture, promoting a more sustainable system.