By Greta Haupt, CanACT member, University of Guelph
Dirt: we walk on it every day without thinking much of it, let alone the value of it. But to farmers, soil is an invaluable resource and a crucial part of our operations. From forage crops to feed animals, to grazed pastures, to cultivated lands growing the high yielding grain crops needed to feed an ever growing population, it all starts with soil. A nutrient-rich and fertile soil is essential for growing the high quality product consumers demand, and therefore is one of the most carefully managed aspects of farming.
One very routine operation for farmers is to have their soil sampled. Basically, a hollow metal tube is pushed into the soil, filling the center of the tube. This can easily be done by hand to get a sample of the full top foot of the soil – the area from which the growing crop will be obtaining much of its nutrients. These samples are then analyzed in a lab for organic matter; macronutrients like nitrogen, potassium and phosphorus; and micronutrients such as boron, calcium, and magnesium, just to name a few. For crop growth, it is important to have all the required nutrients, in the correct quantities. Some nutrients are required in very high amounts, while others are only needed at very low levels – but these are just as critical to good plant growth. At too-high levels, many otherwise essential nutrients can cause toxicity and completely kill off the growing plant.
On top of these considerations, all crops will have different requirements. The farmer must consider what will be planted in that field, not just in the coming year, but also many years down the road, and plan his fertilizer application to suit them all. The levels of nutrients in the soil can also change quite drastically, not just from one field to another, but from one metre to the next, due to changes in soil type, topography, and water drainage through the soil.
While it is important to provide adequate nutrients for the growing crop, farmers also want to avoid over-application. Higher fertilizer application will lead to higher yields only to a point. The plant will take up the nutrients available in the soil until its needs are met. Once it meets those needs, any leftover fertilizer is vulnerable to being lost to the environment. Therefore, over-application of fertilizer negatively impacts a farmer’s bottom line, as the extra cost of fertilizer is not offset by higher yields. Basically, the farmer is always striving to achieve maximum nutrient use efficiency from their plants.
This is not only best for the farmer’s bottom line, but is also good for the environment. Nutrient leaching from fields can be a source of pollution to surface waters, causing eutrophication. As farmers, we realize our role as stewards of the environment, and are constantly striving to apply less fertilizer in very accurate quantities, so that the plant can easily access it. This way, we can ensure the nutrients end up in the crop – and not lost to the environment.
Many farmers are also switching to no-till systems, in which the soil is left undisturbed between the planting of subsequent crops. In this way, the soil surface stays protected by the residues left over from the previous crop. By protecting the surface, the soil is at significantly lower risk of erosion, which can quickly cause the loss of valuable topsoil and large amounts of nutrients. This is another method by which farmers are reducing the loss of nutrients and maintaining better soil quality.
The careful management of soil nutrients is just one small aspect of the work that farmers do to manage their soils. With well-managed fertilizer application, farmers not only achieve great yielding, high quality produce, but also do their part to keep the environment around their farms clean and healthy.
Inside Farming is a series of articles written by Canadian Agricultural Communicators of Tomorrow members at the University of Guelph