Crops need nutrients to make them grow strong and healthy, just like humans. Each nutrient plays a different, but important role in crop growth and development. If crops do not receive the nutrients they need, the result could be weak crop growth and low yield.
Nutrients do exist in the soil, but as the plants grow they use the nutrients up. Farmers need to apply new nutrients every year to replenish the soil. Farmers test their soil to know which nutrients they are low in.
There are four main crop nutrients:
All plants need nitrogen, phosphorus, potassium, and sulfur to grow healthy and strong.
NitrogenNitrogen (N) is the most important nutrient for crop growth and development. Plants need nitrogen to:
- help their cells and tissues grow
- turn energy from the sun into food (called photosynthesis)
- grow strong and healthy and be nutritious to eat after harvesting
This pea plant has pea nodules on its roots.
- Solid (small granules) or manure
- Gas (called anhydrous ammonia)
This farmer is seeding with an air drill. The red tank has seed and some granular fertilizer and the white tank has liquid nitrogen fertilizer.
Phosphorus (P) comes from ancient sea life. All living organisms require phosphorus, especially plants. Plants need phosphorus to:
- Help the plant grow healthy roots
- Store and transport nutrients throughout the plant
- Grow normally and produce fruit/seeds at the right time
- Resist disease (because all the plant parts are well developed)
- Convert energy from the sun into food (photosynthesis)
- Help pulse crops fixate nitrogen (turn nitrogen from the air into a useable form)
If there is not enough phosphorus, the crop will have reduced growth, weak roots, thin shoots, and dark leaves. Too much phosphorus does not harm plants, but will cause it to be lacking in other nutrients.
Potassium (K) or Potash comes from evaporated oceans. Potassium is needed by plants to:
- protect plants from diseases by strengthening their root system
- make plants more resistant to the cold and droughts
- help the plant to soak up water efficiently
- help cycle nutrients through leaves, roots, and stems
A lack of potassium will cause reduced growth and yellowing and dead spots on the leaves. Too much potassium is not toxic for plants, but can affect how much of other important nutrients the plant can absorb.
This is a potash mine in Rocanville, SK.
Saskatchewan has the largest potash industry in the world! We have about 45% of the world’s potash. Potash is mined here and sold to countries all around the world. Because most of the soil in Saskatchewan has high levels of potassium, farmers don’t need to add very much to the soil.
Sulfur (or Sulphur)
Sulfur comes from fossil hydrocarbons which are often found in areas with high volcanic activity. Sulfur is sometimes called the 4th essential nutrient and is very important for plant growth. Plants need sulfur to:
- Help to make the building blocks of proteins
- Turn the energy from the sun into food, which is called photosynthesis
- Make oil
- Use nitrogen best
- Produce healthy flowers
- Grow healthy roots and nodules
Sulfur is a bright yellow crystal in its natural state.
Oilseed crops, forage crops, and legume crops require more sulfur than other crops such as wheat, barley, or oats.
Plants absorb sulfur from the soil with their roots. Sulfur does not move throughout the plant, so plants need constant access to it throughout the growing season from the time the plant starts to grow, to flowering, to maturity.
These legume crops all require more sulfur than many other crops.
These oilseeds crops all require more sulfur than many other crops.
Crops require just 10% as much sulfur as they do nitrogen. If there is not enough sulfur, plants will have short or thin steams, yellow new leaves, delayed and longer flowering, small pods, and reduced yield.
Sulfur and nitrogen work together and a careful balance of both is needed to produce the healthiest crops.
Sulfur helps the plant to be more resistant to the cold, which gives it some frost tolerance.
4-R Nutrient StewardshipThe goal of fertilizing crops is to increase the crop’s production, increase profits, protect the environment, and improve sustainability. Farmers are not just trying to grow good crops, they also have a responsibility to take care of the land and water.
All plants need the right nutrients, at the right rate, at the right time, and at the right place.
If too much fertilizer is added at the wrong time, then the unused fertilizer can go into the soil and eventually into rivers and lakes. Different crops have different nutrient needs. Different crops grow differently, and they also have different root systems so they cannot absorb the same amount of moisture from the soil.
To be good stewards of the land, farmers follow the 4-R Nutrient Stewardship Guidelines.
What are the 4Rs?