Deanna Németh, Horticulture Sustainability Specialist

Although the past week brought some much needed rain, many locations in Ontario were experiencing prolonged dry soil conditions.  These extended periods of very dry soil conditions can reduce Nitrogen (N), Phosphorus (P) and Potassium (K) availability to plants.   

Nitrogen

For N, low soil moisture decreases soil microbe activity. Microbes play an important role in breaking down organic matter and converting organic N to inorganic nitrate nitrogen, a process called mineralization. In dry soils with low N mineralization, there could be less plant available N in the form of either ammonium (NH₄⁺-N) or nitrate (NO₃^–-N) nitrogen.  In dry soils, the risk of NO₃^–-N loss through leaching or denitrification is reduced.  While this means there is more soil N available to crops, plant uptake can be reduced.  When the rains return there a can be…