101 Questions answered
Why Crops Struggle to Thrive
Calcareous soils contain lime and if a soil has more than 5–10% limestone in the surface layers, the pH will be 8 and above in water or between 7.5-7.8pHCa.
The main reason crops struggle in calcareous soil is because the alkaline pH affects nutrient availability. As pH increases, phosphorus and trace elements(iron, manganese, copper and zinc) can become less available, while boron can become toxic. Most dryland cereals don’t like boron levels > 10-15 mg/kg.
Phosphorus nutrition is a particular issue on calcareous soils because phosphorus fertilisers quickly become bound in the soil and unavailable for crop use.
The alkaline soil pH often goes hand in hand with other issues, including salinity and high levels of sodium. Rhizoctonia also like the alkaline pH,leading to a higher disease burden. This is partly due to the inability of crops to overcome the disease which leaves them vulnerable due to poor nutrition.
