The Potash Development Association (PDA) has highlighted the importance of getting both soil structure and chemistry right now, when it comes to determining crop establishment rates and the final yields delivered by winter cereals.
Soils should be well structured, with any compaction issues caused over the previous 12 months, or created during harvest of the previous crop, rectified.
This will allow unimpeded root growth and maximum soil exploration for roots to capture nutrients and water. Alongside this, the soil chemistry should be optimal for growth - soils at a neutral pH.
Soil indices in crop establishment
Soil indices should be at the target levels for the crops being grown: P index 2 and K index 2 for combinable crops.
The aim of this is to ensure there is sufficient availability of nutrition for the establishing crops and their small root systems, as well as providing the required amounts of nutrients at the appropriate times for the crop through the full season.
When it comes to establishment and nutrition, phosphate is one of the first nutrients that comes to mind.
Its lack of mobility in the soil, combined with the small root systems of emerging seedlings, means soils need to be at the target index to ensure sufficient quantities can be obtained by plants.
Phosphate at this timing is involved in root growth and development.
Phosphate deficiency will lead to a reduction in the formation of lateral roots and an inhibition of root elongation.
Sufficient quantities are therefore required to improve rooting, which will enable access to more nutrients and water.
Importance of rooting
Rooting in the autumn is important for improved nutrient and water uptake through the season, with every centimetre of root touching an extra 130t of soil over a hectare.
A plant with a good root mass going into winter will be much healthier and better protected against cold weather over winter, and drought stress in the spring.
Potassium is also required by plants in the autumn to improve their cold tolerance and the survival of plants exposed to various biotic and abiotic stresses.
Cold stress can destroy photosynthetic processes, inhibiting plant growth and development, resulting in lower crop productivity.
At the extreme, it can lead to the failure of cell membranes and cell death when the water inside the cell freezes. Plants improve their cold hardiness by increasing their resistance to intracellar freezing.
High potassium concentrations in plants help to protect against freezing by lowering the cell solution’s freezing point.
This leads to reduced cold damage and increased cold resistance, ultimately increasing yield production.
Frost damage in potassium deficient plants can also be related to water deficiency from the chilling-induced inhibition of water uptake and freezing-induced cellular dehydration.
Increased evidence has shown that crop production is significantly restricted by biotic stresses.
Previous estimates have calculated that weeds produce the highest potential productivity loss (32%), followed by animal pests (18%), fungi and bacteria (15%) and viruses (3%).
Potassium nutrition has been widely reported to decrease insect infestation and disease incidence in many host plants.
From 2,500 references it was found that the application of potassium significantly decreased the incidence of fungal diseases by 70%, bacteria by 69%, insects and mites by 63%, viruses by 41% and nematodes by 33%.