The importance of crop establishment cannot be stressed enough. It is the most critical period within all tillage life-cycles, as it is the time when the yield potential is set.
All challenges crops face during the season serves to reduce the final yield from this potential.
Therefore, any management decisions taken from this point onwards, only helps to limit the reduction in this yield potential.
The autumn season of this year has proved a challenging time for many growers across the country, as a result of poor weather conditions.
Very little can be done about the vast quantities of excess rainfall that have led to flooding in some parts.
However, not all moisture issues this autumn can be attributed to this. In some areas, water can clearly be seen on the surface of fields, as a result of soil compaction issues.
Compaction can be a hidden reason behind the plateauing of crop yields on farm.
According to the Potash Development Association (PDA), compacted soils will restrict root growth – reducing their ability to explore the soil, and to capture sufficient nutrients and water.
Where root growth is restricted, even soils at the target levels for phosphate and potash, may not be able to supply the total rate of nutrient required by the crop during times of peak uptake in the spring.
Crop establishment and waterlogging
Yield losses due to waterlogging may vary between 15% and 80%, depending on the crop species and growth stage, soil type and duration of the stress – resulting in severe economic penalties.
Waterlogging is known to block the oxygen supply to the roots, inhibiting root respiration, resulting in a severe decline in energy status of root cells.
This can affect some important metabolic processes of plants; including stomatal conductance, rate of photosynthesis and root hydraulic conductivity – decreasing their ability to take up most essential nutrients that are positively charged.
However, soils with a good potassium status have been shown to effectively reduce the adverse effects of waterlogging on plants.
Plants show not only increased growth and photosynthetic rate, but also improved nutrient uptake.
Cereal crops need at least as much, if not more, potash than any other nutrient, including nitrogen.
Potash use
Potash is needed in such large amounts because it is the major regulator of solution concentrations throughout the plant.
It controls cell sap content to maintain the turgor of the plant, and supports the movement of all materials within the plant.
Potash supply is, therefore, essential for all nutrient uptake by the roots and movement to the leaves for photosynthesis, and for the distribution of sugars and proteins made by the green tissue for plant growth and grain fill.
