Protect Crop Yields in a Dry Finish

7/09/2007 4:44:29 PM

Get the maximum crop yields from the available soil moisture by maintaining good potassium levels – check with a leaf tissue test now.

 

Potassium plays a unique role in plant development and yield formation and it is particularly important in dry conditions because it is responsible for the stomatal cell turgor which regulates water movement in plants.

 

This season at APAL we have already seen samples from a range of crops showing significant K deficiency and these crops will never reach their yield potential without intervention with a foliar spray.

 

Plants lacking adequate potassium will wilt quickly due to inadequate control of stomatal opening and closing – the plants leak water vapour, wasting valuable soil moisture.  Under drought stress, the rate of photosynthesis will also decrease with a reduction in carbon fixation and a depression in growth.

 

There have been remarkable yield increases reported in a range of annual crops after potassium is applied to deficient crops when soil moisture is limiting.  In some areas K has been called “Clayton’s irrigation”!

 

Keep in mind that as soil moisture decreases, it becomes increasingly difficult for plants to extract potassium from the soil, even though soil levels would normally be regarded as adequate.  In dry conditions there is often a spacial K deficiency at the root surface. This season it is occuring at a time when the plant’s demand for K is the greatest – just before flowering and grain set.  Soil K concentration would need to increase as the soil dries out to maintain a constant K uptake.

 

At the current critical stage of crop development, potassium can be cost effectively applied as a foliar spray using materials like sulphate of potash or commercial foliar mixes.

 

Be aware that saline soil will compound the problem because sodium accumulates at the root surface as soil moisture declines. The sodium presents a barrier to the uptake of potassium unless plants have a high selectivity for K.  Always ensure that crops have an adequate potassium supply when growing on saline soils - regular foliars are very effective.

 

Contact APAL for more information