Tip of the Day: Salt buildup and EC problems Salt buildup appears as white or off-white crystalline crusts or residues on the surface of growing media and sometimes on the base of plant stems, where it can cause salt burn damage. Certain types of media are more prone to this nutrient problem than others—for example, those with porous structures and high rates of water loss are more prone to salt crusting than others. Expanded clay granules and similar media often develop a whitish coating on the surface after a few months use, and this can be common in ebb-and-flow systems. Media beds covered with plastic film—as in the case of rockwool slabs—rarely develop these salt deposits on the surface, as the film prevents excessive moisture loss from the media. Salt buildup occurs when a media, which has been thoroughly wetted with nutrient solution containing dissolved salts, loses moisture to evaporation faster than the minerals are taken up by the plant’s root system. In this case, the moisture is lost to the atmosphere and the minerals stay behind, thus increasing the EC in the media and around the roots. This salt buildup in the root zone can cause damage both through direct contact with the salt crystals around the delicate plant stem, particularly in seedlings, and by increasing the osmotic pressure around the plant roots. Luckily, salt buildup is easily dealt with once growers recognize the symptoms: white crusting is the first sign, as is plant growth becoming stunted, dark, hard and unusually slow. As salt accumulation becomes more severe, the stem area at the base of the plant and roots can be burnt and die back, resulting in wilting during the warmer times of day and, later, disease attack in these areas. Regular monitoring of the EC of the nutrient solution draining from the media helps prevent and diagnose salt accumulation problems. Ideally the EC of the feed solution should not increase as it flows through the root system. If the EC is increasing as its flows through the root system and out the base of the growing container, then salt buildup is likely to occur. However, even plants fed a low EC solution can develop salt accumulation where the atmosphere is dry and high rates of water loss from a porous media occur. In this case, the media will benefit from some leaching from time to time and a thorough clean between crops (or even replacement in severe cases). Some growers prefer to leach excess salts from growing media using plain water; however, this can have negative effects when an actively growing crop is present, as the sudden drop in osmotic pressure in the root zone triggers a large influx of moisture into the root cells, which can result in fruit splitting and soft, weak vegetative growth. Flushing growing media with either a specifically designed flushing solution like Canna Flush or a nutrient one-third to one quater its regular strength is recommended to remove excess salts from the root zone. Carrying this process out every few weeks might be required in certain hydroponic systems, such as shallow flood-and-drain or tray systems in warm climates or summers with high evapotranspiration rates, and often between crops if media is to be reused #Cambridge #CherryHinton #Histon #Hardwick #Cambourne #Haverhill #Ely #Greenfingers #Luton #Bedford #Hitchin #London #GrowYourOwn #Newmarket #Horticulture #Hydroponic #GrowShop indoor-botanics.co.uk/nutrients/314-Advanced-final-phase.html
Posted on: Thu, 22 Aug 2013 10:10:53 +0000
Trending Topics
Recently Viewed Topics
© 2015