Proper storage management is critical to be benefited from the work and costs associated with producing a potato crop. Managing the storage as intensely as the field is necessary to obtain maximum output for better results, keep the following points in mind during the storage season. Common images of the "couch potato" as an inert immovable and most important inactive object are certainly at odds with real potatoes in storage. Real potatoes in storage are quite active and are home for many living, active organisms.
Holding a potato in your hand, one may never guess that on top of and beneath its skin is a miniature world teeming with biochemical activity. Cells of the potato were under going chemical changes they need to stay alive -especially consuming water and converting the stored reserves of carbohydrates and other compounds built up while the plant was alive into energy.
The potato is also home to living micro-organisms also needing food and water. Some of these microorganisms, of course, regularly "consume" potato flesh.
One of the most important activity in potato growing and selling is to manage the freshness of potatoes in the storage so that when it is time to sell the crop, the potatoes are in a of shape that brings the highest return. This is done primarily through the manipulation of three aspects of the storage atmosphere, cool storage humidity, ventilation.
Even the most carefully harvested crops suffer some damage during the process. Allowing tubers to complete built-in curing processes soon after harvest is part of successful long-term storage management.
Maintaining the appropriate storage temperature once the crop is cured is critical. The fact that biochemical activity is faster at warmer temperatures is a natural law. The biochemical activity taking place in a potato is not necessarily grower-friendly.
Starch being converted to reducing sugars and the gradual breaking of dormancy put the grower and crop on the clock as quality can be maintained only for such period. Lengthening this period by keeping the crop at the correct temperature is the key. Ideal temperatures for long-term storage often vary by variety and market. Generally, temperatures should remain at 38-40oF for fresh market and seed crops and 45-55oF for processing crops (exact temperature will depend on variety, and estimated ship date).
Regardless of the holding temperature, the pile temperature should not vary by more than 3F top-to bottom.
Potatoes have ways to store water. Indeed, potatoes may exceed 90 percent by weight due to water storage. So, in this case, more water in the potatoes often means more money in the growers pocket. A storage that is too dry literally pulls water out of potatoes, blowing profit potential out the ventilation system and increasing the occurrence of pressure bruising. A storage that is too wet promotes condensation, thereby favouring bacterial soft rot.
The storage's relative humidity (RH) is strongly tied to its temperature (especially of incoming air) as small changes in temperature create larger changes in relative humidity.
For example, increasing the temperature of a water-saturated (100 percent RH) volume of air at 40oF to 45oF lowers its RH to nearly 80 percent. Relative humidity in a potato storage should remain 94 percent to 98 percent. At present, this is usually best accomplished by maintaining the desired temperature in the storage rather than through operating the humidification system.
Like us, potatoes soon perish without an adequate supply of fresh, oxygenated air. Normal biochemical activity tends to promote the consumption of oxygen and build up of carbon dioxide. Unless given fresh air frequently, the storage will become warm, it lack oxygen, and fill with carbon dioxide. Of course, carbon dioxide rarely builds to lethal levels in an entire storage.
More often, anoxic (oxygen-deficient) pockets develop and tuber quality in a portion of the storage is reduced. Anoxia changes tuber chemistry negatively and promotes the growth of anaerobic microor-ganisms, thereby promoting the development of "hot spots" or "meltdowns" caused by decaying tubers.
Therefore, ventilate frequently and ensure that the entire storage is receiving an adequate supply of fresh air. While supplying fresh air, keep in mind that its temperature and water content relative to the pile's temperature will either raise or lower storage relative humidity (RH).
Water-filled air colder than the pile will actually drop storage RH while water-filled air warmer than the pile will raise storage RH and possibly lead to undesirable condensation.
Good crops can go bad in storage in relatively little time. Watch the storage and stay informed of the conditions inside it, making adjustments if necessary. This requires more than looking from the back window of the house or seat of the pickup to make sure the green and not the red light is on or dialing up the storage's computer. Electronic systems are excellent but there is no substitute for checking storage and crop conditions directly.
Check equipment and look for leaks in the roof, sagging parts of the pile, condensation, etc.
If you have put a good crop into storage, how will you manage it until you made shipment, will influence the bottom line. The figure above depicts why sugars made during the growing season are stored in the potatoes. Normal living processes convert these sugars into by-products which must be removed from the storage. These processes proceed faster at warmer temperatures.
Two important points should be taken under consideration. First, the amount of sugar and water (profit potential) going into storage is fixed at harvest. Second, remove the by-products of the conversion because it reduces tuber quality and weight. Therefore, profit largely depends o storage management.
Courtesy Hortimag
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