Soil Management

Nutrient Deficiency Symptoms… Don’t Wait Until You See Them

eKonomics News Team

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An International Plant Nutrition Institute (IPNI) article detailing the importance of paying close attention to a variety of plant nutrition indicators – although visual nutrient deficiency cues are useful, they should not be used as the sole diagnostic tool.

Symptoms of plant nutrient deficiency begin to appear when one of the essential nutrients is lacking. Sometimes deficiencies appear early in the growing season when soils are cold or wet, and when root activity is low. Deficiencies are also commonly observed later in the season when the soil cannot satisfy the high nutrient demand of a rapidly growing crop. Whether the deficiency is caused by poor root uptake or the low nutrient-supplying power of the soil, proper management practices can help alleviate these problems.

Deficient plants do not initially show any obvious symptoms of nutrient shortage other than slower growth, which can also be due to many factors. In the case of a mild deficiency, plants may never show visual symptoms beyond slow growth and reduced yield. For this reason, it is important to pay close attention to a variety of plant nutrition indicators.

Nutrient deficiency causes a disruption in any number of essential metabolic processes within the plant. Crops mature unevenly because deficiencies rarely occur uniformly across entire fields. This leads to lower yield, harvesting difficulties and lower crop quality. And, as mentioned, this can all occur without diagnostic symptoms appearing.

When deficiency symptoms become noticeable, severe stress is already occurring and steps should be taken to overcome the problem if practical. Knowing which nutrients are mobile or immobile within the plant will help pinpoint the cause of the deficiency. Diagnosing symptoms also requires an understanding of specific crop colors and markers, but it is worth noting that some crops are more susceptible to visible symptoms than others.

Pre-season soil testing should be part of a strategy for preventing nutrient shortages. In addition to helping avoid plant stress, a soil analysis allows decisions to be made to avoid over- or under-application of fertilizer, which can result in economic inefficiencies.

Once plants begin to grow, a useful tactic for diagnosing specific nutrient deficiencies is plant analysis (tissue testing). It is best to compare nutrient concentrations in deficient plants growing in problem areas with healthy plants to identify the differences between the two. It is also helpful to collect soil samples for analysis from the two areas at the same time the plant samples are collected.

Tissue testing is also valuable for monitoring plant health during the season to verify that nutrient concentrations do not drop below nor exceed established critical values. Guidelines have been developed for many crops on what the appropriate nutrient concentrations should be during various growth stages. Supplemental fertilization should be considered if the concentrations fall below these established thresholds.

While visual symptoms are often a convenient and cost-effective way to identify nutrient deficiencies, it is important to be aware of other techniques to identify deficiencies. When nutrient deficiency symptoms appear, first act quickly to diagnose the problem and then make plans to correct it and to avoid having a reoccurrence in the future.

The International Plant Nutrition Institute (IPNI) has a large database of nutrient deficiency images that is continually updated. Visit the website at: http://media.ipni.net.