Nutrient Deficiency

• Visual Symptoms: A Handy Tool in Identifying Nutrient Deficiency in Corn, Cotton and Soybean. 2021. Adotey N., A.M. McClure, T.B. Raper, and R. Florence. Extension Publication, W976.
• Reference Sufficiency Ranges for Plant Analysis in Southern Region of the United States. 2013. Campbell, R.A. Southern Cooperative Series Bulletin #394. NC Dept. of Agriculture and Consumer, Raleigh, NC.

• Visual Symptoms: A Handy Tool in Identifying Nutrient Deficiency in Row Crops. 2020. Adotey, N. A.M. McClure, and T.B. Raper. UTCrops News Blog.

Plants require balanced nutrition for optimal plat growth and development. Plants respond to malnutrition by showing visual symptoms. Generally, a nutrient deficiency occurs as a result of low soil nutrient levels. However, prevailing environmental conditions, soil properties, growth conditions and root diseases may restrict nutrient uptake and induce deficiencies in crops even if soil nutrient levels are estimated sufficient for optimum yield. For example, low or high soil pH, soil compaction and excessively wet or dry soil may prevent nutrient uptake. A handy diagnostic tool to identify nutrient deficiency in crops is via visual observation of symptoms. However, this tool may not always provide a definite diagnosis of the nutrient status of the plant. To address this, visual symptoms should be corroborated with plant tissue and soil testing, and examination of the history of nutrient applications to the field. Adequate knowledge of visual symptoms and tissue testing may help guide
corrective actions in-season or preventive action in the following season to avoid yield loss.

Knowledge of the nutrient deficiency symptoms and underlying causes can play important roles in diagnosing problems in the field. In diagnosing a nutrient deficiency symptoms, the following  important questions should be addressed; (1) Is this a nutrient deficiency problem? (2) Where does the symptoms appear first? and (3) What is the form of the symptoms?

Is this a nutrient deficiency problem? Pattern or lack of pattern on the crop or within the field provides an indication if the symptom is a nutritional deficiency or other factors. If there is lack of pattern on the leaves or the crop or within the field, the symptom is usually due to an insect or disease. The symptoms may have a path but not a pattern.  Nutrient deficiency symptoms have a pattern on the leaves, or the plant or within the field. In the field, these symptoms may occur in irregular (often related to soil conditions) or regular  patterns ( often related to cultural practices). When the leaves of affected plants are folded down the middle like a book, the pattern of symptoms should match up as shown below (Yes).

Where does the symptoms appear first? Where the symptomology occurs on the plant depends on the mobility of the nutrient within the plant (Figure 1). Plant nutrients can be classified as mobile or immobile within the plant. Mobile nutrients such as N, P, K and Mg can be translocated from the older leaves to the developing plant parts. Hence, deficiency symptoms tend to show on older, lower leaves. On the other hand, immobile nutrients like Calcium (Ca), Sulfur (S), and most micronutrients have limited mobility within plants and deficiency symptoms occur in younger, upper leaves.

What is the form of the symptoms? Symptoms associated with deficiency may take several forms including chlorosis, necrosis, and abnormal growth. Chlorosis occurs when the production of chlorophyll is reduced which results in a yellow to pale green leaf color. Nitrogen (N), magnesium (Mg), sulfur (S), and iron (Fe) are nutrients that play important roles in chlorophyll production and function; hence, their deficiencies tend to cause chlorosis. Necrosis is when the plant tissue dies. Necrosis is commonly associated with N, phosphorus (P), and potassium (K) deficiencies. Abnormal growth occurs when inadequate amounts of a nutrient in the plant restrict cell elongation and replication resulting in stunted growth, deformation or crinkled leaves.

An easy way to identify nutrient deficiency is to employ a similar approach as the dichotomous key approach. The dichotomous key consist of two contrasting question which will provide a stepwise guide towards identifying each entity. Below is a figure using dichotomous key to identify symptoms on the bottom of the plant as well as the top of a soybean plant.

Tissue testing is a management tool to diagnose nutrient deficiency and monitor the nutritional status of crops. Based on this testing, timely corrective in-season or preventive action in subsequent season can be taken to improve the crop’s nutrient status and productivity. The most commonly used method for interpreting tissue testing in soybeans is the sufficiency ranges. UT’s tissue analysis recommendations are based on SERA-IEG-6 publication titled “Reference sufficiency ranges for plant analysis in the Southern Region of the United States”.