Soil Analysis

Soil analysis is often used to determine whether the supply of a particular nutrient might limit plant growth. However, soil analysis for predicting Fe deficiency in plants cannot be recommended. Soil analysis to determine Fe availability is confounded by soil environmental factors such as pH, moisture content, temperature, and bicarbonate concentration, and the genetic variability within and between plant species with respect to Fe uptake. Several methods have been devised to extract Fe from soil, the most commonly used being the diethylenetriaminepentaacetic acid (DTPA) extraction method. The critical range for Fe for this test is 2.5–4.5 ppm. If the soil contains less than 2.5 ppm, it is considered deficient in Fe. However, even if soils are sufficient in Fe, this does not mean that the plant will not suffer Fe chlorosis. The uptake of Fe by plants depends on many other factors besides extractable Fe in the soil. These factors are discussed below.