Micronutrients Status Assessment in Three Representative Locations in Ethiopia

Though needed in very small quantities, micronutrients are as important as primary and/or secondary nutrients in yield-formation and in enhancing crop-quality. Twenty four field experiments (18 sulfur response; and six sulfur rate determination), therefore, were conducted to evaluate the micronutrients fertility of soils in three locations in central Ethiopia, during 2013-16. In doing so, 54 surface soil samples (24 before planting; and 30 after wheat harvest) were analysed using standard laboratory (Lab) methods. Some soil and crop yield variables were subjected to SAS statistical analysis. The results showed that iron, zinc, boron and molybdenum were low; whereas cupper and manganese were adequate in most studied soils. Among others, lack of nutrient recycling was the major cause for the observed micronutrients deficiency. Soil factors such as pH, organic carbon, CaCO3 and parent material also have contributed to the low fertility of micronutrients vis-à-vis their contents in soils. Therefore, strategies involving soil enhancement by seed treatment or the use of organic amendments of different sources can be adopted to sustain optimum crop-yields and quality. Hence, in addition to the previous recommendations on sulfur, the deficient micronutrients need to be included in the balanced fertiliser formulas, if soil-test, plant-tissue analysis and/or crop-responses data are available. It is well recognised that, micronutrients application to soils is not economical in large scale productions, possibly due to the different losses in relation to their small quantities to be applied. Furthermore, the deficiencies of elements like zinc and iron can be acute when alkaline soils like that of East-Shewa are brought under irrigation. Because of such problems, and adverse reactions, the use of special protective complexes (chelates), and direct application of the micronutrients to plant-foliage via foliar sprays or fertigation may be recommended. In some cases, food enhancement of the deficient micronutrients can also be adopted.