Molybdenum in soil-plant system: bioavailability, dynamics and implications for sustainable crop production

Soil contains a wide range of elements, but only 17 have qualified as essential for plant nutrition. Among these, molybdenum (Mo) stands out as the least abundant micronutrient in plant tissues. Despite its minimal requirement, Mo plays a crucial role in plant metabolism. Average concentration of Mo in the earth crust is approximately 0.6 mg kg−1, while its content in healthy plant generally falls within the range of 0.2 to 2 mg kg−1. Under Mo stressed conditions, several physiological processes are disrupted in plants, resulting in impaired reproductive stage. However, when Mo concentrations exceed the critical range, it causes toxicity, and ultimately reduce crop yield. Beyond plant health, Mo is equally essential for animal and human metabolism. Its deficiency in humans has been linked to neurological disorders, as well as physiological conditions. Similarly in livestock, Mo toxicity (known as molybdenosis) occurs when cattle consume Mo-rich forages, disrupting copper metabolism. Given its essential role in both plant and animal systems, regulating Mo bioavailability is crucial for optimizing crop productivity while safeguarding human and livestock health. A better understanding of Mo dynamics through soil-plant systems can help to assess the optimum availability and manage its deficiency or toxicity. Bioavailability of Mo in soil-plant systems is governed by various factors, including soil pH, parent material, organic matter content, and adsorption-desorption mechanism. Unlike most micronutrients that are more abundant in acidic soils, Mo availability increases under alkaline conditions. It can be concluded that optimal Mo levels are essential for crop productivity, as deficiencies disrupt nutrient balance while excess leads to toxicity. Soil properties, particularly pH, strongly influence Mo availability, with alkaline soils enhance its uptake. Proper Mo supplementation improves nutrient metabolism and yield, but balanced fertilization is crucial to avoid adverse effects on productivity.