Cadmium is not considered a micronutrient, but is present in a wide range of vegetation, with an average concentration of 0.05 ppm (mg/kg). Depending on the species, the level of cadmium may vary. Plants have the capacity to accumulate cadmium due its bioavailability properties. Most plants can exclude toxic concentrations of cadmium by retaining it in roots or by other means. However, this does not apply to all vegetation, thus, tests should be performed to ensure that cadmium levels are within acceptable limits. The Maximum Permitted Concentration (MPC) of cadmium in the root, tuber, and leafy vegetables is 0.1 ppm of fresh weight (Australia). Cadmium can be found in phosphorus-containing fertilisers, phosphogypsum by-products, some zinc additives, biosolids (sewage sludges), manures and other organic wastes. High levels (up to 160 ppm) of cadmium strongly affect phosphorus metabolism, which is responsible for efficient plant growth, more specifically for cell division and development of new tissue. The addition of zinc to soil may reduce cadmium uptake by plants, however, this does not occur in all plant species. In sandy and acidic soils with low organic content, cadmium availability for plants is increased. The addition of lime, organic content, and more frequent irrigation may help to reduce cadmium concentration in crops. Analytical methods for cadmium content are similar to those for the lead, and can be seen here.