The application of mineral and organic phosphorus fertilizers to arable land has greatly increased crop yield to meet the world food demand. On the other hand, impurities in these fertilizers, such as heavy metals, are being added to agricultural soils, resulting both from the raw materials themselves and the processes used to obtain the final product. Cadmium, a non-essential and toxic heavy metal, has been found in relatively high amounts in common P fertilizers obtained from sediments. This metal poses a high risk for soil fertility, crop cultivation, and plants in general. Furthermore, human health might be compromised by the cadmium concentrations in agricultural and livestock products, due to the bioaccumulation effect in the food web. The accumulation in the different matrixes is the result of the high mobility and flexible availability of this harmful metal. This review summarizes risks to human health, the factors influencing cadmium movement in soils and crop uptake, as well as common plant responses to its toxicity. In addition, it summarizes cadmium balances in soils, trends, long-term experiments, and further studies. Cadmium inputs and outputs in arable soil, together with their calculated concentrations, are compared between two different regions: the European countries (in particular Germany) and China. The comparison appears useful because of the different proportions in the inputs and outputs of cadmium, and the diverse geographical, environmental and social factors. Moreover, these variables and their influences on cadmium contamination improve the understanding of the pollution from phosphate fertilizers and will help to establish future mitigation policies.
The current study focuses on yield and nutritional quality changes of wheat grain over the last 166 years. It is based on wheat grain quality analyses carried out on samples collected between 1850 and 2016. Samples were obtained from the Broadbalk Continuous Wheat Experiment (UK) and from herbaria from 16 different countries around the world. Our study showed that, together with an increase in carbohydrate content, an impoverishment of mineral composition and protein content occurred. The imbalance in carbohydrate/protein content was specially marked after the 1960’s, coinciding with strong increases in ambient [CO2] and temperature and the introduction of progressively shorter straw varieties. The implications of altered crop physiology are discussed.
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