# Phosphorus Dynamics in the Soil-Plant-Environment Relationship in Cropping Systems: A Review
###### Abstract
This is due to a reduction of the chlorophyll biosynthesis and to a higher production of pigments such as anthocyanins [29; 30]. Soluble P is transported through the xylem to all growth points, depending on P concentration, which is located within the adequate range of 0.1-0.3 g P kg\({}^{-1}\) for most crops (grasses and agro-industrial crops, including fruit, legumes, and others) [31]. Figure 1: Phosphorus cycle and N fixation process in the plant–soil–environment system. Although P is important for crops, its dynamics are involved in relationships with other elements. Since P is a macronutrient that limits primary production in many ecosystems, the removal of C from the atmosphere may require large amounts of P. [PERSON] [32] showed that the storage of organic C in mineral soils sequesters large amounts of P. The reasons for the strong enrichment of organic P in soils are mineralization of organic C and formation of microbial necromass rich in P, as well as the strong sorption of organic P to mineral surfaces that prevent its mineralization. The deficiency of supply and availability of phosphorus remains a severe limitation in biological nitrogen fixation and symbiotic interactions. This requirement may be higher than for the growth of roots or shoots of the host plant. There are marked differences in the requirements of plants and rhizobia for P [33], with slow-growing ones more tolerant to low levels of P than fast-growing rhizobia [34]. The nodules themselves are strong sinks of P [35], and nodulation and N\({}_{2}\) fixation are strongly influenced by the availability of P [36]. The phagatized fertilizers most used for agriculture are water soluble and neutral ammonium citrate soluble or citric acid soluble phosphates [37; 38; 39]. Simple superphosphates (SSP), triple superphosphates (TSP), monoammonium phosphate (MAP), and diammonium phosphate (DAP), apart from being used in traditional ways, are the most soluble P sources and the ones that provide the highest efficiency for crops, although they are also the ones that contribute most to environmental pollution. These fertilizers are costly, as their production demands require a high amount of energy, apart from requiring other elements to be soluble, such as sulphuric and nitric acid (imported raw material, which increases the selling price of the product even more). Hence, research is needed on phosphoratized controlled-release fertilizers which can minimize the losses outside the crop in the environment and improve the agronomical effectiveness of the fertilizer use [40; 41]. In this context, materials such as biochar are being tested [42], or others with water-soluble P coatings with an insoluble layer, which creates a physical barrier to slow down the release rate of P. The polymers applied include graphene oxide, a nanomaterial which is being studied as a middle-term P carrier for the crops [43; 44]. This review seeks to explain P dynamics in an agronomic context, evaluating the soil, plant, and environment nexus, while assessing the effects of climate change on P availability in cropping systems and identifying agricultural practices that aim to find the best trade-off between crop productivity and environmental sustainability.