Phosphorus leaching from riparian soils with differing management histories under three grass species

Abstract

Plants release carbon‐based exudates from their roots into the rhizosphere to increase phosphorus (P) supply to the soil solution. However, if more P than required is brought into solution, additional P could be available for leaching from riparian soils. To investigate this further, soil columns containing a riparian arable and buffer strip soil, which differed in organic matter contents, were sown with three common agricultural and riparian grass species. The P loads in leachate were measured and compared with those from unplanted columns, which were 0.17 ± 0.01 and 0.89 ± 0.04 mg kg−1 for the arable and buffer strip soil, respectively. A mixture of ryegrass and red fescue significantly (p ≤ .05) increased dissolved inorganic P loads in leachate from the arable (0.23 ± 0.01 mg kg−1) and buffer strip soil (1.06 ± 0.05 mg kg−1), whereas barley significantly reduced P leaching from the buffer strip soil (0.53 ± 0.08 mg kg−1). This was dependent on the dissolved organic C released under different plant species and on interactions with soil management history and biogeochemical conditions, rather than on plant uptake of P and accumulation into biomass. This suggested that the amount and forms of P present in the soil and the ability of the plants to mobilize them could be key factors in determining how plants affect leaching of soil P. Selecting grass species for different stages of buffer strip development, basing species selection on root physiological traits, and correcting soil nutrient stoichiometry in riparian soils through vegetative mining could help to lower this contribution.

Effects of Adding Native Annual Seeds to South Korea Native Perennial Seed Mixture on Early Stage Vegetation Recovery, Soil Enzymes, and Nutrient Dynamics in Post-Fire Soils

“…Plant roots are pivotal in soil nutrient cycling [64]. Nitrogen uptake by plants is typically faster than other nutrients, hence leaching often reduced for nitrogen more than phosphorus [65,66]. The wildfire might have led to nitrogen being leached from the Control and taken up by plants in the treated pots.…”

Comparison of soil phosphorus index systems for grassland in the cross‐border region of Ireland#

“…This suggests that shallower sampling (as per NI regulations) will result in greater estimation of soil P content. From an agronomic perspective, shallow sampling may not be wholly representative of P reserves which are available for plant use, depending on root characteristics (Gahoonia & Nielsen, 2004; Roberts et al., 2020). However, in a grassland the majority of the root mass is within the top 7.5 cm of the soil profile, and this forms the reasoning behind the shallower sampling depth (Wedderburn et al., 2010).…”

“…Conversely, in other parts of the world including much of the United States, index systems are primarily oriented towards environmental risk, rather than yield (Sharpley et al., 2017). In the present study, the two index systems used on the island of Ireland refer primarily to crop yield, although extensive work has subsequently related both index systems to environmental risk (Cassidy et al., 2017; Jordan et al., 2000; Roberts et al., 2017; Roberts et al., 2020; Watson et al., 2007).…”

Application of riparian buffer zone in agricultural non-point source pollution control—A review

“…The selection of appropriate plant species is also essential to minimize nutrient losses and improve nutrient efficiency. The ability of plants to immobilize P in soil is a critical factor in determining P leaching (Roberts et al, 2020). Vegetation condition, including collocation methods, vegetation type, growth period, and stage, also influences the vegetation characteristics, its impact on soil properties, and its efficiency in removing pollutants from the buffer zone.…”