Phosphorus Leaching from Two Soils with Catch Crops Exposed to Freeze–Thaw Cycles

Abstract

Catch crops have been found to decrease leaching of nitrates into surface water and groundwater, but they also have the potential to increase P loadings to natural waters due to plant destruction during freezing-thawing events. An indoor lysimeter experiment was performed using a clay and a sand soil with four different plant species applied: perennial ryegrass (Lolium perenne L.), honey herb (Phacelia tanacetifolia Benth.), chicory (Cichorium intybus L.), and oilseed radish (Raphanus sativus L.). These plants were exposed to simulated rainfall and freezing events in two separate experiments, one using topsoil columns with plant material added and one with plant material only. The sand and clay soils had significantly different control total-P leaching loads after all freezing events, with a mean of 0.32 kg ha -1 for the clay and 0.88 kg ha -1 (P < 0.001) for the sand. The combined (soil including plant material) total-P leaching loads from the clay soil were in the order: chicory (2.6 kg ha -1 ) > ryegrass (2.3 kg ha -1 ) > oilseed radish (2.2 kg ha -1 ) > honey herb (1.3 kg ha -1 ), with considerably smaller loads from the sand. Phosphorus losses were greater from the plant-only experiment, with chicory (51.7 kg ha -1 ) > oilseed radish (43.2 kg ha -1 ) > honey herb (18.4 kg ha -1 ) > ryegrass (10 kg ha -1 ). The results indicate that soil texture and plant choice can have a large impact on P leaching loads entering natural waters in cold regions and that soils act as an efficient filter for P released from catch crop residues.

The ability of cover crops to reduce nitrogen and phosphorus losses from arable land in southern Scandinavia and Finland

“…Main crops were spring cereals, and cover crops were undersown, unless otherwise stated. Sturite et al 2007;Riddle and Bergström 2013;Øgaard 2015). On plot scale, increased concentrations of dissolved P from plots with undersown Italian ryegrass or white clover, especially in the first runoff after frost, were found in a study by Børresen and Uhlen (1991).This is probably one contributing factor to the increased concentrations of dissolved P in drainage water reported for grasslands and grass/clover crops Turtola and Jaakkola 1995), although the opposite was found in the JOVA monitoring study described above.…”

Biomass production and phosphorus retention by catch crops on clayey soils in southern and central Sweden

“…However, part of the P released from the catch crop biomass is likely to have been lost from the system by surface runoff or leaching during winter and early spring, contributing to the risk of eutrophication in neighbouring streams. This is a particular concern on clayey soils such as those in this study, where P may be transported through macropore flow pathways before sufficient sorption occurs (Riddle and Bergström, 2013). For example, in a laboratory lysimeter study with intact clayey soils and catch crops sampled from the same sites as those used in the present study, the total-P concentration in leachate increased after FTCs compared with before in 95 out of 140 lysimeters (Liu et al, 2014).…”

“…This poses an increased risk of P losses to water (Sharpley and Smith, 1991;Miller et al, 1994). In particular, the P lost from catch crop tissues is a great concern on clayey soils, where the presence of macropores facilitates fast transport of water and P (Riddle and Bergström, 2013). In a laboratory lysimeter study, Liu et al (2014) found that repeated freezing-thawing cycles (FTCs) increased potential P leaching from clay soils with catch crops, in particular from soils with perennial ryegrass and oilseed radish.…”

Properties of Luvisol and spring barley yield as affected by peas as a catch crop

“…It is of particular importance on farms where the lack of animal production causes a shortage of farmyard manure. Growing a catch crop for green manure can bring many benefits for the soil environment, which has been indicated by the research carried out in this area (Berntsen et al, 2006;Piotrowska, Wilczewski, 2012;Riddle, Bergstrőm, 2013). Catch crops take up nitrogen remaining in the soil after harvest of cereals and thus enable reduction of its leaching (Duer, 1996;Vos, van-der-Putten, 2001;Berntsen et al, 2006;Askegaard, Eriksen, 2008;Doltra, Olesen, 2013).…”

“…Many studies have concerned the impact of catch crops grown as green manure on the physical and chemical properties of soil (Hansen, Djurhuus, 1997;Thorup-Kristensen, Dresbøll, 2010;Riddle, Bergstrőm, 2013). Findings presented in the literature relate primarily to the impact of catch crops on soil properties during the early spring (before sowing of spring cereals).…”