Nitrate leaching is not controlled by the slurry application technique in productive grassland on organic–sandy soil

Abstract

The return of slurry is the most important means of fertilization in grassland dairy farming. Broadcast application of slurry induces air pollution by ammonia. Alternatives to broadcast application like sliding shoe or injection have therefore been introduced. These alternatives might, however, cause higher N losses by nitrate leaching because N prevented from volatilization may not completely be utilized for dry matter production. Information on the interactive effects of amount of N input and slurry application technique on nitrate leaching from productive organic-sandy soils are still scarce. Therefore, we tested the hypothesis that slurry application by sliding shoe or injection leads to larger NO 3-N losses via leaching than broadcast application. In a 4-year experiment on cut grassland, we applied N at 0, 160, 240, and 320 kg ha −1 year −1 using four application techniques: in the form of a chemical-synthetic N fertilizer or as cattle slurry applied broadcast, by sliding shoe or shallow injection. We assessed nitrate leaching during winter using suction cups. Additionally, we determined herbage dry matter yields, N offtake, and soil mineral N content to compile N balances for the individual treatments based on these data. Our results show that nitrate leaching during winter did not differ significantly among treatments of N application technique. Nitrate leaching increased significantly with increasing amount of N input, but was on average lower than 16.5 kg N ha −1 for application rates of up to 320 kg N ha −1. Soil mineral N content in autumn was a reasonably good predictor for nitrate leaching, with R 2 of 0.65. The proportion of nitrate leaching of positive N surpluses increased in the order broadcast, sliding shoe, injection, and chemicalsynthetic N application. Our findings demonstrate that the amount of N input but not the technique of application results in a significant effect on nitrate leaching.

Effects on nitrate leaching of the timing of cattle slurry application to leys

“…Since nitrogen uptake by grass during autumn is estimated to be limited to 40–55 kg N ha −1 under Swedish conditions (Aronsson & Torstensson, 2004), the more this limit is exceeded, the larger the leachable fraction of applied nitrogen. The amount of nitrogen applied can thus be expected to have an effect on nitrate leaching (Kayser, Breitsameter, Benke, & Isselstein, 2015), especially if the capacity of the grass to take up nitrogen is exceeded. In this study, significantly higher nitrate leaching after autumn application of slurry was observed only in experiment 2, possibly because higher doses of slurry were applied in that experiment (Table 2).…”

“…This may have limited the amount of nitrogen available for leaching in the grass ley during the second year. Soil mineral nitrogen content in subsoil in autumn can be a reasonably good predictor of nitrate leaching (Delin & Stenberg, 2014; Kayser et al., 2015).…”

Impacts of slurry acidification and injection on fertilizer nitrogen fates in grassland

“…While an increasing number of published studies is dealing with trade-offs of slurry treatment and application techniques, thereby considering greenhouse gas fluxes, nitrate leaching (Maris et al 2021;Cameira et al 2019;Park et al 2018;Kayser et al 2015;Powell et al 2011) and productivity (Baral et al 2021;Regueiro et al 2020;Fangueiro et al 2017;Huijsmans et al 2016), very little is known on fertilizer N partitioning in the plant-soil-system and on full N balances of conventional slurry broadcast spreading compared to injection and acidification. This particularly applies for montane grasslands of the alpine region in Europe and still prevents a holistic assessment how these refined slurry application techniques affect the actual plant N uptake and fertilizer N stabilization in the soil, which is key to preserve soil fertility on the long term.…”

Impacts of zeolite, alum and polyaluminum chloride amendments mixed with agricultural wastes on soil column leachate, and CO2 and CH4 emissions

“…Landspreading is the most common method of slurry application (Lloyd et al, 2012) and while other methods such as sliding shoe and injection are used to limit N losses through ammonia (NH 3 ) volatization (Sistani et al, 2010), Kayser et al (2015) concluded that the amount of N input, rather than the method of application, impacts the extent of NO 3 -N leaching in organic sandy soils. On the other hand, Kleinman et al (2009) reported that incorporation of dairy manure by tillage reduced P losses in leachate because of the destruction of preferential flow pathways in the soil, while Hodgson et al (2016) found that shallow injection of dairy slurry to grassland plots resulted in higher and more prolonged survival of faecal indicator organisms than from surface spreading.…”