Residual soil nitrate as affected by giant reed cultivation and cattle slurry fertilisation

Abstract

The residual soil nitrate (RSN) is the amount of nitrate which remains in soil profile after crop uptake has ceased, typically in the autumn. The RSN is prone to leaching and therefore poses serious environmental concerns, especially in areas with intensive livestock activities. Little is known about the ability of the energy grass giant reed in leaving low RSN. Such ability would add a desirable environmental benefit to giant reed cultivation. This article reports on snapshot measurements of RSN across soil profile in the autumn of three consecutive years: 2010, 2011 and 2012. Soil nitrate content was measured on soil samples collected from the soil layers 0-0.2 m, 0.2-0.4 m, 0.4-0.6 m and 0.6-0.8 m. The RSN of giant reed was compared with RSN of the energy crops sweet sorghum and poplar short rotation coppice (SRC). The three energy crops were treated with two fertilisation regimes: 0 kg N ha–1 (Control) and 20 mm of cattle slurry (CS20). Soil samples were also taken for a reference crop of winter wheat following winter wheat and receiving no N supply. Our findings for the three years of experiment can be summarised as follows: i) in case of the unfertilised Control, the three dedicated energy crops giant reed, sweet sorghum and poplar SRC left in soil profile in the autumn significantly lower amounts of RSN compared to the reference crop of wheat. Hence, all the three energy crops provided in similar manner the environmental benefit of leaving lower RSN; ii) in case of cattle slurry application the real advantage of giant reed cultivation became surprisingly evident. In fact, in three subsequent years the treatment giant reed CS20 never determined RSN significantly higher than RSN for giant reed Control. The RSN for giant reed with treatment CS20 was significantly lower than that the reference crop of wheat in all the three years. Unlike poplar SRC and sweet sorghum, giant reed exerted effective soil nitrate removal with a relatively high rate of cattle slurry application. Hence, this species can be regarded as suitable not only to utilise livestock effluents, but also to reduce the risk of nitrate pollution in many land use situations dealing with nitrogen surplus.

Biomass and methane yield of giant reed (Arundo donaxL.) as affected by single and double annual harvest

“…Such study indicated that giant reed possesses high agronomic efficiency of applied nitrogen (Ceotto et al, 2015) and the ability to reduce the risk of nitrate pollution dealing with nitrogen surplus. (Ceotto et al, 2018).…”

“…According to D’Imporzano et al (2018) the high productivity of giant reed, combined to its low requirement of agronomic inputs, is key for minimizing the environmental impact of the crop. Moreover, giant reed exerts an effective soil nitrate removal, therefore reducing the risk of nitrate pollution (Ceotto et al, 2018). While giant reed has been largely investigated during the last decade, most of the studies focused on the crop harvested when the annual growth has ceased, notably in autumn or winter (Angelini et al, 2009; Borin et al, 2013; Cosentino et al, 2006; Monti & Zegada‐Lizarazu, 2016).…”

Prospects of Bioenergy Cropping Systems for A More Social-Ecologically Sound Bioeconomy

“…For example, when cultivating Virginia mallow [182] in marginal sandy soil, digestate fertilization resulted in significantly less N leaching compared with NPK fertilizer but similar biomass yields and an increased soil carbon content, water holding capacity, and soil basal respiration, indicating an improved fertility of the marginal soil [132,183]. Other perennial biomass crops such as giant reed have the characteristic of leaving very low amounts of residual soil nitrate after harvest, which also helps in reducing potential N leaching over winter [184]. In an intercropping system of triticale and clover grass on two marginal sites, separated digestates were able to substitute mineral fertilizer completely in a long-term experiment (longer than six years) without decreasing biomass yield [185].…”

Model-Based Assessment of Giant Reed (Arundo donax L.) Energy Yield in the Form of Diverse Biofuels in Marginal Areas of Italy

“…We did not consider in our simulation any nitrogen stress on crop growth, according to the low giant reed requirements in the study area, as partly demonstrated by negligible yield differences between fertilized and unfertilized giant reed productivity in CT field experiments [37,70]. Indeed, this species is a rhizomatous grass characterized by high mobility of nutrients between above-and belowground organs: In autumn, before harvest, part of nitrogen in aboveground organs is remobilized and stored in the rhizome, and re-used for tiller emission and growth in the next spring re-sprouting [23,71]. Where these assumptions do not hold, hence our results may be slightly overestimated; in such a case, additional data will be needed for model calibration, possibly considering experiments where giant reed biomass is collected under different fertilization strategies.…”

“…As a matter of fact, in Southern European climates, this crop can be grown in many soils, ranging from heavy clay to loose sands and gravel soils, and also tolerates both high salinity and extended periods of drought [19]. Besides its rusticity, this species can provide several ecosystems services: an outstanding biomass productivity [20]; a substantial soil carbon sequestration [21]; high nitrogen (N) use efficiency [22]; and an effective residual soil nitrate removal across soil profile [23]. Furthermore, the very deep root system allows the crop to adsorb soil pollutants, favoring soil phytoremediation and aggregation [10].…”