Reactive nitrogen losses via denitrification assessed in saturated agricultural soils

Castaldelli, Giuseppe; Colombani, Nicolò; Soana, Elisa; Vincenzi, Fabio; Fano, Elisa Anna; Mastrocicco, Micòl

doi:10.1016/j.geoderma.2018.09.018

Cited by 34 publications

(22 citation statements)

References 62 publications

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“…Thus, denitrification may be boosted in the soils of the studied basin, characterized by the fine texture, low hydraulic conductivity, flat topography, and shallow water table [22,34]. This is consistent with the outcomes of previous laboratory experiments demonstrating high NO 3 − consumption and correspondent N 2 production in soil mesocosms under saturated conditions [21]. Moreover, pyrite oxidation could contribute to remove excess NO 3 − in reducing environments lacking organic carbon substrates [60].…”

Section: Discussionsupporting

confidence: 89%

“…The aim of the present work was to evaluate the relative importance of soil denitrification in buffering N excess at the watershed scale in a deltaic, intensively cultivated, and irrigated sub-basin of the Po River plain, the Po di Volano-Sacca di Goro. This basin was selected as a case study for the following reasons: (1) the homogeneous cropping system, i.e., maize and winter cereal rotation in about two-thirds of the agricultural lands developing in a completely flat territory; (2) the N fertilization supplied almost exclusively as synthetic urea and ammonium nitrate; (3) the capillary network of canals distributing irrigation water in the spring-summer period; (4) the extensive information available on hydrogeological and microbial drivers regulating N processing and transport in surface waters [18,19], soil water [20,21], and groundwater [22,23].…”

Section: Introductionmentioning

confidence: 99%

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In Search for the Missing Nitrogen: Closing the Budget to Assess the Role of Denitrification in Agricultural Watersheds

et al. 2020

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Although representing a paramount mechanism against nitrogen excess in agricultural landscapes, soil denitrification is still a largely unknown term in nitrogen balances at the watershed scale. In the present work, a comprehensive investigation of nitrogen sources and sinks in agricultural soils and waters was performed with the aim of gaining insights into the relevance of soil denitrification in a highly farmed sub-basin of the Po River delta (Northern Italy). Agricultural statistics, water quality datasets, and results of laboratory experiments targeting nitrogen fluxes in soils were combined to set up a detailed nitrogen budget along the terrestrial–freshwater continuum. The soil nitrogen budget was not closed, with inputs exceeding outputs by 72 kg N·ha−1·year−1, highlighting a potential high risk of nitrate contamination. However, extensive monitoring showed a general scarcity of mineral nitrogen forms in both shallow aquifers and soils. The present study confirmed the importance of denitrification, representing ~37% of the total nitrogen inputs, as the leading process of nitrate removal in heavily fertilized fine-texture soils prone to waterlogged conditions.

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

In Search for the Missing Nitrogen: Closing the Budget to Assess the Role of Denitrification in Agricultural Watersheds

et al. 2020

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“…Nitrogen is one of the most important nutrient elements in agricultural production. 37 Soil fertility can be directly reflected by the nitrate and ammonium nitrogen concentrations in the soil. Nevertheless, nitrogen is easily leached.…”

Section: Resultsmentioning

confidence: 99%

Salt-Tolerant Superabsorbent Polymer with High Capacity of Water-Nutrient Retention Derived from Sulfamic Acid-Modified Starch

et al. 2019

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The application of superabsorbent polymers (SAPs) is hindered because their absorption capability is greatly affected by the electrolytes in a solution. A novel modified water-absorbent polymer was fabricated by solution polymerization of sulfamic acid-modified starch and acrylic acid; the swelling ratios of this absorbent polymer were 1026 g/g in deionized water and 145 g/g in 0.9% sodium chloride solution and increased by 99.5 and 13.4%, respectively, when compared with ordinary starch-grafted acrylic SAPs. The water absorption capacity was measured in water at different pH values, salt concentrations, and temperatures. In addition, water and fertilizer retentions were studied by simulated leaching tests in a soil column. The results showed that water absorption capacities of the modified SAP in salt solutions were improved due to the adsorption and transfer of water molecules by the sulfonic acid groups. Compared to the losses when there was no superabsorbent treatment, the water, nitrate, ammonium nitrogen, and water-soluble potassium losses during the salt-tolerant superabsorbent treatment were significantly reduced by 18.5, 22.8, 88.0, and 63.8%, respectively. The method introduced in this study could guide the development and wide application of salt-tolerant SAPs in agriculture and horticulture.

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“…Considering these data linked to the difference of N concentration in the soil (−59 and −26 kg-N ha −1 y −1 , Table 4), it was possible to suppose that N was not preserved into the soil, but, at least partially, was denitrified. As a matter of fact, some clues suggested that denitrification was an ongoing process: (i) the measured denitrification rates showed positive results in all the measuring campaigns, with an average rate of 1 ± 0.1 g N-NO 3 ha −1 d −1 ; (ii) the N-NO 2 concentration in tension lysimeters was 0.42 mg L −1 , suggesting an active denitrification, with four isolated peaks over 1 mg L −1 , indicating that the limiting condition is the availability of the labile organic substrates, which usually leads to transient N-NO 2 accumulation [28,29]; (iii) the average redox potential measured in the tension lysimeters was −112 ± 7 mV, indicating anoxic-hypoxic conditions suitable for denitrification in soils [30]. All the above-mentioned clues can be considered as evidence of the ongoing denitrification process, although they cannot be used directly to quantify this process, which was then estimated via mass balance ( Table 6).…”

Section: Nitrogen Balancementioning

confidence: 99%

Nitrogen Budget of Short Rotation Forests Amended with Digestate in Highly Permeable Soils

et al. 2019

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Bioenergy crops are a promising option for integrating fossil fuels and achieving European environmental targets. Among these, Short Rotation Forestry (SRF) crops and biogas plants have been considered an opportunity for sustainable agricultural development due to their environmental benefits. In this case study, an N balance was performed by comparing an SRF Platanus hispanica plantation with a permanent meadow, both located in an area with highly permeable soils, using two different amounts of organic fertilization (digestate) for each system (0, 170 and 340 kg-N ha−1 y−1). The results obtained indicate that, in the presence of highly permeable soils, the SRF is not effective in retaining N during the initial stage of growth, despite the use of a suitable application rate of digestate. Higher N leaching rates occurred in SRF crops compared to permanent meadows. Moreover, the N potential removal rate did not vary proportionally with the applied dose of digestate. To avoid N leaching excess, the annual applied N should be not only within 170 kg-N ha−1 y−1 (Nitrate Directive legal limits for nitrate vulnerable zone) but should also follow precise and accurate distribution practices, like: controlled grassing between the tree rows and soil’s minimum tillage immediately after the digestate spreading.

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Reactive nitrogen losses via denitrification assessed in saturated agricultural soils

Cited by 34 publications

References 62 publications

In Search for the Missing Nitrogen: Closing the Budget to Assess the Role of Denitrification in Agricultural Watersheds

In Search for the Missing Nitrogen: Closing the Budget to Assess the Role of Denitrification in Agricultural Watersheds

Salt-Tolerant Superabsorbent Polymer with High Capacity of Water-Nutrient Retention Derived from Sulfamic Acid-Modified Starch

Nitrogen Budget of Short Rotation Forests Amended with Digestate in Highly Permeable Soils

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