Search

The benefits of using cover crops for improving soil and water quality are well known. Less clear is whether cover crops, especially those forming a taproot system, can favor solute transport down to the groundwater by modifying soil hydraulic properties and solute dynamics. In this study, we employed 12 lysimeters to conduct a comparative analysis between a taproot cover crop, specifically forage radish (FR), and bare soil (BS), under three water table management conditions. Our objective was to evaluate whether the enhancement of root‐derived macroporosity could have modified water and solute dynamics, and offset the benefits provided by FR that is commonly used to mitigate solute leaching. A tracer solution of bromide (Br−) was added to lysimeters, and solute flux concentrations were determined at different depths during a 25‐day test. Soil moisture and pressure heads were monitored. Water and solute transport parameters were estimated by inverse modeling using HYDRUS‐1D. A complementary laboratory experiment was performed to quantify the effect of FR root apparatus on the macropore structure by using noninvasive X‐ray microtomography (µCT). Results showed that the growth of FR within the lysimeters induced alterations in water and solute dynamics compared with BS. This is primarily attributed to its proficiency as solute scavenger, with an uptake capacity of up to 47% of the total injected tracer. Our comparative analysis instead revealed subtle differences in soil structure and hydraulic properties brought about by the presence of FR. Major changes were observed for the saturated hydraulic conductivity (Ks), which increased from an average of 8.4–49.8 cm day−1 within the 20–45 cm layer in BS and FR, respectively. Additionally, there was a difference in immobile water content (θim), with the values in FR averaging 21% lower than those in BS. These modifications can be attributed to the formation of fissures and channels, primarily concentrated in the proximity of taproot development, without extending into deep preferential flow pathways. These structural changes were supported by the nondestructive µCT analyses. Upon aggregating the effects observed, solute movement to groundwater was not affected by FR compared to BS conditions. Core Ideas: Taproot served as solute scavenger, offsetting the risk of leaching at −60 cm, below its fleshy portion.Taproot‐induced soil hydraulic changes were mainly observed in the 0–45 cm layer.Forage radish caused an increase in the macroporosity where the taproot mainly developed. [ABSTRACT FROM AUTHOR]

In a growing world population scenario, greater demand for food and in turn agricultural input is expected in the coming decades. The development of innovative sustainable amendments and fertilizers such as hydrogels (HGs) relies on this context. HGs are defined as 3D polymeric networks with the ability to absorb and retain a large amount of water (i.e., swellability). HGs swellability makes them ideal platforms for water- and nutrient-controlled release. The literature reflects a notable diversity in HGs composition, properties, and impacts on agroecosystems, resulting in the dissemination of information across multiple publications. Within this context, the primary aim of this scientific review is to systematically compile, critically evaluate, and synthesize the latest findings and relevant literature pertaining to the application of HGs in agroecosystems. We found that this class of materials was consistently found on soil bulk density, crop available water, soil electrical conductivity, cation exchange capacity and main cereal or legume crops performances particularly under moderate water deficit conditions, suggesting their effectiveness for arid and semi- arid areas. Encouraging results were also found on pesticide, agrochemicals, and microorganisms delivering. Thus, the delivery of agronomic inputs with loaded-HG may play a key role in forthcoming agriculture that would minimize the agronomic impact on the environment. Nevertheless, some critical issues still remain open, concerning: (i) the decreased of HG effectiveness following wetting and drying cycles, (ii) the impact of Na+ contained in HG on crop cells, (iii) the HG effect on soil saturated hydraulic conductivity and pH, and (iv) HG biodegradability and their fate into the environment. In conclusion, HGs seem a promising technology to reach/maintain food security and soil health, but future research should address the development of well-defined protocols for producing biowaste-derived HG that will ensure their biodegradability and non-toxicity and will disclose new insights into a circular economy approach agronomy. One of the biggest challenges would be the synthesis of “smart” HG able to respond to environmental stimuli triggering molecule(s) release in soil. [ABSTRACT FROM AUTHOR]

Increasing soil organic carbon (SOC) stocks in agricultural soils is currently of special interest because it can help mitigate global warming through atmospheric carbon (C) sequestration. Recommended management practices, such as conservation agriculture (CA) and conventional tillage with cover crops (CC), could have significant implications for C sequestration potential. A field experiment was carried out in northeast Italy to compare the implementation of CA and CC with conventional agriculture (CV). The experiment began in 2010 on three farms to evaluate SOC stock variation over a 6‐year period. Two extensive soil sampling operations were conducted in 2011 and 2017 in 240 locations, for a total of 1,440 analysed soil samples, considering the SOC stratification within a 0–50‐cm profile. The results suggested that CA changed the SOC distribution rather than the total amount of SOC. Compared to CV, after the introduction of CA, a general increase in SOC (0.25 Mg C ha−1 y−1) was observed in the 0–30‐cm layer, whereas no stock variation was observed in the 0–50‐cm layer. In contrast, compared to CV, the use of CC decreased the SOC stocks by 0.74 Mg C ha−1 y−1 in the 0–50‐cm layer. Over a 6‐year period, no benefit in SOC sequestration was observed with CA and CC. However, we hypothesize that these findings could still be affected by transitory dynamics, highlighting the low soil reactivity to soil‐improving agricultural systems. A longer study period would be required to better understand the potential benefits of CA and CC on SOC sequestration. Highlights: We hypothesized that conservation practices increase SOC after a 6‐year adoptionNo‐tillage enhanced SOC stratification in conservation agricultureC addition with cover crops induced SOC stock reductions due to a priming effectAn SOC increase was not observed after 6 years of conservation practices [ABSTRACT FROM AUTHOR]

Anaerobic digestion has been recently proposed as a more sustainable energy supply chain able to strengthen the existing security of supply provisions. Anaerobic digestate (AD) is the by-product of the anaerobic digestion process and presents organic fertilizer characteristics, but its agronomic usage has been hindered by both agronomic and environmental concerns. In this study, the impact of agricultural liquid (LD) and solid (SD) AD and beef manure (Man) was evaluated on some agro-environmental characteristics. First, the AD fractions functional groups were characterized by FT-IR, and then LD and SD performances were evaluated on soil organic carbon (SOC) stock and carbon dioxide (CO2) emissions and compared to beef manure (Man). The fertilizer impact was also considered with the presence or absence of a shallow water table. Results showed that SD increased of ca. 3 t ha−1 the SOC stock in the 0–20 cm soil profile with respect to LD, while it was comparable to Man despite the lower C input (6.7 vs. 8.7 t C ha−1), due to the presence of more stable compounds (e.g., lignin). The CO2 fluxes were affected by both fertilizer type and water table level. In the absence of a water table, the CO2 emissions (5.5 g CO2 m2 d−1) were driven by carbon content and quality in the fertilizer, while the presence of a shallower water table hindered mineralization of stable SOC and, in turn, reduced emissions (4.4 g CO2 m2 d−1). AD can be considered a beneficial solution to both maintain soil fertility and, at the same time, give new insight into a circular economy model, although further investigation on GHG emissions is required. [ABSTRACT FROM AUTHOR]