Pig slurry incorporation with tillage does not reduce short-term soil CO2 fluxes

Tillage and organic fertilization impact short-term soil CO2 fluxes. However, the interactive effect of these two management practices has been rarely studied under field conditions. The objective of this study was to evaluate the impact of tillage (NT, no-tillage, and CT, conventional tillage) and fertilization strategy (PS, pig slurry, and MF, mineral fertilizer) on short-term soil CO2 fluxes in a rainfed Mediterranean agroecosystem. Soil CO2 fluxes were measured several times during two tillage and pre-sowing fertilization periods in 2012 and 2013 (7 and 6 times in 2012 and 2013, respectively). In the two years studied, tillage and fertilization significantly affected soil CO2 fluxes, but the interaction between both factors was not significant. The application of PS resulted in a sharp and immediate increase in the soil CO2 flux. One hour after the application of the organic fertilizer, soil CO2 emissions increased from 0.05 to 0.70 g CO2 m−2 h−1 and from 0.08 to 0.82 g CO2 m−2 h−1 in 2012 and 2013, respectively. Unlike fertilization, 1 h after tillage similar soil CO2 fluxes were observed in CT and NT plots. However, after 7 h, larger fluxes were observed in CT compared with NT in both years. Cumulative CO2 flux during the first 24 h after fertilization and tillage was about three- and two-fold greater in PS than in MF and in CT than in NT, respectively. The results of this study showed that in rainfed Mediterranean systems, soil management and fertilization have a noteworthy impact on short-term soil CO2 losses though no interactive effects were observed between both management practices.This research was supported by the Ministry of Economy and Competitiveness of Spain (AGL2010-22050-C03-01/02; AGL2013-49062- C4-4-R) and the COMET-Global project (FACCE-JPI grant)

Simulating climate change and land use effects on soil nitrous oxide emissions in Mediterranean conditions using the Daycent model

In Mediterranean agroecosystems, limited information exists about possible impacts of climate change on soil N2O emissions under different land uses. This paper presents a modelling study with a dual objective. Firstly, the biogeochemical Daycent model was evaluated to predict soil N2O emissions in different land uses in a typical Mediterranean agroecosystem. Secondly, the study aimed to determine the impact of climate change on soil N2O emissions in different Mediterranean land uses over an 85-year period. Soil N2O emissions were measured in three land uses (cropland, abandoned land and afforested land) over 18 months (December 2011 to June 2013) in a characteristic Mediterranean site in Spain. For climate change simulations, Daycent was run with and without atmospheric CO2 enrichment using climate data from the CGCM2-A2 model. The cumulative N2O emissions predicted by the Daycent model agreed well with the observed values. The lack of fit (LOFIT) and the relative error (E) statistics determined that the model error was not greater than the error in the measurements and that the bias in the simulation values was lower than the 95% confidence interval of the measurements. For the different land uses and climate scenarios, annual cumulative N2O emissions ranged from 126 to 642 g N2O-N ha−1 yr−1. Over the simulated 85-year period, climate change decreased soil N2O emissions in all three land uses. At the same time, under climate change, water filled pore space (WFPS) values decreased between 4% and 15% depending on the land use and climate change scenario considered. This study demonstrated the ability of the Daycent model to simulate soil N2O emissions in different land uses. According to model predictions, in Mediterranean conditions, climate change would lead to reduced N2O emissions in a range of land uses.Jorge Álvaro-Fuentes acknowledges the receipt of a fellowship from the OECD Co-operative Research Programme: Biological Resource Management in Sustainable Agricultural Systems in 2013. Daniel Plaza-Bonilla received a “Juan de la Cierva” grant from the Ministerio de Economía y Competitividad of Spain. This study was also possible through funds provided by the Aragon Regional Government and La Caixa (grant GA-LC-050/2011), the Ministry of Economy and Competitiveness of Spain (grant AGL2013-49062-C4-4-R) and the COMET-Global project (FACCE-JPI grant). We are grateful to María José Salvador and Javier Bareche for laboratory assistance

A win-win situation-Increasing protein production and reducing synthetic N fertilizer use by integrating soybean into irrigated Mediterranean cropping systems

Over the last decades, non-cereal crops have been displaced in European cropping systems leading to a signif-icant dependency on imported soybean. Continuous maize cropping under Mediterranean irrigated conditions can lead to agronomic and environmental problems. The objective of this work was to assess diversified Medi-terranean irrigated cropping systems to maximize protein production while reducing synthetic N fertilizer use. A field experiment was carried out from 2019 to 2021 in an irrigated area in NE Spain. Four cropping systems, (i) continuous maize (MM), (ii) soybean in a rotation one out of three years (MSrt), (iii) barley-maize double cropping system (BM), and (iv) barley-soybean double cropping system (BS) were assessed at the crop, pre-crop and cropping system level. Productivity in terms of grain, energy and protein yield was measured at the crop and calculated for the cropping system level. As well, synthetic N fertilizer use efficiency was calculated for each cropping system. At the pre-crop level, soybean introduction led to a 28% yield increase in the following cereal (maize or barley) mainly due to the residual N effect. At the cropping system level, soybean in rotation (MSrt) did not lead to a significant increase in total protein production compared to MM (from 895 to 947 kg ha-1 yr- 1), but it mildly increased synthetic N fertilizer use efficiency. Protein production in the BS system (1778 kg protein ha-1 yr- 1) was significantly higher than in all other cropping systems (990 kg protein ha-1 yr- 1 on average). As well, BS was the cropping system with the highest synthetic N fertilizer use efficiency compared to the other cropping systems (251 and 88 kg grain kg synthetic N fertilizer-1). Our results demonstrate that introducing soybean as a double crop following barley is a successful strategy to reduce environmental impacts resulting from N fertilizer use and increase protein production, contributing to plant protein self-sufficiency and cropping systems diversification

Alternatives for sustainable weed control in single- and double-cropped soybean: A case study for Mediterranean irrigated conditions

The irrigated cropping systems in South Europe could benefit from soybean [Glycine max (L.) Merr.] introduction in their maize (Zea mays L.)-based crop rotations. However, sustainable weed management strategies are needed for soybean growers under Mediterranean irrigated conditions. This work aimed to assess the weed control efficacy, and the soybean performance, of alternative management practices for single- and double-cropped soybean. Two field experiments were carried out in northeast Spain in the period 2019-2021. Row width narrowing (75-37.5 cm), herbicide application (yes/no), and roller-crimped rye [Secale cereal (L.) M.Bieb.] cover crop (yes/no) were assessed in the single cropping system experiment (SCS). In the barley-soybean double cropping system experiment (DCS), row width narrowing and herbicide application were assessed. In the SCS, the presence of rye cover crop reduced weed biomass up to 92% compared to the controls without herbicide and cover crop in 2020. In 2021, no effect of the cover crop on weed pressure was found due to the low amount of rye biomass accumulated (11.8 and 3.4 ton DM ha(-1) in 2020 and 2021, respectively). In the DCS, herbicide application attained the expected weed control. Row width narrowing to 37.5 cm did not have an impact on weed pressure nor on soybean yield in either experiment. We concluded that herbicide reduction for single-cropped soybean under Mediterranean irrigated conditions can be achieved by roller-crimping a rye cover crop, provided enough rye biomass is accumulated. In the DCS, our results indicated that further research is needed to find alternatives to chemical weed control

Editorial: crop diversification, a key pillar for the agroecological transition

This research benefited from collaboration within the SusCrop-ERA-NET project LegumeGap receiving funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement N°771134. Daniel Plaza-Bonilla is Ramón y Cajal fellow (RYC-2018-024536-I) co-funded by MICIN/AEI/10.13039/501100011033 and European Social Fund. Moritz Reckling was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—420661662

Do no-till and pig slurry application improve barley yield and water and nitrogen use efficiencies in rainfed Mediterranean conditions?

Tillage and N fertilization strategies including mineral and organic sources need to be studied in combination given their importance on the production cost that farmers face and their potential interaction on crop performance. A four-year (2010–2014) experiment based on barley monocropping was carried out in NE Spain in a typical rainfed Mediterranean area. Two tillage treatments (CT, conventional tillage; NT, no-tillage) and three rates of N fertilization (0; 75 kg N ha−1, applied at top-dressing; 150 kg N ha−1, applied at pre-sowing and at top-dressing at equal rate), with two types of fertilizers (ammonium-based mineral fertilizer and organic fertilizer with pig slurry), were compared in a randomized block design with three replications. Different soil (water and nitrate contents) and crop (above-ground biomass, grain yield, yield components and N concentration in biomass and grain) measurements were performed. Water- and nitrogen use efficiencies (WUE and NUE) as well as other N-related indexes (grain and above-ground biomass N uptake; NHI, nitrogen harvest index; NAR, apparent nitrogen recovery efficiency) were calculated. Barley above-ground biomass and grain yield were highly variable and depended on the rainfall received on each cropping season (ranging between 280 mm and 537 mm). Tillage and N fertilization treatments affected barley grain yields. No-tillage showed 1.0, 1.7 and 6.3 times greater grain yield than CT in three of the four cropping seasons as a result of the greater soil water storage until tillering. Water scarcity during the definition of the number of spikes per m2 under CT would have compromised the compensation mechanism of the other two yield components. Pig slurry application led to the same (3 of 4 years) or higher (1 of 4 years) grain yield than an equivalent rate of mineral N fertilizer. Regardless the N origin, barley yield did not respond to the application of 150 kg N ha−1 split between pre-sowing and top-dressing compared to the 75 kg N ha−1 rate applied as top-dressing. A significant nitrate accumulation in the soil over the experimental period was observed under CT. Greater barley water use efficiency for yield (WUEy), N uptake and grain N content were found under NT than CT in three of the four cropping seasons studied. Moreover, for a given N rate, the use of organic fertilization increased significantly the WUEy as an average of CT and NT. When CT was used, a greater NHI was observed when using pig slurry compared with mineral N as an average of the four years studied. However, the use of different N fertilization treatments (rates or types) under CT or NT did not increase the NUE compared with the control. Our study demonstrates that the use of NT and the application of agronomic rates of N as pig slurry leads to greater barley yield and water- and nitrogen-use efficiencies than the traditional management based on CT and mineral N fertilization.We thank Silvia Martí, Carlos Cortés, Ana Bielsa, Maria José Salvador, Josan Palacio and Héctor Martínez for their technical assistance. Daniel Plaza-Bonilla received a Juan de la Cierva Postdoctoral Grant from the Ministerio de Economía y Competitividad of Spain. This research was supported by the Ministerio de Economía y Competitividad of Spain (grants AGL2007-66320-C02-01, AGL2010-22050-C03-01/02 and AGL2013-49062-C4). This paper has been produced within the context of the Red SIRENA network (Ref. AGL2015-68881-REDT) funded by the Ministerio de Economía y Competitividad of Spain

Soil aggregation and organic carbon protection in a no-tillage chronosequence under Mediterranean conditions

Low-intensity soil management systems like no-tillage (NT) are being increasingly accepted as an essential part of sustainable farming systems. The objective of this work was to study the effects of NT maintenance over time on soil aggregation and soil organic carbon (SOC) protection on a semiarid Mediterranean agroecosystem. A NT chronosequence was established with five phases: (i) conventional tillage (CT); (ii) NT for 1 year (NT-1); (iii) NT for 4 years (NT-4); (iv) NT for 11 years (NT-11) and (v) NT for 20 years (NT-20). N fertilization was based on pig slurry for the whole experimental area. Soil samples were collected from four depths (i.e., 0–5, 5–10, 10–20, 20–30 cm). Dry and water-stable aggregates, SOC concentration and C concentration of water-stable aggregates were measured. SOC concentration reached its maximum value after 11 years under NT. However, the differences between NT phases were only found in the 0–5 cm soil depth. In soil surface (i.e., 0–5 cm), water-stable large macroaggregates (2–8 mm) were 0.02, 0.12, 0.32 and 0.31 g g− 1 dry soil for the NT-1, NT-4, NT-11 and NT-20 phases, respectively. C concentration of microaggregates increased in relation with the number of years under NT. SOC and water-stable macroaggregate stratification were greatest with the increase in the years under NT, emphasizing the close relationship between SOC and aggregation. In Mediterranean semiarid agroecosystems, the increase in the proportion of stable macroaggregates and the enrichment of C concentration within microaggregates are two main mechanisms of SOC protection when NT is maintained over time.This research was supported by the Comision Interministerial de Ciencia y Tecnologia of Spain (AGL 2004-07763-C02-02 and AGL 2010-22050-C03-01). D. Plaza-Bonilla was awarded with a FPU fellowship by the Spanish Ministry of Education. Jorge Álvaro-Fuentes acknowledges the Consejo Superior de Investigaciones Científicas (CSIC) for his contract within the “Junta para la Ampliación de Estudios” (JAE-DOC) programme co-financed by the European Social Fund