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Aims: The surface crust formed by the drop impact of rainfall and/or irrigation is a prevalent characteristic in many Mediterranean soils. However, the temporal variation of soil hydraulic properties induced by surface crust during the high-frequency irrigation has rarely been investigated. Methods: Beerkan infiltration tests in conjunction with the BEST method were used to investigate the effects of surface crusting on the spatio-temporal variation of saturated soil hydraulic conductivity (Ks, mm s−1), sorptivity (S, mm s−0.5), mean pore size (r, mm), number of effective pores per unit area (N, m−2) in Agramunt, NE Spain. Results: In response to autumn tillage, intensive tillage (IT) increased Ks and S due to higher r and N, but both declined after 60 days. Reduced tillage (RT), maintained comparable Ks and S values, despite having a lower N value. After the spring tillage, both IT and RT developed crusted layers, resulting in decreased Ks, S and N. Long-term no-tillage (NT) showed an increasing trend of Ks and S over time, except for the last sampling. Spatial variation (i.e., between the rows, B-row vs. within the row of crops, W-row) of Ks and S was found, and non-crusted soils (W-row) had consistently higher Ks and S than crusted soils (B-row). Conclusions: Conservation tillage i.e., RT and NT improve the surface soil structure and reduce the risk of crust development. Surface cover by crops may help to prevent crust formation within the row of crops, improving soil hydraulic conductivity. [ABSTRACT FROM AUTHOR]

Over the last decades, non-cereal crops have been displaced in European cropping systems leading to a significant 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 Mediterranean 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. • Four cropping systems were assessed at the crop, pre-crop and cropping system level. • Soybean introduction in single cropping systems did not increase protein yield. • Soybean pre-crop effect increased the following cereal yields by 28%. • Barley-soybean double cropping increased protein yield at the cropping system level. • Synthetic N use efficiency was highest in barley soybean double cropping system. [ABSTRACT FROM AUTHOR]

Maize is one of the main irrigated crops in northern Spain. However, the traditional cropping system used for its cultivation has relied on intensive monoculture, demanding significant inputs, and resulting in occasional unprofitable yields. A promising practice to increase the sustainability of farms is the use of double-cropping systems. The aim of this study was to evaluate the combined impact of introducing a legume prior to maize, together with different tillage systems and mineral N fertilization rates on crop yields and water productivity under Mediterranean irrigation conditions. The study compared monocropping maize (MC) versus legume-maize double cropping (DC) with three tillage systems (conventional tillage, CT; minimum tillage, MT; no-tillage, NT), and three mineral N fertilization rates (zero, medium and high). The legumes employed were pea for grain (2019), vetch for green manure (2020), and vetch for forage (2021). The highest yields were found in DC. On the one hand, the benefits associated with legume cropping allowed for increased grain yield of DC maize; on the other hand, the combined biomass of the legume plus maize led the DC systems to achieve significantly higher total biomass (sum of grain and stover) than the MC systems. In addition, a better adaptation of the maize DC phenological cycle to environmental conditions favoured higher yields in this system. Higher water consumptions in DC systems resulted in lower yield water use efficiency (WUE y). However, when only irrigation water was taken into account, DC was the system with the highest irrigation water use efficiency for yield (IWU y). Similarly, the high biomass values generated in the DC system resulted in higher water use efficiency for biomass (WUE b). The tillage system with the highest yields was NT. These results, together with a higher water retention capacity in NT made the water productivity (WUE b , WUE y and IWU y) of these systems higher. The use of high N fertilizer rates did not show any yield or WUE advantage over the medium rate. The results of this study indicate that in Mediterranean agroecosystems, the use of legume-maize double cropping systems together with NT systems and reduction of N fertilization can be a good strategy to maintain crop yields, while saving N fertilizer, and to improve WUE b and IWUE y. [ABSTRACT FROM AUTHOR]

• Crop intensification enhances soil macropores hydraulic conductivity compared to mono-cropping. • Long-term NT improves soil structure and water transport properties. • Soil water flux and pore continuity are greater within than between crop rows. • Intensive tillage creates non-persistent changes on soil hydro-dynamic properties. Soil hydraulic properties and pore continuity are important parameters of soil quality and may differ among tillage systems, crop rotations, and change over time. However, there are some contrasting results, depending on soil type, climate and cultivation history on the spatial and temporal variations. The objective of this study was to determine spatio-temporal dynamics of soil hydraulic properties and pore characteristics (i.e., pore volume, effective porosity, and continuity) on a silt loam long-term tillage field experiment, in Agramunt, NE Spain, during two cropping years. Undisturbed soil samples were used to determine soil water retention, θ(Ψ) , and soil hydraulic conductivity, K(Ψ) , curves in two different tillage systems (intensive tillage, IT vs no-tillage, NT), two crop sequences (short fallow-maize, FM vs legume-maize, LM) and two positions (within the row of crops, W-row vs between the rows of crops, B-row). The results revealed that LM had greater specific hydraulic conductivity, K pc in its macroporosity (>1000 µm) than FM due to greater number of effective pores, N pc and effective porosity, ε pc. Soil water content, θ was greater under IT than under NT at higher soil water matric potential, Ψ (≥-3 cm H 2 O), whilst the opposite was observed at lower Ψ (≤ − 50 cm H 2 O). Long-term NT showed greater hydraulic conductivity, K at higher Ψ (≥ − 10 cm H 2 O) than IT, and no difference at lower Ψ. Although IT had greater pore volume, ϕ pc than NT in the macroporosity and coarse mesoporosity (1000–60 µm) pore size classes, NT had two times greater K pc than IT due to increased N pc , ε pc , and pore continuity, C wpc. K(Ψ) and pore characteristics showed spatial variations (W-row vs B-row). W-row had significantly greater K at higher Ψ (≥ − 3 cm H 2 O) than B-row. Temporal dynamics of soil hydraulic properties and pore characteristics were not evident under IT during crop succession. This study shows that LM increases specific hydraulic conductivity of soil macroporosity by increasing the number of effective macropores and the effective porosity. In a Mediterranean climate, this may improve the hydrological functions of agricultural soil and associated crop yield. Further, long-term NT formed a stable number of effective macropores and coarse mesopores, and showed a greater pore continuity in coarse and fine mesopores, resulting in improved soil water flux. [ABSTRACT FROM AUTHOR]