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- Introduction:
European agriculture is specialized in cereal production, presenting agronomic and environmental risks, and increasing the dependence on imported high-value protein (Watson et al., 2017). For instance, rainfed and irrigated Mediterranean agriculture is highly based on continuous winter cereals and maize (Zea mays L.), respectively. The objectives were to i) redesign and assess Mediterranean rainfed and irrigated cropping systems when introducing grain legumes, ii) maximise soybean (Glycine max Merr.) performance by exploring later maturity groups than currently used, and iii) study alternative soybean weed management strategies for irrigated single and double cropping systems (SCS and DCS, respectively). - Materials and methods:
Redesigned cropping systems were assessed in two on-farm field experiments from 2019 to 2022 and managed under no-till management practices. In the rainfed area, the focus was on diversification with pea (Pisum sativum L.), faba bean (Vicia faba L.) and a multiservice cover crop as alternatives to wheat (Triticum aestivum L.) combined with increasing N fertilization rates (0, 40, 80, 120 kg N ha-1). Under irrigated conditions, crop diversification (soybean introduction) and intensification (from SCS to DCS) were studied as alternatives to continuous maize. In both cases, cropping systems’ productivity (energy and protein) and N use efficiency were calculated (Simon-Miquel et al., 2024a, 2023a). At the soybean crop level, the field experiments focused on soybean maturity groups (from 00 to III) for SCS and DCS (Simon-Miquel et al., 2024b) and sustainable soybean weed management strategies including row width narrowing (75 to 37.5 cm), herbicide application and using a roller-crimped rye (Secale cereale (L.)M.Bieb.) cover crop for SCS and the two former ones for DCS(Simon-Miquel et al., 2023b). - Results:
Legumes introduction in rainfed and irrigated cropping systems led to an increase in protein production and a decrease in energy production per unit of surface. Under rainfed conditions, N fertilization increased protein yields, with the faba bean cropping system presenting the highest yields at all N fertilizer rates. Under irrigated conditions, diversification with soybean in the SCS did not lead to an increase in protein production (921 kg ha-1 yr-1, on average). Instead, intensification with barley (Hordeum vulgare L.)-maize, and especially barley-soybean DCS, showed a higher protein production (1129 and 1778 kg ha-1 yr-1, respectively). A range of 17-28% yield increase was observed in cereals following legumes in rainfed and irrigated cropping systems. In the rainfed systems, 18% and 40% of the total N input in the pea and faba bean cropping systems was supplied by biological N fixation, respectively. A positive net N balance (i.e. biologically fixed N > exported N) was found in most cases, likely contributing to the pre-crop effects. The use of later soybean maturity groups (II and III) than currently used (00 to I) led to yield increases ranging from 33% to 80% in SCS. Regarding soybean weed management, a reduction of 92% of weed biomass was observed when rye biomass was 11.4 t DM ha-1, whereas no effect was found below 4 t DM ha-1. Narrowing row widths did not affect weed pressure or soybean yield, probably due to the presence of mulches (rye in SCS and barley crop residues in DCS). -
Discussion:
Cropping systems redesign with a larger share of grain legumes is a strategy to increase protein production while reducing the need for synthetic N fertilizer in Mediterranean areas, thus contributing to their sustainability. Such an increase in protein production is accompanied by a decrease in energy production (Notz et al., 2023), although partially offset by the positive pre-crop effects of legume crops on the following cereal. Soybean yield under Mediterranean irrigated conditions can be improved with the use of later maturity groups, confirming previously simulated results across Europe (Nendel et al., 2023). The use of a roller-crimped rye cover crop in a soybean SCS can be an effective weed control strategy, provided enough rye biomass is accumulated before soybean planting. -
References
Nendel et al. 2023. https://doi.org/10.1111/gcb.16562
Notz et al. 2023. https://doi.org/10.1007/s13593-022-00861-w
Simon-Miquel, G. et al. 2023a. https://doi.org/10.1016/j.eja.2023.126817
Simon-Miquel, G. et al. 2024a. https://doi.org/10.1016/j.fcr.2024.109307
Simon-Miquel, G. et al. 2024b. https://doi.org/10.1016/j.fcr.2024.109274
Simon-Miquel, G. et al. 2023b. https://doi.org/10.1002/agj2.21409
Watson, C.A.et al. 2017. https://doi.org/10.1016/bs.agron.2017.03.003
| Keywords | Biological N fixation; Grain legumes; on-farm research |
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