False Seedbed for Agroecological Weed Management in Forage Cereal–Legume Intercrops and Monocultures in Greece

Abstract

Intercropping cereals with legumes is a widely used agronomic practice to improve forage yield and quality in forage cropping systems. The main objective of the present study was to investigate the potential of a false seedbed to reduce weed pressure in intercrops and monocultures of annual ryegrass and berseem clover during the 2020–2021 and 2021–2022 growing seasons in western Greece. A split-plot randomized complete block design with four replications was set up. Seedbed manipulations assigned to the main plots included: normal seedbed preparation (NSB) and seeding, and two different false seedbeds. In the first (FSB 1) and second false seedbeds (FSB 2), weeds were controlled by shallow tillage at 1 and 2 weeks, respectively, after the first tillage and immediately before crop sowing. Forages were subplots of berseem clover (BCM) and annual ryegrass monocultures (ARM) and three intercrops with BCM:ARM ratios of 75:25 (ARBC 1), 50:50 (ARBC 2), and 25:75 (ARBC 3). FSB 1 reduced weed biomass by 27% and 34% compared to NSB in 2020–2021 and 2021–2022, respectively (p ≤ 0.001). FSB 2 improved forage yield by 9% and 14% in 2020–2021 and 2021–2022, respectively, compared to FSB 1. Compared to NSB, FSB 2 also increased forage yield by 11% in 2020–2021 and 17% in 2021–2022. Berseem clover biomass was higher in FSB 2 than in NSB main plots in both years. In the first harvest, ARBC 3 was the most weed-suppressive intercrop, which also provided the highest forage yield in both the first and second harvests of both years, followed by ARM and ARBC 2. In the second harvest, forage yield was 11% and 12% higher in ARBC 3 subplots than in ARBC 1 and BCM subplots, respectively. Similar results were obtained for cumulative forage yield from two harvests. Further research is needed to evaluate other alternative practices for agroecological weed management in low-input forage production systems in the Mediterranean region.