Performance of overwinter cover crops in coastal Lebanon

Abstract

The effect of the cover crops, narbon vetch (Vicia narbonensis), oat (Avena sativa), forage radish (Raphanus sativus), on weed suppressionandsoil nitrogenwas studied in field conditions overwinter. The impact of their residues on the productivity of a subsequent corn crop was followed in the summerof the same year. Between mid-November andMarch oat produced, on a dry weight basis,915 g m-2against 402 g m-2for narbon vetch and 292 g m-2for radish. Consequently, weeds were suppressed best in the presence of oat. Narbon vetchwas less effective than radishin controlling weeds, as it was slowerto get established. In terms of mineral nitrogen, soils occupied by radish (13.1 mg kg-1soil) presented smaller concentrations of ammonium-Nthanthose by vetch(18.7 mg kg-1soil)and the control(19.7 mg kg-1soil). Following the overwinter covercrops, plots were split intoone half whereroots only were incorporated,and another half receivingwhole plants. Residues of whole plants promoted higher production of corn in the booting and flowering stages, as compared to roots only. At the 50% doughstage, the highest dry matter yield was 7.6 Mgha-1afternarbon vetch. Cornyield was the smallest after oat, due to N immobilization. This was demonstrated, using the litter bag technique, when oat residues (15.6g N kg-1) lost 31% of their N against 66% for radishresidues(21.1g N kg-1).For an effective control of weeds and nutrient recycling a cover crop, such as oat, is most efficient. In this case, the succeeding summer crop needs to receive some extra nitrogen.

Assessment of Soil Management Practices Enhancing Soil Resilience in Small-Scale Agroecosystems: Case of Mount-Lebanon

“…Another risk is soil water erosion, especially between the beginning of Autumn and the end of Spring, either because the soil is unprotected or only partially protected (Boulal et al, 2011). However, farmers growing winter cover crops manage to mitigate water erosion in winter season (Rouphael et al, 2019). Contrarily, irrigationinduced erosion is dependent on other management practices.…”

“…They reduced soil erosion and runoff, improved nitrogen cycling, weed and pest control, enhanced soil quality and increased yields (Baldivieso-Freitas et al, 2018). In a study from Lebanon, oat (Avena sativa) was used as a strategic overwinter cover crop to suppress or reduce weed and enhance nutrient cycling compared to forage radish and Narbon vetch (Rouphael et al, 2019). Therefore, the adoption of sustainable practices in soil management is essential in the Mediterranean basin (Aznar-Sanchez et al, 2020), particularly, increasing organic matter content to maintain soil productivity and reduce erosion and desertification (Zdruli and Zucca, 2018).…”