Abstract
Abstract Grain corn is the main cereal produced in Portugal. It is grown in intensive monoculture cropping systems that may have negative effects on soil quality, affecting long-term fertility and productivity, and, therefore, the sustainability of the production. A promising management practice to mitigate soil degradation is to grow winter cover crops used as green manure. This study examined the effectiveness of six legume cover crops (LCCs) species in providing agro-ecological services for grain corn systems in the Mediterranean region, specifically in terms of nutrient leaching, nutrient recycling, weed control, and soil fertility. The study was performed in Central Portugal during 2 years, and it assessed legumes/weeds dry biomass yield, their nutrients content, and soil organic matter evolution. Results show that, in general, LCC are well adapted to Mediterranean conditions, yielding large amounts of biomass (up to 8 ton/ha for some clover species). In terms of nutrient leaching mitigation, the overall N–P–K nutrient uptake was 176–20–172 kg/ha. Green manure services enabled a reduction of 35% of N, 50% of P, and 100% of mineral fertilizers for a grain corn production of 12 ton/ha. Weed control by LCC was effective only in the second year of the study and for three clover species (crimson, balansa, and arrowleaf) due to their early establishment and/or high biomass production competing with weeds. Soil fertility was not improved in the short term, LCC incorporation into the soil to a slight depletion of the soil organic matter content.
Highlights
In recent decades, grain corn (Zea mays) has become the main agricultural crop cultivated globally, with more than 1 billion tons produced annually [1]
This study investigated the capacity of six species of legume cover crops (LCCs) to provide agro-ecological services in grain corn systems, to identify the most suitable species for the Mediterranean region
All clover species produced higher dry biomass yields during the second year of the study, whereas yellow lupin and forage pea showed decreasing yield production from the first to the second year. This can be partly explained by earlier flowering of these two species during the second year, with 1 week less of growth before cutting than in the first year, whereas the clover species were cut 2–4 weeks later than in the first year, which led to considerably higher dry biomass production
Summary
Grain corn (Zea mays) has become the main agricultural crop cultivated globally, with more than 1 billion tons produced annually [1]. In Portugal, grain corn is the major cereal grown, representing 56% of total cereal yield, followed by wheat (19%) and rice (16%) [2]. Intensive cropping systems, in particular corn monoculture, can have negative effects on soil quality, affecting long-term fertility and productivity, and, the sustainability of agriculture. In order to improve the sustainability of cropping systems, different management practices have been implemented and investigated. One of the most promising practices suggested to prevent soil degradation is growing cover crops [4,5,6]. Cover crops are a specific form of mixed cropping in which a secondary crop is planted and grown after the main crop is harvested [5]
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