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Contribution of cover crops in cropping systems in relation to crop yield, the nitrogen dynamic in the soil and their impacts on the soil quality

Principal Investigator

Anne Vanasse

Research Institution

Université Laval

External Funding Partners

Ministère de l'Agriculture, des Pêcheries et de l'Alimentation du Québec (MAPAQ): Programme Innov'action agroalimentaire (Cultivons l'avenir 2), Innovagrains

Ces travaux ont été réalisés grâce à une aide financière du Programme Innov'Action agroalimentaire, un programme issu de l'accord Cultivons l'avenir 2 conclu entre le ministre de l'Agriculture, des Pêcheries et de l'Alimentation, et Agriculture et Agroalimentaire Canada.

Project Start

June 2014

Project End

May 2017

Objectives

  • Quantify the effects of cover crops on cash crop yields and on nitrogen dynamic in soil through the use of meta-analysis (compile and classify data from both literature and unpublished studies) and provide information on the effects of cover crops on soil quality and on nitrogen leaching losses.

Impact

  • The identification of the best management practices of cover crops in cash crop production considering the cash crop yield and the soil quality will lead to rapid adoption of cover crop use in producer's cropping rotation.
  • The establishment of the nitrogen contribution from cover crops will improve the production efficacy and greater economical return to producers through efficient use of nitrogen fertilizer.

Scientific Summary

Cover cropping systems is a best management practice that capture and recycle excess nutrients in the soil profile while minimizing soil erosion. There has been a renewed interest in this cropping practice in the last few decades. Interseeded or seeded after a main crop, cover crops (CC) improves fertility and soil quality with a considerable potential to maintain or enhance crop yields by the nitrogen contribution derived from these green manures once returned to the soil, or by the improved soil structure. The potential benefits of CC to crop productivity are determined by the CC type (legumes, non-legumes, and mixtures), the CC biomass production, and the timing and methods of CC termination. Further, synchrony between crop nitrogen (N) demand and CC mineralization is critical in this process for which environmental and management-related factors act as important modulators. Consequently, the performance of CC depends on site-specific factors, making it difficult to identify best management practices.

This project aims to document the impacts of CC on subsequent cash crop yields, the soil quality and the soil nitrate retention. It also aims to establish precisions about the N contribution from CC to adjust the nitrogen fertilizer of the different crops in the fertilization plan. In this study, we performed a meta-analysis of data from 110 field experiments (peer-reviewed or unpublished literature) to provide a comprehensive and quantitative approach of CC influence to cash crop systems. We quantified (1) the effect of CC on cash crop yield, (2) the N contribution of CC to cash crop growth (compared to bare fallow), and (3) the variation of these impacts across a wide range of systems. Data were included if they met the following criteria: (1) CC were grown (intercropping, successive or full season systems) with a subsequent cash crop (corn, soybean, cereals); (2) a control treatment without CC was present; (3) the treatments were replicated; (4) the study has been conducted under humid temperate climate; and (5) cash crop yield, CC biomass and N concentrations in plant tissues were reported, which allowed us to estimate the relative contribution of CC to subsequent cash crop yields in terms of yield ratio (Yield with CC \Control Yield without CC). Nitrogen contribution of CC will be discussed comparing the aboveground N yield of the CC, the apparent recovery of CC N, and the fertilizer replacement value. The modulation of CC benefits on cash crop yields, soil quality and soil nitrate retention, by other factors (i.e., CC types, soil properties, management practices and environmental conditions) will be described.

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sustainability
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