Low-Input Maize-Based Cropping Systems Implementing IWM Match Conventional Maize Monoculture Productivity and Weed Control

Guillaume Adeux,Jean-Marie Savoie,Stéphane Cordeau,Simon Giuliano,Lionel Alletto

doi:10.3390/agriculture7090074

Abstract

Conventional Maize Monoculture (MM), a dominant Cropping System in South-Western France, is now questioned for environmental reasons (nitrate leaching, pesticide use and excessive irrigation). Three low-input Cropping Systems (CS) using diverse weeding strategies (MMLI, a Low-Input MM implementing ploughing, a combination of on-row spraying and in-between row cultivation and cover crops; MMCT, Conservation Tillage MM implementing chemical control and cover crops; Maize-MSW, maize managed similar to MMLI but rotated with soybean & wheat) were compared to a reference system (MMConv, a conventional MM with tillage and a high quantity of inputs). Potential of Infestation of weeds (PI), weed biomass and crop production of these CS were compared during the first five years after their establishment. Yields were also assessed in weed-free zones hand-weeded weekly in 2014 and 2015. Weed communities did not drastically differ among CS. PI and weed biomass were higher in MMCT, especially for Echinochloa crus-galli (L.) P.Beauv. and were comparable between MMConv, MMLI and Maize-MSW. Analysis of covariance between CS and weed biomass did not reveal a significant interaction, suggesting that weed biomass affected yield similarly among the CS. Comparison between weedy and weed-free zones suggested that weeds present at maize maturity negatively affected yields to the same extent for all four CS, despite having different weed biomasses. Grain yields in MMConv (11.3 ± 1.1 t ha−1) and MMLI (10.6 ± 2.3 t ha−1) were similar and higher than in MMCT (8.2 ± 1.9 t ha−1. Similar yields, weed biomasses and PI suggest that MMLI and Maize-MSW are interesting alternatives to conventional MM in terms of weed control and maize productivity and should be transferred to farmers to test their feasibility under wider, farm-scale conditions.

Highlights

Emerging weeds, such as Echinochloa crus-galli (L.) P.Beauv., can generate potential grain yield losses of up to 35% in maize (Zea mays L.) [1]
The present study aims to compare weed pressure and maize yields and explore the link between the two in a five-year low-input cropping system experiment that had the objective to improve cropping system sustainability, mainly through input reduction [42]
The combination of farming practices, such as annual mouldboard ploughing [49], systematic use of pre‐emergence herbicides [50] followed by one or two remedial sprays [51], techniques known to be efficient weed‐management tools, provided acceptable weed control and achieved high yields. This reference cropping that the decision rules and resulting weeding and farming practices were sufficient to ensure the economic viability of this cropping system [42]

Summary

Introduction

Emerging weeds, such as Echinochloa crus-galli (L.) P.Beauv., can generate potential grain yield losses of up to 35% in maize (Zea mays L.) [1]. Herbicides represent 78% of the total number of pesticide applications at the referenced dose in French conventional maize monoculture [2]. The massive use of herbicides favours weed resistance [3] and generates water pollution especially when paired with irrigation and high nitrogen (N) fertilization [4]. Agriculture 2017, 7, 74 monoculture is a dominant cropping system in South-Western France [2]. Maize monoculture has high yields and financial returns but European and French authorities, through the EU Water Directive (2000/60/EC) and the national Ecophyto plan, respectively, encourage farmers to update their farming practices in order to reconcile environmental and economic performances. There is an increasing need to design Integrated Weed Management (IWM) cropping systems that remain profitable and in which weed control does not primarily depend on herbicides [5]

Methods

Results

Discussion

Conclusion