Sustainable alternative to irrigated maize monoculture in a maize-dominated cropped area: Lessons learned from a system experiment
Résumé
Maize is the most-produced food crop in the world and is grown in intensive rotations or in
monoculture (continuous maize) systems. As maize production has expanded massively across the
world, many concerns have emerged about its local environmental and other global impacts.
Agronomists have designed innovative cropping systems and assessed them using system exper-
iments to make arable systems more sustainable. However, knowledge is still lacking on the
sustainability of innovative cropping systems compared to highly intensive systems such as irri-
gated maize-based monoculture. Here, we present the assessment results of a nine-year system
experiment in Alsace, France, developed to compare an innovative system based on a diversified
rotation and innovative management practices (three-year rotation of maize/soybean/winter
wheat (plus a cover crop) combined with reduced tillage) with a continuous maize reference
system. The results cover a six-year assessment period following an initial three-year design
period. Classic criteria, such as profitability, workload, pesticide use, fossil energy consumption
and nitrate leaching, were assessed along with other less studied criteria, such as pesticide
leaching risk, soil structure, soil chemical quality and soil biological activity. Sustainability –
which includes environmental, social and economic dimensions – was assessed with the MASC 2.0
method. Overall sustainability was substantially enhanced in the innovative system (5 out of 7
sustainability classes) in comparison with the low level of the reference system (2 out of 7). This
was due to a clear improvement in the environmental performance (from 2 out of 5 to 5 out of 5)
while social performance was high in both systems (4 out of 5) and economic performance was
low (2 out of 5) due to very low contribution to economic development. Nevertheless, the
innovative system had a major drawback: lower profitability, especially when scenarios included
high maize prices. Furthermore, herbicide use on maize was higher in the innovative system than
in the reference one. Avenues for progress, such as encouraging stakeholder participation at the
assessment stage or additional innovations such as multiple cropping, are suggested.
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