Diversifying grain-based cropping systems for a sustainable agriculture

Picture copyright Adeux et al.

Herbicides jeopardize the sustainability of agriculture. Unfortunately, no alternative weed management tool can level with their efficacy. Based on 17-years of observations, Scientists Adeux et al. showed that diversified crop rotation allowed low herbicide use, long-term weed management, and high productivity in grain-based cropping.

Cultivating globe artichoke and cardoon to prevent weeds in Mediterranean rotations

Picture copyright AH Cain, Inra

Weeds represent one of the most important pests in agroecosystems. Recently, scientists Scavo et al. found that globe artichoke, cultivated and wild cardoon significantly reduced the number of seeds in the soil thanks to their allelopathic activity. They also observed a positive effect on some bacteria involved in the soil N-cycle. The introduction of these species in Mediterranean crop rotations could hence decrease the utilization of synthetic herbicides.

Air-propelled agricultural residues kill weeds

Picture copyright Perez-Ruiz et al.

Crop production often results in abundant agricultural residues, and organic crop production suffers from an overabundance of weeds. Scientists Perez-Ruiz et al. recently showed that several gritty-textured residues, particularly those derived from maize cobs and olive pits, could abrade weed seedlings when propelled by air. Their use can contribute to the non-chemical control of weeds requested by organic farming and offers a potential solution to address herbicide-resistant weeds.

95% less herbicides in maize using improved drone imagery to locate weeds

Picture copyright López-Granados et al.

Johnsongrass, one of the most competitive weeds in maize, is actually controlled by broadcast application of at least two herbicide treatment. Agronomists López-Granados et al. designed a high-resolution method to locate weeds using drones to take visible and near infrared pictures, then algorithms to map johnsongrass patches (light green) in maize rows (dark blue). They deduce that site-specific control would save up to 95% herbicides, which will be consistent with European and the Spanish legislations.

Weeds to reduce nitrogen pollution

Picture copyright WORTMAN

Cover crops reduce nitrogen pollution from croplands, but naturally occurring weeds may provide similar benefits during fallow periods. Agronomist Wortman shows that nitrogen loss is 60% lower in weedy fields than in bare fields. Cover crops are 26% more effective than weeds in reducing nitrogen loss, but given the issues of cover crop adoption, cultivation of fallow weeds looks promising.

Weeds are good for agriculture, yes they are!

Picture copyright Hanzlik and Gerowitt

In industrial agriculture weeds have been considered solely as undesired plant species that should be removed with pesticides. Now scientists have found that weeds could help farming by, e.g., pollination, preventing water and soil runoff, and attracting predators of crop pests. There is therefore a need of weed surveys across Europe. Agronomists Gerovitt and Hanzlik reviewed the methods of weed surveying in 43 surveys, mainly in Europe, covering up to 4423 fields.

 

The fragile weed-bee affair

rollin
Picture copyright ROLLIN et al.

A million-years old relationship has been established between bees and weed flowers. Weeds indeed provide food to bees in the form of tasty pollen, and bees carry pollen from plant to plant to ensure pollination, weed reproduction and diversity. This win-win relationship is endangered by industrial agriculture practices such as weed control and the use of insecticides. Scientists Rollin et al. review agricultural practices that modify weed-bee long-standing collaboration.

 

Weeds do not decrease yields in organic farming

Industrial agriculture is a major cause of global warming due to greenhouse emissions of CO2 and N2O. Reducing the tillage is a potential solution because emissions are lower. However, in organic farming, the lack of herbicide should favour weed infestation. But are weeds really a problem for productivity? Armengot et al. compared the effect of reduced and conventional tillage on crop yields and weeds in a 2002-2011 field experiment under organic farming. They found that despite higher weed infestation by perennial species under reduced tillage, yields of wheat, sunflower and spelt were similar for both tillage systems. Therefore findings show that reduced tillage is a viable cropping system for organic farming.