Reduction of spacing and increase of sowing density to reduce weed pressure

Case studies - Chambre d'Agriculture Occitanie - Aglae - Jérôme Sainte-Marie - Weed management

Field crops Weed control in field crops Weed control

Hautes-Pyrénées (département)

95 ha

1

Loamy soil

Arable crops

Arboriculture

ACS

Irrigated system

Feedback from Jérôme Sainte-Marie, as part of the Aglae project. He explains how he reduced the spacing and increased the seeding density of his maize crop to combat weeds.

Motivations

When I installation on the family farm in 2002, I began implementing no-till for cereal straw crops, soybean and cover crops on part of my farm. I realized that the soil quickly became covered and I had few problems with weeds.

At the same time, I was growing maize with a standard planter and had more difficulty keeping the fields clean because the maize took time to close the furrow. I thought it would be interesting to narrow the maize rows to be able to space the plants on the furrow. Thus each plant would have more room, develop faster and cover the furrow more quickly.

This modification of the spacing between rows and between plants now serves as a lever to limit weed development in my maize, soybean and sorghum fields.

Implementation

Spacing - density, my method

Planting

Between plants: 25cm
Between rows: 40cm

No-till at 40cm

Tools:

1 single-grain planter (Sola) at 40cm
double hopper for seeds and a slug control hopper
corrugated discs at the front
seed positioning, coulter at the front
equipped with a front tank that allows placement of liquid fertilizer at the front of the seed row.

Crops concerned:

Irrigated soybean: The objective is to leave space between plants because, under irrigation conditions, too high a density leads to poor aeration between plants and can promote the appearance of sclerotinia.

Irrigated maize: Planting is done in the living cover of fava bean/phacelia. The goal is for the maize to develop as quickly as possible to cover the soil, close the furrow and prevent the development of possible weeds, especially datura.

Seeding density

Before: Seeding at 75 cm between rows and 17 cm between plants --> seeding density = 85,000 seeds/ha

Today: Seeding at 40 cm between rows and 25 cm between plants --> density = 100,000 seeds/ha

Harvest

Tools: standard maize picker

Specificity: harvesting 2 rows at once

Yield

"Maize programs the number of seeds per ear at an early stage of its development. If maize develops quickly when young, it will increase its seed number programming. In 2016, I used the variety P9900. Since 2017, I have used a variety more suited to my new no-till seeding technique at 40cm (P9838). This variety allows a rapid start of maize and thus ultimately an increase in yield."

Benefits and points of caution

Benefits

Rapid soil coverage
Limits weed development

Points of caution

Requires specific equipment for weed control operations
Reduced forward speed during harvest

My tips for success

Sow on dry soil
Pay attention to poorly distributed cover crop residues on the soil. A heterogeneous cover increases the risk of weed development.
Anticipate variety choices adapted to this density
For more effectiveness, combine with other levers

My outlook

Extend the rotation of my dryland system to 4 years
Implement permanent cover crops

Leviers évoqués dans ce système

My results

Agri-environmental

Reduction of herbicide IFT (0 to 10%)
Reduction of weed pressure
Stability of pest pressure
Stability of disease pressure

Social

Stability of working time
Stability of observation time

Economic

Reduction of mechanization costs
Increase in net margin
Increase in implementation cost

Expert committee opinion

Evaluation according to the ESR analysis grid.

Efficiency

The objective is to increase the efficiency of available control methods through the development of technologies that improve their use or by better positioning. In this context, decision support tools as well as precision agriculture are positioned.