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Question

How do big commercial organic farms control the weeds in their fields?

How do big commercial organic farms, like Earthbound Farms, control the weeds in their fields?

Submitted by: Robyn Flipse


Answer

Expert response from Rob Wallbridge

Farmer

Tuesday, 04/08/2015 12:30

Weed control on organic farms is accomplished using a number of integrated short and long-term strategies. An infographic I recently posted on my own blog illustrates the wide variety of approaches available, but obviously not every strategy will apply to every farm.

 

On large-scale organic vegetable farms, weed control starts with ensuring a healthy soil with fertility levels matched to the particular crop being grown. (Low fertility will often give weeds an advantage over the crop, while excess fertility allows the weeds to flourish alongside the crop.) Fields are usually rotated between vegetable crops and cover crops designed to increase soil health and to break weed, pest and disease cycles.  In both vegetable and cover crops, preventing weeds from setting seeds will reduce the number of weed seeds in the soil in each following year (an old saying goes “one year seeding equals seven years weeding!”).

 

Depending on the crop, some vegetables may be grown on long, narrow sheets of black plastic mulch that suppress weed growth around the crop plants. This mulch is removed at the end of each growing season, although some farmers (myself included) are experimenting with biodegradable mulches made from corn starch. Mulching with other materials like straw is an option for smaller growers, but less likely to be practiced on a larger scale. Research is underway using living mulches and mulches killed by rolling/crimping just before planting; some farms have experimented with it and it may play a larger role in the near future.

 

Another popular option is flame weeding: propane torches pass down crop rows at high speeds, and the blast of heat kills tender young weeds without harming the crop, which is usually protected either by shields or by its larger size. Researchers are also busy investigating option like “blasting” weeds with grit, “cooking” them with steam, or “frying” them with electricity, though none of these options are in current widespread use.

 

Aside from preventive measures and the promise of new innovations, cultivation remains the most popular short-term strategy for immediate weed control. There is a huge diversity of machines designed to weed between rows of plants, and often between the plants themselves -- different implements are better suited to different crops, soils, and farms. A common trait is the desire to eliminate weeds while causing as little soil disturbance as possible; cultivating too much and too deep not only hurts soil structure and soil biology, but it can also damage crop roots and bring new weeds seeds to the surface.

 

Computer and robotic technology is helping make mechanical weed control more efficient and effective: farmers use GPS systems to guide their equipment down crop rows, and sensors can even distinguish between vegetable plants and weeds! This YouTube video describes a number of mechanical weed control methods. (The video mentions the “organic herbicide” option, but at the present time, I am not aware of any organic-approved herbicides that have proven economical and effective for use in commercial production – as computerized, precision tools are developed, products like white vinegar and certain plant oils may become viable options in these situations.)

 

The aim of all these measures is to avoid the weed control option of last resort: hand weeding. The process of removing weeds by hand (usually with some type of tool) is the most definite way to get rid of weeds, but it is also the most labor-intensive and expensive. For particular crops and in certain situations, however, it remains a necessary component of the integrated weed control system.

Answer

Expert response from Rob Wallbridge

Farmer

Tuesday, 04/08/2015 12:30

Weed control on organic farms is accomplished using a number of integrated short and long-term strategies. An infographic I recently posted on my own blog illustrates the wide variety of approaches available, but obviously not every strategy will apply to every farm.

 

On large-scale organic vegetable farms, weed control starts with ensuring a healthy soil with fertility levels matched to the particular crop being grown. (Low fertility will often give weeds an advantage over the crop, while excess fertility allows the weeds to flourish alongside the crop.) Fields are usually rotated between vegetable crops and cover crops designed to increase soil health and to break weed, pest and disease cycles.  In both vegetable and cover crops, preventing weeds from setting seeds will reduce the number of weed seeds in the soil in each following year (an old saying goes “one year seeding equals seven years weeding!”).

 

Depending on the crop, some vegetables may be grown on long, narrow sheets of black plastic mulch that suppress weed growth around the crop plants. This mulch is removed at the end of each growing season, although some farmers (myself included) are experimenting with biodegradable mulches made from corn starch. Mulching with other materials like straw is an option for smaller growers, but less likely to be practiced on a larger scale. Research is underway using living mulches and mulches killed by rolling/crimping just before planting; some farms have experimented with it and it may play a larger role in the near future.

 

Another popular option is flame weeding: propane torches pass down crop rows at high speeds, and the blast of heat kills tender young weeds without harming the crop, which is usually protected either by shields or by its larger size. Researchers are also busy investigating option like “blasting” weeds with grit, “cooking” them with steam, or “frying” them with electricity, though none of these options are in current widespread use.

 

Aside from preventive measures and the promise of new innovations, cultivation remains the most popular short-term strategy for immediate weed control. There is a huge diversity of machines designed to weed between rows of plants, and often between the plants themselves -- different implements are better suited to different crops, soils, and farms. A common trait is the desire to eliminate weeds while causing as little soil disturbance as possible; cultivating too much and too deep not only hurts soil structure and soil biology, but it can also damage crop roots and bring new weeds seeds to the surface.

 

Computer and robotic technology is helping make mechanical weed control more efficient and effective: farmers use GPS systems to guide their equipment down crop rows, and sensors can even distinguish between vegetable plants and weeds! This YouTube video describes a number of mechanical weed control methods. (The video mentions the “organic herbicide” option, but at the present time, I am not aware of any organic-approved herbicides that have proven economical and effective for use in commercial production – as computerized, precision tools are developed, products like white vinegar and certain plant oils may become viable options in these situations.)

 

The aim of all these measures is to avoid the weed control option of last resort: hand weeding. The process of removing weeds by hand (usually with some type of tool) is the most definite way to get rid of weeds, but it is also the most labor-intensive and expensive. For particular crops and in certain situations, however, it remains a necessary component of the integrated weed control system.