Dangerous Respirable Dust Increased by Organic Farming in California

Airborne Dust From Cultivation

Airborne Dust From Cultivation

Health effects of breathing dust can be major. When inhaled, small dust particles can travel easily to the deep parts of the lungs and may remain there, causing respiratory illness, lung damage, and even premature death in sensitive individuals. People in California are exposed to unhealthful levels of small dust particles more frequently than to any other air pollutant measured. California farmers have minimized dust emissions by using herbicides to reduce weed populations instead of plowing the dry soil.  However, organic farmers do not use herbicides and cultivate their fields which results in significant increases in respirable dust in California.

“Respirable dust (RD), defined as particles smaller than 4µm diameter, was collected at the implement from 29 farming operations performed for furrow-irrigated tomato, corn, and wheat crop production over a 2-year period. …Among the cropping systems studied, those that required more tillage or land preparation to be performed when the soil was driest produced the most RD.

Cultivation of organically managed corn caused the greatest increase in RD, more than four times baseline.

In the organically grown crops, all operations related to soil structure improvement were performed in the dry fall. The organically grown corn was disked five times and land planed only once in the fall, while the organically grown tomatoes had four disking and three land-planing operations. As a result, the organically grown tomatoes had a much higher RD production. As in 1994, the organically grown crops produced more respirable dust than their conventional counterparts. The RD increase relative to conventionally grown crops ranged from 15% for the organically grown corn to 40% for the organically grown tomatoes.”

Authors: Clausnitzer, H., and M. J. Singer.
Affiliations: Department of Land, Air & Water Resources, UC Davis.
Title: Intensive land preparation emits respirable dust.
Source: California Agriculture. 1997. 51[2]:27-30

Cover Crops Provide Many Benefits-But Must be Terminated


Cover crops are crops that are planted between the traditional growing seasons and generally without intent to harvest. Cover crops provide many benefits: reduced erosion, reduced nutrient leaching, increased soil organic matter, and improved soil productivity. However, cover crops need to be terminated so that the next crop can be planted and herbicides are a preferred termination method, as described in a recent article about a progressive California tomato farmer……

“During the past seven years, Sano Farms… has also refined a production system for processing tomatoes that uses cover crops, subsurface drip irrigation, and conservation tillage practices. Their system saved fuel by reducing the number of tractor operations, cut fertilizer inputs, reduced labor, improved soil condition, reduced overall variation in yield, and increased tomato yields up to 15% relative to the standard practices that were previously used.

An important component of the integrated tomato production system at this farm is the use of winter-grown triticale cover crop. These cover crops are typically seeded in late October or early November, sprinkler irrigated as part of the farm’s “preirrigation” program for the subsequent year’s crop, and then ended with herbicide typically in early February before the aboveground growth becomes too difficult to manage.”

Authors: Mitchell, J. P., et al.
Affiliations: Department of Plant Sciences, University of California..
Title: Evolution of conservation tillage systems for processing tomato in California’s central valley
Source: Hort Technology. October 2012. 22(5):617-626.