>Pesticide Application and Organic Agriculture

Pesticide Application and Organic Agriculture


Various USDA and other programs have been created to support agricultural areas staying in farming and to support practices that conserve soil, water, and sometimes wildlife.
Category: 
Social Condition

QT: Indicators

What is it?

Pesticide use can impact terrestrial and aquatic biota and ecosystems, as well as affect human health. For this indicator, relative levels of pesticide use in agricultural areas for the 11 subwatersheds from 2008 are reported. In California, data on pesticide use is reported at a relatively fine spatial scale (a square-mile section) in a time series dating back to 1974. The presence of organic farming is another component of wildlife-friendly agricultural practices (Hole et al. 2005). Measures such as the trend in the number of acres farmed and the amount of sales from organic agriculture suggest the level of adoption of such practices. Therefore, trends in organic agriculture in the watershed from the years 2000 to 2005 are also examined. These data are reported at the county level (Klonsky and Richter 2007). Our focus on pesticide use and organic agriculture does not exclude consideration of other positive and negative impacts of farming on community and wildlife health.

Why is it important?

There is a suite of agricultural practices that enhance the ability of working landscapes to support wildlife communities. There is debate about whether biological conservation is best promoted by a strategy of intensive agriculture together with separate conservation reserves or by a strategy of widespread adoption of wildlife-friendly farming practices such as organic agriculture (Fischer et al. 2008). It is clear that management practices such as reduced use or elimination of chemical pesticides or inorganic fertilizers, appropriate management of the un-cropped landscape, and mixed farming (i.e. integration of crops with livestock) benefit a wide variety of taxa in terms of their abundance and species richness at a local scale (Hole et al. 2005, Chamberlain et al. 2010, Fuller et al 2005). Metrics that capture these practices not only indicate improved health of biological communities, but also suggest synergy between economic and ecological health within the watershed. Adoption of organic farming would indicate broader acceptance of wildlife-friendly agricultural practices, as does reduction in total pesticide load.

Target or Desired Condition

This report assumes that the best possible condition for communities and wildlife would be the universal adoption of wildlife-friendly agricultural practices throughout the watershed. Accordingly, this analysis rates “no pesticide use at all” with a score of 100. This analysis assumes the worst possible case as the 95th percentile rate of pesticide use per unit area anywhere in the Sacramento Valley, and assigns this level a score of 0. This also assumes that a rising trend in organic agriculture also reflects approaching the target condition.

What can influence or stress condition?
Pesticide usage is affected by many factors, including change in the crop mix and the number of acres planted, changes in pest pressure, and differing weather conditions (California Department of Pesticide Regulation. 2009.) Economic demand for organic food is another important driver affecting this condition and reflects social desires for more sustainable agricultural practices that don’t harm communities and ecosystems.

Data Sources & Transformations

The California Department of Pesticide Regulation maintains a pesticide use reporting database dating to 1974 (California Department of Pesticide Regulation. 2009) from which we have extracted the most recent (2008) dataset for the Sacramento River Basin counties (Butte, Colusa, Glenn, Lassen, Nevada, Placer, Plumas, Sacramento, Sierra, Sutter, Tehama, Yolo, and Yuba Counties). Trends in the amount of organic farming at a county scale are reported in Klonsky & Richter (2007). Their summary is derived from reports by county of organic crop sales filed with the California Department of Food and Agriculture and available online (CDFA California Organic Program, no date). Map information describing patterns in major crop type across the entire watershed was derived from the California Augmented Multisource Land-cover GIS dataset (Hollander 2007).

Analyses

The pesticide use data was imported into PostGIS and linked to a spatial dataset of the Public Land Survey System for California using identifiers for the meridian, township, range, and section. Total pounds of pesticides per section were calculated using standard SQL queries. This dataset was turned into a raster at 100 meter resolution in Geographic Resource Analysis Support System (GRASS) GIS for tabulation by subwatersheds. The value for the total pounds of pesticides was averaged over the agricultural regions in each subwatershed using the California Augmented Multisource Landcover layer to delineate agricultural pixels. The standard deviation for the indicator value was calculated from a subsample of the pixels in the 100 meter resolution raster map, the fraction of the subsample being chosen so as to randomly draw on average one pixel per square mile section. Trends in the amount of organic agriculture in each subwatershed were assessed qualitatively based on the relationship between crop type patterns and county boundaries.

The value calculated through GIS operations for the number of pounds of pesticide per section averaged over each subwatershed was linearly transformed to an indicator score from 0 to 100. The score of 100 in this scale was assigned for the condition of zero pounds of pesticides, and the minimum score of 0 was assigned for the condition of 19,885 pounds of pesticides, which is the 95th percentile value for the total number of pounds of pesticides on any section in the entire Sacramento Valley watershed.

What did we find out/How are we doing?

Given the intensive agriculture in the Sacramento Valley, it is not surprising that the three lower subwatersheds (Lower Feather, Lower Yuba, and Lower Bear) score low on the index of pesticide use (Figure 1 and Table 1). The mid- to upper-elevation subwatersheds either have very low amounts of land in agriculture or have their agricultural land devoted to pasture; in either case, there are relative small amounts of pesticide applied to agricultural land in these subwatersheds. The trend in organic farming, as indicated by trends in organic acreage (Figure 2) and organic crop sales (Figure 3) is either steady or increasing across time, depending upon the county.

Subwatershed Discussion

Deer Creek — Agriculture in this subwatershed consists mainly of mid-elevation vineyards. The indicator score is near the maximum value of 100, which may reflect fallow lands reported as in agriculture, or simply low levels of pesticide application in this crop type in this region. There are several organic vineyards in the Nevada City area, which is reflected in modest amount of organic agriculture from Nevada County reported in Figures 2 and 3. Based on the Nevada County trends, it appears that there is no upward or downward trend in the amount of organic agriculture in this subwatershed, which will have its own environmental impacts not reflected in the score.

East Branch North Fork Feather — Agriculture here is almost entirely based on livestock grazing and hay production, with no significant use of pesticides. The Plumas County data on organic agriculture shows an increase from essentially no acreage at the beginning of the time period to 3,021 acres in 2005, most of which is pastureland. Some fraction of this increase is assignable to this subwatershed, especially in the Indian Valley area.

Lower Bear — Agriculture production in this subwatershed consists of vineyards in upslope regions and rice and deciduous orchards on the valley floor. Of the three valley floor subwatersheds (the others being Lower Feather and Lower Yuba) it has the best rating for pesticide usage, perhaps because of this cropping pattern diversity. It is difficult to assess trends in organic farming because of an unfavorable alignment of county boundaries and the subwatershed boundary for this analysis.

Lower Feather — Of the subwatersheds in the study, this is the one most dominated by agriculture, with a total of 229,247 acres in agriculture. The indicator score shows fairly high levels of pesticide use, though there is a fair amount of variation, presumably across different crop types. In terms of trends in organic agriculture, the counties that most overlap the subwatershed, Sutter and Butte, show substantial increases in crop revenue, and Butte County shows an increase in acreage as well. Major organic crop types include rice, prunes and peaches.

Lower Yuba — This subwatershed has the lowest indicator score (17) of all the subwatersheds. Agriculture in this subwatershed is mostly limited to deciduous orchards, and dominance by this crop type (which receives high pesticide use) probably accounts for the particularly low score. The increase in sales in organic agriculture in Yuba County is likely mostly due to organic rice and kiwi fruit production, though there may be some organic walnut farming within the watershed.

Middle Fork Feather — Like the East Branch North Fork Feather subwatershed, agriculture in this region is essentially limited to livestock and pasturelands, mostly centered on Sierra Valley. There is no significant use of pesticides in this subwatershed. Some of the increase in organic agriculture in Plumas County discussed above may be attributable to livestock management practices in this subwatershed.

Middle Yuba — Agriculture is an insignificant fraction of land cover on this subwatershed and no appreciable pesticide use.

North Fork Feather — Agriculture is an insignificant fraction of land cover on this subwatershed and no appreciable pesticide use.

North Yuba — There is no appreciable agriculture in this subwatershed, and the indicator cannot be calculated here.

South Yuba — Agriculture is an insignificant fraction of land cover on this subwatershed and no appreciable pesticide use.

Upper Bear — Similar to Deer Creek, the agriculture that exists in this subwatershed is dominated by vineyards, and the indicator value is again near the maximum value of 100. There may be some organic vineyards here, but from the Nevada County trend data, organic farming is probably not changing.

Temporal or Spatial Resolution

Information on pesticide usage is available annually and is reported to each square mile section in the township-range-section geo-referencing system. Information on organic farm production is available annually and is reported for each county.

How sure are we about the findings (Things to keep in mind)

The results of this analysis are limited by the coarse spatial scale of the data. There is no available dataset describing organic agriculture at any finer spatial scale than the county level, which makes attribution to subwatersheds difficult. Moreover, many practices that comprise wildlife-friendly agriculture such as maintenance of hedgerows and appropriate grazing management are difficult to map, requiring much fine-scale survey work. Another limitation is that this analysis takes no account of differences in toxicity in pesticides, instead lumping them together as total pounds of all products applied. The analysis thus is unable to detect usage of what are considered to be less toxic types of pesticides. However, pesticides are by definition toxic to at least some organisms, and given that an ecosystem consists of complex interactions among many different types of organisms, it is very challenging to grade levels of toxicity in terms of impacts on the overall ecosystem. This analysis also makes no attempt to distinguish between levels of pesticides on a per-crop type basis.

Sub-watershed
Area Code Score Trend Confidence
North Fork Feather NFF 99 n/a
East Branch North Fork Feather EBNFF 100 Upward
Middle Fork Feather MFF 100 Upward
Lower Feather LF 51 Upward
North Yuba NY n/a
Middle Yuba MY 98 n/a
South Yuba SY 100 n/a
Deer Creek DC 100 None
Lower Yuba LY 17 Upward
Upper Bear UB 100 None
Lower Bear LB 62 n/a