As an example, Ogunjemiyo et al studied a more simplified crop setting, consisting of a single, highly evapotranspiring crop in an area with simplified meteorological conditions . Similar uniformity occurs throughout much of the Midwest, where mono-cultures of corn and soybean would permit the study of water vapor patterns while reducing the impact of variation in crop type. The Central Valley, with its large variety of crops and management practices, resulting in non-uniform distributions of aerodynamic roughness, ET rates, and landscape structures throughout the scene, was perhaps not the ideal location to test this approach. Unfortunately, the type of data we used, including AVIRIS– derived water vapor, and LST from MASTER, is not widely available outside of data sets acquired for the HyspIRI-Airborne Campaign. We would suggest a targeted campaign, acquiring combined AVIRIS-MASTER for agricultural studies, over more simplified and better instrumented sites would be of great benefit. Beyond advancing our ability to capture patterns of field-level ET with water vapor imagery, this imagery may prove valuable for regional analyses of water transport. There are many challenges associated with linking water vapor to crops at the field-level as outlined above, but the idea behind this work will likely hold at a smaller scale. Lo and Famiglietti found that in the Western United States the irrigation from California has been shown to increase the summer stream flow of the Colorado River by 30 percent. Water vapor imagery, if acquired more consistently and over larger areas, offers an additional tool that could be used to capture finer scale water vapor transport, to complement models and coarser scale observations from sensors such as MODIS. These large movements of water vapor have implications for climate change and land use, and call upon the need to increase monitoring of water vapor patterns in areas with large irrigation inputs. Therefore, 10 liter pot a study that examines the ability of water vapor imagery to assist in regional water transport assessments could be of high value.
CDPR’s draft use regulations, designed to address pesticide runoff and drift, could have a potentially significant economic impact on California agriculture, as well as to the supporting industries and communities, due in part to the large number of active ingredients listed in the draft regulations. Assessing the potential effects of the regulations is complicated by a number of factors. First, pest management programs for many crops, such as alfalfa, walnuts, strawberries, lettuce, rice and several others, include at least one of the CDPR’s targeted 68 active ingredients and efficacious alternatives are not always available. Often, the most common alternatives to an individual active ingredient are also subject to the draft regulations. Second, mandated buffer zones that define the minimum distance that must be left between a sprayed area and a “sensitive aquatic site,” as a function of the application method, are an important component of the regulations. Third, the amount of field acreage affected by buffers depends on the distribution of crop acreage relative to the location of a sensitive aquatic site. Fourth, the draft regulations propose to use the definition of sensitive aquatic site as “any irrigation or drainage ditch, canal, or other body of water in which the presence of pesticides could cause adverse impacts on human health or aquatic organisms.” This article focuses on the potential economic impacts of the draft regulations for rice production in Colusa and Butte counties due to the listing of two selected active ingredients. It is drawn from a larger report that considers the economic effects of the draft regulations for 20 county-crop pairs. The analyses are performed at the county level because the distribution of crop acreage relative to the location of sensitive aquatic sites is an important determinant of potential economic impacts.According to the National Agricultural Statistics Service , California’s rice crop is the second largest in the United States, accounting for 22% of the value of national rice production. Rice is the tenth most valuable crop grown in California, contributing 2.8% to the total value of production in 2009. In 2009 there were 563,974 acres of rice in California.
The statewide average yield was 4.38 tons per acre, production totalled 2,472,614 tons, and the price of rice was $390 per ton with a total farm gate value of $963,526,000. The top rice-producing counties in California by value are Colusa, Sutter, Butte, Glenn, and Yuba, according to county agricultural commissioners’ data reported by NASS. Rice is the most valuable crop in both Colusa and Butte counties. In 2009 rice accounted for 40.7% and 33.9% of total crop value in Colusa and Butte counties, respectively. Colusa was the top rice-producing county in the state, accounting for 25% of the value of all California rice. In 2009 Colusa County farmers grew 152,400 acres of rice, which yielded an average of 4.5 tons per acre, and produced a total of 685,800 tons of rice; the price was $355 per ton, for a total value of production of $243,459,000. In 2009 Butte County farmers grew a total of 103,416 acres of rice, which yielded an average of 4.7 tons per acre and produced a total of 486,055 tons of rice; the price was $379 per ton, for total value of production of $103,265,000. Together, Butte and Colusa counties accounted for 44% of California rice production in 2009.According to data from Demars and Zhang , a draft report under preparation for CDFA, there was a total of 250,800 acres of rice in Butte and Colusa counties in 2009, divided among 4,947 different fields. For that report they used Geographic Information System technology to combine U.S. Geological Survey National Hydrography Dataset and California Department of Water Resources land-use layer data into a common projected coordinate system. These were then run through a custom script that reported the amount and percent of crop land bordering sensitive aquatic sites. Affected Acreage Demars and Zhang concluded that while the actual acreage that would be in 25-ft. buffers was a small share of total acreage , the number of fields affected was a large share of the total number of fields . Thus, the increased management costs due to the buffers could be substantial. Under a 150-ft. buffer, both the acreage in buffers and the number of fields affected were substantial shares of the total: 19% and 96.5%, respectively. We used Demars and Zhang’s findings, along with base yield information from county agricultural commissioners’ reports, cost information from UC Cooperative Extension cost studies, and estimates of yield reduction from the scientific literature to estimate the changes in gross and net revenues for the two counties in response to the regulations.
The most important active ingredients for rice production that would be prohibited for use in buffers under the draft regulations are propanil , which is used as a cleanup herbicide for weed control, and lambda-cyhalothrin , a pyrethroid insecticide which is used to control rice water weevil. Weeds are the most important pest in rice, reducing yields by 17% in the United States as a whole compared with 8% and 7% losses yield losses due to insects and diseases, respectively. Thus,drainage gutter weed control through a combination of water management, herbicide application, and other methods is crucial for sustaining the productivity of U.S. rice-cropping systems. Propanil is the most widely used herbicide in rice. It is a relatively inexpensive material, to which water grass weeds in rice have not yet developed resistance, unlike other available herbicides, including thiobencarb, cyhalofopbutyl, and bensulfuron-methyl. Thus, growers are able to use it as a cleanup herbicide post-planting, following the application of one or more other active ingredients. Most propanil in Butte and Colusa counties is ground-applied, so there is relatively little scope for growers to reduce the impact of the draft regulations by changing from aerial to ground applications. Because of widespread herbicide resistance among common weed species in rice fields, it is difficult to identify post-planting alternatives to propanil as part of an effective weed management program. There are a few cultural alternatives, including increasing the depth of water in order to “drown” weeds, severely drying the field to desiccate sedges, or using flooding to germinate weeds early and then kill them preplant with a broad-spectrum herbicide such as glyphosate. However, none of these methods are a perfect substitute for propanil. Each compromises the efficiency of the production system and may result in considerable yield loss. In order to compute the effects of the draft regulations on total and net revenues, we specify that propanil is used as a cleanup spray, except in the 25-ft. buffer where no cleanup application is made, and that only half of total field acreage requires a cleanup spray. Based on the scientific literature, we assume that rice yields decline by 40% in the untreated buffer. The per-acre cost of treatment declines by 100% in the buffer because no cleanup spray is applied. Also, the uncontrolled weeds in the non-treated buffer zones will produce large quantities of seeds, thereby fortifying the weed seed bank and ultimately increasing weed populations over time. The rice water weevil is one of the most economically damaging invertebrate pests in California rice. Root pruning by larvae reduces growth, tillering, and yield of affected plants. Buffer zone requirements are particularly problematic for rice water weevil management due to its life cycle and distribution in rice fields. This insect overwinters in grassy areas around rice fields; these areas are usually associated with sensitive aquatic sites such as sloughs and ditch banks. In early spring the rice water weevil moves to flooded rice fields but does not tend to establish very far into the fields. A 25-ft. buffer would encompass most of the area where damage from rice water weevil would be expected to occur. Lamda-cyhalothrin is the major insecticide currently used to control rice water weevil. In 2009 all applications of lambda-cyhalothrin in Butte and Colusa counties were made by air, according to CDPR Pesticide Use Reporting data. This is driven by the timing of post planting applications; rice fields are treated with lambda-cyhalothrin when the rice plants have one to three leaves.
At this stage of development, water movement and soil disturbance caused by the equipment used for ground applications can uproot rice plants, reducing stands. Thus, the timing of the application must be changed in order to change the application method and avoid the 150-ft. buffer requirement. Lamda-cyhalothrin applications made after the three-leaf stage of rice are not effective against the rice water weevil. Recent scientific research findings indicate that pre-flood applications of lambda-cyhalothrin can be effective, although this approach has not been adopted widely by growers.The UC Integrated Pest Management Guidelines for rice water weevil list two alternative chemical controls to lambda-cyhalothrin: -cypermethrin and diflubenzuron . -cypermethrin is a pyrethroid that is also listed in the draft regulations. Hence, it would not be a viable alternative to replace lambda-cyhalothrin if the draft regulations were implemented.However, diflubenzuron is also not available as an alternative buffer treatment because of label restrictions that require a 25-ft. vegetative buffer between ground application areas and bodies of water. Given these limitations, growers concerned with rice water weevils would likely use a preventive, pre-flood ground application of lambda-cyhalothrin if the draft regulations were implemented. In order to evaluate the economic effects of the draft regulations on rice water weevil management costs and associated rice revenues, we compare the current post-flood aerial application method to pre-flood ground application to eligible acreage under the draft regulations. Rice water weevils tend to be economic pests near field edges, and growers do not usually treat entire fields. We proxy this management pattern by assuming that the land within 100 feet of the edge of a field represents, roughly, the land that is treated currently. Under the draft regulations, acreage within 25 feet of a sensitive aquatic site cannot be treated with a ground application. We assume that acreage within this buffer is left untreated, and that lambda-cyhalothrin is groundapplied on the remaining eligible acreage within 100 feet of the field edge. Based on the scientific literature, we assume that the acreage treated with a pre-flood ground application sustains a 15% yield loss and the untreated acreage sustains a 23% yield loss.