Agricultural Management Practices
This page will introduce you to valuable information, links and publications regarding agricultural management practices, sometimes called "best" management practices.
Best Management Practices (BMPs): A set of management practices that reduce the potentially negative impact of agricultural operations. These practices are highly adaptable and reflect the individual conditions and capabilities of the farm where they are applied. The goal of the practices is to reduce the off-site movement of applied materials (pesticides and fertilizers) into any surrounding water body, or into groundwater, and does not imply that all practices will work within your farming operation. If the practice adopted achieves that goal, then it is the best practice.
Some examples of management practices are:
CURES Management Practice Slideshows have more information on fertilizer, manure, sediment toxicity and orchard BMPs.
Agricultural Stewardship Publications
The San Joaquin Valley grows more than 250 different types of crops that require a tremendous amount of surface and ground water. This water is used not only for crops but also for groundwater aquifers, water storage and drinking water. Currently, attention has focused on new water regulations and management of water to minimize contamination from agricultural operations. Water quality impacts are categorized as point source or non-point source contamination. Point source runoff comes from water discharged from a pipe, ditch or channel. Non-point source runoff comes from storm or irrigation flow over large parcels of land such as fields, pastures and urban areas. The Irrigated Lands Program (Ag Waiver Program) is an effort to monitor agricultural non-point source contamination that can occur from the following:
- Pesticides (herbicides, insecticides, fungicides)
- Nutrients (fertilizers, septic systems, nitrogen)
- Salinity (naturally occurring and imported salts)
- Trace Elements (naturally occurring elements such as selenium and boron)
- Pathogens (from animal or human waste)
- Temperature changes (related to aquatic life)
- Dissolved Oxygen (related to aquatic life)
- Sediment (soil erosion)
While no specific information regarding grower practices is available, the lack of pesticide detections within the monitoring programs of the Kings, Kaweah, Tule and Kern sub-watersheds indicates that what growers are currently practicing is sufficient to prevent negative impacts on the water of the Tulare Lake Basin.
Laser leveling: Many growers are leveling their fields to improve irrigation efficiency and reduce soil erosion by controlling the velocity of the irrigation water they apply. By making the field uniform in slope, the grower will know when to cut off irrigation water and have no tail water exit the field.
Tail water returns: Some growers with large integrated operations collect their tail water for reuse on the next field in line. All the water is eventually recirculated, and they enjoy very high irrigation efficiency.
Conversion to high efficiency systems: Many growers have or are in the process of converting to drip or micro sprayer irrigation systems, which run according to the crop cover usage. These systems deliver water directly to each plant and have minimal risk of runoff issues.
Irrigation scheduling: With water being a major cost to growers, the application of water exactly when the crop needs it and in the amount needed is becoming more important. In addition, water stress is a great management tool for certain crops to spur plant growth in certain directions (more reproductive growth, less vegetative). Many growers take advantage of irrigation practice review services that give irrigation uniformity evaluations and tips for better management.
Research by the Center for Irrigation Technology can provide more information on new irrigation practices and how to apply them to a variety of agricultural situations.
Other means of capturing runoff:
- Capture storm water using field borders to supplement field irrigation;
- Construct berms at low ends of the field to trap sediment and runoff;
- Use cover crops, vegetation filter strips and buffers to help capture flows; and
- Shorten irrigation runs with checks to manage and capture flows.
The USDA Irrigation and Water Use Glossary
Soil and Sediment Management Practices
GPS guidance: This emerging technology allows a tractor to drive over the same path within a field within inches of the previous pass. This controls the zones where water can collect and run off a field, allowing the grower to better control storm water by knowing which areas of the field will have the lowest infiltration rates. Since implements can go down the same path repeatedly, fertilizers and other chemicals can be directly injected into the soil with minimal disturbance to the surrounding soil. This is linked with the emerging acceptance of conservation tillage/no-till/minimum till.
Conservation tillage: This practice generally improves soil health by leaving the majority of the previous crop's residue on the soil surface to reduce direct impact erosion by rain or sprinkler irrigation. More soil pores remain open for water infiltration, reducing runoff potential. Organic matter increases, allowing more binding sites for applied material to remain within the soil. This practice is very common in the Midwest, where topsoil erosion from rolling hills is a problem.
Vegetated ditches: This type of ditch has been studied as a method to considerably slow water flow and reduce sediment and contaminants from running off into the waterway. Since concentrations of chemicals in vegetated ditches are lower than those in both conventional ditches and inflow water, vegetated ditches may also filter contaminants coming into a property, reducing the impact of local agricultural practices and improving water quality downstream.
Vegetated Buffers and Filter Strips: These buffers and strips are used to reduce contaminant, nutrient and sediment runoff to maintain or improve water quality. Strips of grass or other permanent vegetation are planted between crop fields and water bodies to capture rainfall and sediments while allowing pesticides and nutrients in runoff to break down.
Vegetated buffers can be maintained in permanent vegetation to slow water runoff and protect against bank degradation during storm and flooding events. Buffers help to restore fish and wildlife habitat and foster beneficial native plant and insect communities. The dimensions of the buffer zone and the appropriate plant species for each site depend on the characteristics of the site, such as volume of water flow, slope and soil type.
Cover crops: Many crops can be planted over an entire field to reduce erosion and runoff while improving soil quality. New techniques involve planting annual or perennial crops between rows in orchards and other agricultural fields to significantly reduce soil runoff and nutrient loss, maintaining or improving the quality of the soil in the fields. Native or seeded grasses and legumes can form dense cover in furrows, holding the soil in place and reducing the need to move soil uphill after heavy rains. The grasses can be sprayed with herbicides or weed whacked and allowed to decompose, improving soil fertility, texture and aeration. Crops in furrows can also control weeds, foster beneficial insects and break down pesticides in runoff.
UC SAREP Cover Crop Resource Page
PAM: Polyacrylamide (PAM) is a polymer compound injected or fed into irrigation water at the head of a field supply ditch or discharge point. PAM causes soil particles to drop out of irrigation water, preventing erosion and soil movement. The effect is lasting, with greatly reduced erosion and sediment transport reported in later irrigations.
Improving soil texture: Special tillage equipment can aerate the soil, reducing runoff through increased water penetration and retention. Gypsum or earthworms added to the soil may also have similar effects in compacted soils. These methods have not been studied to reduce pesticide runoff. More research is needed since results vary based on soil types and conditions.
Settling ponds: Water is allowed to rest briefly in settling ponds after being treated with a chemical that gathers tiny particles into larger particles. The flow of water is then slowed and large, heavy particles can settle to the bottom of the pond. The water can then be moved through a vegetated ditch to filter out contaminants. Often the process reduces fertilizer, nutrient and suspended solid loads by 50 to 90 percent or more.
Pesticide application and management: Pesticides represent a considerable expense for the grower, and the adoption of integrated pest management (IPM) programs to limit their usage to times of economic damage has improved the bottom line of many growers. By spraying at certain times in the pest and crop life cycles, pest control can be maximized and amount of pesticide used minimized. Additional concerns over worker safety and increased enforcement of label restrictions regarding applications have also reduced the usage of many pesticides. New chemistries that are more pest specific are in use rather than the broad-spectrum chemistries widely used in previous years, leaving beneficial insects behind to help suppress the damaging species.
University of California IPM Online
Chemistry changes: As stated above, new chemistries that are more pest-specific are in use. These include the new chemistries called insect growth regulators (IGRs), which interrupt the natural development process of the target pest by halting development at the immature stages and/or by sterilizing the adults. These chemistries are very pest specific and leave many beneficial insects behind to maintain suppression.
California Agriculture Research and Reviews
Application changes: New technologies not yet widely available control the application of material within orchards to only when the sprayer passes a tree. If no tree is present, then the sprayer shuts off until a tree is present again. This is promising for new plantings and of little use in mature orchards except on row ends. Such technology is available for herbicide sprayers, essentially spot spraying weeds as the boom passes over the weed.
It is in the grower's best interest to shut off manually during turns because of the waste of valuable material. Many growers insist that either their employees or their application contractors shut off at the ends before turning.
Electrostatic spray systems are used on field crops to have the applied material literally drawn to the plant and repelled by the soil surface. While these are expensive, they are effective in applying chemicals only to the plant where it is needed most, often resulting in rate reductions.
Innovative Technologies in Pesticide Application
Nutrient/Fertilizer Management Practices
General practices: Determine the amount of nitrates already present in the soil by sampling and analysis. Apply nutrients/fertilizers at a rate consistent with the crop requirements.
Rinse water from spray tanks should be evenly rinsed and spread throughout the field. Fertilizer tanks and equipment should be cleaned by rinsing in the field or at a properly planned wash facility. Sludge from the tank should be spread evenly across a field using good agronomic practices to minimize waste and runoff.
When parking equipment, use care to prevent materials from leaking into the storage area. If equipment is known to be in poor condition, completely remove material before parking equipment.
Plant tissue sampling: Collect plant tissue samples to determine mid-to-late-season fertilizer needs. Measure nitrate levels in the irrigation water and adjust nitrate rate accordingly. Split applications of nitrate fertilizer and do not apply excessive amounts of nitrate fertilizer during the rainy season.
On the Horizon
Many different practices are being researched for trapping potentially harmful contaminants within the field or before they reach a major surface waterway, such as the following:
- Organic matter to bind hydrophobic substances within the sediment for future breakdown; and
- Specific enzymes to accelerate the breakdown of specific chemistries.
Each best management practice has it pros and cons. Some practices may need to be used in combination with each other to work effectively, if simply following the existing label restrictions proves inadequate.
Additional Links About Protecting Water Quality On Your Farm
DPR Pesticide Database
Dormant Spray Rules
More Department of Pesticide Regulation Publications
Biologically Integrated Farming Systems
Last updated: 01-21-08