All posts by tlriley3

Tailwater Recovery

Recovering tailwater from irrigation and runoff from rainfall for reuse in subsequent irrigation events is becoming increasingly popular especially in geographical areas designated as critical groundwater.

A tailwater recovery system is a planned, systematic irrigation system that allows for the collection, storage, control, movement, and reuse of runoff water from previous irrigation or stormwater runoff events. The NRCS offers financial assistance via the MRBI and EQIP programs to design and install a system. It offers many long-term benefits including:

  • Greater control and flexibility of water supply for irrigation
  • Reduced groundwater dependence and energy costs from pumping
  • Reduced off-farm impacts on water quality by capturing sediment and nutrient losses in runoff

Tailwater recover irrigation ditch

A tailwater system has several components involving other conservation practices that are eligible for financial assistance including:

  • A drainage recovery pit at the bottom of a field, Practice Code, 447
  • Surface drainage piping, main and laterals, Practice Code 608
  • Conveyance ditches from recovery pit to storage reservoir, Practice Code 607
  • Storage reservoir, Practice Code 436
  • Pumping plants, Practice Code 533
  • Irrigation pipeline, Practice Code 430

These components may include but are not limited to: ditches, culverts, pipelines, water control and/or grade stabilization structures, or other erosion control measures, as needed.

For more information, contact your local conservation district.

– Mike Daniels

Riparian Forest Buffers

A riparian area is the land adjacent to a stream or river or other waterbody. The vegetation in riparian areas provides many benefits such as removing nutrients and sediment from runoff water, protecting water quality, enhancing aquatic habitat, and providing shade to water bodies. Many riparian areas are naturally vegetated; however, many riparian areas have been destroyed or need to be enhanced to realize the benefits listed above. The NRCS provides financial assistance to landowners to restore or The Conservation Corner: Vol. 2, Issue 1 enhance riparian zones including the establishment of riparian forest buffers (Conservation Practice 391).

Arieal view of riparian forest buffer between river and row crop field

This practice involves the planting of selected permanent woody vegetation and shrubs in a strip of a designed width along the riparian area for the purposes of obtaining the benefits mentioned above, as well as providing food and habitat for wildlife. Research on Riparian forest buffers established between streams and agricultural land use have been shown to be up to 80% effective in removing nitrogen and phosphorus from runoff. Riparian forest buffers provide a conservation practice that can be managed separately from in-field agricultural practices and yet maintain effectiveness in managing agricultural runoff.

For more information, contact your local USDA Service Center or your local County Extension office. For further reading check out these publications on riparian buffers:

Riparian Buffers: Functions and Values

A Riparian Area Assessment Guide for Streamside Landowners

– Mike Daniels

Cover Crops

Long before commercial fertilizers and modern pesticides were developed, farmers utilized cover crops to assist with soil fertility and weed control. Today cover crops are an under-utilized soil and water conservation practice. Since the National Agricultural Statistics Service does not routinely collect information on the use of cover crops, the extent of its adoption in terms of acres is relatively unknown. Interest in cover crops seems to be growing especially in the corn belt of the Midwestern United States.

Cover crops as defined in the Encyclopedia of Soil Sciences are those crops that are grown for improving soil, air, and water conservation and quality; nutrient scavenging, cycling and management; increasing populations of beneficial insects in integrated pest management; and/or for short-term (e.g., over-winter) animal-cropping grazing systems. Cover crops are not usually grown to maturity to produce grain, seed or fruit.

Cover crops can provide a variety of soil and water conservation benefits including:

  • Reduce erosion from wind and water
  • Increase soil organic matter content
  • Capture and recycle or redistribute nutrients in the soil profile
  • Promote biological nitrogen fixation
  • Increase biodiversity
  • Weed suppression
  • Provide supplemental forage
  • Soil moisture management
  • Reduce particulate emissions into the atmosphere
  • Minimize and reduce soil compaction

Depending on the soil and climatic conditions of a given field, the benefits of cover crops can vary greatly. One of the barriers to adoption of cover crops is the perceived notion that cover crops are not profitable. While it’s true that cover crops are not grown as a commodity in and of itself, they can provide benefits that over the long-term can provide cost-savings by reducing crop inputs. In fact, some scientists tout cover crops as an important practice to long-term production and sustainability. Although documenting these benefits in terms of dollars is difficult, the cost of cover crops can be offset through USDA-NRCS cost share programs such as EQIP. For example, in the Cache River MRBI project area (See article in this newsletter) eligible producers can receive financial assistance to establish winter cover crops.

Cover crop in corn stubble
Cover crop established after corn in Iowa. (Photo courtesy of the Lime Creek Watershed Improvement District).

Researchers at the University of Arkansas’ Division of Agriculture are investigating the potential benefits of cover crops in helping to control Roundup-Ready resistant pigweed in cotton and soybeans while plant pathologists are investigating the use of winter cover crops in the brassica family such as Indian mustard as a bio-fumigant for nematodes in cotton and strawberry production. Some producers have recently inquired about the use of “tillage radishes” as a cover crop that is touted to break up soil compaction. Little research has been conducted in Arkansas on cover crops that reduce soil compaction to document its effectiveness. Cover crops have long been used in cotton production in Arkansas on sandy soils to reduce the shredding effects of wind-blown soil particles on young cotton plants.

Certainly cover crops are a beneficial soil conservation practice that provides cover to otherwise bare soils and thereby reducing soil erosion, and in turn may reduce sediment loading to streams and rivers. Benefits from cover crops accumulate over time and these benefits can vary from field to field. If you think cover crops may benefit your cropping system but you are hesitant to try due to costs, you can apply for financial assistance from USDA. If establishing cover crops is a new practice, then start small, perhaps in a field or two, and give it some time to observe possible benefits. For information on EQIP or cover crops, contact your local conservation district or County Extension office.

– Mike Daniels

Conservation Crop Rotation

Crop rotation is defined by NRCS as the growing of different crops in sequence in the same field.

It has long been recognized as a practice that can increase yields by reducing the adverse impacts of pests such as weeds, plant disease and insects while promoting nitrogen cycling when using a legume in the rotation. In fact, crop rotation was widely practiced for this purpose long before chemical pesticides and inorganic fertilizers were available; however, crop rotation is still a common practice in Arkansas.

Some common crop rotations in Arkansas include alternating rice with soybean and alternating corn with cotton. Wheat is often included in both rotation scenarios while corn is increasingly included in rice and soybean rotations. Crop rotation is still a recommended practice for specific pests. For instance, the University of Arkansas’ Division of Agriculture recommends crop rotation to help control nematodes in both soybean and cotton production. An increasingly important aspect of crop rotations is its value to slowing or reducing resistance to pesticides.

Crop rotation offers many conservation benefits as well, including:

  • Reduced runoff and erosion
    • Increased organic matter
    • Improved soil tilth and health
    • Reduced pests
    • Fewer chemicals needed
    • Better moisture efficiency
    • Higher yields
    • Improved aesthetics and wildlife habitat

These benefits will vary with soils, crops, climate, management and other factors. However, these benefits are important to increasing long-term profitability and sustainability. The USDA-NRCS provides financial incentives for conservation crop rotation (Practice 328) through programs such as the Environmental Quality Incentives Program (EQIP).

Cover crops on farm, barns in back ground

Conservation crop rotation requirements for programs such as EQIP involves developing and following a conservation crop rotation that may include annual cropping, legumes in rotation, cover crops, and other similar crops used to improve soil health and/or prevent soil loss. The typical rotation may include 2-5 crops grown in sequence. This practice includes keeping records of what cropswill be planted each year in each field.

If cover crops are not used, the crop rotation must include one or more high residue crops, such as corn, rice, grain sorghum, and/or wheat for row crops. Cover crops could be a mix consisting of annual grasses and leguminous type forages. Producers must utilize a minimum of three different crops in the rotation; or two different crops, if a cover crop or perennial hay crop (two or more years) is used as one of the crops in rotation.

Crop rotation is a relatively low-cost practice, but financial incentive programs cost-share the expenses associated with the additional requirements for tillage and planting that may be associated with crop rotations. The low cost of implementation makes it a perfect practice to utilize in an EQIP application package, as it can increase your ranking with minimal investment. Crop rotation also lends itself to easily compliment other conservation practices such as 590-Nutrient Management, 595-Pest Management, 329-Residue Management, and 340-Cover Crops.

In summary, crop rotation is an important conservation and production practice and can be utilized in conservation programs. Crop rotations will likely become increasingly important as we face increased resistance to pesticides. For more information, contact your local County Extension Office or your local USDA Service Center.

– Mike Daniels

Scheduling Irrigation Using an Atmometer (ET Simulator)

Knowing when to irrigate can be a challenge. When crops show signs of water stress, it means irrigation was applied too late. Irrigating on a set schedule, for example once a week, can result in too little or too much water, depending on weather conditions. Crops use water from the soil through evapotranspiration (ET). Evapotranspiration is the combination of evaporation of water from the soil surface and transpiration of water from the plant. The amount of water crops use changes, for example due to the maturity of the crop and the weather (e.g., humidity level or temperature).

The soil has a certain capacity for holding water, known as the field capacity. Immediately following an irrigation or heavy rain the soil is saturated. Excess water drains, and the soil then reaches “field capacity”. Water is depleted from the soil through evapotranspiration. Plants can extract water until the wilting point. At the wilting point, the crop can no longer extract water from the soil and will experience stress. The soil should be kept wet enough so the plant never approaches the wilting point. Therefore, it is important to track crop water use to know how much water is depleted from the soil and when the soil needs to be replenished or irrigated.

Atmometers measure evapotranspiration. They track the crop water use in the field and allow users to know when irrigation should be initiated. The atmometer user selects the maximum amount of water that a crop can use before it needs to be irrigation (called the “deficit”). This number is set conservatively, using a safety factor, to ensure the crop never approaches the wilting point or becomes stressed. The deficit is the difference between the field capacity and the refill point (a set level above the wilting point). The deficit changes depending on the crop growth stage, and is also dependent on the soil texture and the irrigation system used (furrow, flood, or sprinklers).

University of Arkansas is doing on-farm research to validate and develop this method of irrigation scheduling for Arkansas growers. A draft chart for soybeans has been developed and is being tested through the Arkansas Discovery Farms and Soybean Research Verification Program. This chart indicates appropriate water deficits for various soybean stages, soil textures, and irrigation system types. (Note that deficit charts are specific to a region and crop.) Preliminary results indicate that irrigation recommendations based on the atmometer agree with irrigation recommendations based on the Arkansas Irrigation Scheduler.

Atmometer (ET Gauge) in field

Atmometers are made up of a small reservoir of water, covered by a ceramic cup. The ceramic cup is covered by a thin paper wafer and canvas. The water from the reservoir evaporates through the ceramic cup. The paper wafer covering the cup prevents rain water from entering the reservoir but does not hinder evaporation, and the canvas simulates the leaf surface. The amount of evapotranspiration can be viewed in the sight tube. The water level will fall one inch in the sight tube for each inch of water the crop uses. The sight tube contains two adjustable red rings. The top ring is set to the water level in the sight tube each time the soil water profile is full, while the bottom ring is slid down to mark the deficit when irrigation will be necessary (e.g., 1.8 inches below the top red ring). When the water level in the sight tube reaches the lower red mark, the user will know that it is time to irrigate. The atmometer does not account for rain water. Therefore the user should measure rainfall separately, and after a rainfall event, move down the lower red ring the amount of infiltrated rain, to account for water being added to the soil water balance.

Atmometers are simple to set-up and require minimal upkeep. They should be placed adjacent to crop fields, and mounted at least 39 inches high and above the crop canopy, to provide accurate on-site evapotranspiration information. At the beginning of the growing season, the atmometer reservoir should be filled with distilled water, and will likely need to be refilled once during the season. The paper wafer, which prevents rainwater from entering the atmometer, should be replaced annually. To learn more about scheduling irrigation and atmometers, contact your local County Extension office.

– Sarah Hirsh

Irrigation Land-Leveling

Precision land-leveling, or precision grading, is the systematic process of removing soil from areas of higher elevation and depositing in areas of lower elevation in order to create a uniform slope. Precision grading is an approved soil and water conservation practice by the Natural Resources Conservation Service (NRCS standard 464) that is commonly implemented on the soils used for rice production in the Southeastern United States. A uniform slope for surface irrigation helps to increase irrigation efficiency and reduce water loss. Typically,land leveling will reshape the soil surface to a uniform drop of a tenth of a foot per hundred feet. Land-leveled fields usually have straight levees spaced 100 feet apart whereas non-leveled fields have levees that follow the contour and may be variably-spaced depending on the slope.

Precision grading provides many benefits for levee-based flood irrigation of rice and soybeans grown in rotation including: i) improved water management, ii) more efficient water use, iii) reduction of the number of levees required to maintain a given flood depth, iv) reduction of land area dedicated to levees and lost to optimum crop production, v) levees that are straight rather than curved to follow natural contour and vi) decreased risk of prolonged flooding of soybeans which can be detrimental to normal development and growth.

Large tractor land leveling a field

While land leveling offers many benefits, there also can be risks. Depending on elevation differences, the depth of soil removed, “cuts” can range from 0 inches to several feet. In many cases, part or all of the surface horizons can be removed, exposing sub-surface horizons. If the required soil removal is deep enough, sub-surface material may also be removed and deposited on top of surface soil. In many fields, the chemical, biological, and physical properties of the exposed and deposited sub-surface material render it unsuitable for profitable crop production. Corrective action is difficult, expensive and may require several years of treatment to achieve restoration. Growing green manures or treating freshly leveled ground with 2 tons per acre of raw poultry litter can help reduce these concerns.

Of particular concern is exposing soil horizons that contain excessive exchangeable sodium or soluble salts. Soils that naturally contain layers with elevated sodium levels at some depth in the profile comprise an estimated 494,000 acres in Arkansas and include the Lafe, Foley, and Hilleman soil series. Proceed with extreme caution and consult your local County Extension office or Conservation District office if land leveling these soils. In some cases, unaffected top soil can be stockpiled while leveling subsoil and replaced after leveling is complete to avoid exposing areas of high sodium or soluble salts.

Precision land leveling is a sizable investment that can cost hundreds to thousands of dollars per acre depending on the depth of cuts required. Typically, land leveling may require moving 100 to 600 cubic yards per acre at a cost ranging from $1.15 to a $1.50 per cubic yard. In 2013, the NRCS in Arkansas will cost-share land leveling at a rate of $1.40 per cubic yard.

Associated practices that can also be cost-shared with land leveling include: 533-Pumping Plant, 449- Irrigation Water Management, 388 – Irrigation Field Ditch, 430 – Irrigation Pipeline, 607 – Surface Drainage, Field Ditch, 608 – Surface Drainage, Main or Lateral, 410 – Grade Stabilization Structure, 587 – Water Control Structure, and 436 – Irrigation Reservoir.

– Mike Daniels

Wetland Enhancement

The NRCS defines wetland enhancement as, the rehabilitation or reestablishment of a degraded wetland or modifying the conditions of a specific wetland to meet the needs of a specific species or purpose.  Wetland enhancement is intended to provide favorable wetland conditions to targeted species.  These conditions include, hydrologic enhancement of the soil, how deep, how long, and when the soil is saturated, as well as vegetative enhancements as simple as replacing unwanted species with a desired species.

Wetland enhancement is performed on any existing wetland regardless of the level of degradation to enhance the functions of the wetland.  However, wetland enhancement does not apply to other conservation practices such as; 657 Wetland Restoration, or 658 Wetland Creation, nor does it apply to the treatment of water pollution, 656 Constructed Wetland.

When considering wetland enhancement for hydrologic enhancement, care must be taken to ensure that there is an adequate source of water to meet the intended enhancement goal.  Often the installation of water control systems that regulate water levels and timing is required to meet the hydrologic conditions for vegetation and wildlife.   Previously existing drainage systems may require removal or modification.  Parameters to consider when designing a water control structure are covered in conservation practice 410 Grade Stabilization, 587 Structure for Water Control, and conservation practice 657 Wetland Restoration defines embankment design.

Wetland enhancement considerations for vegetation enhancement include plant selection, site preparation, and species colonization rate.  When preforming wetland enhancement where the site will require planting new or additional vegetation, priority must be given to native vegetation adapted to the saturated conditions of a wetland.  Invasive, noxious, and nuisance species should be controlled prior to the wetland enhancement.  Some wetland enhancement sites will not require planting, if the selected native species will dominate the site within 5 years, the site may be left to regenerate naturally.  If the restoration site is known to have contamination from nutrients or pesticides, chosen species should be tolerant to these conditions, however if the site is contaminated with hazardous materials, it must be cleaned prior to beginning wetland enhancement.  Normal seeding practices such as, mechanical or aerial seeding, organic mats, and topsoiling to establish new vegetation may be used in wetland enhancement, so long as there is adequate substrate material.  If the wetland enhancement site’s native vegetation is primarily herbaceous vegetation, several different species should be chosen.  If the wetland enhancement site is forested, when possible, 6 or more species adapted to the site should be chosen for reforestation.

The NRCS has an extensive list of considerations to examine before establishing a wetland enhancement:

  • Replace existing drainage structures for long term (greater than 15 years) easements such as the Wetland Reserve Program.
  • Existing wells not used to supplement wetland hydrology should be decommissioned to prevent ground water contamination.
  • Manipulation of water levels to control unwanted vegetation.
  • Existing wetland functions and/or values that may be adversely impacted.
  • Effect enhancement will have on disease vectors such as mosquitoes.
  • Effects on downstream flows or aquifers that would affect other water uses or users.
  • Effect of volumes and rates of runoff, infiltration, evaporation and transpiration on the water budget.
  • Effects on fish and wildlife habitats that would be associated with the practice.
  • Linking wetlands by corridors wherever appropriate to enhance the wetland’s use and colonization by the flora and fauna.
  • When determining which species to plant, consider microtopography and the different hydrology levels.
  • The effects that location, installation and management may have on subsurface cultural resources.
  • The effect of water control structures on the ability of fish to move in and out of the wetland.
  • Effects on temperature of water resources to prevent undesired effects on aquatic and wildlife communities.
  • Timing of water control to mimic the natural hydrological regime of the area, further enhancing the habitat for aquatic species.
  • Design modifications that will limit potential negative impacts of wetland plants and animals on the project.
  • Biological control of undesirable plant species and pests should be implemented where available and feasible.
  • Inspection schedule for embankments and structures for damage assessment.
  • Depth of sediment accumulation to be allowed before removal is required.

If conditions for wetland enhancement exist, there are financial incentive programs which may cost-share the expenses of the additional requirements. Implementation of conservation cover can be worked into an EQIP application package and may complement other conservation practices such as 356-dike, 657-wetland restoration, 410-grade stabilization, 612-tree/shrub establishment, 580-streambank and shoreline protection, 584-stream channel stabilization, 391-ripariian forest buffer, 393-filter strip, 390-riparian herbaceous cover, and 587-structure for water control.

In summary, wetland enhancement is an important conservation and production practice that can be utilized in conservation programs. Wetland enhancement rehabilitates or re-establishes degraded wetlands. Wetland enhancement provides habitat for many different species of wildlife. Careful selection of the proper native plant species, best suited for the selected site will provide the greatest benefits, restoring prosperity, and increases species diversity to degraded wetlands. For more information contact your local County Extension Office or your local USDA Service Center.