By Leanna Duppstadt
The overarching goal of a buffer is to enhance water quality by intercepting excess nutrients and any sediment from runoff, as well as to maintain streambank integrity. While forested buffers are the best at maintaining streambank integrity with their extensive root system, grasses are the powerhouse for nutrient interception and sediment reduction. They also aid in slowing down the movement of water during a flooding event. A grass buffer has the potential to reduce up to 60% of the sediment and captures sediment-attached phosphorus within the first 15 feet of the buffer. Incorporating the opportunity to harvest these grass buffers give producers more flexibility in their management options and allows for the removal of these excess nutrients so that more can be taken up as the plants regrow.
There are 86,000 miles of streams in Pennsylvania, many of which run through or near productive agricultural land. Forested buffers, while beneficial, can cause problems when they are too close to our fields because of shading and leaf drop, resulting in decreased yields or decreased quality due to the presence of that leaf litter during harvest. Planting a grass buffer could alleviate these issues but there are some considerations to make when the intentions are for this to serve primarily as a buffer and secondarily as a hay crop.
Species Selection
One of these considerations include species selection, based on their ability to tolerate wet conditions, and serve as nutrient load absorbers, while also meeting our agricultural production goals. Most of the species that would be best utilized as both a hay crop and a buffer grass would fall within our group of cool-season perennials, with the potential to use native warm-season perennials. We want a perennial so that we maintain continuous ground cover and root system.
Tall fescue
is often known for its drought tolerance but will also do well in waterways, ditches and pond banks. It has a high overall persistence as it does well under low pH and fertility conditions. It is a deep-rooted, sod-forming grass that will provide thorough ground cover during the growing season and have a high leaf retention moving into fall-early winter.
Meadow Fescue
is not as common as tall fescue, mainly due to lower yields and the introduction of KY31 in the 1940s but is slowly being rediscovered since the 1990s. As a pasture grass, it is a very palatable, high-quality forage that thrives in cooler climates. It can survive in wet soils but does not tolerate constant flooding, similarly to timothy. Meadow fescue has a shorter growth habit, making it stronger as a pasture grass but it still has benefits as dry hay or haylage.
Reed Canarygrass
has a very high tolerance for wet areas, including standing water, as well as a tolerance to low pH. It will grow tall with minimal to no mowing, up to 6 feet under good fertility, and form a dense sod from a solid root system that spreads via short rhizomes. While being known for doing well in very wet conditions, it is also very drought tolerant. It can be difficult to establish and will likely fail under high weed pressure but will grow well and be high yielding once it takes off. Reed canarygrass will green up early in the spring but is sensitive to cold and will brown quickly after fall frosts. It can be mixed with birdsfoot trefoil or red clover, which is typically recommended for hay production. There is the potential for reed canarygrass to become invasive and undesirable, particularly in wet areas since it has an aggressive growth habit. If you are receiving local funding to establish a buffer, it is likely that planting reed canarygrass will be prohibited.
Timothy
has a low tolerance for droughty soils because of its shallow root system and it is adapted best to moist, cool environments but will also not do well in areas that have standing water. Timothy is a bunch-type grass and since it does have a shallow root system, it may not be as effective at nutrient uptake, compared to a more deeply rooted species but could potentially be used as part of a mix and does well for hay production.
Clovers
like red clover or white clover , will do better in wet soils with low pH compared to alfalfa which prefers a more neutral pH and does not like to have "wet feet". Red clover has a prostrate growth habit and thick tap root that can be 24-36 inches deep, compared to white clover which has a low growth habit and spreads via stolons. Red clover is typically more suited for hay production because of its more upright growth and ability to have greater overall biomass compared to the shorter white clover. Red clover can be grown on its own and both red and white clover can be grown in a mix with other cool-season perennial grasses such as tall fescue or timothy.
Birdsfoot trefoil
is adapted to adverse growing conditions and also does well in areas that are not suitable to alfalfa, such as those with poor drainage, poor fertility, and low pH. It has the ability to reseed itself but yields less than alfalfa under ideal conditions, so it should be planted where alfalfa would perform poorly. Birdsfoot trefoil is typically used in a grass mixture to increase yields for hay production but has a late maturity, so take that into consideration when incorporating other species.
Big Bluestem and Switchgrass
are native, warm-season perennial grasses that produce well during hot, dry weather on soils with low moisture, pH, and can even do well with low fertility. If they must be seeded in a poorly drained site, switchgrass would be more tolerant than big bluestem. The limited nutrient input requirements make them ideal for a buffer location where nutrient applications are frowned upon, and deep-rooted plants allow for nutrient scavenging. Although they are typically used in pasture settings, warm-season perennials can be harvested and stored as hay. Warm-season grasses should be seeded alone, as management techniques with mixed stands typically end in failure of one species or another. They can be difficult and expensive to establish so they should be planted as a permanent sod in pastures or hayfields.
Harvest and Maintenance
Harvest maintenance will be another factor that may need to be adjusted slightly compared to how you would manage a regular hay field, since this area will be harvested less frequently and needs to maintain its ability to serve as a good buffer system with good ground cover and dense root systems. Remember, this area is to serve first as a buffer, with the added secondary benefit of potentially providing some stored forage. We would want to consider mowing at higher heights, many of the disc bine mowers don't allow for this but to maintain good cover and longevity of the stand a minimum of 4 inches would be best, even 6 inches, particularly if you are harvesting a warm-season perennial.
When deciding on the design or layout of your buffer. Consider the minimum distance requirements to qualify as a buffer but also consider the size of your equipment and the amount of space you will need to operate it. Potentially allowing enough space for a down and back pass on each side of the stream. Also, think about if this is a buffer in a pasture where there will be streambank fencing and the ability to maneuver around that fencing. Incorporating large gates to enter/exit while also considering the need for a water crossing to transport equipment back and forth.
Maybe this grass buffer will not be ideal for mowing because it sits very wet, almost swampy. In which case a grass buffer may still be best for certain production scenarios when it comes to concerns for leaf litter or yield losses on the edges of fields that are bordered by trees. There may not be the added benefit of harvesting for hay but consider the benefits of nutrient and sediment collection and improved water quality, in combination with the lack of leaves and shading from trees.
Nutrient applications should not be applied to this buffer area. The purpose of this space is to serve as a nutrient load absorber before it reaches the water source. Ideally, fertilizer needs should be limited in this area since they will be taking up any excess or escaped nutrients from adjoining fields. Consider planting at least 30% legume species, like a clover or birdsfoot trefoil, with the grasses to fix nitrogen. This can be used for plant uptake and remediate the need for nitrogen applications.
Weed Control
Consider spraying management of this grass area to avoid infestations of weeds. Routine mowing can help with this problem but isn't always effective if the area is only being harvested once or twice and if the timing isn't appropriate to clip weeds before they set seed. Regularly scouting the buffer to check for weed encroachment will be important.
There are several reasons to control weeds in a buffer zone. First, weeds tend to spread very quickly and easily when not managed and if this is an area that is near a field with row crops, hay, or pasture, then we won't want those weeds to spread into that area. Large weeds can shade out grasses and provide less overall ground cover than our sod-forming grasses, resulting in less sediment collection. Second, if this area is being used for hay production, then we don't want to have weeds present, which would reduce our quality or cause issues with drying time.
It is important to start out as clean as possible so that quick establishment can occur with limited interference from weeds. If possible, utilize the existing vegetation to shade out weeds while working to establish some more desired species. Exposing bare ground to sunlight can cause rapid germination of dormant weed seeds in the soil. Treating for broadleaf species using products like Streamline or Milestone, prior to planting will help to maintain any existing grass populations. Rodeo can be used prior to and after planting for use on problem grasses. Incorporating a residual herbicide, with Rodeo after planting, that includes pendimethalin or prodiamine will help with annual weeds. Oust XP is very active on reed canarygrass if it is not desired in the grass buffer. Rodeo plus Garlon 3A tank mixed will provide control of any woody and herbaceous weeds, have little soil activity, and have aquatic labels. More detailed information about riparian buffer site prep and Weed Management is available from Extension.
There are also certain 2,4-D and triclopyr products that are labeled and allowed in riparian buffers and aquatic areas. Keep in mind that products containing aminocyclopyrachlor or aminopyralid can be used in some pasture settings but can have problems with some residues in hay and manure. For more details about hay and grazing restrictions for some common products, please see Table 2.6-19 in The Agronomy Guide .
Summary
Keep in mind that these are recommendations for effectively maintaining a grass buffer that could be used by anyone, however, if you receive funding for installing a buffer, then you are required to follow those specific guidelines. Always consider production goals as well as your equipment and ability to maintain this buffer zone to get the most benefit.
Programs
There are often programs available from various organizations to help offset some of the costs associated with installing conservations practices, which includes riparian buffers. However, there may or may not be programs available pertaining to a strictly grass-based buffer. To inquire about potential programs, you can contact your county PA NRCS office via their website or contact your local office directly. You can also check with your county Conservation District's local office. There is also the potential for PDA to provide tax credits to help offset the installation costs and you can check their website or reach out to your county conservation district.
Source : psu.edu