What technologies are required to make conservation buffers an effective and cost-efficient means to help America meet its national water quality goals?
This question was the focus of the recent National Conservation Buffer Initiative (NCBI) Science and Technology Conference. Over 300 representatives of public agencies, universities, corporations and private groups gathered January 26-27 in San Antonio, Texas to share information on the scientific basis for conservation buffers. The meeting was organized by the Conservation Technology Information Center at Purdue University.
The NCBI is a new partnership between by the US Dept. of Agriculture and over 90 corporations, commodity groups and private organizations. It has set an ambitious goal for its outreach efforts: to encourage rural landowners to voluntarily establish 2 million miles, equivalent to 7 million acres, of conservation buffers nationwide by the year 2002.
In addition to researchers and USDA representatives, conference participants also heard, via videotaped vignettes, five producers in different regions of the US talk about their practical experiences with buffers.
Representatives from some of the NCBI’s major corporate sponsors, which include Monsanto, Cargill and Novartis, also participated as session moderators. Wallie Hardie, North Dakota farmer and chair of the National Corn Growers Association, said that conservation buffers are compatible with modern corn production practices and pledged his association’s help in increasing awareness of their potential benefits among corn producers nationwide.
Richard Lowrance, of the USDA Agricultural Research Service in Georgia, said that conservation buffers can provide “goods and services” to benefit both the environment and the landowner. By trapping sediment, absorbing excess nutrients and controlling erosion, he said that practices such as filter strips, grassed waterways and riparian buffer strips can help improve and maintain water quality in streams bordered by crop and pastureland.
Buffer Limitations
While many speakers extolled the virtues of buffers, a few provided a dose of reality by discussing their practical limitations. Theo Dillaha of Virginia Tech University emphasized that buffers to protect water quality must be carefully designed to insure their effectiveness and long service life.
According to Dillaha, the necessary conditions for buffers to be effective in non-point source pollution control are shallow, uniform flow of runoff from fields at a low velocity, long term storage or periodic removal of accumulated nutrients absorbed and sediments trapped by the buffer plants, and regular maintenance after establishment. He recommended specific measures to prevent the concentration of runoff within fields which can locally inundate streamside buffers, and the periodic harvesting of trees and grass within buffers to maintain their vigorous vegetative growth and filtering capacity.
Riparian buffer strips alone cannot be counted upon as the sole best management practice for water quality protection, according to Theo Dillaha. They must be combined, he said, with other, in-field conservation practices, for example, no-til and contour grass strips, that help reduce the sediment and nutrient load before runoff reaches streamside buffers.
The effectiveness of riparian buffers in removing excess nutrients such as nitrate is site specific, and depends on how much of the runoff passes through the active root zone of grass and trees in the buffer, according to Art Gold of the University of Rhode Island.
Where streambanks are steep and nitrate-laden runoff infiltrates upslope into deep-flowing groundwater, riparian buffers alone will not be able to filter out nutrients unless their roots are deep enough to tap groundwater, he said.
Recognizing that single buffer practices may not be able to do the job alone, speakers emphasized the importance of developing individualized conservation strategies for each farm and employing a combination or “toolkit” of different buffer practices. Other speakers described how, in addition to their environmental benefits, buffers can also help boost crop production and diversify farm income.
Bruce Wight of the National Agroforestry Center described how buffer practices such as windbreaks and living snow fences can increase the yield and quality of sheltered crops. In a video vignette, North Dakota farmer Wayne Carter reported how living snow fences provide an essential addition to soil moisture by distributing snow evenly across his fields.
A few speakers showed examples of how conservation buffers can directly benefit landowners by helping to create new farm business enterprises. Larry Butler of the Natural Resources Conservation Service (NRCS) illustrated how groups of adjacent landowners in Texas have formed wildlife management cooperatives and are planting buffers to attract game birds, which in turn attract hunters willing to pay for their sport. Gene Garrett of the University of Missouri described how farmers in the Midwest are growing black walnut, both for nuts and high-value timber, in combination with shade-tolerant pasture crops (alley cropping agroforestry) for short and long term income diversification.
CRP Funds Available
In following established public policy that rural landowners deserve some financial incentives to adopt conservation practices that will benefit society at large, some new USDA programs provide attractive financial motivations for planting conservation buffers. Parks Shackleford of the Farm Services Agency said that most buffer practices are eligible for the continuous sign-up provisions of the Conservation Reserve Program (CRP) which pays landowners not only an annual rental rate on 10-15 year contracts, but also provides cost-sharing up to 50% for establishment costs, plus an extra 20% incentive for highpriority practices such as riparian buffer strips and windbreaks.