Economic, agronomic, and ecological costs/benefits of field border management practices in agricultural systems of Mississippi
Federally subsidized conservation practices such as field borders, filter strips, and riparian buffers improve environmental quality through erosion control, herbicide retention, and wildlife habitat enhancement while offsetting lost opportunity costs of producers. However, despite direct financial compensation (cost-share/incentive payments), use of conservation buffers in conventional rowcrop agriculture has not gained widespread support. USDA-NRCS has identified the need for evaluation of benefits associated with conservation buffer practices and perceived obstacles to producer adoption. Furthermore, development of agricultural policy which promote sustainability require that information on ecological benefits be integrated with knowledge of agronomic and economic impacts to producers.
- Assess opportunity costs of participation in field border management programs by yield mapping fields in relation to crop type, proximity to edge, buffer establishment and landscape context (adjacent plant community type).
Quantify spatial distribution of weed species in relation to field border management, crop type, proximity to edge, and landscape context.
Assess effects of field border management practices on wildlife habitat quality using diversity and abundance of ground nesting grassland bird species, population performance parameters of radio-marked northern bobwhite, and foraging efficiency of human-imprinted bobwhite chicks.
During the 2001 growing season we used Global Positioning System (GPS) guided yield monitors were to quantify true yields in field margin areas targeted for field border management practices. Within 9 fields, we established paired field bordered and unbordered segments (4 pairs in corn, 10 pairs in soybeans) to evaluate effects of field borders while controlling for field/producer-specific cropping practices. We completed GPS-referenced yield monitoring of crops from these fields. We are currently analyzing yield data from these plots to determine effects of herbaceous field borders on infield yield. Additionally, we secured spatially explicit yield data for 77 fields, totaling ~5000 ac planted to corn and soybeans, on adjacent properties to examine the broader question of effects of adjacent field margin communities on yield of corn and soybeans. Specifically we are examining edge vs interior yield in fields with herbaceous and wooded adjacent plant communities to determine effects of adjacent community on relative yield reduction.
Spatial distribution of weed species were sampled from geographically referenced grids placed adjacent to field bordered and non-field bordered edges, extending into the crop field. Each grid (n= 14 pairs of bordered and unbordered) consisted of 80 sampling points. Distribution, composition, percent canopy cover, and densities of weed species were recorded relative to proximity of field borders and landscape elements during the growing season. Additionally, species composition, density, and cover were measured along line transects within adjacent edge vegetation to characterize and identify adjacent plant communities. During 2001, weed species data were recorded from 2,320 sampling points. However, in 2002, weed species data were recorded twice at each of the 2,320 grid points. Sampling occurred approximately 2 months apart. In 2001, a total of 360 adjacent plant community points were sampled associated with field bordered areas while 240 points were sampled for non-field bordered communities. Adjacent plant communities were sampled twice in 2002 (600 points). A total of 307 plant species have been recorded within field borders and adjacent plant communities. Data are currently being analyzed.
Breeding season and winter line-transect surveys were used to determine relative abundance and diversity of non-game grassland bird species between bordered and unbordered fields. Transects (n=79, length=200m) were stratified based on adjacent plant community type (grass strip, grass block, wood strip, and wood block; n = 10/treatment combination). Preliminary analyses indicate that during winter, field bordered fields had a greater abundance of birds than non-bordered fields, however, species richness was relatively similar across adjacent plant community types. Specifically, winter sparrows, especially song sparrow and savanna sparrow were more abundant on bordered edges. Breeding season abundance and species richness followed a similar trend. However, field border effects varied by species and adjacent plant community during both seasons. Indigo buntings, dicksissels, common yellowthroat, yellow-breasted chat, and northern cardinals were more abundant along bordered edges.
Northern bobwhite fall density estimation and breeding season call count indices were used to determine changes in bobwhite density and relative abundance, respectively. Preliminary results indicate that field border sites had consistently higher fall densities than non-bordered sites across all years of study (Figure 2A). Breeding season call count indices varied from year to year. However, pooled across all years of study, field bordered sites were higher than non-bordered sites.
Adult northern bobwhite were captured in Feb.-Mar. (years 2000-2002) using baited walk-in funnel traps, fitted with a radio transmitter. A total of 93 and 54 northern bobwhites were monitored daily during the 2001 and 2002 breeding seasons (April - Sept), respectively. Human imprinted bobwhite chicks (n = 700) were foraged in fields with and without field borders to evaluate the value of field borders on chick foraging efficiency. Northern bobwhite survival, reproduction, habitat use, and chick foraging trial data are currently being compiled and analyzed.
Impacts and Contributions/Outcomes
To date, we have provided popular articles addressing benefits of field border practices and our current research to the following outlets: Alabama Wildlife Federation, Delta F.A.R.M., Delta Wildlife, and Mississippi Wildlife Issues. Additionally, in May 2001 we conducted a Buffer Short Course. This meeting, hosted by the Forest and Wildlife Research Center, MSU and sponsored by the USDA-NRCS Wildlife Habitat Management and Watershed Science Institutes featured scientists and policy experts from around the country presenting information on technical specifications for implementation of conservation buffers and findings of recent and ongoing research of the benefits of conservation buffers. Approximately 60 USDA-NRCS biologists, conservationists, and agronomists throughout the Southeast attended. The short course included both scientific presentations and a field tour of a private farm in Clay County, MS on which numerous buffer practices have been implemented.