Abstract
Tall fescue (Schedonorus arundinaceus) is a common perennial forage in cattle pastures of the southeastern United States. A mutualistic fungal endophyte normally infects the grass and produces ergot alkaloids toxic to livestock, but fungal biotypes that have no ergot alkaloid production have been developed. Here remote sensing methods were used to assess plant health in 1 ha grazed paddocks with application amongst different combinations of fertilizer sources (inorganic and broiler litter) and endophyte associations (wild, novel–tall fescue MaxQ type with novel endophyte, and free). Broiler litter fertilization is common in the region due to the presence of many chicken farms. Moreover, broiler litter costs are comparable to inorganic fertilizer depending on distance from source to application. Incorporating remote sensing, we tested the sensitivity of three indices: normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and land surface water index (LSWI) to assess fescue plant health. Indices were obtained from satellite imagery provided by Landsat 7 ETM+ between the years 2005 and 2009. Sensitivity analytics suggested that LSWI was the optimum index to determine fescue plant health. The year experiencing drought (determined by annual precipitation) showed significant difference between fertilizer types (p = 0.05) and a nearly significant difference between endophyte associations (p = 0.08). There was no significant difference in years with normal or wet precipitation rates due to tall fescue endophyte association or type of fertilization. Limited availability of satellite imagery during parts of the five years of study might have influenced outcomes of statistical analyses. Nevertheless, the data and findings point to the potential use of satellite imagery in assessing grazingland tall fescue health and advancing the concept of poultry manureshed in the region or elsewhere where poultry manure production is extensive.
Highlights
Georgia is an exemplary location of poultry manureshed potential as it lies within a region that contributes 60% of the United States annual 8.6 billion broiler production, resulting in nearly 10 million Mg y−1 of byproduct broiler litter [26]
Employing the use of Landsat 7 ETM+ satellite imagery, we evaluated the plant health proxies of different combinations of fertilization regime and tall fescue endophyte association
Stocking rates were calculated for each paddock in each year (Figure 3)
Summary
Agricultural systems in the United States have become more specialized in recent decades, but few systems have been developed to promote the recycling of surplus manure nutrients to nearby croplands [1]. There are many consequences when large amounts of nutrients accumulate in and around feeding operations, including detrimental impacts to soil, water, and air quality, as well as quality of life for livestock [2,3,4]. Agricultural producers in the United States have used livestock manure nutrients as a source of crop fertilizer [5,6,7,8]. Regions that support a particular livestock type do not always
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