Using broadband crop residue angle index to estimate the fractional cover of vegetation, crop residue, and bare soil in cropland systems

Vegetation Fractional Cover (VFC) is an important global indicator of land cover change, land use practice and landscape, and ecosystem function. In this study, we present the Global Vegetation Fractional Cover Product (GVFCP) and explore the levels and trends in VFC across World Grassland Type (WGT) Ecoregions considering variation associated with Global Livestock Production Systems (GLPS). Long-term average levels and trends in fractional cover of photosynthetic vegetation (FPV), non-photosynthetic vegetation (FNPV), and bare soil (FBS) are mapped, and variation among GLPS types within WGT Divisions and Ecoregions is explored. Analysis also focused on the savanna-woodland WGT Formations. Many WGT Divisions showed wide variation in long-term average VFC and trends in VFC across GLPS types. Results showed large areas of many ecoregions experiencing significant positive and negative trends in VFC. East Africa, Patagonia, and the Mitchell Grasslands of Australia exhibited large areas of negative trends in FNPV and positive trends FBS. These trends may reflect interactions between extended drought, heavy livestock utilization, expanded agriculture, and other land use changes. Compared to previous studies, explicit measurement of FNPV revealed interesting additional information about vegetation cover and trends in many ecoregions. The Australian and Global products are available via the GEOGLAM RAPP (Group on Earth Observations Global Agricultural Monitoring Rangeland and Pasture Productivity) website, and the scientific community is encouraged to utilize the data and contribute to improved validation.

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Effects of Cover Crop Residue and Preplant Herbicide on Early Leaf Spot of Peanut

Plant Disease ◽

10.1094/pdis-91-7-0822 ◽

2007 ◽

Vol 91 (7) ◽

pp. 822-827 ◽

Cited By ~ 4

Author(s):

E. G. Cantonwine ◽

A. K. Culbreath ◽

K. L. Stevenson

Keyword(s):

Leaf Spot ◽

Cover Crop ◽

Crop Residue ◽

Soil Surface ◽

Bare Soil ◽

Plant Tissues ◽

Cercospora Arachidicola ◽

Winter Cover Crop ◽

Strip Tillage ◽

Herbicide Glyphosate

Epidemics of early leaf spot, caused by Cercospora arachidicola, of peanut (Arachis hypogaea) are delayed in strip-tilled compared to conventionally tilled fields. This effect may be due to applications of glyphosate used to kill the winter cover crop in strip-tilled fields and/or the presence of cover crop residue at the soil surface of strip-tilled fields. Preplant herbicide (no herbicide, glyphosate, and paraquat), reciprocal residue (plus residue in conventionally tilled plots and minus residue in strip-tilled plots), and added straw mulch were evaluated to determine their effects on early leaf spot epidemics (AUDPC based on incidence and severity, and final percent defoliation) in conventionally tilled and strip-tilled plots. Additional experiments were conducted to characterize the effects of mulch (straw, fumigated straw, and plastic straw [Textraw]) treatments on disease, and to study tillage effects on disease in nonrotated peanut fields. Glyphosate and paraquat had no effect on AUDPC values or defoliation. The addition of straw to conventionally tilled plots significantly reduced disease levels. Cover crop and straw treatments had no significant effect on disease in the strip-tilled plots. AUDPC values were highest in the bare soil plots, lowest in the straw and fumigated straw plots, and intermediate in the plots with Textraw. Fewer initial infections were detected in the Textraw plots compared to the bare soil plots based on results of a trap leaf experiment. Strip-tillage did not consistently suppress early leaf spot epidemics in nonrotated fields. These results show that the presence of cover crop residue is partly responsible for the early leaf spot suppression observed in strip-tilled fields. Cover crop residue may interfere with the dispersal of primary inoculum from overwintering stroma in the soil to the plant tissues.

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Comparison of Hyperspectral Versus Traditional Field Measurements of Fractional Ground Cover in the Australian Arid Zone

Remote Sensing ◽

10.3390/rs11232825 ◽

2019 ◽

Vol 11 (23) ◽

pp. 2825 ◽

Cited By ~ 2

Author(s):

Claire Fisk ◽

Kenneth Clarke ◽

Megan Lewis

Keyword(s):

Spatial Scale ◽

Arid Zone ◽

Ground Cover ◽

Field Measurements ◽

Bare Soil ◽

Point Sampling ◽

Calibration And Validation ◽

Fractional Cover ◽

In Situ Methods

The collection of high-quality field measurements of ground cover is critical for calibration and validation of fractional ground cover maps derived from satellite imagery. Field-based hyperspectral ground cover sampling is a potential alternative to traditional in situ techniques. This study aimed to develop an effective sampling design for spectral ground cover surveys in order to estimate fractional ground cover in the Australian arid zone. To meet this aim, we addressed two key objectives: (1) Determining how spectral surveys and traditional step-point sampling compare when conducted at the same spatial scale and (2) comparing these two methods to current Australian satellite-derived fractional cover products. Across seven arid, sparsely vegetated survey sites, six 500-m transects were established. Ground cover reflectance was recorded taking continuous hyperspectral readings along each transect while step-point surveys were conducted along the same transects. Both measures of ground cover were converted into proportions of photosynthetic vegetation, non-photosynthetic vegetation, and bare soil for each site. Comparisons were made of the proportions of photosynthetic vegetation, non-photosynthetic vegetation, and bare soil derived from both in situ methods as well as MODIS and Landsat fractional cover products. We found strong correlations between fractional cover derived from hyperspectral and step-point sampling conducted at the same spatial scale at our survey sites. Comparison of the in situ measurements and image-derived fractional cover products showed that overall, the Landsat product was strongly related to both in situ methods for non-photosynthetic vegetation and bare soil whereas the MODIS product was strongly correlated with both in situ methods for photosynthetic vegetation. This study demonstrates the potential of the spectral transect method, both in its ability to produce results comparable to the traditional transect measures, but also in its improved objectivity and relative logistic ease. Future efforts should be made to include spectral ground cover sampling as part of Australia’s plan to produce calibration and validation datasets for remotely sensed products.

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Modeling site-specific wild oat (Avena fatua) emergence across a variable landscape

Weed Science ◽

10.1614/ws-05-142r1.1 ◽

2006 ◽

Vol 54 (5) ◽

pp. 838-846 ◽

Cited By ~ 14

Author(s):

Eric R. Page ◽

Robert S. Gallagher ◽

Armen R. Kemanian ◽

Hao Zhang ◽

E. Patrick Fuerst

Keyword(s):

Water Potential ◽

Crop Residue ◽

Seedling Emergence ◽

Bare Soil ◽

Slope Aspect ◽

Weibull Function ◽

Wild Oat ◽

Site Specific ◽

Wheat Field ◽

The Impact

The spatial and temporal pattern of wild oat emergence in eastern Washington is affected by the steep, rolling hills that dominate this landscape. The objective of this study was to assess the impact of landscape position and crop residue on the emergence phenology of wild oat. Emergence of a natural wild oat infestation was characterized over two growing seasons (2003 and 2004), at two wheat residue levels (0 and 500 g m−2), and at five landscape positions differing in slope, aspect, and elevation in a no-till winter wheat field. Wild oat emerged 1 to 2 wk earlier at south-facing landscape positions than at north-facing landscape positions. Crop residue delayed wild oat emergence by 7 to 13 d relative to bare soil at south-facing positions in 2003 and had a reduced effect on emergence at north-facing landscape positions. Therefore, preserving surface residues tended to synchronize emergence across the landscape and may facilitate better timing of weed control where residue is present. Emergence of wild oat was modeled as a function of thermal time adjusted by water potential using a Weibull function. Temperature explained more variation in the model than water potential. This model explained much of the variability in wild oat emergence among landscape positions over these 2 yr and may be useful as a tool to predict the timing of wild oat emergence. Results also indicate that site-specific modeling is a plausible approach to improving prediction of weed seedling emergence.

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Time to "Rewet the Swamp" – Application of Georgian Data Cube to Elucidate Drainage Patterns and Potential for Wet Agriculture and Forestry on Kolkheti Lowland

10.5194/egusphere-egu21-16511 ◽

2021 ◽

Author(s):

Izolda Matchutadze ◽

Aliosha Bakuridze ◽

Ira Abuladze ◽

Nana Shakarishvili ◽

Mamuka Gvilava

Keyword(s):

High Water ◽

Bare Soil ◽

Data Cube ◽

Biofuel Production ◽

The Black Sea ◽

Vegetation Removal ◽

Fractional Cover ◽

Drainage Patterns ◽

Water Detection ◽

Black Sea Coast

<p>It was established recently that gravity drainage is inefficient on Kolkheti Lowland along the Black Sea coast of Georgia and that novel approaches are urgently recommend, such as implementing rewetting schemes to restore ecosystem services and enhance economic values of these areas through wet agriculture, biofuel production with native wetland species, and/or afforestation, to achieve sustainable outcomes in both ecologic and economic terms. Water Detection, Fractional Cover and Urbanization remote sensing tools, provided by Georgian Data Cube (comprising Landsat sensor Analysis Ready Data), developed recently with UNEP/GRID support, were applied on multi-year timescale basis for Kolkheti lowland to identify priority areas with high potential for rewetting. Water Detection tool allowed establishment of low effectiveness drainage areas, as demonstrated by high cumulative values for the presence of water, indicating water-logged areas as potential intervention sites for wet agroforestry. Water Detection combined with Fractional Cover tool allowed comparative analysis of non-photosynthetic vegetation and bare soil areas versus high water detection areas to single out those lands on the Kolkheti lowland, where drainage seems effective and dry agriculture is pursued versus those lands where drainage is not effective and dry agriculture is not actually happening. Urbanization tool can also be applied to detect human activities, such as agricultural activities, visualising those areas, which are subjected to active vegetation removal on an annual basis due to crop harvesting and those areas, where vegetation was not removed, staying vegetated most of the time, interpreted as abandoned agricultural lands. Regular patters combining non-use agricultural with cumulative water covered areas could thus help locate candidate sites for piloting wet agriculture on Kolkheti Lowland in Georgia. In addition to sustainable economic practices, rewetting could certainly benefit core ecological areas of Kolkheti Lowland, protected by both national designation as Kolkheti National Park and international designation as Central Kolkheti Ramsar Site.</p>

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