Remote Sensing Carbon
S. Chod Stephens, V. Philip Rasmussen, R. Douglas Ramsey, Ralph E. Whitesides, Gregory S. Searle, Robert L. Newhall; Utah State University, Logan, Utah
The quantification of soil organic carbon across various landscapes is necessary in order to assess and manage terrestrial carbon sequestration efforts in agriculture and natural environments. Since soils rich in SOC are most often identified by their dark appearance, most research has looked at reflectance within visible bands to quantify and map carbon variability. However, many properties of soil make carbon inventory difficult. Research has shown that moisture has a tremendous effect on reflectance based models. Soils with little organic matter, in particular, are dominated by soil moisture with regard to reflectance. Soil moisture will decrease reflectance in similar ways that organic carbon will. The objective of this research was to observe the relationship between soil organic carbon and reflectance at different moisture levels and formulate a model to quantify organic carbon stored within the soil. During the 2003 and 2004 growing seasons, reflectance measurements were collected from three replications of four carbon levels using a spectroradiometer (350-2500nm). A line source irrigation system provided variable water treatment levels within each plot. Carbon was highly correlated with reflectance in certain portions of the SWIR region of the electromagnetic spectrum. Regression analysis showed that visible reflectance did not correlate with SOC as well as SWIR.
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Applied Remote Sensing in Agriculture: Managing Grain Protein in Wheat
Dennis Wright, Program Manager; Doug Ramsey, Co-PI; Doran Baker, Co-PI; V. Philip Rasmussen, Geospatial Extension Specialist; NASA Affiliated Research Center; Utah State University, Logan, Utah
Wheat producers are concerned about grain protein content because protein is an indicator of wheat quality, and therefore crop value. Wheat protein is managed by the amount of preseason nitrogen (N) supplemental N during anthesis. However, N is expensive and may be harmful to the environment if over-applied. Subsequently, wheat growers must make decisions if additional N will improve grain quality and yet be cost-effective. In this study, we examined remote sensing as a tool to estimate crop N levels, and then observed how additional N improved crop quality. Four rates of N (0, 76, 191, 248 kg N ha-1) were applied before planting in four randomized replications. At anthesis, half of each plot received additional N (58 kg N ha-1). Remote sensing estimates from an optical sensor, a field spectroradiometer, and imagery from aerial and satellite platforms were significantly correlated with plant N (P<.01). Coefficient of determination (r2) values for major broad-band indices (NDVI, RVI, GNDVI, and DVI) and plant N, preseason N, yield and grain protein gave consistent results. A midseason application of N increased protein in all treatments, but had greater effect on protein when plans were N stressed. Results indicate that remote sensing is a viable method of crop N estimation and is useful to assist growers in assessing canopy health and managing protein in wheat.
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Potato Canopy Detection Using Satellite Imagery
Potato growers in Idaho have faced increasingly unstable prices for successive years, making potato farming a risky livelihood. Some of the challenges contributing to the grower receiving a price that is less than production costs are:
- new varieties that produce higher yields and less culls
- increased competition from surrounding states
- loss of "grown in Idaho" marketing edge
- the carbohydrate conscious (Atkins) diets
- there are few buyers and many sellers, putting the sellers at the mercy of buyers
- growers lack good information on supply and demand, preventing rational decisions regarding supply and pricing
- no national or state organization exists to facilitate information gathering and exchange
- decreased consumption among the general public
In general, the major cause of the depressed return to the producer is that supply exceeds demand year after year. In order to address these issues, a super cooperative is being formed. This is made possible by the Capper-Volstead Act. It allows producers to come together without the threat of anti-trust or price-fixing regulation so that such supply and demand issues can be addressed. Other farm groups such as dairy, peanut and citrus have come together to successfully control supply and stabilize prices.
This study focuses on separating potato canopy from other crops in the major potato growing areas of Idaho. This is necessary to ensure that the acreage is being decreased among members of the cooperative. Initially, an attempt will be made to use free MODIS data that will make this an extremely cost effective endeavor. However, in the event that MODIS is too coarse, another inexpensive platform (likely RESOURCESAT-1, AWiFS) will be utilized.
A Low-Cost Alternative for Precision Nutrient Management
The purpose of this project is to demonstrate the ability to implement precision nutrient management as a feasible and desirable alternative to more expensive grid and less effective conventional nutrient management practices. Grid sampling and spreading is cost prohibitive for dryland farmers in Utah. Conventional methods can be improved by using emerging technologies. Different fertilizer rates are applied to different field zones rather than one rate over the entire field. Much of this technology already exists and is being adapted to the needs of agriculture. This study evaluates one method available to farmers.
Digital Image Enhancement
This 1998 bare soil image was obtained from the NRCS, and using a slide scanner converted into digital format. Light colored soils are evident and with the aid of software such as Adobe Photoshop, soil contrasts are further enhanced for our eyes to interpret more easily. Pixel distribution and histogram analysis are also useful analytical tools.
After enhancing the image, soil samples can be taken more strategically and at less cost. Those areas or zones showing similar color can be sampled together and fertilizer can be spread appropriately in those zones. Delineating the soils into zones creates a low-cost alternative to grid soil sampling and a more effective nutrient management program. For further analysis of the fields performance, yield mapping is strongly suggested.