Percentage Of Soil Cover Research Articles

Effects of Cultural Practices on Agronomic and Reflectance Characteristics of Soybean Canopies1

AbstractUnderstanding the relationship between the reflectance measured and the various cultural practices used in today's soybean production is key for further development and use of remote sensing as a tool for crop monitoring. Field experiments were conducted at the Purdue Agronomy Farm in West Lafayette, Ind. in 1978 and 1979 to study the reflectance factor (RF) of soybean (Glycine max L. Merr.) canopies as affected by differences in row width, population, planting date, cultivar, and soil type (Typic Argiaquoll and Typic Hapludulf). Reflectance factor (RF) data were acquired with a Landsat‐band radiometer (Exotech 100), which is a four band radiometer with a 15‐degree field of view that measures radiance in the following wavelength regions: 0.5–0.6, 0.6–0.7, 0.7–0.8, and 0.8–1.1 µm. Agronomic measurements included plant height, leaf area index, development stage, total fresh and dry biomass, and percent soil cover.Row width, planting date, and cultivar influenced the percent soil cover, leaf area index, biomass, and development stage of the soybean canopies. Changes in these agronomic variables were manifested in the canopy reflectance. Soil color and moisture were important factors influencing RF in single Landsat bands; however, the near infrared/ red reflectance ratio and the greenness transformation were less sensitive than the single bands to changes in soil background. Variations in spectral responses are strongly associated with planting date during early to mid‐season, with the row width during mid‐season to near maturity, and with cultivar at maturity. This information should be useful in applications of remote sensing for identifying crops and estimating crop condition and yields.

Effects of Management Practices on Reflectance of Spring Wheat Canopies1

AbstractAnalyses of multispectral measurements from satellites offer the potential to monitor and inventory crop production. The crop canopy is a dynamic entity influenced by many cultural and environmental factors. In order to quantify and understand some of these potential sources of variation in spectral measurements of crops, an experiment was conducted on a Williams loam (fine−loamy, mixed Typic Argiborolls) at the Williston, North Dakota, Agricultural Experiment Station in 1977. The effects of soil moisture, planting date, nitrogen fertilization, and cultivar on reflectance of spring wheat (Triticum aestivum L.) canopies were investigated. Spectral measurements were acquired on eight dates throughout the growing season with a radiometer (Exotech 100 A) in four wavelength bands (0.5 to 0.6, 0.6 to 0.7, 0.7 to 0.8, 0.8 to 1.1 µm) at 3.5 m above the plots. On the days spectral data were taken, measurements of crop maturity stage, leaf area index, biomass, plant height, percent soil cover, and soil moisture were also taken.In this experiment, planting date and available soil moisture were the primary agronomic factors affecting reflectance of spring wheat canopies from tillering to maturity. Comparisons (R2) of treatments indicated that during seedling and tillering stages, planting date was associated with 36 and 85% of variation in red (0.6 to 0.7 µm) and near infrared (0.8 to 1.1 µm) reflectances, respectively. As the wheat headed and matured, less variation in reflectance was associated with planting date and more with available soil moisture. By mid July soil moisture accounted for 73 and 69% of the variation in reflectance in red and near infrared bands, respectively. Differences in spectral reflectance among treatments were attributed to changes in leaf area index (LAI), biomass, and percent soil cover. Cultivar and N fertilization rate had little association with the variation in reflectance of these canopies. Agronomic practices resulting in differences in LAI, biomass, and percent soil cover potentially can be monitored by remote sensing and this information may be useful in estimating crop production.

Conservation of Sandy Soils with a Surface Mulch

ABSTRACT AMULCH surface cover on sandy soils will reduce wind erosion, in-crease soil moisture storage, improve dry aggregate stability, and increase crop yields. The percent soil surface covered with varying amounts of cotton gin trash, wheat, and sorghum stubble was determined. The percent soil cover was used to develop a mulch coefficient (100 percent soil cover equals a mulch coefficient cf 1.0). The mulch coeffi-cient was related to soil moisture stor-age, crop yield, evaporation, wind ero-sion loss, and runoff using the results of this study and previous research by other scientists. A mulch coefficient of 0.6 to 0.8 was sufficient to control wind erosion and runoff. Good soil moisture storage, evaporation reduction, and crop yields have been obtained with a mulch coefficient of 1.0.

Percent Soil Cover by Six Vegetative Mulches1

AbstractEstimates of percent soil cover by straw or stalk type vegetative mulches can be calculated by means of measuring the average length, diameter, and weight of a random sample of clean, oven‐dry material. Efficiency of soil cover per unit weight for mulches at Akron, Colo., were spring barley > winter wheat = spring oats > sudangrass > grain millet > grain sorghum.