Oklahoma State University–Stillwater

About: Oklahoma State University–Stillwater is a education organization based out in Stillwater, Oklahoma, United States. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 18267 authors who have published 36743 publications receiving 1107500 citations. The organization is also known as: Oklahoma State University & OKState.

Construction of an intergranular volume compaction curve for evaluating and predicting compaction and porosity loss in rigid-grain sandstone reservoirs

Abstract: To evaluate compaction as a factor in porosity evolution, a plot of intergranular volume vs. depth was constructed using data from relatively uncemented reservoir sandstones from a variety of depths, ages, and geographic locations. The resulting intergranular-volume-decline curve reveals that sands compact mechanically and intergranular volume declines rapidly, from about 40 to 42% at the surface, to about 28% at 1500 m. Between about 1500 and 2500 m, intergranular volume continues to decline slowly, until the framework stabilizes at around 26% (maximum potential porosity in the absence of cement or matrix). No further significant decrease in intergranular volume is observed to the depth limits of the data set at 6700 m. Comparison of intergranular volume and volume of quartz cement for different formations reveals no obvious balance between intergranular pressure solution (as monitored by intergranular volume) and quartz cementation. This indicates that grain-to-grain pressure solution and quartz cement precipitation do not proceed concomitantly on the thin-section scale. Moreover, grain compaction is limited (to about 26% intergranular volume) in rigid-grain sandstones, which suggests that the occurrence and distribution of deep porosity is a function of the volume of cement available to fill the intergranular pores. Therefore, deep, porous sandstones are relatively uncemented rather than undercompacted.

Optical Sensor‐Based Algorithm for Crop Nitrogen Fertilization

Abstract: Nitrogen (N) fertilization for cereal crop production does not follow any kind of generalized methodology that guarantees maximum nitrogen use efficiency (NUE). The objective of this work was to amalgamate some of the current concepts for N management in cereal production into an applied algorithm. This work at Oklahoma State University from 1992 to present has focused primarily on the use of optical sensors in red and near infrared bands for predicting yield, and using that information in an algorithm to estimate fertilizer requirements. The current algorithm, “WheatN.1.0,” may be separated into several discreet components: 1) mid‐season prediction of grain yield, determined by dividing the normalized difference vegetative index (NDVI) by the number of days from planting to sensing (estimate of biomass produced per day on the specific date when sensor readings are collected); 2) estimating temporally dependent responsiveness to applied N by placing non‐N‐limiting strips in production fields each...

Valuing urban wetlands: A review of non-market valuation studies

Abstract: Wetlands provide a range of valuable ecosystem services from water purification and nutrient retention to recreation and aesthetics. The value of these services is often difficult to quantify and document to policy makers and the general public. Economists have developed non-market approaches to address difficult issues related to valuation of the environment. This paper reviews recent literature on non-market valuation as applied to wetlands, with a particular focus on the value of urban wetlands. Wetland valuation studies have generated a wide range of values, in part due to differences in what is valued and in part due to differences in methodology. Several studies have shown that property owners value proximity to wetlands in urban areas. In addition, studies have found positive values for recreation (fishing and hunting), commercial fishing, water purification, and other ecosystem services provided by wetlands, although little of this work has been done on urban wetlands. Valuation studies can provide useful information about relative rankings of value, showing, for example, that certain types of wetlands or certain services are more highly valued than others. Whether the absolute magnitude of valuation estimates is correct is less clear.