Ambient ammonia measurements using laser photo-acoustic spectroscopy

Ammonia concentrations reached minimal levels (approximately 0.1 ppb) in early winter, followed by a sudden later winter increase. A direct relationship between ambient ammonia levels and air temperature was inferred from the data (linear correlation coefficient r=0.53). Ammonia concentrations were determined to be directly related to the absolute humidity of the air (r=0.72); a weaker relationship between ammonia concentrations and relative humidity was discovered (r=0.37). The data also indicated that ammonia levels were generally higher within continental air masses than those of maritime origin. Soil parameters such as pH and moisture content were found to have a major bearing on the release of gaseous ammonia from soils in the region

On-site measurement of soil moisture content using an acoustic system

Precision agriculture is a farming management concept based on observing and responding to intra-field variations.  One of the most important soil properties in farming is soil moisture content and it is necessary to develop new technique for measuring this property in a precision farming system.  This study investigates the measurement of moisture content in soil using an on-site, easy to use and real-time acoustic wave system.  The system consists of the propagation of acoustic waves such as sweep frequency sound wave (10-300 Hz) and multiple tone sound waves (120 Hz) through the soil.  Some properties of these acoustic waves enable estimation of soil water content such as peak amplitude (A), total power (TP), total harmonic distortion (THD) and signal to noise ratio (SNR).  The results showed that the best model for estimating the soil moisture content was the model that expressed relationship between A and soil moisture content with R2 = 0.999 (using sweep frequency) and relationship between TP and soil moisture content with R2 = 0.999 (using multiple tone).  It is argued that the change in the sound characteristics related to the soil moisture content can be used for a continuous monitoring and control of irrigation of crops.   Keywords: acoustic waves, soil moisture content, sound propertie

A fast ethanol assay to detect seed deterioration

The most common way to test seed quality is to use a simple and reliable but time- and space-consuming germination test. In this paper we present a fast and simple method to analyse cabbage seed deterioration by measuring ethanol production from partially imbibed seeds. The method uses a modified breath analyser and is simple compared to gas chromatographic or enzymatic procedures. A modified method using elevated temperatures (40°C instead of 20°C) shortened the assay time and improved its sensitivity. The analysis showed an inverse correlation between ethanol production and seed quality (e.g. the final percentages or speed of germination and the number of normal seedlings). The increase in ethanol production was observed when cabbage seeds were deteriorated by storage under ambient conditions or hot water treatments, both of which reduced the number of normal seedlings. Premature seeds produced more ethanol upon imbibition than mature seeds. Ethanol production occurred simultaneously with oxygen consumption, indicating that lack of oxygen is not the major trigger for ethanol production

Proposing an Appropriate Soil Water Content Estimation Technique for Iran

Limitation of water resources is one of the major factors in the agricultural development of Iran. In recent years. Iran suffers from increases water consumption and drought conditions, This is why efficient water management in agriculture production becomes an inevitable requirement. One of the main aspects of water management in agriculture production is operating any type of irrigation system efficiently. A good on-farm irrigation water management requires a routine monitoring of soil water content (SWC). Recently a substantial number of different experimental methods in categories of direct, indirect, ground based and remote sensing have been developed to determine the SWC, and a large body of knowledge is now available on theory and applications. The need for indirect ground-based automatic methods for obtaining water content or indices of water content is evident when the time and labor involved in direct sampling is considered. In view of Iran conditions, selecting the best soil water measurement technology for the optimal management of irrigation system is a challenge for managers and the decision makers. This research aims to (i) compile the available ground based SWC measurement methods and discuses along with their advantages and their limitations, (ii) propose a technique that will be most useful for Iran condition. Considering regional parameters of Iran, these researchers found tensiometers as a proper technique for good water management. This technique with lower price in addition with other advantages could be more effective in development of Iran Agricultural Mechanization

Radar systems for the water resources mission, volume 1

The state of the art determination was made for radar measurement of: soil moisture, snow, standing and flowing water, lake and river ice, determination of required spacecraft radar parameters, study of synthetic-aperture radar systems to meet these parametric requirements, and study of techniques for on-board processing of the radar data. Significant new concepts developed include the following: scanning synthetic-aperture radar to achieve wide-swath coverage; single-sideband radar; and comb-filter range-sequential, range-offset SAR processing. The state of the art in radar measurement of water resources parameters is outlined. The feasibility for immediate development of a spacecraft water resources SAR was established. Numerous candidates for the on-board processor were examined

Index to NASA Tech Briefs, 1975

This index contains abstracts and four indexes--subject, personal author, originating Center, and Tech Brief number--for 1975 Tech Briefs

A Survey on Subsurface Signal Propagation

Wireless Underground Communication (WUC) is an emerging field that is being developed continuously. It provides secure mechanism of deploying nodes underground which shields them from any outside temperament or harsh weather conditions. This paper works towards introducing WUC and give a detail overview of WUC. It discusses system architecture of WUC along with the anatomy of the underground sensor motes deployed in WUC systems. It also compares Over-the-Air and Underground and highlights the major differences between the both type of channels. Since, UG communication is an evolving field, this paper also presents the evolution of the field along with the components and example UG wireless communication systems. Finally, the current research challenges of the system are presented for further improvement of the WUCs