Soil fertility is conventionally evaluated by soil properties such as C, N, and P contents. Evaluation of soil fertility is
now becoming a routine work for soil management and crop production. However, laboratory-analysis based determination of soil
properties is time and cost consuming, which is not suitable for precision agriculture. Here, infrared spectroscopy (IR) appears
as an alternative and fast technique to measure soil fertility. The IR transmission method is generally used in soil qualitative
analysis, while the IR reflectance can be used in soil quantitative analysis, and most of soil-related research is focused
on reflectance spectroscopy. Infrared reflectance spectra, including diffuse reflectance spectra and total attenuated reflectance
spectra, are involved in soil quantitative analysis. We observe an excellent performance of predicting soil C and N contents
using IR spectra. Moreover, in most of cases the predictions of the contents of soil P, K, Ca, Mg, S, and some other microelements
are satisfactory. Soil water, soil clays, and soil microbes can also be characterized and evaluated using IR spectroscopy.
In recent years, a new method named infrared photoacoustic spectra was applied in soil analysis. Infrared-photoacoustic spectra
is indeed more convenient for sample pretreatment and spectra recording, and the recorded soil spectra contain more useful
information versus conventional reflectance spectroscopy. Though currently the application of infrared photoacoustic spectroscopy
in soil analysis is limited, it appears promising to measure soil fertility. The application of infrared spectroscopy in soil
fertility is largely dependent on spectra pretreatment and multivariate calibration due to strong interferences in the spectra.
Partial least square (PLS) and artificial neural network (ANN) are two widely used mathematical tools in the prediction of
soil properties, and more mathematical tools combined models will benefit the prediction performance. To make full use of
soil infrared spectra, soil spectra library construction is needed in future, and a standard procedure should be first decided
in the construction. Based on soil infrared spectra library soil fertility can be fast evaluated combining suitable mathematical
model, which will play an important role in the sustainable agriculture. 相似文献
Recent studies have expanded the interests about microbial community and function following the rapid development of high-throughput sequencing techniques in the freshwater ecosystem. In this study, we aimed to attain a deep understanding of microbial community structure and potential nitrogen metabolism in Hulun Lake, a shallow hypereutrophic steppe lake in the Mongolian Plateau in China. The result demonstrated that cyanobacteria were the most dominant phylum. Network analysis showed both intra- and inter-phylum co-occurrence were pervasive, and there were modular structures in the microbial assemblages. The cluster dominated by proteobacteria was mainly negatively connected to the cluster dominated by both proteobacteria and actinobacteria. Cyanobacteria were tightly clustered together and positively connected to these two clusters. The major nitrogen metabolism pathways were glutamine synthetase–glutamate synthase and assimilatory nitrate reduction, indicating the nitrogen was mainly retained in the lake by microbial uptake. Cyanobacteria contributed 43.25% gene reads involved in the overall nitrogen metabolism but mainly contributed to assimilatory nitrate reduction and nitrogen fixation, aggravating the lake eutrophication. This study adds to our knowledge of microbial assemblages and nitrogen metabolism in the shallow hypereutrophic lake and provided an insight understanding for the purposes of lake ecosystem’s protection and efficient management in the Mongolian Plateau.
Anaerobic dechlorination is an effective degradation pathway for higher chlorinated polychlorinated biphenyls (PCBs). The enhanced reductive dechlorination of PCB-contaminated soil by anaerobic composting with zero-valent iron (ZVI) was studied, and preliminary reasons for the enhanced reductive dechlorination with ZVI were investigated. The results show that the addition of nanoscale ZVI can enhance dechlorination during in-vessel anaerobic composting. After 140 days, the average number of removed Cl per biphenyl with 10 mg g?1 of added nanoscale ZVI was 0.63, enhancing the dechlorination by 34 % and improving the initial dechlorination speed. The ZVI enhances dechlorination by providing a suitable acid base environment, reducing volatile fatty acid inhibition and stimulating the microorganisms. The C/N ratios for treatments with the highest rate of ZVI addition were smaller than for the control, indicating that ZVI addition can promote compost maturity. 相似文献