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Jiang H.-L.,Henan Agricultural University | Liu G.-S.,Henan Agricultural University | Wang R.,Enshi Tobacco Company of Hubei Province | Liu S.-D.,Nanyang Tobacco Company | And 7 more authors.
Soil Science | Year: 2011

Recent precision agriculture research has focused on the use of management zones (MZ) as a method for variable-rate fertilizer application. A 4-ha tobacco-planted field was selected to define MZ using tobacco quality as basis. To achieve this objective, we collected 111 soil samples from the top 20 cm on an approximately 20-m grid of the study area in March 2009. Classical statistics showed a large variability of all soil nutrients. Results of geostatistics analysis indicated that the eight soil properties examined were best represented through spherical models. Four quality-limiting factors for tobacco were found by stepwise multiple regression analysis. These factors were selected as the variables for delineating MZ. Management Zone Analyst was used to delineate MZ as well as to provide the fuzzy performance index and normalized classification entropy to determine the optimum cluster number. Results showed that the optimum number of MZ in the study area was 4. Furthermore, analysis of variance indicated the heterogeneity of soil variables among the four MZ. Based on the clearly defined MZ, we conclude that tobacco-planted fields can be managed in a site-specific manner by these methods. Copyright © 2011 by Lippincott Williams & Wilkins. Source

Hou-Long J.,Henan Agricultural University | Hou-Long J.,Chongqing Tobacco Research Institute | Guo-Shun L.,Henan Agricultural University | Rui W.,Enshi Tobacco Company of Hubei Province | And 2 more authors.
Communications in Soil Science and Plant Analysis | Year: 2012

The spatial variability of soil total nutrient levels, which may be greatly affected by parent material, plays an important role in both agriculture and environment, especially with regard to soil fertility and soil quality. Little research has been done that addresses the spatial characteristics of total nutrients. Soil samples (0-20 cm) were taken from 111 points on an approximately 20-m grid in March 2009 using a global positioning system (GPS) to define sample locations. Sixteen soil total chemical properties were analyzed by classical statistical and geostatistical methods. Soil aluminum (Al), calcium (Ca), chromium (Cr), copper (Cu), nitrogen (N), sodium (Na), silicon (Si), strontium (Sr), titanium (Ti), and vanadium (V) exhibited strong spatial dependence, with the nugget-sill ratios ranging from 3.39% (Na) to 23.53% (Si). Soil barium (Ba), iron (Fe), potassium (K), manganese (Mn), phosphorus (P), and zinc (Zn) had moderate spatial dependence, with nugget-sill ratios of 3.39% to 23.53%. The spatial correlation distances varied from 15.7 m (Zn) to 286.5 m (Cr). The clearly patchy distributions indicated that significant positive correlations among Al, Ba, Fe, K, Mn, Na, Si, Ti, and V led to strong positional similarity. The interpolated maps of the nutrients showed the spatial distributions of the soil variables, which is helpful for better understanding their spatial variability and delineating the potential agricultural management zone. The soil total nutrient distribution maps could be used as the basis for site-specific fertilizer application to improve quality and increase yield of flue-cured tobacco in the study area. © 2012 Copyright Taylor and Francis Group, LLC. Source

Jiang H.-L.,Henan Agricultural University | Jiang H.-L.,Chongqing Tobacco Company | Liu G.-S.,Henan Agricultural University | Liu S.-D.,Chongqing Tobacco Company | And 4 more authors.
Archives of Agronomy and Soil Science | Year: 2012

Currently, efficient and cost-efficient methods are needed to manage fields in order to maximize economic return, minimize environmental impact, and improve soil and crop site-specific management. Management zones (MZs) of uniform production potential may offer a solution to the problems associated with grid soil sampling while still effectively describing variability in soil properties. In this study, a hillside field of 4 ha was selected as the study site and 111 soil samples were taken from the topsoil (0-20 cm), on an ~20-m grid. Soil samples were analyzed for pH, organic matter, active soil organic matter, total nitrogen, alkalytic nitrogen, available phosphorous, available potassium and cation-exchange capacity. Their spatial variability was analyzed and spatial distribution maps were constructed using geostatistical techniques. Principal component analysis (PCA) and fuzzy c-means clustering algorithm were then performed to delineate MZs, and eigenvalues were used to select the principal components (PCs) for cluster analysis. Fuzzy performance index and normalized classification entropy were used to determine the optimum cluster number. The results revealed that the optimum number of MZs for this study area was three and analysis of variance indicated that the MZs were reasonable for the area. Based on the description of MZs, it was concluded that the area could be managed in a site-specific way. © 2012 Copyright Taylor and Francis Group, LLC. Source

Deng J.,Nanjing Agricultural University | Deng J.,Enshi Tobacco Company of Hubei Province | Chen X.,Nanjing Agricultural University | Du Z.,Nanjing Agricultural University | Zhang Y.,Nanjing Agricultural University
Water Resources Management | Year: 2011

The seasonal drought and the low available soil moisture affect the agricultural production in red soil region, China. Therefore, it is necessary to simulate and predict the dynamic changes of soil water in the field. Presently, dynamic model has been applied to obtain the soil water information. While the simulation accuracy of dynamic model depends on many complicated parameters, which are difficult to obtain. In this study, the various nonlinear Stochastic Model of soil water simulation systems and chaotic time series analysis methods of prediction systems had been set up. In the nonlinear Stochastic Model of soil water simulation systems, the daily soil water content simulated by Least squares support vector machine (LS-SVM) with the meteorological factors had more stabilities and advantages in soil water simulation performance over the Back Propagation Artificial Neural Network (BP-ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS). In chaotic time series analysis method of prediction systems, the various signal preprocessing methods including the appropriate de-noising methods and wavelet decomposition methods were applied to preprocess the original chaotic soil water signal. The results of the prediction systems showed that the appropriate de-noising methods and the tendency of wavelet transformation had less effect on the delay time (τ) and embedding dimension (m). The de-noising methods may ignore the detail information of the soil water signal, while the appropriate wavelet transformation to get smaller Maximum Lyapunov Exponent (λ1) of the chaotic soil water signal detail and tendency information can improve the predicting capacity. © 2011 Springer Science+Business Media B.V. Source

Bu G.-J.,Hubei University | Yu J.,Chengdu University of Technology | Di H.-H.,Enshi Tobacco Company of Hubei Province | Luo S.-J.,Hubei University | And 2 more authors.
Huanjing Kexue/Environmental Science | Year: 2014

Ion chromatography, fluorescence spectroscopy, UV-visible absorption spectroscopy and multivariate statistical analysis were applied to study the composition and evolution characteristics of dissolved organic matter (DOM) and heavy metal extracted from chicken manure during composting, and the influence of organic matter evolution on the bioavailability of these heavy metals was further investigated. The result showed that, a large number of organic acids were generated during the active stage, and their concentrations were in the range of 2 097.55-2 155.61 mg·L-1, 39.24-51.58 mg·L-1, 12.52-12.90 mg·L-1 and 1.68-2.31 mg·L-1, respectively. During the curing stage, protein-like matter was degraded, whereas humic-like substances were formed, which increased the humification degree, condensation degree and stability of DOM. The content (1.069-7.106 mg·L-1) of dissolved iron ranked first during composting, that of dissolved Al, As, Cr, Cu and Mn (0.1-1.008 mg·L-1) ranked second, and the concentration of dissolved lead was the lowest. Concentrations of all heavy metals decreased during composting except aluminum. Furthermore, the result from correlation analysis showed that these dissolved heavy metals were bound with DOM, and their bioavailability was low. It could be concluded that, the bioavailability of the heavy metals in chicken manures became lower through the decrease of dissolved heavy metals and the binding between dissolved heavy metals and humic-like substances. ©, 2014, Science Press. All right reserved. Source

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