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Pingdingshan, China

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 | Guo-Shun L.,Henan Agricultural University | Xin-Zhong W.,Henan Agricultural University | Wen-Feng S.,Henan Agricultural University | And 4 more authors.
Soil Science | Year: 2010

Spatial variability in soil properties has long been observed within uniformly managed fields. Understanding the spatial characteristics of soil properties would be helpful in the development of site-specific management. Uniform management results in overapplication in areas with high nutrient levels and underapplication in areas with low nutrient levels. The objective of this study was to quantify the degree of spatial variability of soil properties. This is important to tobacco quality across flue-cured tobacco (Nicotiana tabacum) plantation fields. Fourteen soil properties were analyzed by geostatistical techniques. Soil organic matter (OM) had significantly positive correlations with active soil OM, total N (TN), available N, available phosphorus, available potassium, Cu, Fe, and Mn. Soil TN, Zn, cation exchange capacity, and silt showed strong spatial dependence, with nugget-sill ratios ranging from 3.39% to 23.43%. Other soil properties showed moderate dependence, with nugget-sill ratios of 30.87% to 49.99%. Spatial dependence ranged from 34.3 m (Zn) to 376.3 m (Mn). The OM contour map showed highest similarity with that of TN. Variography and kriging are useful tools for soil-sampling strategies and variable-rate application in site-specific farming. Copyright © 2010 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


Guo-Shun L.,Henan Agricultural University | Hou-Long J.,Henan Agricultural University | Shu-Duan L.,Nanyang Tobacco Company of Henan Province | Xin-Zhong W.,Henan Agricultural University | And 7 more authors.
Soil Science | Year: 2010

The analysis and interpretation of the spatial variability of soil properties are keystones in site-specific management. Soil sampling interval is typically used in establishing management zones for sitespecific application of nutrients. Sampling intensity is an important factor that can potentially limit the accuracy of the management zone. The objectives of this study were (i) to quantify the spatial variability of soil properties across tobacco plantation fields, (ii) to select the reasonable sampling interval for eight soil variables to minimize cost and maximize evaluation accuracy, and (iii) to provide a theoretical basis for setting a reasonable sampling interval in precision agriculture. Soil samples were collected at approximately 20 m at 0-to 20-cm depth. The coordinates of each of the 111 points were recorded using global positioning system. Using a geographic information system software platform, the soil sampling points from the primary scheme were regularly deleted to create comparative schemes. The geostatistical method was used to produce distribution maps of the soil nutrients. Seven sampling points were randomly selected. The interpolation of the values of the seven soil points was compared under three sampling intervals with their actual measurements. The interpolation errors of soil organic matter and available copper were lowest in the 60-m sampling interval. In the 20-m sampling interval, alkaline hydrolyzable N, available phosphorus, available potassium, available iron, and available zinc had the least errors of interpolation. Available manganese had the least interpolation error at the 40-m sampling interval. Overall, the sampling efficiency could be further improved. The method can be applied in a practical and costeffective manner to facilitate soil sampling. Copyright © 2010 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Source

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