Spatial Variability Of Soil Nutrients Research Articles

A new approach to measure spatial variability of soil parameters and field technique to test-value specific fertilizer recommendations

<p>Information on the distribution of soil properties is important to know the status of nutrients in the soils based on which fertilizer nutrients are recommended. Given the variability of nutrients in the soils, making a site-specific fertilizer recommendation seems to be a compelling work. To determine the spatial variability of soil nutrients and to make judicious and precise fertilizer recommendations, new measures are designed with this study. These measures are tested against the soil samples (n = 43) for total nitrogen (N), organic matter (OM), phosphorus (P2O5), and potassium (K2O) in the study area. The descriptive statistical analysis indicated an average of low nitrogen and organic matter, while phosphorus was found to be very high and the level of potassium was high. The spread of nutrients across the data sets, however, included low, medium, high, and very high levels of ratings. The Deviation Square Index was developed and applied for the variability measurement and found that the largest variation was with phosphorus distribution, followed by potassium, nitrogen, and organic matter. The coefficient of variation (CV%) analysis also exhibited similar trends in nutrient distributions. Nitrogen was the main determinant explaining the variations in rice yield, while phosphorus and potash were negatively related to the yield. An index of fertilizer nutrient recommendation called Test-Value Specific Dose (TVSD) was developed and used to calculate the nutrient recommendation for each sampled location. This new method gave easy and more accurate doses of fertilizer over the blanket recommendation to fit the variations across the soil samples.</p>

Spatial differentiation of soil nutrients and their ecological chemometrics based on geographic detector in National Agricultural Park of Tangchang, Southwest China.

In order to analyze the spatial variability of soil nutrients and their ecological chemometrics in Tangchang Town, National Agricultural Park, 20 influencing factors were selected: soil pH, Cd, Hg, As, Cu, Pb, Cr, Zn, Ni, Se, elevation, slope, aspect, land use type, distance from industrial land, distance from commercial land, distance from railway, distance from residential area, distance from highway and distance from river. The effects of various influencing factors on the spatial variability of total organic carbon (TOC), total nitrogen (N), total phosphorus (P), total potassium (K) and ecological stoichiometry were analyzed by means of geographic detector. The results showed that average contents of soil TOC, N, P and K in the study area are 10.24 g kg-1, 1.33 g kg-1, 1.14 g kg-1 and 23.60 g kg-1, respectively, and there were significant differences in the spatial distribution of soil nutrients and their eco-stoichiometry in the study area, and TOC, N, P, K, C/N, C/P, C/K, N/P, N/K and P/K has a significant correlation with each other and most correlation coefficients are above 0.5 or below -0.5. Factor detection showed that soil properties, distance from railway and distance from residential area had the most significant explanatory power to the spatial heterogeneity of soil nutrients and eco-stoichiometry. Interaction detection showed that the interaction between soil properties with other factors was the most important factor affecting the spatial differentiation of soil nutrients and their ecological chemometrics, and elevation, distance from railway and distance from residential area were also important factors. Risk detection showed that the differences of soil nutrients and their ecological stoichiometry were most significant in the subregions of soil properties (pH, Cd, Hg, As, Cu, Pb, Cr, Zn, Ni and Se).

Investigation on Zoning Management of Saline Soil in Cotton Fields in Alar Reclamation Area, Xinjiang

Aiming at assessing the problems of the high land salinity, high spatial variability of soil nutrients, sloppy management, and low efficiency in the Xinjiang region, research on the precise delineation method of field management zones is being conducted to facilitate differentiated fertilizer management for farmers and increase the level of saline soil improvement. Taking the plots in the experimental area as the research object, traditional statistics, principal component analysis, and fuzzy c-mean classification were applied to divide the management zoning in the study area, and the suitability and effectiveness of the management zoning were evaluated. The study area was at a mild salinization level; the soil organic matter and total nitrogen content were at a low level; total phosphorus was at a medium level; and total potassium and pH reached a high level. pH had a coefficient of variation <0.1, which was weak, and the other soil attributes were of medium variability intensity. The spatial distribution of the soil attributes was highly variable. The results of the principal component analysis showed that the six soil attributes grouped into statistical factors could be divided into three principal components. The results of the fuzzy c-means classification showed that the study area could be divided into four management zones, and there were significant differences in the soil salinity, organic matter, soil nutrients, and other attributes in the different management zones. The different soil attributes could be utilized to determine the management zoning of farmland in the study area with the help of fuzzy c-mean classification.

Utilisation of Intrinsic and Extrinsic Soil Information to Derive Soil Nutrient Management Zones for Banana Production in a Smallholder Farm

In South Africa (SA), smallholder farmers contribute significantly to food production and play an essential role in the nation’s food and nutritional security. However, there is a lack of basic understanding of the spatial variability of soil nutrients and their controlling factors in these smallholdings, which subsequently hinders their agricultural production. In this work, we assessed the spatial variability and structure of key soil nutrients required by banana fruit, identified their factors of control, and delineated management zones in a smallholder farm. We used a regular grid (50 m × 50 m) to collect a total of 27 composite samples from the 0–30 cm depth interval and analysed for soil physicochemical properties. Our classical statistics results indicated that phosphorus (P), potassium (K), calcium (Ca) and zinc (Zn) varied highly, while magnesium (Mg) and total nitrogen (TN) varied moderately across the plantation. On the other hand, geostatistics revealed that P and K were strongly spatially dependent (implying a good structure), while Mg and Zn were moderately spatially dependent (indicating a moderate structure) across the banana plantation. Soil Ca and TN contents were found to be weakly spatially dependent (meaning there was no structure) across the farm. The spatial prediction maps showed that P, Mg and Zn contents were high in the northeast part (underlain by Valsrivier) and low in the northwest part (underlain by Westleigh) of the banana plantation farm. Similarly, K and Ca were low in the northwest part (underlain by Westleigh), but they were high in the south to southwest portion (underlain by Glenrosa) of the farm. Soil TN was high in the west part (underlain by Westleigh) and low in the east-northeast part (underlain by Valsrivier) across the plantation. Three management zones (MZs) were delineated for soil P, K and Ca, while for other nutrients (Mg, Zn and TN), two MZs were delineated. The results of this study provide baseline information for site-specific management of fertilisers to supplement soil nutrients in the field to improve banana productivity.

Soil differentiation and soil comprehensive evaluation of in wild and cultivated Fritillaria pallidiflora Schrenk

Few studies have focused on the growth, soil quality and sustainability of medicinal plants under different soil conditions. In this study, the spatial heterogeneity of soil physical and chemical properties, the diversity of rhizosphere soil microbial community structure, and the characteristics of growth of the wild and cultivated medicinal plant, Siberian fritillary (Fritillaria pallidiflora Schrek) were analyzed, and the soil quality and ecosystem sustainability were comprehensively evaluated. The results showed that there was significant spatial variability of soil nutrients in the different habitats. Nitrate nitrogen (NO3-N) was strongly variable, while those of the soil organic carbon (SOC) and available phosphorus (AP) were moderately variable. There was little variability among the soil available potassium (AK), electrical conductivity (EC), pH and ammonium nitrogen (NH4-N). Inverse Distance Weighting spatial interpolation showed that SOC, NO3-N, NH4-H and EC were highly distributed in the southeastern part of the wild area, and the soil was more acidic in the original habitat than in the planting habitat. There was little AK and AP in the native habitat, and there was a high content in the planting habitat. Simultaneously, the soil microbial communities of the two soils also differed. The wild-type soil showed a “fungal” type, while the planted soil showed a “bacterial” type. Pathogenic bacteria were among the primary microflora in the planting area. In general, it is difficult to maintain the sustainable development and geo-herbalism of F. pallidiflora in today's cultivation mode because of the significant differences in soil nature, spatial heterogeneity and microbial community structure for the growth of F. pallidiflora. Therefore, future planting should focus on transforming it from intensive to mountain forest planting. This is highly significant for improving the planting efficiency of F. pallidiflora, protecting their geo-herbalism and germplasm resources, and maintaining the stability and sustainable development of the ecosystem.

Diagnosis of the Spatial Variability of Soil Nutrients and Economics of Precision Management in Degraded Pastures

Most Brazilian pastures are in some stage of degradation, either by the reduction of soil fertility or inadequate management. The objective of this study was to diagnose the stage of pasture degradation and the diagnosis and management of the spatial variability of available phosphorus (P) and potassium (K+). A total of 100 soil samples were collected at a depth of 0–20 cm for available P and K+ contents determination. Geostatistical analyses of the obtained data were carried out to produce maps of the spatial distribution of available P and K+, using kriging, and allow the recommendation of fertilizers doses. The cost/benefit ratio of fertilizer recommendation and application was evaluated at fixed and variable rates. The different stages of pasture degradation were directly related to the reduction of soil fertility, as well as to the adopted management. The variability of soil available P and K+ presented spatial dependence, and the pattern of distribution resulted in the stage of the pasture degradation. The diagnosis of the level of pasture degradation associated with the use of geostatistical techniques under a precision agriculture perspective favors the efficient use of fertilizers, as well as correct decision-making and cost reduction regarding soil management.

Nutrient Transformation in Different Land Use Systems

Land use is an emerging socio-economic activity wherein a region of one major specific purpose utility may be converted into another land for general purpose utility. Land use and management practices influence soil nutrients related to soil processes, such as erosion, oxidation, mineralization and leaching, consequently modifying the transport and redistribution processes. Deforestation is widespread in the tropics, and future changes in land use may have an impact on soil nutrient conversions. Understanding how the ecosystem operates and estimating the effects of future land use change on soil properties require characterising the spatial variability of soil nutrients in relation to site properties such as climate, land use, topography, and other variables.

Assessing farm-scale spatial variability of soil nutrients in central India for site-specific nutrient management

Assessing farm-scale spatial variability of soil nutrients in central India for site-specific nutrient management

Spatial variability of soil nutrients in apple orchards and agricultural areas in Kinnaur region of cold desert, Trans-Himalaya, India.

The mountain ecosystem is highly vulnerable to climate changes fraught with a multitude of problems related to environment, food, and nutritional security. Quantification of the soil fertility status can provide an efficient way to devise strategies for sustainable crop production. The lack of information on the soil fertility status prompted us to delineate the spatial variability of the soil attributes, viz., pH, electrical conductivity (EC), soil organic carbon (OC), and the macronutrients (nitrogen (N), phosphorus (P), and potassium (K)). The extensive soil sampling was carried out from the apple orchards (AO) and potential areas under agricultural land (AL) in Kinnaur region of cold desert, Trans-Himalaya, India. Descriptive statistics was employed for the exploratory analysis of data representing a wide variation (coefficient of variation, CV = 5.70-58.62%). The available N and P, categorized as low (< 280kgha-1) to medium (280-560kgha-1) and low (4-10kgha-1) to high (> 25kgha-1), respectively, were the main limiting factors in crop production. The availability of the K was categorized as medium (118-280kgha-1) to high (> 280kgha-1). The geostatistical analysis was carried out to check the spatial dependency in the dataset. The principal component analysis (PCA) was carried out and the dominant PCs were used in fuzzy c-means clustering for the delineation of management zones (MZs). The management zones highlight the need for area-specific interventions for ameliorating soil degradation and increasing apple productivity. The soil nutrient maps in spatial scale would help to provide precise fertilizer recommendations for sustainable production and environmental conservation.

Analysis of Spatial Variability and Influencing Factors of Soil Nutrients in Western China: A Case Study of the Daliuta Mining Area

An understanding of the spatial variation and influence factors of soil nutrients in mining areas can provide a reference for land reclamation and ecological restoration. Daliuta was used as the study area. The spatial variability of soil nutrients was analyzed using traditional statistics and geostatistics. The effects of topography, mining history, and soil erosion were discussed. The results indicate that the soil pH of the Daliuta mining area is slightly acidic to slightly alkaline, and the soil organic matter, available nitrogen, available phosphorus, and available potassium belonged to the five levels (very low), six (extremely low), five (extremely low), and four (moderately low), respectively. The soil water and salt content indicated that the soil environment in the mining area is arid and has normal levels of salinity. The organic matter, available nitrogen, available phosphorus, available potassium, and soil salt varied moderately, and the pH did not change much, while the soil water varied strongly. The organic matter, pH, and soil salinity are moderately spatially autocorrelated, and the available nitrogen, available phosphorus, available potassium, and soil water are weakly spatially autocorrelated. Each nutrient index had a certain spatial trend effect. The slope, aspect, elevation, and topographic wetness index are the primary topographic factors that control the spatial distribution of soil nutrients. The organic matter, pH, and soil salinity are moderately spatially autocorrelated, and the available nitrogen, available phosphorus, available potassium, and soil water are weakly spatially autocorrelated. Each nutrient index had a certain spatial trend effect. The slope, aspect, elevation, and topographic wetness index are the primary topographic factors that control the spatial distribution of soil nutrients. Soil erosion and mining history are also important factors that lead to the spatial variation of soil nutrients.

Spatial variability of soil nutrients under sugarcane cropping system in semi-arid tropics of western India using geostatistics and GIS

The present study aimed to assess the spatial variability and mapping of soil macro and micro nutrients under sugarcane cropping system in semi-arid tropics of western Maharashtra using geostatistics and Geographic Information System (GIS). Totally 205 surface soil samples were collected at 200 x 200 m interval using the grid sampling technique in three distinct landforms. In order to assessand mapping the spatial variability of soil fertility properties, geo-statistical analysis was carried out by using best fitted models in GIS. The geostatistical analysis shows that Standardized Root Mean Square Error (RMSSE) for almost all variables expect for CaCO3 (0.96) and Mn (0.97) were close to one, which indicates a good prediction. Results showed that the available N and P varied from 125.4 to 216.4 and 7.2 to 19.7 kg ha−1, respectively, whereas, available K was ranged from 278.7 to 975.2 kg ha−1. The available Mn and Cu status of soils were sufficient with 4.12 to 21.12 and 1.57 to 4.68 mg kg−1, respectively. However, significant portion of the study area showed deficiency of available Zn. The assessed spatial variability of various soil nutrients helps in site-specific nutrient management and crop planning decisions to improve sugarcane productivity.

Spatial variability of soil nutrients under the rice-fallow system of eastern India using geostatistics and Geographic Information System

Spatial variability of soil nutrients under the rice-fallow system of eastern India using geostatistics and Geographic Information System

Spatial-Temporal Variation of N, P, and K Stoichiometry in Cropland of Hainan Island

Elemental stoichiometry reflects the interaction between plants, soil, and microorganisms, and links biogeochemical patterns with physiological limitations. The stoichiometry of elements in farmland soil is an important part of the function of the agroecosystem. Soil nitrogen (N), phosphorus (P), and potassium (K) are the main macronutrients in terrestrial ecosystems, which are closely related to biogeochemical cycles. Studying the temporal and spatial variability of soil nutrients in tropical farmland is of great significance for exploring the variation of soil nutrients and promoting the sustainable development of tropical agriculture. In this study, soil samples in the farmland of Hainan Island were collected at three different stages for exploring temporal and spatial variations of N, P, and K stoichiometry. Results showed that soil concentrations of available N, P, and K changed markedly with the temporal and spatial variability. The highest available N, P, and K concentrations appeared at the stage of 2016–2020 with values of 110.40 mg/kg, 51.91 mg/kg, and 82.76 mg/kg, respectively, while their lowest values were observed in 2010–2015 with 66.34 mg/kg, 11.27 mg/kg, and 45.77 mg/kg, respectively. The available nitrogen content in the three time periods first increased and then decreased with the increase of available potassium content, an opposite trend was observed between available nitrogen and phosphorus. The content of N increased in Haikou, Lingao, Ding’an, and P increased in Wengchang, and Lingshui and K increased in Danzhou and Wanning as time increased.

Soil Sampling Spacing Based on Precision Agriculture Variable Rate Fertilization of Pomegranate Orchard

ABSTRACT Variable rate fertilization is one of the core technologies of precision agriculture, and it is particularly important to develop a representative field sampling scheme with less workload. A grid sampling of 1 m × 1 m was conducted on a pomegranate garden of 414 m2 in Nanzhuang Town, Jianshui County, Honghe Hani and Yi Autonomous Prefecture, Yunnan Province, and set up 7 groups of sample point deletion schemes to study the reasonable sampling spacing of soil nutrients. Based on the grading standard of soil nutrients in plow layer, the distribution of soil nutrients was statistically analyzed by using classical statistical methods to reveal the spatial distribution variability of soil nutrients. We then utilized a geostatistical method to interpolate the soil nutrient to obtain the soil nutrient distribution map, and compared the soil nutrient distribution map of the deletion sampling scheme with the original sampling scheme A in shape and area. Results revealed that the deletion scheme E was the most consistent with the sampling results of the full coverage sampling scheme A, and the number of soil sampling could be reduced by half under the premise of meeting the requirements of precise fertilization. The field experiment showed that the variable rate fertilization could save 26%, 54% and 34% nitrogen, phosphorus and potassium fertilizer compared with the farmers’ conventional fertilization, the total yield of soft seed pomegranate increased by 41.52%, and the sugar content, sugar–acid ratio and vitamin C content of pomegranate grain increased by 11.79%, 51.26% and 31.59%. The results also provide support to determine sampling spacing, spatial variability of soil nutrients and variable rate fertilization in precision farming.

Spatial variability of soil nutrients in seasonal rivers: A case study from the Guo River Basin, China

Agricultural non-point source pollution refers that substance such as nitrogen and phosphorus cause water environment pollution through surface runoff and underground leakage in agricultural production activities. Water environment pollution related to agricultural non-point source pollution in the Huaihe River Basin is becoming more and more prominent. Therefore, it is necessary to analyze the characteristic of soil nutrient in cultivated land and explore the spatial variation and influencing factors of soil nutrients at the watershed scale. A total of 239 topsoil samples were collected from the Guo river basin, and the related factors of soil organic matter (SOM), total carbon (TC), total nitrogen (TN), total phosphorous (TP), total potassium (TK) and potential of hydrogen (PH) were studied by using descriptive statistics and geostatistical methods. The results showed that TK and PH were weak variation, while SOM, TC, TN and TP were medium variation. Soil pH, TP, TK, TC and SOM had moderate spatial variability, which was caused by both random factors and structural factors such as soil texture, soil type, fertilization and local ecological restoration management. Soil TN showed a strong spatial correlation, mainly due to soil texture and soil type. If the recommended fertilization amount is still given based on the average value of soil nutrients ignoring the spatial heterogeneity, it will not only affect crop production efficiency and fertilizer utilization, but may also cause greater environmental pollution. This study can provide a theoretical basis for the management of agro-ecological environments throughout the basin area.

Can Dominant Canopy Species Leaf Litter Determine Soil Nutrient Heterogeneity? A Case Study in a Tropical Rainforest in Southwest China

Litterfall significantly contributes to the fine-scale (defined here as < 1 ha) soil nutrient heterogeneity in the tropical forest ecosystem. However, the relationship between species-specific litter and spatial pattern of soil nutrients remains unclear. Therefore, our main aim is to test the hypothesis that dominant species-specific leaf litter contributes significantly to the fine-scale soil nutrient heterogeneity. In a Parashorea chinensis–dominated tropical rainforest in Southwest China, we selected a 1-ha plot, conducted intensive soil sampling (99 ha−1), litter trapping (99 ha−1), and top 5 species’ leaf litter sorting. We then analyzed the spatial variation patterns and correlations of soil nutrients with top 5 species litter nutrient fluxes using scale-wise wavelet analysis. Our results suggested that the fine-scale spatial variability of soil nutrients was not influenced by nutrient fluxes of dominant species leaf litter, whereas total litterfall nutrient fluxes depicted clear correlations with soil nutrients in studied forest and scale. This study did not detect the signature of dominant tree species-specific leaf litter on the fine-scale soil nutrient heterogeneity. In contrast, total litterfall distinctly modified soil nutrient heterogeneity at fine-scale. Our results highlight the potential importance of whole community litter and non-leaf litter on the regulation and maintenance of fine-scale soil nutrient heterogeneity in hyper-diverse tropical rainforests.

Geostatistical Analysis on Spatial Variability of Soil Nutrients in Vertisols of Deccan Plateau Region of North Karnataka, India

Different methods of land use and management have a significant effect on soil properties distribution. Understanding of variations in soil nutrients in agricultural land use is important. An increase in extraction of nutrients, soil degradation, and management of nutrients is leading to a decline in quality of vertisols across the Deccan plateau of India. Though there are studies on spatial variability of vertisols macronutrients, studies on available calcium (Ca) and available magnesium (Mg) are rare. This study is conducted in Gulbarga taluk, north Karnataka, India, to evaluate the variability of soil pH, Ca, Mg, and Zinc (Zn). A total of 78 samples of soils are collected at 0 to 15 cm depth based on the accessibility and distribution of field patterns. Four subsamples represent a single composite sample. Agilent 4200 MP-AES (Microwave Plasma-Atomic. Emission Spectrometer) was used for determining the concentration of soil nutrients. The soil nutrients represent wide variation in coefficient of variation (CV) with a value of 6 % (for pH) to 70.9 % (for Zn). The soil pH showed a significantly positive correlation to Ca and a negative correlation to Mg. Geostatistical investigation indicates spherical model is the best fit for all nutrients. Except for Ca, all nutrients showed moderate spatial dependence. Ordinary kriging is used to generate spatial variability maps. The maps of spatial variability are highly variable in nutrients content and indicate that site-specific management needs to be taken by local authorities and improve the livelihood of marginal farmers and also for sustainable agriculture.

Study on spatial variability of soil nutrient and the evaluation of soil quality based on GIS

In this study, geostatistics and GIS were applied to analyze the spatial variability of soil nutrient and the soil quality combined with the research variability property and spatial data in research area. The purpose of this paper is to study the spatial variability regulations between soil quality conditions and soil nutrient. The results show that the spatial variability degree of organic matter (OM), total nitrogen (TN), available potassium (AK), available phosphorus (AP), alkaline nitrogen (AN) and pH is 42%, 33%, 31%, 67%, 58% and 13%. pH is weak variability, TN and AK is low variability, all OM, AP and AN are moderate variability. The spatial distribution of soil nutrient is different, but there are some relationships in partial area.

Spatial variability of soil nutrients and GIS-based nutrient management in upland of Tamil Nadu: A case study from Valapadi Block, Salem district

Spatial distribution of soil nutrients is not normally considered for small holder farms in Tamil Nadu resulting in blanket fertilizer application which leads to low efficiency of some applied nutrients. This study focuses on applying geospatial analyses to map from 39 revenue villages of Valapadi block of Salem district, Tamil Nadu to identify nutrient distribution. Soil samples were taken from these 640locations and analysed soil reaction, EC, OC, major nutrients viz. nitrogen (N), phosphorus (P) and potassium (K) and micro nutrients (Fe, Mn, Cu and Zn). Spatial models of the contents were generated through geo statistical analysis to map the status of N, Pand K nutrients across the locations. Study results indicated that proportion of area of soils are neutral (56.1%) and non saline. Low OC was distributed in 68.2% area and low in available N (91.5%), P (39%) and K (52.8%) respectively. The soils are deficient in Zn (37.3%) and sufficient in Fe (75.6%), Cu (80.7%) and Mn (97.0%).Distribution pattern for P, K, Cu and Mn were rated of low to high and mapped. Outcome of this study could enhance site-specific nutrient recommendation in upland of Tamil Nadu.

Spatial variability of soil nutrients and its affecting factors at small watershed in gully region of the Loess Plateau

Spatial variability of soil nutrients and its affecting factors at small watershed in gully region of the Loess Plateau