Spatial variability and evaluation of status of micronutrients in selected soils around Taihu Lake, China

Background, aim, and scope  Soil micronutrients are essential for plant growth and human health. Spatial variability and evaluation of soil micronutrient status are the research hotspot. The plain of northern Zhejiang Province, around Taihu Lake, China, is a key agriculture production area. With the rapid development of agriculture in Zhejiang Province, the management of soil micronutrients is of increasing concern to sustain crop productivity and human health. Soil-available micronutrients in the study region have not previously been studied in detail. Primary objective of this research was to examine the spatial distribution and evaluation of soil-available micronutrients in the arable land in this agriculturally important region using geostatistics. The controlling factors for the spatial variability of available micronutrients were interpreted. The research findings attained in the present study are of fundamental significance in providing a guideline for precise agriculture management practice and sustaining food security. Materials and methods  Amounts of available Fe, Mn, Cu, Zn, B and Mo in 1893 soil samples taken from the arable land in nine counties in northern Zhejiang Province, around Taihu Lake, were measured and their spatial distribution patterns were investigated. Available Mn, Fe, Cu, and Zn were extracted with DTPA and analyzed by inductively coupled plasma–atomic emission spectroscopy. Available B was extracted with boiled water, then determined by inductively coupled plasma–optical emission spectroscopy. Available Mo was extracted with Tamm reagent and was then determined by inductively coupled plasma-mass spectrometry. Geostatistics was conducted for the data processing. Results  More than 50% of the arable land were deficient in available Mo, while more than 70% had extremely low amount of available B. Amounts of available Cu, Zn and Mn were relatively high, whereas the soils are extremely sufficient in available Fe. The geostatisticical data shows that Mn, Cu, Zn, and Mo were best fit with an exponential model, while Fe and B were best fit with a spherical and linear model, respectively. Copper and Mo had strong spatial dependency, which is attributable to the effects of natural factors including parent material, topography, and soil type; Fe, Mn, and Zn had medium spatial dependency; however, B had weak spatial dependency, indicating an involvement of anthropogenic factors. Nevertheless, the six micronutrients studied all show spatial distribution trend to a certain extent. Discussion  Based on the provincial classification standard of soil micronutrients and the results of the present study, regionalized management of soil micronutrients was recommended. We divided the soil micronutrients investigated in the present study into three types: Type I (Fe), Type II (Mn, Cu, and Zn) and Type III (B and Mo). Type I is sufficient, and its amount needs to be controlled; otherwise, it will be toxic to crops. Type II is enough and its amount does not need to be increased currently through micronutrient fertilization. However, Type III is deficient in substantial areas in the region studied and its cause of deficiency needs to be investigated; its availability needs to be improved to sustain the crop production and food quality. The availability of B and Mo in the north of Zhejiang Province should be regionally managed. Over the past two decades, the spatial variability of soil-available micronutrients in the study region was attributable to the soil formation factors as well as anthropogenic activities such as fertilization, cultivation, and other soil management practices. The lower available B and Mo concentrations in the arable land were apparently due to continuous cropping and intensive applications of fertilizers without adequate supply of micronutrients. The high available Fe and Mn concentrations in the soils were attributed to increasing soil acidification and relatively high soil organic matter contents. The high available Cu and Zn levels of the soils in this region were attributed to intensive utilization of animal manure as fertilizers. Conclusions  Based on the provincial classification standard and the results from the present study, regionalized management of soil micronutrients was recommended. Moreover, the present study would provide an insight into understanding the basis for the development of innovative strategies for land management practices such as precision farming and environmental risk assessment. Recommendations and perspectives  The research findings attained in the present study would help to improve our understanding of spatially variable availability of soil micronutrients and providing a quantitative basis for decision and policy making to develop innovative agricultural management strategies to sustain micronutrient nutrition. Further research should be conducted to elucidate the relationship between soil micronutrient and plant growth and human health.     

Point pedotransfer functions for prediction of water retention of selected soil series in a semi-arid region of western Iran

This study was conducted to derive point pedotransfer functions (PPTFs) for soil water retention (SWR) in western Iran. Topsoil and subsoil of 63 soil series, which were representative of different regions of Hamadan province, were sampled. Soil water retention was determined by the sand box and pressure plate at matric suctions (h _m) of 0, 1, 2, 5, 10, 25, 50, 100, 200, 500, 1000 and 1500 kPa. PPTFs were derived through multiple linear regressions for the topsoils and subsoils. These used particle size distribution, bulk density, organic matter, calcium carbonate and gravel contents as easily-available inputs. To increase the accuracy of the PPTFs, saturated water content was also included as an input variable in a group of PPTFs but they are not better as assessed using the Akaike Information Criterion. All of the PPTFs were statistically significant (p < 0.001) and could be used to predict the SWR. The absolute effect of bulk density on the SWR diminished as h _m increased. Bulk density decreased the SWR for low h _m and increased it for high h _m. In the wet range, organic matter increased the SWR. Clay and silt increased SWR whereas gravel decreased it. The effect of calcium carbonate on SWR was negligible.     

稻米和土壤微量元素的空间变异

Consumption of rice is the main source of micronutrients to human in Asia. A paddy field with unknown anthropogenic contamination in Deqing County, Zhejiang Province, China was selected to characterize the spatial variability and distribution of micronutrients in rice grain and soil. A total of 96 paired soil and rice grain samples were collected at harvest. The micronutrients in the soil samples were extracted by diethylenetriamine pentaacetic acid (DTPA). The mean micronutrient concentrations in rice grain were 3.85 μg Cu g-1, 11.6 μg Fe g-1, 39.7 μg Mn g-1, and 26.0 μg Zn g-1. The mean concentrations were 2.54 μg g-1 for DTPA-Cu, 133.5 μg g-1 for DTPA-Fe, 30.6 μg g-1 for DTPA-Mn, and 0.84 μg g-1 for DTPA-Zn. Semivariograms showed that measured micronutrients in rice grain were moderately dependent, with a range distance of about 110 m. The concentrations of the DTPA-extractable micronutrients all displayed strong spatial dependency, with a range distance of about 60 m. There was some resemblance of spatial structure between soil pH and the grain Cu, Fe, Mn, and Zn. By analogy, similar spatial variation was observed between soil organic matter (SOM) and DTPA-extractable micronutrients in the soil. Kriging estimated maps of the attributes showed the spatial distributions of the variables in the field, which is beneficial for better understanding the spatial variation of micronutrients and for potentially refining agricultural management practices at a field scale.     

Comparison of soil tests to determine micronutrients status in Argentina soils

Abstract

Soil extraction techniques to measure the status of available micronutrients for plants are important in the diagnosis of deficiency or toxicity. Mehlich 3 (M3), EDTA (pH=8.2), DTPA‐TEA, and Soltanpour and Schwab (SS) solutions were confronted for their ability to extract simultaneously copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe). Argentinean soils from different taxonomic orders with widely varying properties were investigated. The values obtained showed that DTPA‐TEA and SS solutions extracted similar amounts of Zn, Fe, and Mn, while EDTA dissolved comparatively higher amounts of Fe and Mn. Mehlich 3 yielded the highest extractions for the four micronutrients. Soil pH not only affected the extraction of Mn by DTPA‐TEA, SS, and EDTA extractions, but also the extraction of Fe by EDTA. The organic carbon affected the determination of Fe and Zn in all cases. The correlations of the different tests for Cu, Zn, Mn, and Fe were significant. The results suggest that for the determination of the bioavailable status of micronutrients, any of the studied tests could be applied using the soil edaphic properties as factors to improve the correlations between them and standardize the methods.     

Variability of soil properties in a landscape ecological survey in the Tuscan Apennines,Italy

The aim of this study is to test a landscape-ecological classification developed for surveys which make use of aerial photographs. This classification is based on relief, parent material and vegetation but leaves out soil properties which are important in landscape ecology. For this purpose, the variability of 11 surface soil characteristics is studied in selected plots of 2 × 3m, along a transect in an area of dissected fluvio-lacustrine deposits near Florence, Italy. It appears that much more than the 5 observations which were made in each plot are needed to establish reasonably accurate estimates of the mean of the variables.By means of a non-parametric test it is demonstrated that the adopted landscape-ecological classification is suitable for further surveying. This test is based on a comparison of all sample combinations for each variable, and for the variables combined per mapping unit. A discriminant function analysis confirms the results of this test.     

土壤微量元素含量及其影响因素的研究

论述了临沂市土壤中硼、锌、锰、铜、铁等5种主要微量元素的状况与其它因素的关系。有效硼含量0．09～3．67mg／kg，平均0．35mg／kg；有效锰22～572mg／kg，平均244mg／kg；有效锌0．15～4．02mg／kg，平均O．53mg／kg；有效铜0．09～5．78mg／kg，平均1．03mg／kg；有效铁3．2～162mg／kg，平均21．5mg／kg；有效锰2．0～131．4mg／kg，平均23．4mg／kg。不同土壤类型的以上5种微量元素有明显差异，其特征是砂姜黑土缺锌，棕壤、水稻土富含铁、铜、锰、锌；成土母质是影响土壤微黾元素的重要因素之一，发育在基性岩上的土壤一般含量较高，而由红土母质发育的土壤则含量较低。土壤有机质含量与土壤微量元素有明显正相关关系，其中速效锌、速效硼和速效铜与有机质的关系尤为显著。     

土壤微量元素含量及其影响因素的研究

论述了临沂市土壤中硼、锌、锰、铜、铁等5种主要微量元素的状况与其它因素的关系。有效硼含量0.09~3.67 mg/kg,平均0.35 mg/kg;有效锰22~572 mg/kg,平均244 mg/kg;有效锌0.15~4.02 mg/kg,平均0.53 mg/kg;有效铜0.09~5.78 mg/kg,,平均1.03 mg/kg;有效铁3.2~162 mg/kg,平均21.5 mg/kg;有效锰2.0~131.4 mg/kg,平均23.4 mg/kg。不同土壤类型的以上5种微量元素有明显差异,其特征是砂姜黑土缺锌,棕壤、水稻土富含铁、铜、锰、锌;成土母质是影响土壤微量元素的重要因素之一,发育在基性岩上的土壤一般含量较高,而由红土母质发育的土壤则含量较低。土壤有机质含量与土壤微量元素有明显正相关关系,其中速效锌、速效硼和速效铜与有机质的关系尤为显著。     

Trace metal concentrations in selected biological,sediment, and water column samples in a Northern New England river

A baseline ecosystem study was undertaken in a relatively non-industrialized New England river to determine trace metal levels of Cr, Cu, Pb and Zn concentrations in water column, sediment, fish, mollusks and aquatic macrophytes. Additional analyses were completed on fish and mollusks for Hg. Results showed metal concentrations in the study area were in general agreement with literature values. Both mollusks and aquatic macrophytes exhibited the highest levels of accumulated metals.     

Variability of soil physical quality and erodibility in a water-eroded cropland

Physical degradation of the soil increases its susceptibility to erosion by water action. However, relatively few studies have evaluated the opposite, i.e., the impact of water erosion on soil erodibility. This study was conducted in a corn field in Ohio. Some sites within the field have experienced water-induced soil erosion following heavy rainstorms. Physical characteristics of the soil were compared between eroded (ER) and un-eroded sites (UN). Compared with ER, the soil in UN had lower penetration resistance (4.87 vs. 4.53 MPa), bulk density (1.45 vs. 1.33 Mg m^?3), and sand content (17.4 vs. 14.2%), and higher shear strength (80.1 vs. 125.3 KPa), hydraulic conductivity (3.0 vs. 3.4 cm h^?1), intrinsic permeability (31.9 vs. 36.4 × 10^?10 cm²), and contents of soil organic carbon (36.1 vs. 32.1 g kg^?1), total nitrogen (3.3 vs. 3.1 g kg^?1), clay (25.2 vs. 24.2%), silt (60.5 vs. 58.4%), and very fine sand (3.4 vs. 1.1%). Also Munsell's variables differed between ER and UN (1.24 vs. 0.54 for hue, 4.59 vs. 4.35 for value, and 1.99 vs. 1.79 for chroma, respectively). The erodibility factor (K) was lower in UN than in ER (0.00327 vs. 0.00354 Mg ha h ha^?1 MJ^?1 mm^?1, respectively). Hence, it is suggested the ER sites within the corn field agroecosystem are more susceptible to accelerated erosion as compared with UN sites.     

Effect of manures and fertilizers on soil physical properties,build-up of macro and micronutrients and uptake in soil under different cropping systems: a review

Combined application of manures and fertilizers played a pivotal role in the improvement in soil physico-chemical properties, macro and micronutrients distribution and their transformations under different cropping systems. Based on a cropping system, the different levels of manures and fertilizers were used to study improvement in physico-chemical properties of soil. The aim was to explore the appropriate application of organic manures and inorganic fertilizers for improved sustainable yields of a cropping system. Intensive cropping systems lead to N, P, K, Zn, Cu, Fe, and Mn deficiencies in surface and subsurface soil, which could be refreshed with combined application of manures and fertilizers. The application of manures and fertilizers controls the pH and electrical conductivity of soil. Moreover, manures and fertilizers showed improvement is soil physical conditions viz. bulk density, particle density, porosity, and water holding capacity etc. Manuring coupled with fertilization helped to great extent for macro and micronutrient transformations in the soil. Under these transformations, the soil solution and water soluble component (fractions/pools) of soil is enriched with macro and micronutrients. There was a consistent declining trend of DTPA-extractable Zn, Cu, Fe, and Mn in the sub-surface soil in comparison to the surface layer, which may be ascribed to increase in pH with increase in depth and decrease of organic matter with depth. Similarly, manures reduced the concentration of residual macro and micronutrients in soil. Recently, integrated nutrient management system (INMS) is gaining importance vis-a-vis maintaining the soil fertility with conjunctive use of chemical fertilizers plus organic manures.     

Changes in soil properties and the availability of soil micronutrients after 18 years of cropping and fertilization

Micronutrient deficiencies are common in many parts of China's Loess Plateau. The objective of this experiment was to study the effects of long-term cropping and fertilization practices on soil properties and micronutrient availability in this region. The field plot experiment began in 1984. It included five cropping systems and four fertilizer treatments. In September 2002, soil samples were collected and soil pH, organic matter content, available P, and CaCO₃ were measured. Total and available Zn, Cu, Mn, and Fe were also determined. The relationship between soil properties and available micronutrients was determined by correlation and path analysis. After 18 years, soil pH and CaCO₃ levels were lower in the cropped and fertilized treatments compared to the fallow treatment. In contrast, soil organic matter and available P levels were higher in cropped compared to fallow treatments. A comparison of unfertilized treatments indicated that available Zn and Cu levels in cropped treatments were lower compared to the fallow treatment, probably due to the removal of these micronutrients from the system through crop uptake and harvest. In contrast, available Mn and Fe levels were higher in cropped treatments compared to the fallow treatment. The impacts of fertilization on available micronutrients varied with cropping systems. Generally, available Zn and Fe were higher in fertilized compared to unfertilized treatments, but available Cu was not significantly influenced by fertilization. Fertilization tended to increase available Mn in continuous wheat and maize, but reduced available Mn in continuous clover and the crop–legume rotation. The total (plant available + unavailable) micronutrient contents were lower in the four cropped-treatments compared to the fallow treatment. The addition of manure or P fertilizer increased total Zn, Fe, and Mn, but had no significant effect on total Cu. The results of correlation analysis and path analysis indicated that soil organic matter exerts a significant and direct effect on the availability of Zn, Mn, and Fe, but has little influence on available Cu. The effects of available P, CaCO₃, and pH on micronutrient availability were indirect, passing through soil organic matter. The results of this study suggest that long-term cropping and fertilization altered several important soil properties and increased the plant available micronutrient content of this loess-derived soil.     

Chemistry of bulk precipitation throughfall,soil water and stream water in a small catchment in Devon,England

Monthly mean concentrations of potassium, calcium, sodium, magnesium chloride and nitrate-nitrogen were determined from samples of bulk precipitation, throughfall, soil water and streamflow collected weekly between April 1975 and September 1977 in a small catchment in Devon, England. Soil water concentrations are compared with the analysis of exchange capacity in composite soil samples. Rain contributed much sodium and chloride to total catchment output, and potassium was selectively enriched in throughfall. Calcium and magnesium concentrations were high in soil water samples and on the soil exchange complex.     

Interactive effects of biochar and micronutrients on faba bean growth,symbiotic performance,and soil properties

Leguminous crops are significantly involved in the global symbiotic biological N₂ Fixation (BNF), an eco‐friendly process in the agriculture system. Biochar is considered as a vital amendment in improving growth and quality of crops and soils. Few investigations have been conducted to determine the combination effect of biochar with microelements on growth of legumes and soil properties. This study was designed to study the effect of soybean straw‐derived biochar (SSDB) with or without microelements on soil microbial and chemical properties, growth, yield, and seed chemical composition of faba bean (Vicia faba L.). Results revealed that dehydrogenase (DHA) and phosphatase (P‐ase) activities were markedly improved with the increase of SSDB rates under addition of microelements and their highest values were recorded after 90 d. Significant increases were noticed in nodulation activities, nodulation numbers (30.1–72.8), concentrations of N (1.62–1.93%), P (0.15–0.21%), and K (0.53–0.67%), and seed chemical constituents due to the addition of SSDB in the presence of microelements. Moreover, the combination of biochar with microelements caused significant changes in microbial counts. Overall, this investigation shows the potential and role of SSDB in enhancing the growth quality of faba bean seeds as well as an improvement of soil characteristics.     

Metal micronutrients relationships in crop,soil, and common weeds of two maize (Zea mays L.) fields

Deficiencies of metal micronutrients are common in some calcareous soils. Samples of aerial parts of maize and five common weeds and also soil beneath these plants were collected and analyzed to investigate the status and relationships of metal micronutrients in soil, crop, and common weeds of maize field trials at two sites. Results showed that Fe concentration in five studied weeds was higher than that of maize; the highest Fe concentration was found in Convolvolus arvensis and Echinochloa crus-galli (first site) and in Convolvolus arvensis tissues (second site). At both sites, the highest Mn concentration was observed in aboveground parts of Echinochloa crus-galli. The concentration of Mn (both sites) and Fe and Cu (second site) were remarkably higher in Echinochloa crus-galli tissues in comparison with maize. Also the concentrations of Fe (both sites) and Cu (second site) were considerably higher in Convolvolus arvensis tissues in comparison with maize. Available Fe was the highest in the soil beneath Convolvolus arvensis and Portulaca oleracea (first site) and beneath Convolvolus arvensis and Cenopodium album (second site). The high value of available Fe in the soil beneath Convolvolus arvensis may explain why Fe concentration was the highest in aerial parts of this weed species.     

Effects of different levels of soil salinity on yield attributes,accumulation of nitrogen,and micronutrients in Brassica spp.

The present study was conducted to assess the effect of soil salinity on yield attributes as well as nutrient accumulation in different plant parts of seven Brassica cultivars from two different species raised in pot culture experiment with two levels of salinity treatments along with control corresponding to soil electrical conductivity (EC) values of 1.65 (S₀), 4.50 (S₁) and 6.76 (S₂) dS m^?1. The experiment was consisted of twelve replications in a completely randomized design. Imposition of salinity stress affected various yield attributing characters including plant height, which ultimately led to severe yield reduction. However, tolerant cultivars, CS 52 and CS 54 performed better under salt treatment showing lesser yield loss. Salinity stress reduced the nitrogen (N) content in leaves of the Brassica plants, which reflected in decreased seed protein content. Reduced accumulation of iron (Fe), manganese (Mn) and zinc (Zn) was observed in leaf, stem and root at flowering and post-flowering stages, while CS 52 and CS 54 showed less reduction than susceptible cultivars under salinity stress.     

武汉市典型地区土系的研究

本文以典型区土壤详查和环境研究为基础 ,采用《中国土壤系统分类》(修订方案 1 995)的标准划分了土壤的高级分类单元 ;探讨了土系的划分原则、依据及土系的描述方法 ,并拟定了区域土系检索系统 .为土系的研究和土系制的应用提供范例