Toxic Metals in Soil–Plant Systems,edited by Sheila M. Ross

Water, Air, &; Soil Pollution -     

Pressurized Hot Water and DTPA‐Sorbitol as Viable Alternatives for Soil Boron Extraction. I. Boron‐Treated Soil Incubation and Efficiency of Extraction

Abstract

Serious challenges associated with hot water extraction, the standard extraction method for water‐soluble boron (B), limit its use in commercial soil‐testing laboratories. Several alternatives to make B testing more practical have been proposed and studied; none of the alternatives have readily replaced the hot water method. Two relatively new, promising B extraction methods are pressurized hot water and DTPA‐Sorbitol. Very little reported work compares B extraction values obtained from the standard hot water extraction method and these two alternative methods. This study was conducted to complete an initial step in validating new procedures—extracting the designated nutrient from fertilized, incubated soils by using standard and alternative extraction methods and comparing the resulting values. The three extraction methods were used to extract B from samples of calcareous sand and silt loam soils and limed, loamy fine sand, all which had been treated with 10 levels of B (0–8 mg kg^?1) and incubated for 7 and 28 days. The amount of B extracted increased as the rate of B application increased with all three soil‐extraction methods. High correlations (r 0.977–0.999) were observed between extractable B and rate of B application with all three procedures. Correlations between the amount of extractable B using hot water extraction and the value obtained with an alternative extraction method were similar for both methods (r=0.89). Hot water generally extracted the least and pressurized hot water the most B regardless of soil type, rate of application, or duration of incubation. This study suggests the more easily used methods of pressurized hot water and DTPA‐Sorbitol could be recommended as replacements to the cumbersome hot water extraction.     

Mechanisms for the Movement of Fe,Mn,Cu and Zn to Plant Roots in Loessal Soil and Lou Soil

The pot experiments were conducted in the artificial climate laboratories to determine the relative importance of mass flow and diffusion in supplying ,Fe,Mn,Cu,and Zn to wheat,soybean and maize plants growing in loessal soil and lou soil.It was found that the calculated relative contribution of mass flow of iron,manganese,copper and zinc to plant uptake varied from 5% to more than 100%,depending on the crop species and soil types as well as plant growth stage,soil moisture,atmosphere humidity,etc.The results also showed that the major transportation mechanisms of these micronutrients in soil-root system varied with the crop and its growth,climate and soil,singnificantly,In general,mass flow was more important for Cu and Zn and diffusion was more significant for Fe and Mn at the seedling stage.     

Pressurized Hot Water and DTPA‐Sorbitol as Viable Alternatives for Soil Boron Extraction. II. Correlation of Soil Extraction to Responses of Boron‐Fertilized Alfalfa

Abstract

Pressurized hot water and DTPA‐Sorbitol are two relatively new, proposed alternative soil boron (B) extraction methods for which no data on yield or plant nutrient uptake have been reported for validation. Both methods initially have shown significant correlation with the hot water extraction method in untreated soils as well as soils incubated with various levels of B. The objective of the research was to extract samples of B‐treated soils by using all three extraction methods and correlate the B values obtained to yield, B tissue concentration, and total B removal of alfalfa (Medicago sativa). Greenhouse and field experiments on alkaline and limed acid soils naturally low in hot water‐extractable B were conducted to test alfalfa response to B fertilizer. In the greenhouse, highly significant relationships exist between plant uptake and extractable B with all three methods at varying levels of applied B, but no alfalfa yield response was observed. All three methods result in accurate predictions of plant B tissue concentrations and total B removal. The field experiment exhibited a significant positive relationship between total alfalfa yield and extractable B using hot water and pressurized hot water extractions. Extractable B using DTPA‐Sorbitol was not related to total alfalfa yield in the field experiment. This work, coupled with the earlier incubation studies, supports the pressurized hot water extraction method as an improvement over hot water in diverse soil types. The lack of relationship in the acid soil supports DTPA‐Sorbitol as an improvement over hot water in alkaline soils.     

Soil fertility survey in Western Usambara Mountains, Northern Tanzania

Soil samples from thirty sites representing four agro-ecological zones in the Western Usambara Mountains （WUM） of the Lushoto District in northern Tanzania were collected and analyzed for different nutrients. The results suggested that the major soil fertility constraint was P deficiency. On the basis of critical levels established in other areas, 90% of the soils were ranked as P deficient. This was followed by N, which was ranked as inadequate in 73% of the sites. Magnesium, K, and Ca also appeared limiting with 67%, 53% and 50% of the soils falling below the established critical values, respectively. A few soils （10%） were also found to contain exchangeable Al. The metallic micronutrients （Cu, Fe, and Zn） were adequate in all soils. Two sites had excessive Mn that could lead to toxicity in crops, and one was Mn deficient.     

Towards “New Soil Geography”: Challenges and Solutions. A Review

Eurasian Soil Science - This paper provides a review of the current state of soil geography and budding directions for the development of pedogeographic research. We mention some new ideas in the...     

Soil Cover of the Cis-Ol’khon Area,Baikal Region

Eurasian Soil Science - Active development of the Cis-Ol’khon area in the past decades enhanced the conflicts between land users related to multifunctional land use (residential,...     

Hans Løkke and Cornelis A.M. van Gestel: Handbook of Soil Invertebrate Toxicity Tests

Water, Air, &; Soil Pollution -     

Physico—Chemical Properties and Laboratory Hyperspectral Reflectance of Coastal Saline Soil in Shangyu City of Zhejiang Province, China.1

45 and 50 composite soil samples were collected, respectively, from two agricultural fields, that were enclosed and reclaimed from coastal tidal-fiat areas in 1996 and 1984 respectively, in Shemgyu of Zhejiang Province, China, to investigate the physico-chemical properties and the hyperspectral characteristics of the saline soils and to make an assessment on their relationships. The reflectance spectra of saline soils were measured using a spectroradiometer in laboratory. The mean spectral curves of the saline soils from the two sites different in reclamation year showed that the saline soil taken from the recently reclaimed land with higher salinity demonstrated a lower reflectance intensity in the spectral region from about 550 nm to 2300 nm. In addition, nine absorption bands, i.e., 488 nm, 530 nm, 670 nm, 880 nm, 940 nm, 1400 nm,1900 nm, 2 200 nm and 2 300 nm, were chosen as the spectral bands to investigate the relationships between soil physico-chemical properties by means of Pearson correlation analysis. Finally, the first two principal components were calculated from nine absorption bands and used to discriminate the saline soil samples taken from two sampled fields. The results indicate that it is feasible to detect physico-chemical properties of saline soils from fields reclaimed for varying time periods on the basis of the hyperspectral data.