Sequentially extracted phosphorus fractions in peat‐derived soils

Phosphorus (P) forms were sequentially extracted from peat derived soils (Eutric Histosols and Gleysols) at eight sites in Saxony‐Anhalt (Germany) to disclose general differences in P pools between mineral and organic soils and to investigate effects of peat humification and oxidation in conjunction with land use and soil management on the P status of soils. Overall 29 samples providing a wide variety of basic chemical properties were subjected to the Hedley fractionation. The Histosol topsoils contained more total P (P_t) (1345 ± 666 mg kg^—1) than the Gleysol topsoils (648 ± 237 mg kg^—1). The predominant extractable fractions were H₂SO₄‐P (36—63 % of P_t) in calcareous and NaOH‐P_o (0—46 % of P_t) in non‐calcareous Histosols. These soils had large pools of residual P (13—93 % of P_t). Larger contents and proportions of P_o and of labile P fractions generally distinguished organic from mineral soils. Regression analyses indicated that poorly crystalline pedogenic oxides and organic matter were binding partners for extractable and non‐extractable P. Intensive management that promotes peat humification and oxidation results in disproportional enrichments of labile P fractions (resin‐P, NaHCO₃‐P_i, and NaHCO₃‐P_o). These changes in P chemistry must be considered for a sustainable management of landscapes with Histosols and associated peat derived soils.     

Aspects of peat conservation and water management

An extended water regime model was used for calculating the evapotranspiration, groundwater recharge, and peat mineralization (CO₂ and N release) for various fen locations with grassland utilization in dependence on the groundwater level. The results show that an increasing groundwater level leads to a strong decline of the actual evapotranspiration E_t. For example, increasing the groundwater level from 30 to 120 cm diminishes the E_t by up to 230 mm a^—1. A positive groundwater recharge only takes place at groundwater levels of 90 cm and more. At smaller distances the capillary rise into the rooting zone during the summer months is greater than the water seepage during the winter months, so that a negative groundwater recharge‐balance is reached in the course of a year. The CO₂‐ and the N‐release, as well as the annual decline in peat thickness, increase significantly with rising groundwater levels. The results show, that varying the groundwater level can influence the water regime and the peat mineralization significantly. The lower the groundwater level the less is the peat decomposition. The demand for a groundwater level as small as possible is, however, limited by an agricultural utilization of the fens. Choosing the optimum groundwater level should consider the aims (1) peat mineralization, (2) gas emission (CO₂, CH₄, N₂O), and (3) crop production. If a grassland utilization is supposed to be made possible and all three aims above are given equal importance, the groundwater level should be maintained at 30 cm. At this distance, about 90 % of the optimum plant output can be reached. The peat mineralization can be reduced to 30 to 40 % of the maximum peat mineralization. The gas emission amounts to 50—60 % of the maximum value.     

Effect of extreme acid and alkali treatment on surface properties of soils

Effects of natural or anthropogenic soil acidification and alkalization on chemical or biological properties have been studied extensively while little is known about changes in physicochemical characteristics, such as surface area or adsorption energy. To investigate this, samples of six Polish soils (Inceptisols, Mollisols) and three Korean soils (Alfisols, Ultisols) of different origin and mineral composition were acidified and alkalized with elevated concentrations of hydrochloric acid and sodium hydroxide ranging from 0.001 to 1 mol dm^—3. Surface properties of these soils were studied. The surface area and average adsorption energy decreased in general in both treatments. The treatments induced the decrease in amount of high and medium energy centers, however the fraction of low energy centers increased. The behavior of surface properties differed from the above at treatments at highest reagent concentrations, especially for Korean soils, rich in clay and iron oxides. The general pattern of the adsorption energy decrease observed in most of the soils indicates that the overall water binding forces become lower after treatments. In this case the soil water may be more available for plants, despite its amount decreases.     

Rooting pattern and nitrogen uptake of three cauliflower (Brassica oleracea var. botrytis) F1‐hybrids

In a two‐year field trial at the sites Ruthe (Germany, loess soil, Orthic Luvisol) and Schermer (The Netherlands, marine clay soil, Eutric Fluvisol) the cauliflower F₁‐hybrids Marine, Lindurian and Linford were compared in their efficiency of N use from limiting and optimum supplies of N. Limiting N was N_min at planting. Optimum N was 250 kg ha^—1 as the sum of inorganic N content of the soil (N_min) at planting and fertilizer‐N. Marine was the most efficient variety, producing the highest shoot dry‐matter and quality (% class 1 curds) at both limiting and optimum N supplies. The N supply did not affect the horizontal and vertical distribution of root length density per soil volume (RLD, cm cm^—3) irrespective of variety. The RLD decreased exponentially with increasing soil depth. Varietal differences in RLD were not found at Ruthe, whereas at Schermer Marine had the highest RLD in all soil layers investigated (0 to 60 cm). No correlations were found between RLD and residual N_min at harvest, except at limiting N supply in Schermer where a strong negative correlation was found between RLD in the 45 to 60 cm layer and N_min at harvest. Thus, varietal differences in N efficiency are speculated to be rather due to different internal N‐use efficiency than to differences in N‐uptake efficiency.     

Characterization of Functional Properties of Gluten Proteins in Spelt Cultivars Using Rheological and Quality Factor Measurements

Wet glutens of 27 European spelt (Triticum aestivum ssp. spelta (L.) Thell.) cultivars were examined using fundamental rheological methods (oscillatory and creep tests) in conjunction with the determination of moisture contents of these glutens and the wet gluten contents of the flours. Furthermore, SDS sedimentation volumes were determined. A special baking test for spelt was developed that encompassed the characteristic elements used in the production of traditional German spelt speciality breads. Various significant correlations between gluten properties and baking results were found for three sets of spelt cultivars obtained from different demographic locations and years of harvest. Furthermore, the relationship between baking results (response) and gluten properties (predictors) could be modeled quite well with the help of multiple linear regression analysis. Radar charts used to profile the gluten properties of a particular cultivar showed a great amount of diversity within the spelt material, but there were also similarities between several cultivars. The differences between spelt cultivars should be taken into account when characterizing spelt in general terms or when comparing spelt and modern wheat.