L. J. Cihacek

Application of flue gas desulfurization gypsum and its impact on wheat grain and soil chemistry.

The 11 major electricity-generating coal combustion stations in the northern Great Plains have the potential to produce almost 1 million Mg of flue gas desulfurization gypsum (FGDG) annually, which is a very attractive fertilizer (Ca and S) and amendment for sodic and acid soils. The potential environmental impacts of applying FGDG to soils in this region have not been fully investigated. The objectives of this research were to determine the influence of FGDG on soil chemical characteristics and to determine the impact that FGDG has on hard red spring wheat ( L.) yields and element analysis of the grain. Flue gas desulfurization gypsum and commercial gypsum were applied at rates of 0, 2.24, 11.2, and 22.4 Mg ha to two soils in southwestern North Dakota in the spring of 2007. Soil and grain chemistries were monitored for two growing seasons. Wheat grain yields and elemental analysis of the grain were generally not affected by the gypsum treatments, indicating that the gypsum products did not negatively affect plant productivity. In addition, soil elemental analysis was similar across the treatments at both sites in both years. The results from this study indicate that its application to soil at rates used for sodic soil remediation (Mg ha) did not negatively affect the chemistries of either the soils or the wheat evaluated in this study compared with a commercial gypsum product or control soils.

Relationships between the Mehlich-III soil test extraction procedure and standard soil test methods in North Dakota

Abstract One hundred surface soil samples were randomly selected from actual fanner samples submitted to the North Dakota State University Soil Testing Laboratory for comparing the usefulness of the Mehlich‐III extractant with results from currently used methods for extracting phosphorus (P), potassium (K), zinc (Zn), iron (Fe), manganese (Mn), and copper (Cu) from neutral to alkaline pH soils from the northern Great Plains. Soil pHs were distributed across a range from pH 7.0 to 8.3. The Mehlich‐III extractant correlated well with P, K, and Zn values obtained by the Olsen, neutral normal ammonium acetate (1M NH4OAc, pH 7.0) or DTPA (diethylenetriamenepentaacetic acid) extraction procedures, respectively. The Mehlich‐III extractant was somewhat correlated with Cu by the DTPA method but poorly correlated with DTPA‐extractable Fe and Mn. The Mehlich‐III extractant appears to be adequate for extraction of P, K, and Zn across concentration ranges normally found in most agricultural soils in North Dakota.

Phosphorus source effects on alfalfa yield, total nitrogen content, and soil test phosphorus

Abstract Recent studies showing a lack of response by alfalfa (Medicago sativa L.) to phosphorus (P) fertilization have raised concerns about the efficacy of commonly used P fertilizer materials in the southwestern United States. Studies were conducted between 1982 and 1985 in southeastern New Mexico to evaluate (i) alfalfa yield response to different P sources, (ii) the effect of P fertilizer source on forage total nitrogen (N) content and leafiness, and (iii) the effect of P fertilizer source on soil test P. Nine P sources were applied annually from 1982 through 1984 at a rate of 58 kg P/ha. Alfalfa was grown during 1985 without fertilization to examine the residual effect of P sources. Triple superphosphate (TSP) and monoammonium phosphate (MAP) gave the highest alfalfa forage yields over the 3‐year application period, but no residual fertilizer effects were observed when fertilization was discontinued. Fertilization did not affect forage leafiness. Except for a small N response in forage total N conte...

Evaluation of an aluminum digestion block for routine total soil phosphorus determination by alkaline hypobromite oxidation

Abstract Total soil P was determined in six soils differing in pH, and in organic matter, total Fe, clay and sand contents. This study was undertaken to determine whether replacement of a sand bath.digestion procedure by an Al‐block digestion procedure affected the efficacy of an alkaline NaOBr method for determining total soil P. An Al digestion block was used for soil oxidation with NaOBr‐NaOH and the results were compared with a sand bath NaOBr method and a HC1O4 method. Temperature variability was very low in the digestion block (S.D.= ±1.4°C) when compared with the sand bath (S.D.= +20.1°C). The digestion block resulted in a greater precision in total P determination when compared to the sand bath (S.D.= ±3.7 vs. ±5.6, respectively). Linear relationships were obtained with the sand bath digestion technique (R2 = 0.981) and with the HC1O4 method (R2 = 0.982). Using an Al digestion block for NaOBr‐NaOH oxidation of soils for total P determination allows for a simple, precise alternative to sand bath di...

Characterization of the sulfur retained by soils exposed to hydrogen sulfide

Abstract We recently reported studies showing that air‐dry and moist soils have substantial capacities for sorption of hydrogen sulfide (H2S) from air. Studies to characterize the S retained when air‐dry and moist soils were exposed to air containing 2% H2S showed that a large fraction (average 79%) of this S was in the form of elemental S (S°) and that very little (0.1% or less) was in the form of sulfide. The recovery of sorted S as sulfate averaged 5.9% with the air‐dry soils and 3.0% with the moist soils. The 42 soils used in this work were selected so that they differed markedly in physical and chemical properties. Statistical analyses of the relationships between these properties and the recovery of sorbed S as elemental S showed that this recovery was significantly correlated with the amount of soil Mn that was extractable by dithionite‐citrate buffer. This suggests that Mn compounds in soils catalyze oxidation of sulfide‐S to elemental‐S when soils are exposed to air containing H2S.

Potential carbon sequestration and nitrogen cycling in long-term organic management systems

The fertility and soil health of organic agroecosystems are determined in part by the size and turnover rate of soil carbon (C) and nitrogen (N) pools. Our research contrasts the effects of best management practices (BMP) (reduction in soil disturbance, addition of organic amendments) on C and N cycling in soils from two field sites representing five organic agroecosystems. Total soil organic C (SOC), a standard measure of soil health, contains equal amounts of biologically and non-biologically active C that is not associated with release of mineral N. A three-pool first-order model can be used to estimate the size and turnover rates of C pools but requires data from a long-term incubation. Our research highlights the use of two rapid C fractions, hydrolysable and permanganate (0.02 M) oxidizable C, to assess shifts in biologically active C. Adoption of BMP in organic management systems reduced the partitioning of C to the active pool while augmenting the slow pool C. These pools are associated with potentially mineralizable N supplied by residues, amendments and soil organic matter affecting the concentration and release of mineral N to crops. Our data show that minimizing disturbance (no tillage, pasture) and mixed compost additions have the potential to reduce carbon dioxide emissions while enhancing slow pool C and or its turnover, a reservoir of nutrients available to the soil biota. Use of these rapid, sensitive indicators of biological C activity will aid growers in determining whether a BMP fosters nutrient loss or retention prior to shifts in total SOC.

Effects of Soil Sample Grinding Intensity on Carbon Determination by High‐Temperature Combustion

Abstract Recently, many studies related to carbon (C) sequestration by soils have been reported. However, little information has been reported related to the need for and effects of grinding soils on C analysis by high‐temperature combustion. We studied the effects of grinding five glacially derived soils of varying textural composition and organic matter content to 2‐mm, 1‐mm, 0.5‐mm, 0.25‐mm, and 0.15‐mm particle sizes on the measurement of total, inorganic, and organic C content using a high‐temperature combustion technique. Medium‐textured soils showed significantly higher total and organic C values for the 2‐, 1‐, and 0.5‐mm particle sizes than for the 0.25‐ and 0.15‐mm particle sizes compared to soils that were high in sand or clay. Grinding did not appear to affect inorganic C values. Grinding the soils to 0.15 mm, in all cases, greatly reduced the variability of C values by as much as two‐ to six‐fold when compared to 2‐mm soils. We recommend that soils be ground to pass a 0.15‐mm (100‐mesh) screen prior to C analysis by high‐temperature combustion.

DTPA‐extractable iron soil test correlation with hybrid grain sorghum production on gypsum affected soils

Abstract Two studies on a complex of Holloman soils (fine‐loamy, gypsic, thermic, shallow Typic Torriorthents) and Reeves soils (fine‐loamy, gypsic, thermic Typic Gypsiorthids) were conducted to correlate DTPA‐extractable Fe with grain sorghum stover or grain yield. Study #1 included sampling successive plots along two transects across areas of variable Fe chlorosis expression. Study #2 included sampling paired sites (normal vs. chlorotic) in three fields. Fe analysis was conducted on air‐dry soil samples in Study #1 and both air‐dry and field‐moist soil samples in Study #2. Soil test Fe (air‐dry soils) was significantly correlated with grain yield but not stover yield in Study #1 (r=0.589** and 0.114, respectively). In Study #2, air‐dry soil test Fe was significantly correlated with grain and stover yield (r=0.618* and 0.594*, respectively) but moist soil test Fe was significantly correlated with only stover yield (r=0.606*). Air‐dry and moist soil test Fe showed no correlation.

Capacity of soils for sorption of sulfur dioxide

Abstract Studies with 41 soils selected to obtain a wide range in properties showed that air‐dry and moist soils have substantial capacities for sorption of SO2from air (averages, 1.80 and 9.98 g S kg‐1soil, respectively). Soil properties influencing the capacities of air‐dry soils for sorptlon of SO2included clay content, surface area, DCB‐soluble Mn, CaCO3equivalent, dpH, acid‐titratable basicity, and sulfate sorption capacity. The corresponding capacities of moist soils were influenced by surface area and soil properties associated with CaCO3equivalent. It was possible to closely predict the SO2sorption capacities of both air‐dry and moist soils (R2‐ 0.913 and 0.939, respectively) from consideration of their properties

Soil Inorganic Carbon Sequestration as a Result of Cultivation in the Mollisols

Soil inorganic carbon stock and its response to land use in grassland ecosystems are poorly understood. A detailed examination of soil organic and inorganic carbon distribution at depth in Mollisols of the U.S. Northern Great Plains and the Russian Chernozem shows that cultivation of these soils decreased soil organic stock and increased soil inorganic carbon stock. The global significance of these results is that one of the most fertile and productive agricultural soils in the world that was initially native grasslands incorporated massive amounts of organic matter into the soil during cultivation. This dramatic event (going from equilibrium native grassland state to being plowed) caused a loss of organic carbon, and our analysis indicates that there may have been a corresponding gain of soil inorganic carbon in fertile calcium rich soils in the temperate grassland ecosystem. Mollisols may be a significant sink of inorganic carbon through pedogenic carbonate formation, which may partially offset carbon loss from soil organic matter decomposition.