Showing papers in "Soil Science in 2011"

Nitrogen and phosphorus availability in biochar-amended soils

Abstract: Biochar, a solid coproduct from the thermochemical production of bioenergy, has been reported to increase nutrient availability in soils through increased cation retention and decreased phosphate adsorption. The objectives of this study were to determine biochar effects on N and P availability in the presence and absence of external nutrient inputs. Biochar was obtained from hydrothermal pyrolysis of corn cobs at 305°C with 20 min of retention time. Biochar was added to two soils at three biochar rates (0, 2, and 20 g/kg) in combination with either two N rates (0 and 100 mg/kg) or two P rates (0 and 20 mg/kg) and incubated for 56 days. Soils were extracted for Mehlich-3 P and KCl-extractable NO 3 -N and NH 4 -N at 0, 3, 10, 17, 28, and 56 days after soil amendment. Biochar application at 20 g/kg increased NH 4 -N concentrations by 1.1 to 4.8 mg kg ―1 during the first 10 days and consistently decreased NO 3 -N recovery by 5 to 10 mg kg ―1 for the duration of the study. Biochar decreased Mehlich-3 P concentrations in soil by 0.9 mg kg ―1 in the absence of P additions and increased Mehlich-3 P concentrations by 3.3 mg kg ―1 when added with a P source. Furthermore, biochar increased Mehlich-3―extractable P by 5.4 mg kg ―1 in the soil when applied with N fertilizer. Results indicate that biochar-amended soils may need additional N after biochar addition to maximize crop production.

Comparison of Ammonium Sulfate With Other Nitrogen and Sulfur Fertilizers in Increasing Crop Production and Minimizing Environmental Impact: A Review

Abstract: Ammonium sulfate (AS) provides critical plant nitrogen (N) and sulfur (S) nutrients. Compared with other N fertilizers, such as urea and ammonium nitrate (AN), AS may have some potential agronomic and environmental benefits. These are (i) no potential toxicity of aqueous NH3 and nitrite to p

Charcoal Ash and Volatile Matter Effects on Soil Properties and Plant Growth in an Acid Ultisol

Abstract: There is a growing interest in converting organic wastes to charcoal for use as a sustainable soil amendment with a potential to improve soil productivity and sequester C. Three consecutive greenhouse experiments were conducted to investigate the effects of charcoal with different ash and volatile matter (VM) contents on soil properties and maize (Zea mays) growth and to evaluate the effect of time on charcoal performance. Five charcoal amendments (high-VM corncob, low-VM corncob, Kiawe, Binchotan, and a gasification charcoal of Leucaena leucocephala) applied at a 2.5% (wt/wt) rate were compared with a zero-charcoal control with and without fertilization. Only the gasification charcoal significantly increased maize growth without fertilization. The low-VM corncob charcoal with fertilization significantly increased maize growth by 164% compared with the fertilized control in the first planting cycle. Maize growth in the high-VM corncob charcoal supplemented with fertilizer treatment was significantly lower than that of the fertilizer-alone treatment in the first planting cycle. The negative effect of the high-VM charcoal on the fertilizer was caused by bioavailable carbon in the charcoal, which increased soil microbial activity and could have caused N immobilization. Both the beneficial and detrimental effects of charcoal did not persist beyond the first planting cycle, suggesting that charcoal impacts are temporary. Whereas charcoal ash and VM content seem to be important parameters for predicting charcoal behavior in the short-term, more research is needed to examine a broader spectrum of feedstocks exposed to varying thermal treatments.

Zeolite Soil Application Method Affects Inorganic Nitrogen, Moisture, and Corn Growth

Abstract: Adoption of new management techniques that improve soil water storage and soil N plant availability yet limit N leaching may help improve environmental quality. A benchtop study was conducted to de- termine the influence of a single urea fertilizer rate (224 kg N ha j1 ) applied with band or fully mixed zeolite (clinoptilolite) application rates (up to 90 Mg ha j1 )o n NH 4-N and NO3-N concentrations in a Portneuf silt loam (coarse-silty, mixed, mesic, durinodic Xeric Haplocalcid). Two ad- ditional greenhouse experiments were carried out to test the soil moisture status and corn (Zea mays L.) growth in a Wolverine sand (mixed, frigid Xeric Torripsamment). Mixing urea fertilizer into silt loam soil resulted in greater urea mineralization as compared with band application of fertilizer + zeolite, and the mixed zeolite was more effective at sorbing and pro- tecting NH4-N against nitrification. Increasing the rate of mixed zeolite into sandy soil increased the soil moisture content, and mixed zeolite soils contained 1.3% more soil moisture as compared with band zeolite appli- cations. After 6 weeks of corn growth in amended sandy soil, zeolite application at 22 Mg ha j1 seemed to increase corn weight compared with controls. However, increasing zeolite rate up to 90 Mg ha j1 caused a decrease in corn weight, likely caused by the elevated zeolite Na content (3%). Fully mixing zeolite into soil reduced the rate of nitrification likely because of NH4 + adsorption in the zeolite mineral lattice. Thus, mixing

Physical effects of organic matter amendment of a Southeastern US coastal loamy sand.

Abstract: Abstract We tested 12 organic sources as amendments for E horizon and a mixture of E and Bt horizons of a southeastern coastal loamy sand. Amendments were intended to increase carbon and improve soil physical properties. Amendments included biochar, cellulose, corn (Zea mays L.) stalk, corn starch, cotton (Gossypium hirsutum L.) hull, cotton meal, manure residual, peanut (Arachis hypogaea L.) hull, poultry litter, soybean (Glycine max L. Merr.) plant, wheat (Triticum aestivum L.) straw, and wood shavings. Amendments were added at a rate of ∼1% (wt wt−1) or ∼22 Mg ha−1 organic carbon content to 450 g soil and incubated in a laboratory for 60 days. Cellulose, corn stalk, and corn starch amendments had the most dry-sieved aggregation at 35% versus the control, peanut hull, poultry litter, wood shavings, and biochar, which had the least at 21%. Biochar, wood shavings, and corn starch–amended treatments had the highest penetration resistances at 0.25 to 0.38 MPa above the mean; cellulose and cotton meal had the lowest at 0.24 to 0.32 MPa below the mean. Poultry litter and manure residual–amended treatments needed the least amount of water added to maintain 0.1 (wt wt−1); cellulose, biochar, and soybean plant needed the most. All needed less than the control. Mixing Bt horizon into the E improved most physical properties. All amendments improved some physical properties—more carbon, more aggregation, or reduced soil penetration resistance. Biochar retained 26% of its carbon, more than other amendments that retained 13% to 23%.

Water-Extractable Soil Organic Carbon and Nitrogen Affected by Tillage and Manure Application

Abstract: Water-extractable organic matter (WEOM) contains labile organic carbon (C) and nitrogen (N) and is sensitive to soil management. The objective of this study was to determine the quantity and spectral properties of soil WEOM responding to types of nutrient addition and tillage managements. Soil samples were taken from treatments (con- ventional tillage, no-tillage, poultry litter, and NH4NO3 application) of a 10-year experiment in Watkinsville, Georgia, at different times and soil depths. Air-dried soil samples were extracted by deionized water followed by filtration (G0.45 Km), and soluble C and N, absorptivity at 254 nm, and fluorescence excitation/emission matrix in the extract were determined. Results showed that poultry litter application accumulated higher amounts of water-extractable organic C and N than NH4NO3 application. But no significant difference was found between tillage and no-tillage for both water-extractable C and N. Absorptivity at 254 nm decreased during cropping years for conventional tillage and NH4NO3 application, indicating accumulation of aliphatic organic compounds in WEOM, but the fluorescence-measured humification index showed an opposite trend. For no-tillage and poultry litter application treatments, there was no difference in absorptivity over the sampling time. Parallel factor analysis of excitation/emission matrix data showed that WEOM consisted of three fluorophore components: humic-, fulvic-, and tyrosine- like ''compounds,'' and relative distribution of these components differed among treatments and changed over soil depths. The tyrosine-like com- ponent tended to accumulate in the lower sampling depth (915 cm). Overall, the quantity and spectral properties of WEOM responded to the types of nutrient application and tillage practices.

Direct Chemical Speciation of P in Sequential Chemical Extraction Residues Using P K-Edge X-Ray Absorption Near-Edge Structure Spectroscopy

Abstract: Sequential chemical extraction is a common analytical approach used to separate soil P into operationally defined fractions based on solubility in increasingly strong extractants. However, there are some concerns that the relationship between these operationally defined pools and the true ch

Depth Distribution and Predictors of Soil Organic Carbon in Podzols of a Forested Watershed in Southwestern Canada

Abstract: Forest soils of coastal British Columbia, Canada, may store significant amounts of organic matter because of the cool climate and high forest productivity of the area. The objectives of this study were to determine the distribution of soil organic carbon (SOC) in the profile and to identify the most important predictors of SOC in Podzols of a forested watershed in southwestern British Columbia. We sampled 9 soil profiles in undisturbed forest plots by morphological horizon and measured SOC using a dry combustion method. We also determined soil pH, texture, moisture content, total nitrogen, loss on ignition, and pyrophosphate- and oxalate-extractable Fe and Al. The average soil profile stored 15.9 kg C/m2 over a depth of 100 cm, which is higher than SOC stocks estimates for inland Canadian forests. The organic layer (LFH) only accounted for one fourth of the C stock. Sixty percent of the profile SOC (including the forest floor) was found in the subsoil of depth greater than 20 cm. Studies of SOC dynamics that only sample the topsoil are therefore inappropriate. Although the clay concentration was low (∼5%), the clay fraction accounted for one third of SOC. This suggests that organo-mineral interactions were an important factor for SOC storage. The major predictors of SOC in the mineral horizons were organically complexed Al and Fe and short-range order inorganic material. Crystalline clays also seemed to play a role in organic matter accumulation, but were not as important as poorly crystalline compounds. In the organic layer, organically complexed Fe forms correlated negatively with SOC, indicating that the amount of Fe available for adsorption to organic matter is limited. Organically complexed Al did not show the same negative association, suggesting the existence of a mechanism for upward translocation of Al into the FH horizon.

Coupled Liquid Water, Water Vapor, and Heat Transport Simulations in an Unsaturated Zone of a Sandy Loam Field

Abstract: Information on the coupled liquid water, water vapor, and heat transport under arable field conditions is still limited, particularly for unsaturated soils of semi-arid and arid regions such as New Mexico. HYDRUS-1D model was applied to evaluate various transport mechanisms associated with temporal variations in water content and soil temperature in the unsaturated zone of a sandy loam furrow-irrigated field located at Leyendecker Plant Science Research Center, Las Cruces, New Mexico. The model was calibrated using measured soil water content and soil temperature at 5-, 10-, 20-, and 50-cm depths during a 19-day period (day of the year [DOY] 85 to DOY 103, 2009) and validated for a 31-day period (DOY 104 to DOY 134, 2009). Measured and optimized soil hydraulic and thermal properties and hourly meteorological data were used in model simulations. HYDRUS-1D simulated water contents and soil temperatures correlated well with the measured data at each depth. The total liquid water flux, composed of isothermal and thermal liquid water flux, dominated the soil water movement during early periods after irrigation, whereas the contribution of total water vapor flux, composed of primarily thermal and much smaller isothermal water vapor flux, increased with increasing soil drying. During the soil drying process, the total liquid flux within 15-cm depth eventually changed to water vapor flux near the surface. The upward total liquid and vapor fluxes decreased from 5 cm, indicating that vapor flux was much higher in the layer near the soil surface. The total vapor flux in this unsaturated soil layer was approximately 10.4% of the total liquid and vapor fluxes during the simulation period.

Can Contaminant Elements in Soils Be Assessed by Remote Sensing Technology: A Case Study With Simulated Data

Abstract: In this article, we propose that reflectance spectroscopy or remote sensing technology is a rapid and inexpensive tool to monitor heavy-metal contamination in soils. We analyzed three data sets by both chemical and reflectance spectroscopy methods. Despite the data sets being obtained from different locations and at different times, all three data sets gave similar results; that is, those that were well correlated with Fe also had higher predictive accuracy: Ni, Cr, and Co in Baguazhou Island; Ni, Cr, and Cu in Jiangning County; Ni, Cu, and As in some areas of Baguazhou Island had close correlations with Fe, with greater R. Cd and Pb in Baguazhou Island; Cd, As, and Hg in Jiangning County; Hg, Pb, and Cd in some areas of Baguazhou Island had low correlations with Fe. The predictions of these elements were also the least among all the elements. The same results were found for the prediction of global calibration. The consistent trends acquired by the four performances, that is, the order of prediction accuracy for contaminant elements was approximately the same as the order of their correlation coefficients with Fe, strongly suggesting that the successful prediction of the spectrally featureless contaminant elements by reflectance spectra is not only statistically coincident, but representative of an underlying or general relationship between the spectra and the elements. The relationship is indicative of a physical mechanism between reflectance spectra and trace elements. The F statistic shows that the performance of the simulated HyMap, TM, and QuickBird bands also gave satisfactory results. These two observations demonstrate that heavy-metal contamination can be monitored successfully using remote sensing technology.

Colloid and Phosphorus Leaching From Undisturbed Soil Cores Sampled Along a Natural Clay Gradient

Abstract: The presence of strongly sorbing compounds in groundwater and tile drains can be a result of colloid-facilitated transport. Colloid and phosphorus leaching from macropores in undisturbed soil cores sampled across a natural clay gradient at Aarup, Denmark, were studied. The aim of the study w

Low-molecular-weight Organic Acids Exuded by Millet ( setaria italica (l.) Beauv.) Roots and Their Effect on the Remediation of Cadmium-contaminated Soil

Abstract: Cadmium (Cd)-contaminated soils are of concern because of their possible effects on ecosystems and human health. Millet (Setaria italica (L.) Beauv.) is moderately tolerant to salinity and poor soil fertility as well as pristine soils contaminated with trace elements. It has been hypothesized that low-molecular-weight organic acids (LMWOA) exuded into the rhizosphere may play important roles in Cd uptake by millet. Thus the objectives of this study were to assess the LMWOA exudations of millet in Cd-contaminated soils and to evaluate the capacity of millet to remove Cd for phytoremediation. Millet was grown for 3 weeks in soils containing between 0 and 1,000 mg Cd kg−1. These soils and plant tissues were analyzed for Cd content after harvest. The Cd accumulated in millet tissues was significantly increased with increasing Cd-amended rate. The total LMWOA concentrations in root exudates were significantly correlated with the amount of Cd accumulated in millet shoots and roots. High levels of Cd amendment stimulated secretion of LMWOA, a process capable of reducing Cd toxicity via the formation of Cd-organic complexes (Cd-LMWOA), thereby detoxifying the contaminated soil.

Selenite Adsorption and Desorption in Selected South Dakota Soils as a Function of pH and Other Oxyanions

Abstract: Changes in soil pH and chemical composition of solutions in vadose zone strongly affect selenite (SeO 3 2― ) adsorption and desorption properties. In this study, batch experiments were carried out to evaluate the properties of SeO 3 2― adsorption and desorption in four South Dakota soils as a function of pH and the presence of competitive oxyanions. Selenite adsorption capacity of the soils was strongly dependent on soil pH and decreased with increasing pH between 5 and 9. Selenite adsorption capacity increased with increasing specific surface area of the soils, and Langmuir isotherm was described as an SeO 3 2― adsorption behavior. The presence of phosphate (HPO 4 2― ) in solution significantly decreased the partition coefficient values and adsorption maximum from Langmuir isotherm on all tested soils. Although HPO 4 2― addition affected SeO 3 2― adsorption in all soils, the effect had depended on the pool size of SeO 3 2― adsorption site. The competitive effect between SeO 3 2― and HPO 4 2― was less apparent in soils with a high adsorption capacity, and the competitive effect was more apparent in low―adsorbing capacity soils. The amount of SeO 3 2― adsorbed per unit area was lower in the presence of HPO 4 2― in solution, but the depression by HPO 4 2― addition was greater in low―adsorbing capacity soils compared with high―adsorbing capacity soils because of the much fewer adsorption sites. Contrary to HPO 4 2― , sulfate in solution had little effect on SeO 3 2― adsorption on all tested soils, which indicates that specific adsorption plays a major role in the adsorption of SeO 3 2― . The desorption of adsorbed SeO 3 2― was found to be dependent on the amount of SeO 3 2― initially adsorbed on soils and HPO 4 2― in solution. Significantly more SeO 3 2― desorbed when HPO 4 2― was in solution compared with sulfate.

Nutrient Availability to Corn From Dairy Manures and Fertilizer in a Calcareous Soil

Abstract: The expansion of the dairy industry in southern Idaho has lead to increased application of manures to meet crop nutrient demands which can alter the uptake pattern of both macro- and micro-nutrients. A greenhouse study was conducted to determine the effects of dairy manure, composted dairy manure, and fertilizer (mono-ammonium phosphate, MAP) application on soil test phosphorus (P), microbial activity, and nutrient uptake by silage corn. Two Portneuf soils, having either a low or high soil test P concentration, were amended with the three treatments at four application rates (25, 50, 100, and 200 mg P kg-1) with four replications of each treatment in a randomized complete design. Treatments were incubated for two weeks, then planted with corn grown for approximately three weeks. Soil samples were analyzed prior to planting, whereas plant samples were analyzed at the end of the growing period. Increases in Olsen P from P additions were greatest in the MAP and least in the manure treated soils. Plant dry matter production and tissue P concentration did not differ with treatment. Tissue K increased with manure and compost addition while tissue Ca decreased; there was also a decrease in tissue Mg with compost application. Tissue Zn increased with manure applications, while tissue Mn decreased with manure and compost application on the Low-P soil. It is important to consider plant nutrient interactions when applying manure and compost to feed-crops as imbalances in K, Ca, and Mg can have a negative impact on animal health.

Elemental and Fourier Transform-Infrared Spectroscopic Analysis of Water- and Pyrophosphate-Extracted Soil Organic Matter

Abstract: Soil organic matter (SOM) plays an important role in soil fertility and, thus, in sustaining potato production. To investigate the impact of crop rotation on SOM composition, we sequentially extracted SOM by water (WEOM) and sodium pyrophosphate solution (PEOM) from different 3-year potato crop rotations with or without irrigation and quantified its elemental compositions. Different contents of P, Ca, Al, and Fe were observed among the PEOM fractions from fields with different crop rotations. Elemental contents in PEOM from irrigated treatments were consistently lower than those from the corresponding rainfed treatments. The structural features of these WEOM and PEOM samples were further characterized by Fourier transform-infrared (FT-IR) spectroscopy. Generally, the impacts of rotation and irrigation practices reflected on the changes of FT-IR band intensities in 3,020-2,800 cm−1 (aliphatic groups) and 1,640-1,600 cm−1 (aromatic compounds) of WEOM samples. The FT-IR spectroscopic analysis indicated that PEOM was more enriched in aliphatic, carboxyl, and aromatic compounds than WEOM. However, neither crop rotation nor irrigation changed the relative abundance of these functional groups in PEOM. This research improves our understanding of how the properties of SOM may be impacted by crop management.

Alleviating Soil Acidity With Crop Residues

Abstract: Soil acidity, which is characterized by mainly aluminum (Al) toxicity and often calcium (Ca) deficiency, is a serious constraint for crop production. To separate these two factors and to alleviate the acidity problem using organic materials instead of lime, a greenhouse experiment was conducted on two acid soils of Hawaii. Eight treatments were established: (i) unamended (control); (ii) 4 cmolc/kg as Ca(OH)2; (iii) 4 cmolc/kg as MgO; (iv) 4 cmolc/kg as CaSO4 · 2H2O; (v) 10 g/kg ground fresh cowpea (Vigna unguiculata) leaves; (vi) 10 g ground, dried, fresh cowpea leaves ashed at 350°C for 4 h and then added to 1 kg soil; (vii) 10 g/kg ground fresh pineapple (Ananas comosus) crowns; and (viii) ashed pineapple at rate equivalent to (vii). Desmodium intortum cv. greenleaf, which is a tropical forage legume highly sensitive to soil acidity, was used as the test plant. The results indicated that treatments 1 to 4 could distinguish Al toxicity from Ca deficiency in acid soils and that crop residues could be used to alleviate soil acidity; the fresh cowpea amendment was most effective. More specifically, soil pH was raised moderately by crop-residue amendments, yet exchangeable Al was lowered substantially. Furthermore, soil-solution Al was complexed substantially by dissolved oxidizable carbon, particularly by organic acids produced by the crop residues. There was a good correlation between plant growth and the activity of total monomeric hydrolytic species of Al (Σ{Al}). Significant growth reduction would be expected when Σ{Al} > 12.0 μM.

Revisiting Soil Carbon and Nitrogen Sampling: Quantitative Pits Versus Rotary Cores

Abstract: Increasing atmospheric carbon dioxide and its feedbacks with global climate have sparked renewed interest in quantifying eco- system carbon (C) budgets, including quantifying belowground pools. Belowground nutrient budgets require accurate estimates of soil mass, coarse fragment content, and nutrient concentrations. It has long been thought that the most accurate measurement of soil mass and coarse fragment content has come from excavating quantitative soil pits. However, this methodology is labor intensive and time consuming. We propose that diamond-tipped rotary cores are an acceptable if not supe- rior alternative to quantitative soil pits for the measurement of soil mass, coarse fragment content, C and total nitrogen (N) concentrations. We tested the rotary core methodology against traditional quantitative pits at research sites in California, Nevada, and New York. We found that soil cores had 16% higher estimates of less than 2-mm soil mass than estimates obtained from quantitative pits. Conversely, soil cores had 8% lower estimates of coarse fragment mass compared with quantitative pits. There were no statistical differences in measured C or N con- centrations between the two methods. At the individual site level, dif- ferences in estimates for the two methods were more pronounced, but there was no consistent tendency for cores to overestimate or under- estimate a soil parameter when compared with quantitative pits.

The Effects of Slash Pile Burning on Soil and Water Macronutrients

Abstract: Significant effects of slash pile burning on soil chemistry and water quality were observed in forested sites in the eastern Sierra Nevada Mountains of Nevada. Slash piles in upland and meadow sites were instrumented postburn with ceramic cup lysimeters, runoff collectors, and resin stakes (Plant Root Simulator™ probes) along transects from pile centers to unburned areas. Ash and soil samples also were collected along these transects. The pH and concentrations of most nutrients in the soil were highest in the centers of the piles. Larger piles had lower levels of total carbon and total nitrogen in the pile centers (indicative of high burn temperatures and volatilization) compared with smaller piles. There also were differences between meadow and non-meadow systems including higher soil NO3− and lower SO42− amounts in the meadow areas. Soil solution data indicated that peak concentrations exceeded US Environmental Protection Agency water quality standards for both NO2−-N and NO3−-N at all three sites and were 2.5 to 3 times the standards in two sites. Runoff solution peak concentrations also exceeded the standards but only in the meadow site.

Crop Residue Input and Decomposition in a Temperate Maize-Soybean Intercrop System

Abstract: Producers in the Argentine Pampa are implementing legume-based intercropping to maintain crop productivity. The objectives of this study were to quantify carbon (C) and N inputs from crop residues and their rate of decomposition in maize (Zea mays L.) and soybean (Glycine max L. Merr.) sole

Changes in Preferential Flow Path Distribution and Its Affecting Factors in Southwest China

Abstract: Preferential flow is important in solute transport in the soil, and it indirectly affects the quality of the groundwater. The objectives of the present study were to investigate the distribution characteristics of preferential flow paths under different land-use types (forestland, shrubland, and farmland) and to determine the factors that affect the formation of these paths. Dye tracer experiments were conducted at six sites covering the three land-use types. The relationship of the preferential flow paths to the properties of the soil, root length per soil volume, root holes, and root surface area was analyzed using a partial correlation method. The results show dye coverage of greater than 50% at a soil depth of 0 to 10 cm and dye coverage of less than 30% below a depth of 20 cm in all of the land-use types. The vertical distribution differed widely in the various land-use types. Shrubland and farmland had more preferential flow paths in the topsoil compared with forestland, in contrast to the conditions in the deeper soil layers. The soil chemical properties and the saturated hydraulic conductivity in the preferential flow paths were quite different from those in the soil matrix. The soil organic matter content was approximately 5% to 20% higher in the preferential flow paths than in the soil matrix. The average value of the saturated hydraulic conductivity was 41.3 mm min in the preferential flow paths compared with 21.4 mm min in the soil matrix. The percentage of preferential flow paths in the soil was significantly affected by roots with a diameter of less than 5 mm, root holes, and the root surface area. These findings suggest that land use is significant in the distribution of preferential flow paths, and root characteristics are important in the formation of preferential flow paths.

Effects of Composting Swine Manure on Nutrients and Estrogens

Abstract: Application of raw manure to fields can contribute ammonia, pathogens, and volatile organic compounds at concentrations that may give rise to adverse odors and environmental concerns. In addition, raw manures contain reproductive hormones that could impact the endocrine systems of sensitive

Effect of Municipal Solid Waste Compost and Sewage Sludge on Enzymatic Activities and Wheat Yield in a Clayey-Loamy Soil

Abstract: In the Mediterranean region, difficult climate conditions and inadequate land management have led to a reduction of the organic matter content of soils. As a solution, municipal solid waste (MSW) compost and sewage (S) sludge were investigated for their effectiveness in maintaining soil fertility. Clayey-loamy soil was amended with 0, 40, and 80 t ha -1 of MSW compost or S sludge and cultivated with Triticum durum. Soil was sampled 15 and 70 days after sowing, and the activities of arylsulphatase, phosphatase, dehydrogenase (DH), β-glucosidase (β-GLU), urease, and catalase (CAT) were assayed. The wheat was harvested after 68 days, then soil properties as well as plant growth and K + and Na + contents were determined. Almost all soil enzymatic activities were significantly (P < 0.01) affected by amendment dose, sampling time, and their interaction. At 15 days, MSW compost had a moderate effect on DH, β-GLU, and CAT activities under both applied doses. A significant increase of all the measured activities was observed after 70 days at either 40 t ha -1 or 80 t ha -1 (ranged between 16%-160% and 10%-81%, respectively), likely providing a long-term nutrient release. The activities of arylsulphatase, phosphatase, DH, CAT, and β-flu (only with the lower dose) were strongly enhanced at 15 days after S sludge treatment. After 70 days, an increase of the enzymatic activities occurred with S sludge, although its beneficial effect was reduced mainly at 80 t ha -1 presumably because of the presence of micropollutants in the sludge. Plant growth was significantly improved by 40 and 80 t ha -1 of compost (93% and 126%, respectively); however, less impact was observed with S sludge. Overall, the results suggest that addition of MSW compost could enhance the fertility of degraded soils and promote plant growth.

Spatial Variability of Soil Properties in Agricultural Fields of Southern New Mexico

Abstract: Estimating the spatial variability of soil physical and chemical properties is a prerequisite for soil and crop-specific management. The objectives of this study were to determine the degree of spatial variability and variance structure of soil physical and chemical properties on a 40-ha agr

Phosphorus and Nitrogen Fertilization Effect on Phosphorus Uptake and Phosphatase Activity in Ryegrass and Tall Fescue Grown in a Chilean Andisol

Abstract: A series of short-term experiments were carried out to assess the effect of phosphorus (P) and nitrogen (ammonium [NH(4) (+)-N] or nitrate [NO(3)(-)-N]) fertilization on P uptake and phosphatase activity in ryegrass and tall fescue cultivated under greenhouse conditions. Ryegrass or tall fescue plants were grown in an acidic Andisol in the presence or absence of P and increasing doses of NO(3)(-)-N or NH(4)(+)-N fertilizers. At the end of the experiment, soil phosphatase activity (P-ase(Rhiz)), pH, and Olsen-P were determined in the rhizosphere soil. Plant biomass, P uptake, and root surface phosphatase (P-ase(Root)) were also assayed for both plant species. Furthermore, soil incubation experiments at increasing doses of P, NO(3)(-)-N, or NH(4)(+)-N were performed to evaluate the fertilizer effect on soil phosphatase activity (P-ase(Bulk)) and microbial biomass carbon in the bulk soil. In the absence of plants, P-ase(Bulk) was inhibited and microbial biomass carbon was raised at increasing P supply levels. In the greenhouse experiments, P uptake by tall fescue was about 67% higher than that of ryegrass at low soil P availability, which suggests that tall fescue was less sensitive to P deficiency than ryegrass. For both plant species, P-ase(Rhiz) did not vary as a consequence of P addition. On the other hand, fertilization with the highest NH(4)(+)-N dose strongly decreased soil pH and shoot P content, as well as it increased P-ase(Root) activity. This fact denotes that P-ase(Root) behaved as a strategic response parameter to P stress with insufficient impact on plant P nutrition in both plant species.

Sorption Indices to Estimate Risk of Soil Phosphorus Loss in the Rathbun Lake Watershed, Iowa

Abstract: To rank and better understand the risk of P loss from potentially erodible soil materials in the Mollisol-dominated watershed of Rathbun Lake in southern Iowa, we sampled seven representative soil materials at four floodplain sites. We compared the samples by using a variety of characteristics and indices, including particle size distribution; total P, C, and N; P sorption indices; equilibrium P concentration; and degree of P saturation, as assessed by dithionite, oxalate, and Mehlich 3 extraction (M3) methods. None of the Mehlich 3 P values of samples in the present study were high enough to suggest a high risk of water impairment caused by P. Equilibrium P concentration (EPC) values ranged from 0.01 to 0.23 mg L 1 . We found that EPC values were significantly correlated with Fe extractable by oxalate or the M3, as well as with total C and total N. The oxalate and M3 provided generally consistent degree of phosphorus saturation indices, leading us to propose three general risk categories for these soil materials: low, intermediate, and high. We conclude that poorly crystalline Fe oxides and organic matter are likely to exert considerable control over the release of P to stream water from materials eroded from these sites. Moreover, risk rankings based on degree of phosphorus saturation values may not be consistent with interpretations of P mobility that are derived from EPC and sorption indices.

Effects of Combined Phosphorus-Zinc Fertilization on Grain Zinc Nutritional Quality of Wheat Grown on Potentially Zinc-Deficient Calcareous Soil

Abstract: A 2-year field experiment was conducted (i) to study the effect of combined P and Zn fertilization on the Zn nutritional quality of wheat grown on potentially Zn-deficient calcareous soil and (ii) to identify which soil Zn fraction had the greatest effect on grain Zn concentration. Results showed that Zn fertilization increased grain Zn concentrations by 13% in 2006–2007 and 15% in 2007–2008. However, the application of 200 kg P2O5 ha combined with Zn fertilizer reduced grain Zn concentrations by 38% in 2006–2007 and 17% in 2007–2008 compared with the control (no fertilizer treatment). The phytic acid (PA) concentration and the PA:Zn molar ratio in wheat grain increased as P fertilizer application rate increased, regardless of the Zn fertilizer application rate. Zinc fertilization alone increased diethyltriaminepentaacetic acid–Zn by 220% in 2006–2007 and 470% in 2007–2008 compared with the no Zn fertilizer treatment. The combined application of P and Zn also increased diethyltriaminepentaacetic acid–Zn and loose organic matter–bound Zn, but the increase became smaller as the P fertilizer application rate increased. In conclusion, P fertilizer application rates to the potentially Zn-deficient calcareous soil used in this study should be less than 100 kg P2O5 ha to ensure the efficacy of the Zn fertilizer. Among the soil Zn fractions in this study, loose organic matter–bound Zn had the greatest correlation with grain Zn concentration.

Impact of Land Use Change and Soil Erosion in Upper Mississippi River Valley on Soil Organic Carbon Retention and Greenhouse Gas Emissions

Abstract: The dynamics of soil organic carbon (SOC) are affected by many factors including land use, management history, soil type, climate, and soil landscape processes. The primary objective of this research was to compare the storage of SOC on sloping woodland and cropland landscapes of northwestern Illinois. The cropland area was cultivated using a moldboard plow system for 125 years, and then the primary tillage was changed to chisel plow for the last 25 years. The woodland area was never cleared or cultivated. The SOC concentrations of various soil layers, to a depth of 0.5 m, were measured. The woodland landscape had significantly higher SOC in the surface layers on all landscape segments than at the cultivated site. For both land uses, the subsurface layers had similar SOC levels. Results suggested that the cropland land- scape retained 52% of the total SOC on a volumetric basis during the last 150 years of cultivation, soil erosion, and agricultural use. The other 48% of the SOC was either deposited in the water or released to the atmosphere. Results suggest that if mesic-frigid temperature line moved north because of climate change, then the current uncultivated forest soils would be used for cropland, and additional SOC will be released to either the stream or atmosphere and not maintained in soil even with a chisel plow system.

Effects of Annual Turkey Litter Application on Surface Soil Quality of a Texas Blackland Vertisol

Abstract: Proper application management is essential to minimize adverse environmental effects and maximize agronomic benefits of land applying poultry litter as a nutrient source and soil amendment. In this study, turkey (Meleagris gallopavo) litter was applied to five cultivated fields (target rates 4.5, 6.7, 9.0, 11.2, 13.4 Mg ha j1 ) and to two pasture fields (target rates 6.7, 13.4 Mg ha j1 ) to evaluate the effects on surface soil quality in the Vertisol-dominated Texas Blackland Prairie. A culti- vated field that received only inorganic fertilizer and two pasture fields (one native prairie and one grazed pasture) served as ''controls.'' Despite the annual variability in litter composition, actual application rates, and weather conditions, 7 years of litter application produced several sig- nificant differences in surface soil properties. Litter application pro- duced significant increasing trends in soil organic C and extractable P for several cultivated and pasture fields. Similarly, after seven annual litter applications, litter rate was significantly related to total N, total P, extractable P, Zn, and Cu in the cultivated fields and to total P, extract- able P, Zn, and Cu in the pasture fields. These observations coupled with previous findings indicate that annual litter application rates should be within 2.2 to 4.5 Mg ha j1 for cropland and 4.5 to 6.7 Mg ha j1 for pasture to limit the buildup of extractable P, Zn, and Cu in the soil. Although these target rates appear to be appropriate, the annual vari- ability in litter composition (both nutrients and moisture) can, if not accounted for, make it difficult to determine proper application rates. Therefore, preapplication soil and litter testing and spreader calibration is strongly recommended so that litter application supplies only crop nu- trient requirements (typically P) and balances agronomic and environ- mental concerns.

Comparisons of Soil Microbial Communities Influenced by Soil Texture, Nitrogen Fertility, and Rotations

Abstract: Two agricultural soil microbial communities were analyzed using phospholipid fatty acid (PLFA) analysis to identify coarse differences between community compositions after a 3-year nitrogen (N) rate study on cotton followed by a rotational cereal crop. The soils studied were a Wasco sandy loam and Panoche clay loam. The study compared the influence of soil type, soil N levels, and how rotation crops affected soil microbial biomass. Principal component analysis of the PLFA signatures indicated that microbial communities were significantly different between the two soil types after 3 years of similar management and cotton residue inputs. The Panoche soil showed a greater total microbial biomass than the Wasco soil. Phospholipid fatty acid biomarker results showed that the Panoche soil was characterized by a fungal population, and the Wasco soil showed evidence of a bacterial composition. The observed microbial response to different soil N levels was negligible, but crop yields were highly responsive to N treatments. Cereal rotations after 3 years of cotton produced a substantial increase in microbial biomass, but did not alter the community composition of either soil. Results suggested that microbial communities found in the two soils responded to changes in residue inputs from subsequent crop rotations by increasing total microbial biomass, but community composition was not influenced by changes in crop type or N additions. Based on the results of this study, soil texture had a more decisive role in soil microbial composition and consequent microbial activity than N fertilization or different rotational crops after 3 years of similar management.

Sorption of tylosin on agricultural soils

Abstract: The wide use of manure on farms could cause pharmaceutical chemicals (such as antibiotics) to be transported to surface aquatic and groundwater systems. The purpose of this study was to assess sorption and mobility of tylosin (TYL), the most used antibiotic compound in swine industry, in topsoils. Sorption of TYL was measured for the three soils using a batch technique. The experimental data showed that the sorption could attain apparent equilibrium within 24 h, and little or insignificant desorption hysteresis was observed. The Freundlich isotherm equation fit the data well, with the nonlinearity parameter n ranging from 0.83 to 1.03. The single-point distribution coefficients (KD) were in a narrow range from 1.7 to 12 L kg−1. The KD values correlated well with soil pH, but poorly with the soil organic carbon content. The study indicated that the mobility of TYL is less than that of smaller and polar antibiotics and that the soil-bound TYL could readily be transported to groundwater.