Phosphorus fractions in poultry litter as affected by flue‐gas desulphurization gypsum and litter stacking

Previous research has shown that the addition of flue‐gas desulphurization (FGD) gypsum to poultry litter decreases water‐soluble P. No information is currently available, however, on extractable P fractions in poultry litter and P availability as affected by gypsum. The first objective of this work was to evaluate the effect of incubation time and rate of gypsum addition to litter alone or litter mixed with soil on total P and inorganic P in sequential extracts of H₂O, 0.5 m NaHCO₃, 0.1 m NaOH and 1 m HCl. Poultry litter was mixed with 25, 50, or 75% gypsum (by weight) and incubated alone or mixed with soil for 63–93 days at 25 °C, with periodic sequential extractions. For litter alone or litter mixed with soil, adding gypsum decreased total P and inorganic P in the H₂O fraction and increased both P forms in the NaHCO₃ fraction. These changes did not affect plant P availability as measured by Mehlich‐1 P. Increasing incubation time decreased total P and inorganic P in the H₂O fraction of litter alone or litter mixed with soil, which was apparently caused by P immobilization by fungi. A second objective of this study was to evaluate P in the H₂O and NaHCO₃ fractions of litter as affected by stacking time and depth. Litter was stacked to a height of 1.2 m with samples taken immediately after stacking and 31 days later to be sequentially extracted for total P and inorganic P. Stacking time did not affect P in the H₂O fraction, but it increased P in the NaHCO₃ fraction by 25%. These results suggest that stacking poultry litter may increase the amount of labile P.     

Soil compaction and poultry litter effects on factors affecting nitrogen availability in a claypan soil

Soil compaction may affect N mineralization and the subsequent fate of N in agroecosystems. Laboratory incubation and field experiments were conducted to determine the effects of surface soil compaction on soil N mineralization in a claypan soil amended with poultry litter (i.e., Turkey excrement mixed with pine shavings as bedding). In a laboratory study, soil from the surface horizon of a Mexico silt loam soil was compacted to four bulk density levels (1.2, 1.4, 1.6 and 1.8 Mg m⁻³) with and without poultry litter and incubated at 25 °C for 42 days. A field trial planted to corn (Zea mays L.) was also conducted in 2002 on a Mexico silt loam claypan soil in North Central Missouri. Soil was amended with litter (0 and 19 Mg ha⁻¹) and left uncompacted or uniformly compacted. Soil compaction decreased soil inorganic N by a maximum of 1.8 times in the laboratory study; this effect was also observed at all depths of the field trial. Compacted soil with a litter amendment accumulated NH₄⁺-N up to 7.2 times higher than the noncompacted, litter-amended soil until Day 28 of the laboratory incubation and in the beginning of the growing season of the field study. Ammonium accumulation may have been due to decreased soil aeration under compacted conditions. Application of litter increased soil N mineralization throughout the growing season. In the laboratory study, soil inorganic N in unamended soil was negatively correlated with soil bulk density and the proportion of soil micropores, but was positively related with soil total porosity and the proportion of soil macropores. These results indicate that soil compaction, litter application and climate are interrelated in their influences on soil N mineralization in agroecosystems.     

Distribution of phosphorus in size fractions of sandy soils with different fertilization histories

A major challenge in sustainable crop management is to ensure adequate P supply for crops, while minimizing losses of P that could negatively impact water quality. The objective of the present study was to investigate the effects of long‐term applications of different levels of mineral fertilizers and farmyard manure on (1) the availability of P, (2) the relationship between soil C, N, and P, and (3) the distribution of inorganic and organic P in size fractions obtained by wet sieving. Soil samples were taken from the top 20 cm of a long‐term (29 y) fertilization trial on a sandy Cambisol near Darmstadt, SW Germany. Plant‐available P, determined with the CAL method, was little affected by fertilization treatment (p < 0.05) and was low to optimal. The concentration of inorganic and organic P extracted with a NaOH‐EDTA solution (P_NaOH‐EDTA) averaged about 350 mg (kg dry soil)^–1, with 42% being in the organic form (P_o). Manure application tended to increase soil C, N, and P_o concentrations by 8%, 9%, and 5.6%, respectively. Across all treatments, the C : N : P_o ratio was 100 : 9.5 : 2 and was not significantly affected by the fertilization treatments. Aggregate formation was weak due to the low clay and organic‐matter content of the soil, and the fractions > 53 μm consisted predominantly of sand grains. The different fertilization treatments had little effect on the distribution of size fractions and their C, N, and P contents. In the fractions > 53 μm, P_NaOH‐EDTA ranged between 200 and 300 mg kg^–1, while it reached 1260 mg kg^–1 in the fraction < 53 μm. Less than one third of P_NaOH‐EDTA was present as P_o in the fractions > 53 μm, while P_o accounted for 70% of P_NaOH‐EDTA in the smallest fraction (< 53 μm). Therefore, 16% and 28% of P_NaOH‐EDTA and P_o, respectively, were associated with the smallest fraction, even though this fraction accounted for < 5% of the soil mass. Therefore, runoff may cause higher P losses than the soil P content suggests in this sandy soil with a weak aggregate formation. Overall, the results indicate that manure and mineral fertilizer had similar effects on soil P fractions.     

Aerobic and anaerobic burning alter trace metal availability in peat soils: evidence from laboratory experiments

As global warming becomes more pronounced, climate change and human activities are leading to frequent peat fire incidents. Fire plays an important role in the environmental distribution of trace metals in peat soils. In the current study, we collected peat soils from six peatlands of the Great Khingan Mountains in Northeast China, where wildfires have often occurred in recent decades. To investigate the transformation of trace metals in peat soils by fire, burning experiments at 250°C (light) or 600°C (severe) and under aerobic (AE, flaming) and anaerobic (AN, smouldering) conditions (AE250, AE600, AN250, AN600) were carried out in the laboratory to investigate the effect of different burning intensities on the distribution of Cu, As, Pb, and Cd in peat soils. The European Community Bureau of Reference (BCR) sequential extraction method for metal fractions was applied for partitioning four fractions (exchangeable, reducible, oxidizable, and residual). The results showed that AE600 significantly decreased the percentages of oxidizable Cu, As, Cd and Pb (Cu_oxi, As_oxi Cd_oxi and Pb_oxi) compared with those of the original samples, e.g., Cu_oxi decreased from 68.84% ± 12.76% to 15.82% ± 8.02% in peat under moss, which might result from organic matter decrease. Under AN250 conditions, the exchangeable As (As_exc) and Pb (Pb_exc) significantly increased by more than twice. Different burning intensities significantly changed the various fractions of Cu, e.g., more than 20% Cu_oxi transferred to exchangeable and reducible fractions as the temperature increased. Most of the available fractions of As transformed to residual As after burning. Our study suggests that the AE600 treatment increased the ecotoxicity and bioavailability of Cu, Pb and Cd in peat soils, while AN250 burning decreased the potential ecotoxicity of Cu, As, and Pb. Compared with lower temperature flaming burning (AE250), the ecotoxicity and bioavailability of Cu and Pb were greater in high temperature (AE600) conditions. Smouldering fires at both temperatures (AN250 and AN600) maintained a high potential ecotoxicity and bioavailability of Cu and Pb in peat soils.     

Enzyme activities and litter decomposition in agricultural soils in northern,central, and southern Germany

Although enzyme activities were extensively investigated in soils with reference to abiotic environmental conditions and human impact, their role in litter decomposition is not fully understood. Therefore, decomposition rates and enzyme activities were studied using nylon bags and three litter types buried in silty‐loamy Cambisols and Luvisols in northern, central, and southern Germany under similar averaged temperature and precipitation and a maritime to continental gradient. After 180 d, the ash‐free mass remaining ranged between 15% and 68% for the Triticum, Secale, and Lolium litter. The enzyme activities were mainly controlled by the litter type and the decomposition time and less but significant by site. The highest decomposition rate occurred at the central German site for Lolium litter associated with highest arginine ammonification and urease activity in litter. In contrast, the recalcitrant Secale and Triticum litter were decomposed more rapidly at the northern and southern site where urease, protease, and arginine ammonification was high in the bulk soil. The β‐glucosidase activity was similar in soil and litter at the three locations and was not correlated to the velocity of litter decomposition. Since the abiotic environmental factors at the maritime to continental gradient did not explain the site‐specific velocity of both rapidly decomposing and refractory litter, enzyme activities related to the N cycling like arginine ammonification and urease activity were recognized to velocity of litter decomposition.     

Runoff and losses by erosion in soils amended with sewage sludge

In order to promote the transformation of a burnt Mediterranean forest area into a dehesa system, 10 t ha⁻¹ of dry matter of the same sewage sludge in three different forms: fresh, composted and thermally‐dried, were added superficially to field plots of loam and sandy soils located on a 16 per cent slope. This application is equivalent to 13ċ8 t ha⁻¹ of composted sludge, 50 t ha⁻¹ of fresh sludge and 11ċ3 t ha⁻¹ of thermally‐dried sludge. The surface addition of a single application of thermally‐dried sludge resulted in a decrease in runoff and erosion in both kinds of soil. Runoff in thermally‐dried sludge plots was lower than in the control treatment (32 per cent for the loam soil and 26 per cent for the sandy soil). The addition of any type of sludge to both soil types also reduces sediment production. Significant differences between the control and sludge treatments indicate that the rapid development of plant cover and the direct protective effect of sludge on the soil are the main agents that influence soil erosion rates. Results suggest that the surface application of thermally‐dried sludge is the most efficient way to enhance soil infiltration. Copyright © 2003 John Wiley & Sons, Ltd.     

Distribution and Dynamics of Phosphorus in an Agricultural Watershed with a Long-Term History of Poultry Waste Application

The objective of this research is to investigate the effects of long-term broiler litter application on soil phosphorus (P) and water quality and examine the spatial variations of soil P at a private poultry farm in Mississippi. Results indicated that the littered soil had 86 times more Mehlich III–extractable P in the surface horizon compared to the nonlittered soil. When compared to the runoff from nonlittered soil, mean soluble phosphate (PO₄)-P concentrations in the littered soil's runoff were 85 times greater throughout the study. Mass loss of P from the littered field was significantly greater than from the nonlittered field, and it decreased with each sequential runoff event. There were no linear relationships between the spatial variations of litter application rates and the P spatial variability in the littered soil; however, the variations in soil P levels could be a result of the cumulative effects of more than 20 years of litter application.     

Simultaneous extraction of P and K from IOWA soils with bray 1 solution containing NH4Cl

Abstract

The effects of combining the Bray 1 extracting solution with ammonium chloride (NH₄C1) for simultaneous extraction of P and K were studied in several experiments. For pooled data from the experiments in which the Bray 1 solution containing 0.5 mol L^‐1 NH₄C1 was used, the relationship between the amounts of P and K extracted by the combined solution (P_C and K_C)and the amounts extracted separately by Bray 1 (P_R) and 1 N neutral NH₄OAc (K_R) are given by P_C = 2 + 0.906 P_R, r = 0.988 and K_c = 14 + 1.033 K_R, r = 0.944. Variations were observed in different experiments when the concentration of NH₄C1 and the conditions of the experiment were varied.     

Cold and hot water–extractable organic matter as indicators of litter decomposition in forest soils

Mild extractions were used as indicators of easily decomposable organic matter (OM). However, the chemical composition of extracted OM often remained unclear. Therefore, the composition of cold and hot water–extractable OM was investigated in the O horizons (Oi, Oe, Oa) of a 170 y old beech stand (Fagus sylvatica) in the Ore Mtns., SE Germany. To simulate litter decomposition, the O horizon samples were incubated for 1 week under defined conditions. Cold‐ and hot‐water extracts were analyzed and chemically characterized by pyrolysis–field ionization mass spectrometry (Py‐FIMS). The C and N concentrations were always lower in the cold‐(C: 2.69 to 3.95 g kg^–1; N: 0.14 to 0.29 g kg^–1) than in the hot‐water extracts (C: 13.77 to 15.51 g kg^–1; N: 0.34 to 0.83 g kg^–1). The C : N ratios of both extracts increased with increasing depth. Incubation increased the concentrations of C and N in all water extracts, while C : N ratios of extracts decreased. The molecular‐chemical composition of cold and hot water–extracted OM revealed distinct differences. Generally, cold water–extracted OM was thermally more stable than hot water–extracted OM. The mass spectra of the hot water–extracted organic matter revealed more intensive signals of carbohydrates, phenols, and lignin monomers. Additionally, the n‐C₂₈ fatty acid and the n‐C₃₈–to–n‐C₅₂ alkyl monoesters clearly distinguished the hot‐ from the cold‐water extract. A principle‐component analysis visualized (1) alterations in the molecular‐chemical composition of cold‐ and hot‐water extracts due to previous incubation of the solid O horizon samples and (2) a decomposition from the Oi to the Oh horizon. This provides evidence that the macromorphological litter decomposition was reflected by the chemical composition of water extracts, and that Py‐FIMS is well‐suited to explain at the molecular level why OM decomposability is correlated with water‐extracted C.     

Comparing concurrent in situ and batch‐extracted trace element concentrations

Different procedures to investigate dissolved trace element concentration at the transition from unsaturated to saturated zone in soils were compared by concurrent sampling of soil solution and solid soil material in this zone. The in situ sampled soil solution from the percolated water was used to measure in situ concentrations, while solid soil material was used to measure concentrations at two liquid–solid ratios using batch experiments on 250 sample pairs. The liquid–solid ratios were 2 L kg^–1 and 5 L kg^–1. At 5 L kg^–1, the ionic strength was adjusted with Ca(NO₃)₂ to a sample‐specific value similar to in situ, while at 2 L kg^–1, the ionic strength was not adjusted. The extracted concentrations of most trace elements exhibited a statistically significant but weak correlation (p value < 0.01) to the corresponding in situ concentrations. In the liquid–solid ratio of 2 L kg^–1 extracts, Pb and Cr showed very poor comparability with the in situ equivalent. A likely cause was the enhanced dissolved‐organic‐C release in the extract due to the lower ionic strength compared to in situ conditions in combination with effects from drying and moistening soil samples. For the other elements, correlation increased in the order As < Cu, Zn, Sb, Mo, V < Cd, Ni, Co where adjustment of the ionic strength led to slightly better results. In addition to the element‐specific shortcomings, it appeared that low concentration levels of in situ concentrations were generally underestimated by batch extraction methods. The liquid–solid ratio of 2 L kg^–1 extracts could only be used as a method to predict exceedance of thresholds if a safety margin of approximately one order of magnitude higher than the thresholds was adopted. The ability of the batch‐extraction methods to estimate in situ concentrations was equally limited.     

Influence of soil phosphorus status,texture, pH and metal content on the efficacy of amendments to pig slurry in reducing phosphorus losses

Cost‐effective strategies for using chemically amended organic fertilizers need to be developed to minimize nutrient losses in surface and groundwater. Coupling specific soil physical and chemical characteristics with amendment type could increase their effectiveness. This study investigated how water‐extractable phosphorus (P) was affected by chemical amendments added to pig slurry and how this effect varied with soil properties. A 3‐month incubation study was conducted on 18 different mineral soils, stored at 10 °C and 75% humidity and treated with unamended and amended slurry which was incorporated at a rate equivalent to 19 kg total P (TP )/ha. The amendments examined were commercial‐grade liquid alum, applied at a rate of 0.88:1 [Al:TP ], and commercial‐grade liquid poly‐aluminium chloride (PAC ), applied at a rate of 0.72:1 [Al:TP ]. These amendments were previously identified by the authors as being effective in reducing incidental losses of P. The efficacy of the amendments varied with the soil test P, the degree of P saturation (DPS ) and the Mehlich aluminium, iron and calcium, but not soil texture. Chemical amendments were most effective in soils with DPS over approximately 20%. Due to their high cost, the incorporation of amendments into existing management practices can only be justified as part of a holistic management plan where soils have high DPS .     

Effects of Two Organic Wastes in Combination with Phosphorus on Growth and Chemical Composition of Spinach and Soil Properties

Abstract

Most agricultural soils in Iran are usually low in organic matter (OM). Therefore, increasing OM in these soils is of great concern. Environmental pollution caused by chemical fertilizers has created an interest in the integrated use of organic wastes with inorganic fertilizers. The main purpose of this greenhouse study was to evaluate the impact of two organic wastes and phosphorus (P) on the growth, and elemental composition of spinach (Spinacia oleracea L.) and soil chemical properties. Treatments consisted of four levels of municipal waste compost, MWC (0, 1, 2, and 4%), five rates of poultry manure, PM (0, 1, 2, 3, and 4%), and three P levels (0, 25, and 50 mg kg^?1 as KH₂PO₄). Application of P and MWC alone or in combination significantly increased the top dry weight of spinach. However, spinach growth was markedly increased up to 3% PM and suppressed with the higher rate, probably due to an excess of soluble salts in the soil. Moreover, the enhancing influence of P on spinach seedling growth was more pronounced at lower levels of MWC and PM. Plant P concentration tended to increase with increasing P, MWC, and PM application rates, whereas nitrogen (N) concentration was only affected by the two organic wastes treatment. Manganese (Mn) concentrations decreased, and copper (Cu), lead (Pb), and cadmium (Cd) increased by soil P application. However, P addition significantly decreased zinc (Zn) concentration only in MWC-treated spinach. Spinach plants enriched with either of the two biosolids accumulated more Mn, Zn, Pb, Cd, chloride (Cl), and sodium (Na) than control plants. Furthermore, spinach grown on MWC-amended soil contained higher Mn, Zn, Cu, and Pb and lower N, Cl, and Na than those raised on PM-treated soil. Postharvest soil sampling indicated that application of the two biosolids significantly increased concentration of soluble salts, (EC_e), OM, TN, NaHCO₃-extractable P, and DTPA-extractable iron (Fe), Mn, Zn, Cu, Pb, and Cd.     

Effect of low‐temperature biochar derived from pig manure and poultry litter on mobile and organic matter‐bound forms of Cu,Cd, Pb and Zn in sandy soil

Numerous studies conducted so far have shown that biochar has a significant effect on physical, chemical and biological properties of soils. Biochar can be used to alleviate the effects of soil contamination with organic and inorganic compounds, for instance, to reduce the mobility of heavy metals. The aim of the research was to evaluate the effect of pig manure and poultry litter, as well as biochars produced from these materials at a temperature of 300 °C on Cu, Cd, Pb and Zn contents in mobile and organic matter‐bound forms in soil. The research was conducted under laboratory conditions. The materials were introduced into sandy acid soil in doses of 0.5, 1.0 and 2.0% w/w. The application of pig manure‐derived biochar (BPM) and poultry litter‐derived biochar (BPL), depending on the amount added, reduced the mobility of copper from 28 to 69%, from 77 to 100% in the case of cadmium, from 94 to 99% in the case of lead, and from 15 to 97% in the case of zinc. The 2% amendment of pig manure (PM) and poultry litter (PL) caused an increase in the content of Cu extracted with NH₄NO₃ in comparison with the control treatment. A similar situation was observed in the case of zinc after the application of 0.5 and 1% amendments of pig manure (PM). Cu, Cd, Pb and Zn contents extracted with 0.025 mol C₁₀H₂₂N₄O₈ were higher than contents of these elements extracted with 1 m NH₄NO₃, mainly due to different extraction force of the extractants. The obtained results indicate that, compared with the content determined in soil from the control treatment, 1 and 2% amendments of both unconverted and thermally converted materials to the soil had a greater effect on contents of Cu, Pb and Zn in the organic matter‐bound fraction than the 0.5% amendment. The organic materials applied did not affect the content of cadmium in organic matter‐bound fraction.     

Relation between soil P test values and mobilization of dissolved and particulate P from the plough layer of typical Danish soils from a long‐term field experiment with applied P fertilizers

Accumulation of phosphorus (P) in agricultural topsoils can contribute to leaching of P which may cause eutrophication of surface waters. An understanding of P mobilization processes in the plough layer is needed to improve agricultural management strategies. We compare leaching of total dissolved and particulate P through the plough layer of a typical Danish sandy loam soil subjected to three different P fertilizer regimes in a long‐term field experiment established in 1975. The leaching experiment used intact soil columns (20 cm diameter, 20 cm high) during unsaturated conditions. The three soils had small to moderate labile P contents, expressed by water‐extractable P (3.6–10.7 mg/kg), Olsen P (11–28 mg/kg) and degree of P saturation (DPS) (25–34%). Mobilization of total dissolved P (TDP) increased significantly (P < 0.05) from the intact soil columns with increasing labile P, whereas the increase in particulate P (PP) with increasing labile P content was modest and statistically insignificant. We found concentrations up to 1.5 mg TP/L for the plough layer of this typical Danish sandy loam soil. This highlights that even a moderate labile P content can be a potential source of TDP from the plough layer, and that a lower concentration margin of optimum agronomic P levels should be considered.     

Model calculations of water dynamics in lysimeters filled with granular industrial wastes

A three‐year long lysimeter experiment with a fine‐grained aluminum (Al) recycling by‐product and a mixture of this by‐product and a coal combustion waste was conducted. The wastes were proposed as possible soil substitutes in an engineered surface barrier covering a potash mining residue mount. To evaluate the suitability of the wastes as surface barrier material, their hydrological behavior under field conditions must be known. Lysimeter experiments provide one means to study the hydrological behavior of soils or soil‐like materials. However, it is difficult to estimate the long‐term hydrological behavior from short‐term lysimeter studies. The present study was conducted therefore to derive from short‐term lysimeter observations the long‐term hydrological behavior of the two waste materials. The lysimeter data were used to calibrate the one‐dimensional soil water flow model HYDRUS‐1D. With the calibrated model, hydrological simulations for the site of the residue mount were carried out for a period of 31 yr. Calculated long‐term annual seepage from the lysimeters was 237 mm for the pure Al waste and 186 mm for the mixture, or 39% and 24% of the average annual precipitation (764 mm). The average discharge of the bare mount is 482 mm or 63%. We conclude that a soil cover could considerably reduce the discharge and that the mixture is better suited as surface barrier than the pure Al waste.     

Acidity,nutrient stocks,and organic‐matter content in soils of a temperate deciduous forest with different abundance of European beech (Fagus sylvatica L.)

The production and composition of leaf litter, soil acidity, exchangeable nutrients, and the amount and distribution of soil organic matter were analyzed in a broad‐leaved mixed forest on loess over limestone in Central Germany. The study aimed at determining the current variability of surface‐soil acidification and nutrient status, and at identifying and evaluating the main factors that contributed to the variability of these soil properties along a gradient of decreasing predominance of European beech (Fagus sylvatica L.) and increasing tree‐species diversity. Analyses were carried out in (1) mature monospecific stands with a predominance of beech (DL 1), (2) mature stands dominated by three deciduous‐tree species (DL 2: beech, ash [Fraxinus excelsior L.], lime [Tilia cordata Mill. and/or T. platyphyllos Scop.]), and (3) mature stands dominated by five deciduous‐tree species (DL 3: beech, ash, lime, hornbeam [Carpinus betulus L.], maple [Acer pseudoplatanus L. and/or A. platanoides L.]). The production of leaf litter was similar in all stands (3.2 to 3.9 Mg dry matter ha^–1 y^–1) but the total quantity of Ca and Mg deposited on the soil surface by leaf litter increased with increasing tree‐species diversity and decreasing abundance of beech (47 to 88 kg Ca ha^–1 y^–1; 3.8 to 7.9 kg Mg ha^–1 y^–1). The soil pH_(H2O) and base saturation (BS) measured at three soil depths down to 30 cm (0–10 cm, 10–20 cm, 20–30 cm) were lower in stands dominated by beech (pH = 4.2 to 4.4, BS = 15% to 20%) than in mixed stands (pH = 5.1 to 6.5, BS = 80% to 100%). The quantities of exchangeable Al and Mn increased with decreasing pH and were highest beneath beech. Total stocks of exchangeable Ca (0–30 cm) were 12 to 15 times larger in mixed stands (6660 to 9650 kg ha^–1) than in beech stands (620 kg ha^–1). Similar results were found for stocks of exchangeable Mg that were 4 to 13 times larger in mixed stands (270 to 864 kg ha^–1) than in beech stands (66 kg ha^–1). Subsoil clay content and differences in litter composition were identified as important factors that contributed to the observed variability of soil acidification and stocks of exchangeable Ca and Mg. Organic‐C accumulation in the humus layer was highest in beech stands (0.81 kg m^–2) and lowest in stands with the highest level of tree‐species diversity and the lowest abundance of beech (0.27 kg m^–2). The results suggest that redistribution of nutrients via leaf litter has a high potential to increase BS in these loess‐derived surface soils that are underlain by limestone. Species‐related differences of the intensity of soil–tree cation cycling can thus influence the rate of soil acidification and the stocks and distribution of nutrients.