Potential hazards of lime application in a damaged pine forest ecosystem in Berlin,Germany

Ninety percent of the pines (P. Sylvestris) in the forests of Berlin (West) are classified as damaged. Needle and leaf analyses do not indicate nutrient deficiencies. In site of high S-inputs (55 kg ha^?1 yr^?1 with throughfall) total acid inputs are moderate (2.4 kmol ha^?1 yr^?1) due to their neutralization by carbonatic dusts. Heavy metal depositions have led to accumulations in the forest floor (e.g. Pb 150 mg kg^?1, Cd 0.5 mg kg^?1). The dominating soil type, a cambic arenosol (Ustipsamment) is strongly acidified (pH 3.2 – 4.0) and poor in available nutrients. On an experimental plot, the application of dolomitic lime (6.1 tons ha^?1) and fertilizer (145 kg ha^?1 K₂SO₄) led to a significant increase m pH and base saturation in the top 10 cm of the mineral soil after 2 yr. The data on element fluxes give evidence for increased mineralization rates, enhanced heavy metal accumulation in the forest floor and increased soil solution concentrations of potentially hazardous substances (Al, Cd, NO₃). The lime application is discussed in terms of site specific effects on ecosystem stability and groundwater quality.     

Atmospheric deposition to grassland canopies: Lysimeter budgets discriminating between interception deposition,mineral weathering and mineralization

Lysimeter experiments were used to determine atmospheric input to grassland canopies. The combined effect of interception deposition + mineral weathering + mineralization was calculated from input/output budgets. Four types of lysimeters were used, either filled with very pure quartz sand or chalk grassland soil, and either without vegetation or planted with Brachypodium pinnatum (L.) Beauv., Combination of budgets for these four types of lysimeters yielded separate estimates of interception deposition and mineral weathering + mineralization. Ratios between total deposition and bulk deposition were 1.74 and 1.93 for N and S, respectively. Sources and sinks of H⁺ for lysimeters with chalk grassland soil and planted with Brachypodium (abbrev. CP-lysimeters) were about 10 times larger than for lysimeters without plants and filled with quartz sand. The contribution of atmospheric input to total H⁺-sources was 80% for bare lysimeters filled with quartz sand, and only 12% for CP-lysimeters. Bulk deposition and total atmospheric deposition of N was 1.25 and 2.18 kmol ha^?1 yr^?1, respectively, whereas N mineralization of chalk grassland soil yielded 1.62 kmol ha^?1 yr^?1, ‘Acid rain’ has only a minor influence on H⁺-transformations within a chalk grassland ecosystem, but N cycling is seriously affected by atmospheric input.     

Comparison of two methods to assess the carbon budget of forest biomes in the Former Soviet Union

The sink of CO₂ and the C budget of forest biomes of the Former Soviet Union (FSU) were assessed with two distinct methods: (1) ecosystem/ecoregional, and (2) forest statistical data. The ecosystem/ecoregional method was based on the integration of ecoregions (defined with a GIS analysis of several maps) with soil/vegetation C data bases. The forest statistical approach was based on data on growing stock, annual increment of timber, and FSU yield tables. Applying the ecosystem/ecoregional method, the area of forest biomes in the FSU was estimated at 1426.1 Mha (10⁶ ha); forest ecosystems comprised 799.9 Mha, non-forest ecosystems and arable land comprised 506.1 and 119.9 Mha, respectively. The FSU forested area was 28% of the global area of closed forests. Forest phytomass (i.e., live plant mass), mortmass (i.e., coarse woody debris), total forest plant mass, and net increment in vegetation (NIV) were estimated at 57.9 t C ha^?1, 15.5 t C ha^?1, 73.4 t C ha^?1, and 1.0 t C ha^?1 yr^?1, respectively. The 799.9 Mha area of forest ecosystems calculated in the ecosystem/ecoregional method was close to the 814.2 Mha reported in the FSU forest statistical data. Based on forest statistical data forest phytomass was estimated at 62.7 t C ha^?1, mortmass at 37.6 t C ha^?1; thus the total forest plant mass C pool was 100.3 t C ha^?1. The NIV was estimated at 1.1 t C ha^?1 yr^?1. These estimates compared well with the estimates for phytomass, total forest plant mass, and NIV obtained from the ecosystem/ecoregional method. Mortmass estimated from the forest statistical data method exceeded the estimate based on the ecosystem/ecoregional method by a factor of 2.4. The ecosystem/ecoregional method allowed the estimation of litter, soil organic matter, NPP (net primary productivity), foliage formation, total and stable soil organic matter accumulation, and peat accumulation (13.9 t C ha^?1, 125.0 t C ha^?1, 3.1 t C ha^?1 yr^?1, 1.4 t C ha^?1 yr^?1, 0.11, and 0.056 t C ha^?1 yr^?1, respectively). Based on an average value of NEP (net ecosystem productivity) from the two methods, and following a consideration of anthropogenic influences, FSU forests were estimated to be a net sink of approximately 0.5 Gt C yr^?1 of atmospheric C.     

Assessment of critical loads and their exceedance on Dutch forests using a multi-layer steady-state model

Critical acid loads for Dutch forests were derived using a multi-layer steady-state model that includes canopy interactions, nutrient cycling, mineral weathering and N transformations. Values were calculated for combinations of 12 tree species and 23 soil types for a 10×10 km grid. Critical acid loads thus derived increased with decreasing soil depth. Nearly 90% of the values varied approximately between 1500 and 4000 mol_c ha^?1 yr^?1 at 10 cm soil depth and between 750 and 2000 mol_c ha^?1 yr^?1 at the bottom of the rootzone. Separate critical loads calculated for N and S at the bottom of the rootzone varied between approximately 300 and 1000 mol_c ha^?1 yr^?1 for N and between 150 and 1250 mol_c ha^?1 yr^?1 for S. Using deposition data of 1990, a median reduction of the deposition by approximately 75% was calculated to achieve the critical loads at the bottom of the rootzone. The overall uncertainty in this value was estimated to be about 10%, although it can be much larger for specific soil types such as clay and peat soils. For N a larger reduction deposition percentage was calculated than for S, especially for coniferous forests with a high present N input.     

Soil Physical Properties and Organic Matter Fractions Under Forages Receiving Composts,Manure or Fertilizer

A field study was conducted to assess the benefits, with respect to soil physical properties and soil organic matter fractions of utilizing composts from a diversity of sources in perennial forage production. A mixed forage (timothy-red clover (Trifolium pratense L.) and monocrop timothy (Phleum pratense L.) sward were fertilized annually with ammonium nitrate (AN) at up to 150kg and 300 N ha^?1 yr^?1, respectively, from 1998-2001. Organic amendments, applied at up to 600 kg N ha^?1 yr^?1 in the first two years only, included composts derived from crop residue (CSC), dairy manure (DMC) or sewage sludge (SSLC), plus liquid dairy manure (DM), and supplied C to soil at 4.6 and 9.2 (CSC), 10.9 (SSLC), 10.0 (DMC) 2.9 (DM) Mg C ha^?1. Soil samples (0-5cm; 5-10cm;10-15cm) were recovered in 2000 and 2001. Improvements in soil physical properties (soil bulk density and water content) were obtained for compost treatments alone. Composts alone influenced soil C:N ratio and substantially increased soil organic carbon (SOC) concentration and mass (+ 5.2 to + 9.7 Mg C ha^?1). Gains in SOC with AN of 2.7 Mg C ha^?1 were detectable by the third crop production year (2001). The lower C inputs, and more labile C, supplied by manure (DM) was reflected in reduced SOC gains (+ 2.5 Mg C ha^?1) compared to composts. The distribution of C in densiometric (light fraction, LF; >1.7 g cm^?3) and particulate organic matter (POM; litter (>2000μm); coarse-sand (250-2000μm); fine-sand (53-250μm) fractions varied with compost and combining fractionation by size and density improved interpretation of compost dynamics in soil. Combined POM accounted for 82.6% of SOC gains with composts. Estimated compost turnover rates (k) ranged from 0.06 (CSC) to 0.09 yr^?1 (DMC). Composts alone increased soil microbial biomass carbon (SMB-C) concentration (μg C g^?1 soil). Soil available C (C_ext) decreased significantly as compost maturity increased. For some composts (CSC), timothy yields matched those obtained with AN, and SOC gains were derived from both applied-C and increased crop residue-C returns to soil. A trend towards improved C returns across all treatments was apparent for the mixed crop. Matching composts of varying quality with the appropriate (legume/nonlegume) target crop will be critical to promoting soil C gains from compost use.     

Critical loads for nitrogen deposition on forest ecosystems

Critical loads for N deposition are derived from an ecosystem's anion and cation balance assuming that the processes determining ecosystem stability are soil acidification and nitrate leaching. Depending on the deposition of S, the parent soil material, and the site quality critical N deposition rates will range between 20 to 200 mmol m^?2 yr^?1 (3 to 14 kg ha^?1 yr^?1) on silicate soils and reach 20 to 390 mmol m^?2 yr^?1 (3 to 48 kg ha^?1) on calcareous soils.     

Soil Acidification Induced by Ammonium Sulphate Addition in a Norway Spruce Forest in Southwest Sweden

The contributions of different acidifying processes to the total protonload (TPL) of the soil in control plots (C) and ammonium sulphate treatedplots (NS) were studied in a Norway spruce stand in Southwest Sweden during 1988–1998. The annual deposition of inorganic nitrogen and sulphate was on average 18 kg N and 20 kg S ha^-1. In addition the NS treated plots received 100 kg N and 114 kg S ha^-1 annually. The amounts of nutrients added to the ecosystem by wet and dry deposition and the leaching at 50 cm depth were calculated. The net atmosphericproton load, the proton load by nitrogen transformations in the soil, the sulphate sorption/desorption in the soil and the excess base cation accumulation in biomass were calculated. There was no leaching of inorganic nitrogen from control plots during the study period. The net atmospheric proton deposition, originating from sulphuric and nitric acid deposition, was the main contributor to TPL in control plots. The addition of ammonium sulphate increased the leaching of ammonium, nitrate, sulphate, magnesium and calcium but not of potassium. The TPL in NS plots was about ten times that in control plots. The nitrogen transformation processes were the main contributors to TPL to NS soil, in the beginning by ammonium uptake and later also by nitrification. The pH decreased by 0.4 units in the mineral soil. The between-year variation in TPL during the eleven year period in C plots (200–1500 mol_c ha^-1 yr^-1) and in NS plots (1000–13000 mol_c ha^-1 yr^-1) was mainly dependent on the sorption or release of sulphate. Both in C and NS, the TPL was buffered mainly by dissolving solid aluminium compounds, most probably some Al(OH)₃ phase.     

Effect of soybean inoculation with Bradyrhizobium and wheat inoculation with Azotobacter on their productivity and N turnover in a Vertisol

A long-term field experiment was conducted for 8 years on a Vertisol in central India to assess quantitatively the direct and residual N effects of soybean inoculation with Bradyrhizobium and wheat inoculation with Azotobacter in a soybean–wheat rotation. After cultivation of soybean each year, its aerial residues were removed before growing wheat in the same plots using four N levels (120, 90, 60 and 30 kg ha^?1) and Azotobacter inoculation. Inoculation of soybean increased grain yield by 10.1% (180 kg ha^?1), but the increase in wheat yields with inoculation was only marginal (5.6%; 278 kg ha^?1). There was always a positive balance of soil N after soybean harvest; an average of +28 kg N ha^?1 yr^?1 in control (nodulated by native rhizobia) plots compared with +41 kg N ha^?1 yr^?1 in Rhizobium-inoculated plots. Residual and direct effects of Rhizobium and Azotobacter inoculants caused a fertilizer N credit of 30 kg ha^?1 in wheat. Application of fertilizers or microbial inoculation favoured the proliferation of rhizobia in crop rhizosphere due to better plant growth. Additional N uptake by inoculation was 14.9 kg N ha^?1 by soybean and 20.9 kg N ha^?1 by wheat crop, and a gain of +38.0 kg N ha^?1 yr^?1 to the 0–15 cm soil layer was measured after harvest of wheat. So, total N contribution to crops and soil due to the inoculants was 73.8 kg N ha^?1 yr^?1 after one soybean–wheat rotation. There was a total N benefit of 13.8 kg N ha^?1 yr^?1 to the soil due to regular long-term use of microbial inoculants in soybean–wheat rotation.     

Nutrient fluxes from a soil treatment process for pig slurry

Abstract. The effects of pig slurry applications to a hydrologically isolated field treatment plant (at Solepur) were studied over a period of eight years. Thirty repeated doses, averaging 160 m³ ha^?1 were applied from April to October of each year (1991–1995), to reach a total application of 4930 m³ ha^?1. All slurry samples were analysed for their total solids (TS), macronutrient (C, N, P, K, Ca) and micronutrient (Cu, Zn) content. In total, 284 tonnes of total solids (57 t TS ha^?1 yr^?1), 115 tonnes of carbon (23 t C ha^?1yr^?1), 24.5 tonnes of nitrogen (4900 kg N ha^?1 yr^?1), 7964 kg of phosphorus (1593 kg P ha^?1 yr^?1), 16 518 kg of potassium (3304 kg K ha^?1 yr^?1), 183 kg copper (37 kg Cu ha^?1 yr^?1) and 266 kg zinc (53 kg Zn ha^?1 yr^?1) were applied to the soil. Thus, this site provides an opportunity to assess the balance and to examine the long‐term behaviour of nutrients under conditions of intensive land application of pig slurries or similar effluents. The main nutrient fluxes through the soil‐water system were determined for each element. Over 40% of the total carbon applied was retained by the soil. About 25% of the slurry nitrogen applied remained in the soil profile and 12.5% was leached through the drainage water as nitrate. Most of the slurry phosphorus applied was retained in the soil profile either as P‐Dyer extractable (83%), or as total soil phosphorus (112%); <0.01% was found in the drainage water. Forty‐three per cent of the potassium applied in the slurry was recovered from the soil profile and 15% was recovered in the drainage water. Most of the copper (62%) and zinc (74%) applied in the slurry remained in the soil as EDTA extractractable forms; very low percentages (0.05% and 0.6% respectively) were found in the drainage water.     

Effect of different fertilization modes on soil organic carbon sequestration in acid soils

ABSTRACT

A meta-analysis of 297 treatment data from the Vezaiciai Branch of the Lithuanian Research Centre for Agriculture and Forestry long-term field experiment published from 2006 to 2015 was used to characterize the changes in SOC under different fertilization treatments and residue management practices in Lithuania’s acid soil. A meta-analysis was performed to quantify the relative annual change (RAC) of SOC content and the average RAC rate of SOC under four fertilization modes (farmyard manure (FYM) (40?t?ha^?1)); alternative organic fertilizers (in the manure background (40?t?ha^?1)); FYM (60?t?ha^?1); alternative organic fertilizers (in the manure background (60?t?ha^?1)) in two soil backgrounds (naturally acid and limed soil). The average RAC under four fertilization modes was 1.46 g?kg^?1?yr^?1, indicating that long-term fertilization had considerable SOC sequestration potential. Incorporation of alternative organic fertilizers in unlimed soil showed negative effects (?0.39 and ?0.66 g?kg^?1?yr^?1) in the observed long-term experiment. The RAC in the limed soil with incorporated organic fertilizers (FYM and alternative organic fertilizers), compared to the control, and varied from 0.25 g?kg^?1?yr^?1 in the treatment with incorporated alternative organic fertilizers (in the manure background (40?t?ha^?1)) to 0.71 g?kg^?1?yr^?1 in the soil with FYM (60?t?ha^?1). In this study, the average RAC rate of SOC under organic fertilization treatments in limed soil (5.07–6.54%) was longer than organic fertilization in unlimed soil (2.11–3.49%), which might be attributed to the application of organic manure that would result in a slow release of fertilizer efficiency. Our results indicate that the application of manure (40 or 60?t?ha^?1) showed the greatest potential for C sequestration in agricultural soil and produced the longest SOC sequestration duration.     

A preliminary review of weathering rates in relation to their method of calculation for acid sensitive soil parent materials

The release of base cations from chemical weathering is the fundamental process by which base cations lost through leaching or biological uptake are replenished. Soils with a high content of easily weatherable minerals will, in general, be readily able to neutralise incoming acidity and satisfy biological requirements through this supply of base cations from weathering. Conversely those soils with a low content of such minerals will be unable to buffer acid inputs or meet biological demands and will be vulnerable to acidification. It is evident therefore that an accurate estimate of the rate of chemical weathering is a prerequisite for any assessment of ecosystem sensitivity to acidification. The principal methods by which these calculations are made can be grouped into those based on element depletion in soil horizons calculated against a conservative element reference, catchment fluxes, laboratory studies and the use of mathematical models which utilise data from each of these sources. A review of the published data has been undertaken to determine if a systematic variation in weathering rates can be observed for a range of parent materials and/or methods used. Variations of 0.03–0.8 keq ha^?1yr^?1 for K⁺, 0.0–1.0 keq ha^?1yr^?1 for Na⁺, 0.01–1.39 keq ha^?1yr^?1 for Mg²⁺ and 0.0–5.8 keq ha^?1yr^?1 for Ca²⁺ were found. In general individual cation weathering rates determined from catchment fluxes, and also the model MAGIC, are dominated by Ca²⁺, with Mg²⁺ being the next most significant release rate. However it has not been possible to determine any other systematic variations due to the limited number of sites where weathering rate has been determined by more than one method.     

Long-term nitrogen balance for pearl millet (Pennisetum glaucum L.) in an acid sandy soil of Niger

On acid sandy soils of Niger (West Africa) fertilizer N recovery by pearl millet (Pennisetum glaucum L.) is often more than 100 per cent in years with normal or above average rainfall. Biological nitrogen fixation (BNF) by N₂-fixing bacteria may contribute to the N supply in pearl millet cropping systems. For a long-term field experiment comprising treatments with and without mineral fertilizer (F) and with and without crop residue application (CR) a N balance sheet was calculated over a period of six years (1983-1988). After six years of successive millet cropping total N uptake (36-77 kg N ha^?1 yr^?1) was distinctly higher than the amount of fertilizer N applied (30 kg N ha^?1 yr^?1). The atmospheric input of NH₄-N and NO₃-N in the rainwater was about 2 kg N ha_?1 yr^?1, 70 % in the form of NH₄-N. Gaseous NH₃ losses from urea (broadcast, incorporated) were estimated from other experiments to amount to 36 % of the fertilizer N applied. Nitrogen losses by leaching (15 to > 25 kg N ha^?1 yr^?1) were dependent on the treatment and on the quantity and distribution of single rainfall events (>50 mm). Decline in total soil N content (0-60 cm) ranged from 15 to 48 kg N ha^?1 yr^?1. The long-term N balance (1983-1988) indicated an annual net gain between 6 (+CR-F) and 13 (+CR+F) kg N ha^?1 yr^?1. For the control (-CR-F) the long-term N balance was negative (10 kg N ha^?1 yr^?1). In the treatment with crop residues only, the N balance was mainly determined by leaching losses, whereas in treatments with mineral fertilizer application the N balance depended primarily on N removal by the millet crop. The annual net gain in the N balance increased from 7 kg ha^?1 with mineral fertilizer to 13 kg ha^?1 in the combination mineral fertilizer plus crop residues. In both the rhizosphere and the bulk soil (0-15 cm), between 9 and 45% of the total bacterial population were N₂-fixing (diazotrophic) bacteria. The increased N gain upon crop residue application was positively correlated with an increase in the number of diazotrophic and total bacteria. The data on bacterial numbers suggest that the gain of N in the longterm N balance is most likely due to an N input by biological nitrogen fixation. In addition, evidence exists from related studies that the proliferation of diazotrophs and total bacteria in the rhizosphere due to crop residue application stimulated root growth of pearl millet, and thus improved the phosphorus (P) acquisition in the P deficient soil.     

Calculating critical loads of acid deposition with PROFILE — A steady-state soil chemistry model

A steady state soil chemistry model was used to calculate the critical load of acidity for forest soils and surface waters at Lake GÄrdsjön in S.W. Sweden. The critical load of all acid precursors (potential acidity) for the forest soil is 1.64 kmol_c ha^?1 yr^?1, and 1.225 kmol_c ha^?1 yr^?1 for surface waters. For the most sensitive receptor, the critical load is exceeded by 1.0 kmol_c ha^?1 yr^?1, and a 80% reduction in S deposition is required, if N deposition remains unchanged. The critical load is largely affected by the present immobilization of N in the terrestrial ecosystem which is higher than the base cation uptake. The model, PROFILE, is based on mass balance calculations for the different soil layers. From measurable soil properties, PROFILE reproduces the present stream water composition as well as present soil solution chemistry. The model calculates the weathering rate from independent geophysical properties such as soil texture and mineral composition.     

Carbon sequestration in Norway spruce in south Sweden as influenced by air pollution,water availability,and fertilization

Carbon sequestration in 30 yr old Norway spruce in south Sweden following manipulation of nutrient and water availability is presented. The site has an annual precipitation of 1100 mm and a deposition of about 20 kg N and 25 kg S per ha^?1 yr^?1. The soil type is a poorly developed podzol. Treatment include irrigation; artificial drought; ammonium sulphate addition; nitrogen-free-fertilization and irrigation with liquid fertilizers including a complete set of nutrients. The experiment has a randomized block design with four replicates per treatment. A comprehensive investigation of the above ground C storage on an areal basis was made at the start of the experiment and after 3 yr of treatment. After 3 yr of treatment with simulated N-S deposition using ammonium sulphate (100 kg N, 114 kg S ha^?1 yr^?1), C accumulation rates in the above ground compartments had increased by 37%. Similarly, irrigation caused increased C accumulation rates by 25%, whereas simulated drought during the vegetation period during 2 yr followed by 1 yr of recovery caused a 15% reduction of the C accumulation rates. Irrigation combined with liquid fertilization (100 kg N ha^?1 yr^?1), including all important nutrient elements, led to 65% increase in C accumulation rates compared to the control. The C sequestration of the latter treatment gradually increased and, during yr 5 of treatment, 8.6 Mg C ha^?1 accumulated in stems and branches, compared to 3.6 Mg ha^?1 for the control. It is concluded that there is a strong interaction between N-deposition and C accumulation rates in Norway spruce in south Sweden. The C accumulation rates are also sensitive to water availability. The study indicates a great potential to cultivate Norway spruce in south Sweden as a renewable energy source. A shift in energy source from fossil fuels to renewable energy sources will directly reduce the net emissions of CO₂ to the atmosphere.     

Influence of acid deposition on element cycling in mature sugar maple forest,Algoma, Canada

Forestry studies were undertaken within the Turkey Lakes Watershed to determine the impact of long-range transport of air pollutants on biogeochemical processes in old-growth sugar maple forest on shallow Precambrian-derived till soils in the Algoma District of Ontario, Canada. Distributions of organic matter and macroelements were determined in the tree- and field-layer vegetation, the forest floor and the mineral soil of the study site. Annual tree growth was largely offset by mortality, resulting in a relatively stable standing stock of ca. 245 t ha^?1. Annual aboveground litter production averaged 3.7 t ha^?1 yr^?1, chiefly in the form of deciduous leaf fall. The average pH of the precipitation (4.3) was reduced considerably by contact with the forest canopy. Throughfall was enriched with other elements, principally K and, to a lesser extent, Ca and Mg. The cationic composition of the forest-floor percolates, on the other hand, was dominated primarily by Ca and only to a lesser extent by Mg and K. The stand receives moderate acid deposition, mainly from average inputs of 33–36 kg ha^?1 yr^?1 of SO₄ ^2? and 24–29 kg ha^?1 yr^?1 of NO₃ ^? distributed throughout the year. Atmospheric inputs add to substantial natural NO₃ ^? production, notably within the forest floor and upper mineral soil, and contribute to leaching of bases, principally Ca and Mg, from the rooting zone. Active recycling of elements together with weathering of primary minerals should assist in preserving the base status of the site.     

Nitrogen Balance in the Magruder Plots Following 109 Years in Continuous Winter Wheat

Abstract

The Magruder plots are the oldest continuous soil fertility wheat research plots in the Great Plains region, and are one of the oldest continuous soil fertility wheat plots in the world. They were initiated in 1892 by Alexander C. Magruder who was interested in the productivity of native prairie soils when sown continuously to winter wheat. This study reports on a simple estimate of nitrogen (N) balance in the Magruder plots, accounting for N applied, N removed in the grain, plant N loss, denitrification, non‐symbiotic N fixation, nitrate (NO₃ ^?) leaching, N applied in the rainfall, estimated total soil N (0–30 cm) at the beginning of the experiment and that measured in 2001. In the Manure plots, total soil N decreased from 6890 kg N ha^?1 in the surface 0–30 cm in 1892, to 3198 kg N ha^?1 in 2002. In the Check plots (no nutrients applied for 109 years) only 2411 kg N ha^?1 or 35% of the original total soil organic N remains. Nitrogen removed in the grain averaged 38.4 kg N ha^?1 yr^?1 and N additions (manure, N in rainfall, N via symbiotic N fixation) averaged 44.5 kg N ha^?1 yr^?1 in the Manure plots. Following 109 years, unaccounted N ranged from 229 to 1395 kg N ha^?1. On a by year basis, this would translate into 2–13 kg N ha^?1 yr^?1 that were unaccounted for, increasing with increased N application. For the Manure plots, the estimate of nitrogen use efficiency (NUE) (N removed in the grain, minus N removed in the grain of the Check plots, divided by the rate of N applied) was 32.8%, similar to the 33% NUE for world cereal production reported in 1999.     

Manure application has an effect on the carbon budget of a managed grassland in southern Hokkaido,Japan

Abstract

The carbon (C) budget of managed grassland in a cool-temperate region of Japan was estimated using a combination of eddy covariance and the biometric method for five years, to evaluate the effect of manure application. Chemical fertilizer was applied to the fertilizer (F) plot at a rate of 79 ± 20 kg N ha^?1 yr^?1. In the manure (M) plot, dairy cattle manure was applied at a rate of 10 Mg fresh matter ha^?1 yr^?1 (1923 ± 407 kg C ha^?1 yr^?1, 159 ± 68 kg N ha^?1 yr^?1). There was no significant difference in seasonal gross primary production (GPP) and harvest between the treatment plots, indicating that both fertilizer and manure can increase the biomass production. Annual net ecosystem production (NEP) and ecosystem respiration (RE) was significantly different between the treatment plots. The difference in RE, and between M and F plots approximates heterotrophic respiration of manure (RHm), which ranged from 0.9 to 1.3 Mg C ha^?1 yr^?1. Average annual RHm was 1.1 ± 0.4 Mg C ha^?1 yr^?1, and accounted for 56% of the total amount of applied manure C. The annual net biome production (NBP) in the M plot (from 0.0 to 1.5 Mg C ha^?1 yr^?1) was significantly higher than in the F plot (?1.4 to 0.5 Mg C ha^?1 yr^?1). The long-term effect of manure application combined with chemical fertilizer did not reduce grass production compared with chemical fertilizer only; however, manure application decreased the NEP throughout manure decomposition, and long-term manure application enhanced the NBP.     

An evaluation of the pesera soil erosion model and its application to a case study in Zakynthos, Greece

Abstract. The Pan‐European Soil Erosion Risk Assessment (pesera ) model was evaluated using existing soil erosion data collected under various types of climate, vegetation, landscape and soil conditions. The data used represent a variety of typical Mediterranean land uses such as winter wheat, vines, olives and bare, stony land prevailing in hilly areas. Using this data, the model was calibrated for sediment transport by overland flow and results compared to measured soil erosion values from runoff plots and a watershed on a monthly basis. The performance of the model was assessed statistically, showing that it can be satisfactorily used for predicting soil erosion rates under the conditions included in the study. The overall model estimate including all the available experimental data was 0.69 t ha^?1 yr^?1 with a maximum error of 1.49 t ha^?1 yr^?1. After validation, the model was applied to a small watershed (60 ha) of great ecological importance for the sea turtle Caretta caretta. For this purpose, soil and vegetation maps were compiled from all the necessary data for applying the model. The model was run for three years using daily data from an existing nearby meteorological station. The predicted and measured soil erosion rates for a 7‐month period were 0.31 t and 0.18 t, respectively. Application of the model to each mapping unit showed the over‐riding importance of land use for sediment generation under the given climatic conditions. Bare land, occupying 5.5% of the watershed area, generated up to 69% of the total sediments estimated for the watershed. It is concluded that the pesera model can be used as a regional diagnostic tool under a range of soil, topographic and climatic conditions for identifying the best land use type and vegetation cover to protect hilly areas from soil erosion. The calculated overall root mean square error for the model is 0.06 t ha^?1 yr^?1, compared to a soil erosion rate of 0.04 t ha^?1 yr^?1, which can be tolerated for protecting the area for the sea turtle.     

Yard Trimmings as a Source of Nitrogen for Crop Production

Yard trimmings from sources rich in grass clippings have the potential to supply nutrients for crop production. Our objectives were to estimate N availability from yard trimmings and determine their effects on crop production, soil nutrients, and organic matter levels. We conducted a field experiment, comparing three consecutive years of yard trimmings applications (22, 44, or 66 Mg ha^?1 yr^?1 dry weight) with inorganic N (112 kg N ha^?1 yr^?1) and zero-N controls in a silage corn (Zea mays L.) - winter triticale (Triticosecale spp.) rotation. The yard trimmings were screened and ground, and allowed to heat for a short period. They were incorporated each spring before planting corn. We measured crop yield and N uptake, and estimated apparent N recovery (ANR). We measured soil inorganic N two weeks after yard trimmings application and after corn harvest. In a one-year on-farm demonstration, we compared three sources of yard trimmings applied at a single rate. Yard trimmings applied at 44 Mg ha^?1 dry weight provided sufficient available N to replace inorganic N. For silage corn grown with summer irrigation, estimated ANR in the crop was 7% in Year 1, 19% in Year 2, and 18% in Year 3 at the 44 Mg ha^?1 yard trimmings rate, compared with a mean ANR of 65% for the inorganic N treatment. Postharvest soil nitrate residual (0-to 120-cm depth) was similar for the 44 Mg ha^?1 treatment and inorganic N treatment. We observed variation in N availability with year and source of material. Yard trimmings also increased soil test K and organic matter.     

Long-Term Fertilization Effects on Rice Productivity and Nutrient Efficiency in Korean Paddy

ABSTRACT

Long-term fertilization tests evaluated rice (Oryza sativa) productivity in relation to application of nitrogen (N)-phosphorus (P)-potassium (K) (120-34.9-66.7 kg ha^{? 1}, respectively) during 1967–1972 and N-P-K (150-43.7-83.3 kg ha^{? 1}, respectively) during 1973–2000. The comparison treatments (NP, PK, and NK) and the control (not fertilized) were selected for calculating nutrient efficiency. Rice grain yield increased at a 17.78 kg ha^{? 1} yr^{? 1} in the control, mainly due to development of improved cultivars. Phosphorus management was found to be important for indigenous fertility and rice productivity in this paddy soil. Yield increased significantly with P fertilization. Without N fertilization (PK), rice productivity increased 56.85 kg ha^{? 1} yr^{? 1} from 62% of NPK at the initial stage to 74% after passing 34 years, which might be affected by increasing biological N fixation with P accumulation in soil. In NK treatment, rice yield increased at a relatively low rate (37.82 kg hr^{? 1} yr^{? 1}) from the same rice productivity with that of NPK in 1967 to 91% after 34 years. In comparison, yield increased at a high rate (62.82 kg hr^{? 1} yr^{? 1}) without K fertilization (NP) from ca. 90% of NPK and might exceed the yield of NPK after 64 years of long-term fertilization. Therefore, K fertilization level might be readjusted after long-term fertilizing in paddy soil.