Application rate and composting method affect the immediate and residual manure fertilizer value in a maize–rice–rice–maize cropping sequence on a degraded soil in northern Vietnam

A field experiment was carried out in northern Vietnam to investigate the effects of adding different additives [rice (Oriza sativa L.) straw only, or rice straw with added lime, superphosphate (SSP), urea or a mixture of selected microorganism species] on nitrogen (N) losses and nutrient concentrations in manure composts. The composts and fresh manure were applied to a three-crop per year sequence (maize–rice–rice) on a degraded soil (Plinthic Acrisol/Plinthaquult) to investigate the effects of manure type on crop yield, N uptake and fertilizer value. Total N losses during composting with SSP were 20% of initial total N, while with other additives they were 30–35%. With SSP as a compost additive, 65–85% of the initial ammonium-N (NH₄-N) in the manure remained in the compost compared with 25% for microorganisms and 30% for lime. Nitrogen uptake efficiency (NUE) of fresh manure was lower than that of composted manure when applied to maize (Zea mays L.), but higher when applied to rice (Oriza sativa L.). The NUE of compost with SSP was generally higher than that of compost with straw only and lime. The mineral fertilizer equivalent (MFE) of manure types for maize decreased in the order: manure composted with SSP?>?manure composted with straw only and fresh manure?>?manure composted with lime. For rice, the corresponding order was: fresh manure?>?manure composted with SSP/microorganisms/urea?>?manure composted with lime/with straw alone. The MFE was higher when 5 tons manure ha^?1 were applied than when 10 tons manure ha^?1 were applied throughout the crop sequence. The residual effect of composted manures (determined in a fourth crop, with no manure applied) was generally 50% higher than that of fresh manure after one year of manure and compost application. Thus, addition of SSP during composting improved the field fertilizer value of composted pig manure the most.     

Effect of lignite amendment on carbon and nitrogen mineralization from raw and composted manure during incubation with soil

The application of animal manure as a source of plant nutrients requires the determination of the amount and pattern of nutrient mineralization from manure.A laboratory incubation study was conducted to investigate the influence of lignite amendment and lignite type on carbon(C) and nitrogen(N)mineralization in raw(feedstock) and composted cattle manure following application to soil at 30 and 60 t ha^-1.The mineralization of C and N was determined by measuring changes in CO2 evolution ...     

MSW Compost Reduces Nitrogen Volatilization During Dairy Manure Composting

Manures lose N through volatilization almost immediately after deposit. Attempts to control losses include the addition of a C source to stimulate nitrogen immobilization. Composting is a treatment process that recommends the addition of carbonaceous materials to achieve a C:N ratio of 30:1 to stimulate degradation and immobilize nitrogen. Dairies near cities may be able to reduce N loss from manures by composting with urban carbonaceous residues such as municipal solid waste (MSW) or MSW compost that, by themselves, have little agronomic value. Studies were conducted using a self-heating laboratory composter where dairy solids were mixed with MSW compost to determine the reduction of N loss during composting. One-to-one mixtures (v/v) of dairy manure solids and MSW compost were composted and NH₃ volatilization, CO₂ evolution and temperatures were compared to composting of manure alone. Addition of MSW compost resulted in increased CO₂ evolution and reduced N loss. Nitrogen loss from composting dairy manure alone was four to ten times greater than that from composting dairy manure mixed with MSW compost. Adjustment of the C:N ratio to 25 by adding MSW compost to manure appeared to be the major factor in reducing N losses.     

Effects of activated charcoal and tannin added to compost and to soil on carbon dioxide,nitrous oxide and ammonia volatilization

Given high mineralization rates of soil organic matter addition of organic fertilizers such as compost and manure is a particularly important component of soil fertility management under irrigated subtropical conditions as in Oman. However, such applications are often accompanied by high leaching and volatilization losses of N. Two experiments were therefore conducted to quantify the effects of additions of activated charcoal and tannin either to compost in the field or directly to the soil. In the compost experiment, activated charcoal and tannins were added to compost made from goat manure and plant material at a rate of either 0.5 t activated charcoal ha^?1, 0.8 t tannin extract ha^?1, or 0.6 t activated charcoal and tannin ha^?1 in a mixed application. Subsequently, emissions of CO₂, N₂O, and NH₃ volatilization were determined for 69 d of composting. The results were verified in a 20‐d soil incubation experiment in which C and N emissions from a soil amended with goat manure (equivalent to 135 kg N ha^?1) and additional amendments of either 3 t activated charcoal ha^?1, or 2 t tannin extract ha^?1, or the sum of both additives were determined. While activated charcoal failed to affect the measured parameters, both experiments showed that peaks of gaseous CO₂ and N emission were reduced and/or occurred at different times when tannin was applied to compost and soil. Application of tannins to compost reduced cumulative gaseous C emissions by 40% and of N by 36% compared with the non‐amended compost. Tannins applied directly to the soil reduced emission of N₂O by 17% and volatilization of NH₃ by 51% compared to the control. However, emissions of all gases increased in compost amended with activated charcoal, and the organic C concentration of the activated charcoal amended soil increased significantly compared to the control. Based on these results, tannins appear to be a promising amendment to reduce gaseous emissions from composts, particularly under subtropical conditions.     

Effect of Woody Peat as an Additive on Maturity and Gaseous Emissions During Pig Manure Composting

Woody peat was used as an additive to compost with pig manure in 1.2 m³ composting reactors under aerobic conditions for a 77?days period to estimate the effect on the compost maturity and gaseous emissions (NH₃, N₂O, and CH₄). Pig manure was also composted with cornstalks (the traditional method) as a control treatment. The results showed that both cornstalks and woody peat composts reached the required maturity standard. Composting with woody peat as a bulking agent was found to reduced NH₃ emissions by 36% than the cornstalks amended treatment. Although CH₄ emission increased by adding woody peat, N₂O emission was considerably reduced, resulting in a slight decrease in total greenhouse gas emissions. More importantly, woody peat could reduce the losses of total carbon and total nitrogen, improve the compost quality as fertilizer.     

Effect of nitrite accumulation on nitrous oxide emission and total nitrogen loss during swine manure composting

Abstract

The present study investigated the nitrogen balance in swine manure composting to evaluate the effect of nitrite (NO^? ₂) accumulation, which induces nitrogenous emissions, such as N₂O, during compost maturation. During active composting, most N losses result from NH₃ emission, which was 9.5% of the initial total nitrogen (TN_initial), after which, NO^? ₂ began to accumulate as only ammonia-oxidizing bacteria proliferated. After active composting, the addition of mature swine compost (MSC), including nitrite-oxidizing bacteria (NOB), could prevent NO^? ₂ accumulation and reduce N₂O emission by 70% compared with the control in which NO^? ₂ accumulated as a result of delayed growth of indigenous NOB. Total N₂O emissions in the control and in the treatment of MSC addition (MA) were 9.3% and 3.0% of TN_initial, respectively, whereas N losses as the sum total of NH₃ and N₂O over the whole period were 19.0% (control) and 12.8% (MA) of TN_initial, respectively. However, the difference in total N losses was markedly greater than that measured as NH₃ and N₂O, which were 27.8% (control) and 13.3% (MA) of TN_initial, respectively. These results demonstrated that the magnitude of nitrogen losses induced by NO^? ₂ accumulation is too large to ignore in the composting of swine manure.     

Passively Aerated Composting of Straw-Rich Pig Manure: Effect of Compost Bed Porosity

Straw-rich manure from organic pig farming systems can be composted in passively aerated systems as the high application of straw results in a compost bed with good structure and porosity. The passively aerated composting process was simulated in one-dimensional reactors of 2 m³ for straw-rich manure with compost bed densities of 1100, 700 and 560 kg m^?3. Temperature profiles over the reactor height were monitored online and ammonia emissions were measured periodically. The composition of the compost bed over the reactor height was determined at the end of the composting process. The composting process strongly depends on the density of the compost bed. At a density of 1100 kg.m^?3, the porosity of the bed is too low to initiate natural convection, and aerobic degradation fails and anaerobic conditions may lead to emissions of methane and odorous compounds. At a density of 560 kg.m^?3, the porosity of the bed is high and the high rate of natural convection will keep the temperature low thereby preventing the removal of pathogens and weeds. Best results were observed at a density of 700 kg.m^?3 for which aerobic degradation and drying were adequate and temperatures were high enough to kill pathogens and weeds. On basis of the Ergun equation, which describes the airflow in porous media with internal heat generation, this corresponds to a compost bed permeability of 7×10^?8 m². It was also shown that it is possible to compost animal manures with a low C/N ratio without significant emissions of ammonia. This can be established by trapping the initial ammonia emissions in a straw filter, which is placed on top of the compost bed. Ammonia absorbed in the straw filter and in the compost bed were removed by nitrification and denitrification. The passively aerated composting system results in a compost bed which is highly heterogeneous with respect to temperature, oxygen level and its composition. It is proposed that in this way a highly diverse microbial community in the compost bed is established which can perform various microbial conversions. The extensive composting system is most promising for on-farm production of an organic fertilizer from straw-rich manure, since the costs of the process and the level of ammonia emissions were low.     

Mass and Nutrient Losses During the Composting Of Dairy Manure Amended with Sawdust or Straw

Composting has become an increasingly popular manure management method for dairy farmers. However, the design of composting systems for farmers has been hindered by the limited amount of information on the quantities and volumes of compost produced relative to farm size and manure generated, and the impact of amendments on water, dry matter, volume and nitrogen losses during the composting process. Amendment type can affect the free air space, decomposition rate, temperature, C:N ratio and oxygen levels during composting. Amendments also initially increase the amount of material that must be handled. A better understanding of amendment effects should help farmers optimize, and potentially reduce costs associated with composting. In this study, freestall dairy manure (83% moisture) was amended with either hardwood sawdust or straw and composted for 110-155 days in turned windrows in four replicated trials that began on different dates. Initial C:N ratios of the windrows ranged from 25:1 to 50:1 due to variations in the source and N-content of the manure. Results showed that starting windrow volume for straw amended composts was 2.1 to 2.6 times greater than for sawdust amendment. Straw amended composts had low initial bulk densities with high free air space values of 75-93%. This led to lower temperatures and near ambient interstitial oxygen concentrations during composting. While all sawdust-amended composts self-heated to temperatures >55°C within 10 days, maintained these levels for more than 60 days and met EPA and USDA pathogen reduction guidelines, only two of the four straw amended windrows reached 55°C and none met the guidelines. In addition, sawdust amendment resulted in much lower windrow oxygen concentrations (< 5%) during the first 60 days. Both types of compost were stable after 100 days as indicated by CO₂ evolution rates <0.5 mg CO₂-C/g VS/d. Both types of amendments also led to extensive manure volume and weight reductions even after the weight of the added amendments were considered. However, moisture management proved critical in attaining reductions in manure weight during composting. Straw amendment resulted in greater volume decreases than sawdust amendment due to greater changes in bulk density and free air space. Through composting, farmers can reduce the volume and weights of material to be hauled by 50 to 80% based on equivalent nitrogen values of the stabilized compost as compared to unamended, uncomposted dairy manure. The initial total manure nitrogen lost during composting ranged from 7% to 38%. P and K losses were from 14 to 39% and from 1 to 38%, respectively. There was a significant negative correlation between C:N ratio and nitrogen loss (R₂=0.78) and carbon loss (R₂=0.86) during composting. An initial C:N ratio of greater than 40 is recommended to minimize nitrogen loss during dairy manure composting with sawdust or straw amendments.     

Effect of Organic Amendment Derived from Co-Composting of Chicken Slurry and Rice Straw on Reducing Nitrogen Loss from Urea

Co-composting of chicken slurry and rice straw with clinoptilolite zeolite and urea as additives was conducted to determine the characteristics of a compost and their effects on controlling ammonium (NH₄⁺) and nitrate (NO₃^?) losses from urea. Quality of the compost was assessed based on temperature, moisture content, ash, pH, electrical conductivity, carbon/nitrogen (C/N) ratio, NH₄⁺, NO₃^?, macronutrients, heavy metals, humic acid, microbial population, germination index, and phytotoxicity test. Moisture content and C/N ratio of the compost were 43.83% and 15, respectively. Total N, humic acid, ash, NH₄⁺, NO₃^?, phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na) increased after co-composting rice straw and chicken slurry. Copper, iron (Fe), manganese (Mn), zinc (Zn), and microbial biomass of the compost were low. The germination rate of Zea mays on distilled water and Spinacia oleracea growth on peat-based growing medium (PBGM) and compost were not significantly different. Urea amended with compost reduced N loss by retaining NH₄⁺ and NO₃^? in the soil.     

Assessment of the Reliability of a Commercial Maturity Test Kit for Composted Manures

Stability significantly affects the potential for beneficial utilization of composts but is difficult to measure by farmers and compost producers. A simple four hour test (the Solvita® maturity test) that measures CO₂ evolution and ammonia emission from compost samples was compared to a traditional three-day, 25°C, CO₂ evolution rate procedure and to measurements of ammoniacal nitrogen concentrations in manure composts to assess the reliability of this test. Three composts — 1) Dairy manure amended with wheat straw, 2) The same dairy manure but amended with sawdust and 3) Swine manure amended with sawdust and ground wood pallets — were composted in windrows for 120 days. Samples were removed weekly to biweekly. CO₂ evolution rates of the three composts decreased from initial means (n=6) of 3.41, 3.42 and 9.35 to 0.63, 0.76 and 0.31 mg CO₂-C g^?1 VS day^?1, for the dairy manure-straw, dairy manure-sawdust, hog manure composts, respectively. The corresponding mean Solvita CO₂ test values for these composts increased from 3.4, 3.0 and 3.2 to 6.8, 6.5 and 7.0, respectively. Correlation analysis between CO₂ evolution rates and Solvita CO₂ test values gave linear correlation coefficients (r) of ?0.82, ?0.78, and ?0.87 for the straw-amended dairy manure, the sawdust-amended dairy and the hog manure composts, respectively. The Solvita NH₃ test gave highly significant correlations (p<0.0001) with ammoniacal-N concentrations (correlation coefficients (r) = ?0.43, ?0.64 and ?0.65, respectively). The Solvita® maturity index, a combination of Solvita CO₂ and NH₃ values, correlated significantly with both CO₂ evolution rate and ammoniacal-N concentrations. However, the Solvita CO₂ index alone was the best predictor of compost CO₂ evolution rate or stability. The Solvita Maturity test, which combines the Solvita CO₂ and NH₃ tests, provided useful information about the potential for the development of a toxic response in plants due to excessive concentrations of ammoniacal-N present in some stable compost samples that would not have been detected if the CO₂ stability test were used by itself. We conclude that the Solvita maturity test provided a simple, inexpensive relative test of compost stability and NH₃ emission for diverse samples of composted manures. Even so, it did not accurately predict their CO₂ evolution rates measured by respirometry nor their ammoniacal-N concentrations. The test would be most useful for on-farm applications.     

Chemical Amendments and Process Controls To Reduce Ammonia Volatilization During In-House Composting

Composting inside high-rise, caged layer facilities can produce atmospheric ammonia (NH₃) concentrations exceeding standards for human and poultry health. Control measures that reduce NH₃ volatilization are necessary for in-house composting to be sustainable. Due to differences specific to in-house composting — low carbon to nitrogen ratios of composting material, continuous manure addition, and frequent turning — it is not known whether NH₃ control measures used previously for poultry manure will work. The objectives of this study were to evaluate various amendment and process controls on NH₃ produced during simulated in-house composting in the lab, and to evaluate select chemical control measures during composting inside a high-rise layer facility. Ten amendments (aluminum sulfate; chloride salts of aluminum, calcium, magnesium, and potassium; gypsum; sodium bisulfate; zeolite (clinoptilolite); straw; and cellulose) and four process controls (moisture; temperature; turning frequency; and particle size) were evaluated in lab incubations in 1 L vessels wherein samples of poultry manure compost were incubated to simulate composting. Vials of boric acid solution were used to capture NH₃ evolved during incubations. With the exception of zeolite and cellulose, all amendments reduced NH₃ capture. Low moisture and temperature also reduced NH₃ capture, although managing temperature and moisture to achieve low NH_g would adversely impact microbial activity and other desired benefits of composting. When evaluated inhouse, aluminum sulfate, calcium chloride and magnesium chloride did not reduce NH evolution from compost measured on three different dates with a gas sensor. Spatial variability along treated segments of windrow apparently masked amendment effects. At the end of a six-week composting cycle, total nitrogen content was higher in compost treated with aluminum sulfate than control or chloride salt treatments. Aluminum sulfate and process controls such as moisture content, carbon source and particle size have potential to reduce NH₃ loss from poultry manure composted inside high-rise layer structures. In-house compost management to reduce NH₃ volatilization must consider the cost of amendments, effectiveness, and impacts on the composting process.     

Toxicity Evaluation of Weathered Coal Fly Ash–Amended Manure Compost

The general use of manure compost is limited by its residualtoxicity, and hence a study was performed to evaluate the use ofweathered coal fly ash (lagoon ash) to alleviate the toxicity ofmanure compost. Mature and immature manure compost were amendedwith lagoon ash at 0, 5, 10 and 20% (w/w dry weight basis), andtheir phyto-toxicity was evaluated by germination and root lengthgrowth of lettuce seed. The immature manure compost hadsignificantly higher contents of NH₄-N, PO₄-P, andacid- and water-extractable Cu and Zn contents than those of mature manure compost. Ash amendment caused asignificant increase in electrical conductivity (EC), but adecrease in NH₄-N, PO₄-P, and DTPA-, CaCl₂- andwater-extractable Cd, Cu, Pb and Zn contents of both manurecompost. Addition of lagoon ash at a rate of 5% for immaturemanure compost and 10% for mature manure compost resulted in ahigher seed germination rate and root length growth. Thegermination index demonstrated significant negative correlationswith EC, NH₄-N and DTPA extractable Cd, Cu, Pb and Zncontents. The present study supports the use of lagoon ash foramending manure compost to reduce the availability of traceelements and NH₄-N.     

Residual Effects of Novel versus Traditional Organic Amendments for Rain-fed No-till Barley: Yield,Nutrient Uptake,and N2O Emissions

Organic amendments recycle nutrients, but N₂O emissions are both environmental and agronomic concerns. We conducted a 4-year field experiment to determine no-till barley (Hordeum vulgare L.) yield and nutrient uptake and soil N₂O emissions following a single application of six amendment treatments: (1) no amendment (Check); (2) synthetic N fertilizer (Fert); (3) fresh beef cattle feedlot manure (ManureF); (4) beef cattle feedlot manure compost (CompostR); (5) beef cattle feedlot manure composted with cattle mortalities (CompostM); and (6) separated solids from anaerobically digested cattle feedlot manure (ADM). Barley grown in Year 1 (2006), Year 2 (2007), and Year 4 (2009) (with Year 3 (2008) under fallow) had higher grain yields from ManureF (4.73 Mg ha^?1) in Year 2 and ADM (6.30 Mg ha^?1) in Year 4 (p < 0.05) than other treatments. The grain N and P contents were not affected (p > 0.05), but N uptake over 3 years (112.8 kg N ha^?1 yr^?1), and P uptake in Year 1 (19.1 kg ha^?1 yr^?1) and Year 2 (14.3 kg ha^?1 yr^?1) from ManureF, were higher (p < 0.05×) than other treatments. The cumulative N₂O emissions from ManureF in Year 1 (1.488 kg N ha^?1) and from ADM in Year 2 (1.072 kg N ha^?1) were higher (p < 0.05) than other treatments while the fraction of applied N emitted as N₂O was small (0.00 to 0.79%) and not affected by treatment. However, the percentages of applied N emitted as N₂O from compost and ADM were similar to synthetic fertilizer and livestock manure.     

Mineralization and N Fertilizer Equivalent Value of Composts as Assessed by Tall Fescue (Festuca arundinacea)

The capability to determine nitrogen availability of composts is necessary to ensure that such materials will provide sufficient fertilization to the growing crop and cause minimal environmental degradation. A greenhouse study using tall fescue as a bioindicator was used to evaluate nitrogen availability of two biosolids composts, two mixed yard waste-poultry manure composts, and one commercially-processed poultry litter. Five inorganic nitrogen (as NH₄NO₃-N) treatments applied at 0, 22.5, 45, 67.7, and 90 mg N/kg soil were employed to establish an N calibration curve. Yield, fescue biomass total nitrogen (as total Kjeldahl N (TKN)), and soil TKN and KCl extractable NO₃^?-N and NH₄⁺-N concentrations of the organically amended treatments were compared to the inorganically fertilized treatments to determine amendment N mineralization rates and N fertilizer equivalent values (NFEV). Nitrogen mineralization rates were greatest in the poultry litter (21%) and Panorama yard waste compost (5%) amended pots. The NFEV of these amendments were 49% and 10%, respectively. Wolf Creek biosolids compost and Huck's Hen Blend yard waste compost immobilized N (?5% and 0.18%, respectively), and had percent NFEV of ?0.66% and 0.19%, respectively. Rivanna biosolids compost immobilized N (?15%), but the NFEV was 30% due to the relatively high inorganic N content in the amendment. Nitrogen mineralization and NFEV were generally greater in amendments with greater total N concentrations and lower C:N values. The total N concentration and C:N values were less reliable variables in predicting N mineralization and percent NFEV when a significant portion of the total N was in the inorganic form. Nitrogen equivalency value and N mineralization for each amendment increased with time of sampling, indicating the potential for early season N insufficiency to plants fertilized with compost due to lack of synchrony between N mineralization and plant N needs.     

Manure amendment reduced plant uptake and enhanced rhizodegradation of 2,2′,4, 4′-tetrabrominated diphenyl ether in soil

To test whether manure amendment in soil reduces plant uptake of persistent organic pollutants, carrot (Daucus carota L.) was used as a model plant and 2,2′,4,4′-tetrabrominated diphenyl ether (BDE-47) was selected as a model persistent organic pollutant to conduct a pot experiment with contaminated soil amended by composted pig manure. The results showed that the concentration and bioconcentration factors (BCFs) of BDE-47 in the edible part of carrot significantly decreased from 229.7?±?28.2 to 43.4?±?20.4 ng g^?1 and from 1.86?±?0.5 to 0.15?±?0.03, respectively, with increasing composted pig manure dose from 0 to 4%. Organic matter (OM) derived from composted pig manure played a dominant role in reducing persistent organic pollutant bioavailability in soil. Composted pig manure amendment and carrot cultivation jointly altered the bacterial community composition in soil, especially the rhizosphere. Rhizodegradation of BDE-47 was enhanced from 8.6 to 28.5% with increasing composted pig manure dose from 0 to 4%, corresponding to increased soil microbe diversity and polybrominated diphenyl ether-degrading bacteria (Sphingomonas, etc.) abundance in the rhizosphere. This study is the first, to the best of our knowledge, to provide an effective agronomic strategy of manure amendment to reduce plant uptake and simultaneously enhance rhizodegradation of persistent organic pollutants in soil, and thus potentially reduce human health risks through dietary intake.     

Effect of Adding Flue Gas Desulphurization Gypsum on the Transformation and Fate of Nitrogen during Composting

The objective of this study was to investigate the effect of adding flue gas desulphurization gypsum (FGDG) on the transformation and fate of nitrogen during co-composting of dairy manure and pressmud of a sugar refinery. The ammonia absorption of FGDG was investigated. The changes in compost temperature, pH, electrical conductivity (EC), moisture, organic matter, the C/N ratio, Kjeldahl N, NH₄⁺-N, NO₂^?-N, NO₃^?-N were assessed. The addition of FGDG did not significantly affect compost temperature, pH, EC, moisture, and organic matter degradation. However, the addition of FGDG significantly increased the NH₄⁺-N content in the compost during the thermophilic phase, and the NH₄⁺-N maximal content in the compost with FGDG (CP+G) was 59.9% more than that in the compost without FGDG (CP–G). FGDG was thought to create the formation of (NH₄)₂SO₄ and the cation exchange between NH₄⁺ and Ca²⁺. The NO₂^?-N content in the CP+G peaked on day 15, and was not observed in the CP–G. In the final compost products, the NO₃^?-N concentration in the CP–G was more than that in the CP+G, which was 1451 (CP–G) and 1109 mg·kg^?1 (CP+G) dry material. This might be due to the NO₂^? accumulation in the CP+G, which accelerated N loss in the form of N₂O. There is a strong correlation between N₂O emission and NO₂^?-N accumulation in the composting process. Compared with the original N content in the compost mixture, the N loss in CP–G and CP+G were 15.0 and 10.8%, respectively. These results revealed that NH₄⁺-N conservation effect was improved during the thermophilic phase and the total N loss was mitigated by adding FGDG into composting materials. FGDG could be utilized as a potential amendment to conserve nitrogen during composting.     

Nitrogen Availability from Compost in High Tunnel Tomato Production

High yield agricultural systems, such as high tunnel (HT) vegetable production, require a large supply of soil nutrients, especially nitrogen (N). Compost is a common amendment used by HT growers both to supply nutrients and to improve physical and biological soil properties. We examined commercially-available composts and their effects on soil N, plant N uptake, and tomato yield in HT cultivation. In addition, a laboratory study examined N and carbon (C) mineralization from the composts, and the usefulness of compost properties as predictors of compost N mineralization was assessed under field and laboratory conditions. The field study used a randomized complete block design with four replications to compare four compost treatments (all added at the rate of 300 kg total N ha^?1) with unamended soil and an inorganic N treatment (110 kg N ha^?1). Tomatoes were grown in Monmouth, Maine during the summers of 2013 and 2014. Compost NO₃^?-N and NH₄⁺-N application rates were significantly correlated with soil NO₃^?-N and NH₄⁺-N concentrations throughout the growing season. Marketable yield was positively correlated with compost total inorganic N and NO₃^?-N in both years, and with NH₄⁺-N in 2014. There were no significant differences among composts in percentage of organic N mineralized and no correlations were observed with any measured compost property. In the laboratory study, all compost-amended soils had relatively high rates of CO₂ release for the initial few days and then the rates declined. The compost-amended soils mineralized 4%–6% of the compost organic N. This study suggested compost inorganic N content controls N availability to plants in the first year after compost application.     

Cocomposting of Beet Vinasse and Grape Marc In Windrows and Static Pile Systems

Two composts were obtained by cocomposting a concentrated depotassified beet vinasse and grape marc using an aerated static pile and a windrow system. The composting mixtures comprised grape marc (83%) and vinasse (17%) for the aerated static pile system and grape marc (77%), vinasse (20%) and phosphate rock (3%) for the windrow. Changes in temperature followed a similar path for both mixtures, however the thermophilic phase was longer in the aerated static pile (25 days) than in the windrow (10 days). This fact caused differences in both organic matter degradation, weight losses (21% for static pile and 10% for windrow) and gas losses during the process. Nevertheless, the composts obtained by the two systems had a high fertilizer nutrient value (18.2 g kg^?1 N; 3.1 g kg^?1 P; 13.6 g kg^?1 K, C/N 16.1 for compost obtained in static pile and 20.6 g kg^?1 N; 13.7 g kg^?1 P; 13.1 g kg^?1 K; C/N 18 for compost obtained in windrow). A high degree of stability was reached in both composting systems (124 cmol_c kg^?1 CEC for static pile and 153 cmolc kg^?1 CEC for windrow at 80 days of composting). The chemical and physical properties of both vinasse composts suggest their possible use as soil conditioner.     

不同处理对高含水率奶牛粪便好氧堆肥的影响

针对奶牛养殖场粪便含水率高,堆肥处理成本高的特点,采用以干燥玉米秸秆为调理剂,在较高初始含水率条件下（70%～80%）,进行了强制通风堆肥槽和翻转式堆肥仓的对比试验,并且探讨了晾晒脱水作为预处理对堆肥效果的影响。结果表明,各处理堆体升温迅速,且均在50℃以上维持8～12d,满足堆肥无害化的卫生标准（GB7959—1987）要求。至堆肥结束时,各处理含水率均降至40%以下,C/N均降至20以下,WSOC均低于16g·kg-1,NH4＋-N含量均低于0.4g·kg-1;除采用堆肥槽在初始含水率为65%下堆肥NH4＋-N/NO3--N〉3尚未腐熟完全外,其他处理NH4＋-N/NO3--N均小于0.5,腐熟情况较好;所有处理的GI均大于50%,其中采用堆肥槽在较高初始含水率堆肥和晾晒预处理后堆肥GI已达80%,基本消除了植物毒性。采用较为开放的堆肥槽时,以玉米秸秆作调理剂,在较高的初始含水率条件下堆肥效果更好;以晾晒脱水作为预处理后堆肥,可减少所需调理剂的用量,节约了堆肥的成本。     

Effects of form of effluent,season and urease inhibitor on ammonia volatilization from dairy farm effluent applied to pasture

Purpose

With land application of farm effluents from cows during housing or milking as an accepted practice, there are increasing concerns over its effect on nitrogen (N) loss through ammonia (NH₃) volatilization. Understanding the relative extent and seasonal variation of NH₃ volatilization from dairy effluent is important for the development of management practices for reducing NH₃ losses. The objectives of this study were to determine potential NH₃ losses from application of different types of dairy effluent (including both liquid farm dairy effluent (FDE) and semi-solid dairy farm manure) to a pasture soil during several contrasting seasons and to evaluate the potential of the urease inhibitor (UI)—N-(n-butyl) thiophosphoric triamide (NBTPT, commercially named Agrotain^®) to reduce gaseous NH₃ losses.

Material and methods

Field plot trials were conducted in New Zealand on an established grazed pasture consisting of a mixed perennial ryegrass (Lolium perenne L.)/white clover (Trifolium repens L.) sward. An enclosure method, with continuous air flow, was used to compare the effects of treatments on potential NH₃ volatilization losses from plots on a free-draining volcanic parent material soil which received either 0 (control) or 100 kg N ha^?1 as FDE or manure (about 2 and 15 % of dry matter (DM) contents in FDE or manure, respectively) with or without NBTPT (0.25 g NBTPT kg^?1 effluent N). The experiment was conducted in the spring of 2012 and summer and autumn of 2013.

Results and discussion

Results showed that application of manure and FDE, both in fresh and stored forms, potentially led to NH₃ volatilization, ranging from 0.6 to 19 % of applied N. Difference in NH₃ losses depended on the season and effluent type. Higher NH₃ volatilization was observed from both fresh and stored manure, compared to fresh and stored FDE. The difference was mainly due to solid contents. The losses of NH₃ were closely related to NH₄ ⁺-N content in the two types of manure. However, there was no relationship between NH₃ losses and NH₄ ⁺-N content in either type of FDE. There was no consistent seasonal pattern, although lower NH₃ losses from fresh FDE and stored FDE applied in spring compared to summer were observed. Potential NH₃ losses from application of fresh FDE or manure were significantly (P?<?0.05) reduced by 27 to 58 % when NBTPT was added, but the UI did not significantly reduce potential NH₃ volatilization from stored FDE or manure.

Conclusions

This study demonstrated that NH₃ losses from application of FDE were lower than from manure and that UIs can be effective in mitigating NH₃ emissions from land application of fresh FDE and manure. Additionally, reducing the application of FDE in summer can also potentially reduce NH₃ volatilization from pasture soil.