The response of soil organic matter to manure amendments in a long-term experiment at Ultuna, Sweden

In a long-term field experiment started in 1956 on a clay loam soil at Uppsala, Sweden, changes of organic carbon in the topsoils receiving various organic amendments at the rate of 200 kg C ha^'1 year^'1 were studied to determine soil organic matter characteristics, variations of δ¹³C in the soil and to estimate a carbon balance. Fallow and mineral fertilizer without N led to a significant decrease of soil organic matter (SOM) in the soil, green manure maintained the SOM content, and animal manure and peat increased the SOM content significantly. The stable portion of the added organic materials after 37 years of continuous input was 12·8, 27·3, and 56·7%, for green manure, animal manure and peat, respectively. This was reflected by half-lives of organic carbon originating from the amendments between 3·0 (green manure) and 14·6 years (peat). The isotopic composition of SOM changed both due to mineralization (continuous fallow) and the addition of amendments is topically different from soil humus (green manure, animal manure). The isotopic effect was used to calculate the percentage of carbon derived from animal manure present for the year 1993. This value (55·4%) was larger than that derived from the carbon balance, which indicated a priming effect of the animal manure on the initial soil humus. Mineralization of microbially available organic substances led to an increase in the degree of humification on plots not receiving organic amendments. Adding peat and animal manure resulted in a decrease of the humification index due to the continuous input of poorly humified material. The extinction ratio (E₄/E₆) and ratio of fulvic acid to humic acid changed considerably in the peat treated plots. Fourier transform infrared (FTIR)-measurements of the extracts showed that peat characteristics can be detected in peat treated soils. The other amendments did not alter the characteristics of the extractable humic substances.     

Temperature response of ammonia and greenhouse gas emission from manure amended silty clay soil

Soil temperature plays an important role in organic matter decomposition, thus likely to affect ammonia and gaseous emission from land application of manure. An incubation experiment was conducted to quantify ammonia and greenhouse gas (GHG) (N₂O, CO₂ and CH₄) emissions from manure and urea applied at 215?kg N ha^?1 to Fargo-Ryan silty clay soil. Soil (250?g) amended with solid beef manure (SM), straw-bedded solid beef manure (BM), urea only (UO), and control (CT) were incubated at 5, 10, 15, and 25 °C for 31 days at constant 60% water holding capacity (WHC). The cumulative GHGs and NH₃ emission generally increased with temperature and highest emission observed at 25 °C. Across temperature levels, 0.11–1.3% and 0.1–0.7% of the total N was lost as N₂O and NH₃, respectively. Cumulative CO₂ emission from manure was higher than UO and CT at all temperatures (P?<?0.05). Methane accounted for <0.1% of the total C (CO₂?+?CH₄) emission across temperatures. The Q₁₀ values (temperature sensitivity coefficient) derived from Arrhenius and exponential models ranged 1.5–3.7 for N₂O, 1.4–6.4 for CO₂, 1.6–5.8 for CH₄, and 1.4–5.0 for NH_3. Our results demonstrated that temperature significantly influences NH₃ and GHG emissions irrespective of soil amendment but the magnitude of emission varied with soil nutrient availability and substrate quality. Overall, the highest temperature resulted in the highest emission of NH₃ and GHGs.     

Influence of Soil Properties and Manure Sources on Phosphorus in Runoff during Simulated Rainfall

Runoff from agricultural fields amended with animal manure or fertilizer is a source of phosphorus (P) pollution to surface waters, which can have harmful effects such as eutrophication. The objectives of this study were to evaluate the impact of soil P status and the P composition of manure sources on P in runoff and characterize the effects of manure sources on mass loss of dissolved reactive P, total dissolved P, and total P in runoff. Soil boxes set at 5% slopes received 7.5 cm h^?1 of simulated rainfall for 30 min. Study soils included a Kenansville loamy sand (loamy siliceous subactive thermic Arenic Hapludults, a Coastal Plain soil) and a Davidson silt loam (kaolinitic thermic Rhodic Kandiudults, a Piedmont soil). Soil test P concentrations ranged from 16 to 283 mg P kg^?1. Sources of P included broiler litter, breeder manure, and breeder manure treated with three rates of aluminum sulfate (Al₂(SO₄)₃) 0, 3.9, and 7.8 kg m^?2, di-ammonium phosphate (DAP), and an un-amended control. All manure sources were surface applied at 66 kg P ha^?1 without incorporation. Water extractable P represented an average of 10 ± 6% total P in manure. Runoff samples were taken over a 30-min period. Piedmont soil contained greater amounts of clay, aluminum (Al), and iron (Fe) concentrations, and higher P sorption capacities that produced significantly lower dissolved reactive P, total dissolved P, and total P losses than the Coastal Plain soil. Runoff P loss did not differ significantly for low and high STP Coastal Plain soils. Water extractable P in manures accounted for all dissolved reactive P lost in runoff with dissolved reactive P correlating strongly with water extractable P concentration (r² = 0.9961). Overall, manures containing the highest water extractable P concentrations contributed to the largest amounts of dissolved reactive P in runoff. Manure treated with 3.9 and 7.8 kg m^?2 of Al₂(SO₄)₃ (alum) decreased dissolved reactive P in runoff by 29%. While this soil box runoff study represents a worst-case scenario for P loss, highly significant effects of soil properties and manure sources were obtained. Management based on these results should help ameliorate harmful effects of P in runoff.     

Changes in the soil phosphorus status of agricultural land in the Netherlands during the 20th century

The Netherlands has a high cumulative mean phosphorus (P) balance. In the 20th century, cumulative mean P surpluses were ca. 4500 kg P₂O₅/ha. The annual surpluses have levelled off because of manure application limits from 1984 onwards. We report the effect of soil type, land use, and manure policy on changes in soil P of fields in the Netherlands during the 20th century. We used data (>5 million soil P tests) from the soil analysis laboratory BLGG AgroXpertus. Our results show that soil P has increased on average to fairly high and high ratings. Differences between regions and between land use have remained high from the first records in the 1930s; on arable land the increase continued until the end of our study period while on grassland no changes are evident in the last decades. In general regions with high livestock density have high soil P status. Soil P increased in the order bulbfields < grassland < arable land < maize land < horticulture, and in the order loess < clay < peat < sand soils. Spatial variations in P values reflect more the market value of the crops and regional availability of animal manure than (fertilizer) recommendations. Manure policy since 1984 has resulted in increasingly tight restrictions on P application from manure and fertilizers, but the effects are not yet clearly reflected in changed trends in soil P.     

不同金属盐强化乙醇/水预处理对蔗渣酶解效率的影响

预处理过程可以破坏木质纤维素生物质的致密结构、降低生物抗性,是木质纤维素生物质经酶解制备糖基平台化学的重要步骤。该研究以蔗渣为原料,在预处理温度为160 ℃、预处理时间为10 min时,选取0.025 mol/L 的不同金属盐FeCl₃、CrCl₃、AlCl₃、CuCl₂、FeCl₂、ZnCl₂、MnCl₂、MgCl₂、CaCl₂、NaCl、LiCl、Na₂CO₃对蔗渣进行乙醇/水预处理,并对预处理后样品进行酶解,探究不同金属盐强化乙醇/水预处理对蔗渣酶解效率的影响和规律,并进一步通过扫描电镜（scanning electron microscopy, SEM）、X射线衍射（X-ray diffraction, XRD）、傅里叶变换红外光谱（fourier transform infrared spectroscopy, FT-IR）和热重（thermogravimetric, TG）对蔗渣原料和预处理后的固体进行表征,探究金属盐强化乙醇/水预处理后蔗渣表面形貌与结构变化对酶解效率的影响,分析作用机理。结果表明:与原料甘蔗渣相比,不同金属盐强化乙醇/水预处理后样品中葡聚糖的质量分数从45.5%增加到77.2%,预处理后样品酶解48h后的葡萄糖得率也由51.14%增加到最高93.08%。其中,三价金属盐（FeCl₃、CrCl₃和AlCl₃）对蔗渣酶解效率的提升最为显著,这可归因于三价金属盐强化乙醇/水预处理可以更加有效的去除蔗渣中的半纤维素和木质素,增加酶对纤维素的可及性。后续表征分析也表明经过三价金属盐（FeCl₃、CrCl₃和AlCl₃）强化乙醇/水预处理后的样品比经过二价金属盐（CuCl₂、FeCl₂、ZnCl₂、MnCl₂、MgCl₂和CaCl₂）和一价金属盐（NaCl、LiCl和Na₂CO₃）强化乙醇/水预处理表面结构破坏更为彻底,结晶度相对增加最大,木素和半纤维素去除率最多,热稳定性也相对最高。该研究结果将为后续木质纤维素生物质的高效转化与利用提供参考。     

福建省农业生态系统氧化亚氮排放量估算及特征分析

N2O是重要的温室气体,了解福建省农业生态系统N2O排放情况及其年代变化规律,对于寻找减排的技术路线与对策,进而实现全国的控制目标有重要意义。本研究基于福建省农业活动水平数据,采用区域氮素循环模型IAP-N方法,估算1991—2010年福建省农业生态系统氧化亚氮(N2O)的排放量(以纯氮量计)并分析其排放特征。结果表明:(1)1991—2010年福建省农业生态系统N2O排放总量(包括农田直接、间接排放,田间秸秆燃烧排放,粪便管理系统排放)呈先增加后降低趋势,从1991年的23 675.3 t·a–1增加到2006年的32 610.4t·a–1,之后降低至30 810.7 t·a–1(2010年)。1991—1995年、1996—2000年、2001—2005年、2006—2010年农业生态系统年平均N2O排放量分别为26 170.7 t·a–1、29 870.0 t·a–1、32 085.8 t·a–1、31 287.6 t·a–1。各类型排放量大小依次为:农田直接(66.2%)-粪便管理系统(20.7%)-农田间接(12.9%)-田间秸秆燃烧(0.2%)。(2)1991—2010年,农田N2O直接排放量呈先增加后降低趋势,从1991年的15 108 t·a–1增加到2006年的21 547 t·a–1,之后下降到2010年的20 594 t·a–1。4个时期年平均N2O直接排放量分别为17 073.0 t·a–1、19 976.8 t·a–1、21 183.4 t·a–1、20 778.6 t·a–1。农田旱作(包括蔬菜地、非蔬菜旱地、水旱轮作的旱季)N2O排放占农田N2O直接排放量的83.0%~90.7%,是农田直接排放的关键源。(3)1991—2010年间,福建省粪便管理系统N2O排放量保持在5 213.2~6 988.0 t·a–1,变化较稳定。粪便管理系统N2O排放的关键源为猪,占粪便管理系统N2O排放量的57.4%~67.9%。(4)2010年,农业生态系统N2O排放高值区主要分布在漳州市、南平市、泉州市和宁德市,其N2O排放量均在4 000 t·a–1以上,占全省总排放量的61.7%,应优先考虑削减这些地区的N2O排放。研究结果为决策者合理利用肥料,制定福建省农业生态系统温室气体减排措施提供科学依据。     

蜉金龟堆肥和自然堆肥类胡敏酸的表征及特性研究

分别用焦磷酸钠和氢氧化钠浸提新鲜牛粪、蜉金龟堆肥(APCM)和自然堆肥(腐熟牛粪)产物中的类胡敏酸,采用元素组成、红外光谱及差热分析研究了其结构特征。元素分析结果表明,蜉金龟堆肥焦磷酸钠浸提物——类胡敏酸(NaHLA)的芳香性低于新鲜牛粪和自然堆肥,而碳水化合物及氮元素含量增加。蜉金龟堆肥氢氧化钠浸提物——类胡敏酸(PAHLA)的碳水化合物和氮元素含量也高于新鲜牛粪和自然堆肥,而自然堆肥PAHLA的芳香性略低于新鲜牛粪和蜉金龟堆肥。红外光谱分析结果表明,与自然堆肥NaHLA相比,蜉金龟堆肥NaHLA中羧酸脂类化合物、酮类化合物、脂肪族化合物及碳水化合物有所增加。与新鲜牛粪PAHLA相比,蜉金龟堆肥和自然堆肥PAHLA的碳水化合物、脂肪族化合物、酚类化合物及纤维素酯类减少,同时蜉金龟堆肥PAHLA的酰胺化合物在蜉金龟消化过程中被其吸收。差热分析结果表明,自然堆肥NaHLA的热稳定性高于新鲜牛粪和蜉金龟堆肥,而蜉金龟堆肥NaHLA的脂族化合物、外围官能团和分子内部芳香结构含量较高,分子结构较复杂。蜉金龟堆肥PAHLA存在两个放热峰,而新鲜牛粪和自然堆肥的中温放热峰消失。综上,蜉金龟堆肥和自然堆肥采用两种提取液浸提出类胡敏酸的结构特征存在差异性。     

Mineralization of carbon and nitrogen from fresh and anaerobically stored sheep manure in soils of different texture

A sandy loam soil was mixed with three different amounts of quartz sand and incubated with (¹⁵NH₄)₂SO₄ (60 g N g^-1 soil) and fresh or anaerobically stored sheep manure (60 g g^-1 soil). The mineralization-immobilization of N and the mineralization of C were studied during 84 days of incubation at 20°C. After 7 days, the amount of unlabelled inorganic N in the manure-treated soils was 6–10 g N g^-1 soil higher than in soils amended with only (¹⁵NH₄)₂SO₄. However, due to immobilization of labelled inorganic N, the resulting net mineralization of N from manure was insignificant or slightly negative in the three soil-sand mixtures (100% soil+0% quartz sand; 50% soil+50% quartz sand; 25% soil+75% quartz sand). After 84 days, the cumulative CO₂ evolution and the net mineralization of N from the fresh manure were highest in the soil-sand mixutre with the lowest clay content (4% clay); 28% fo the manure C and 18% of the manure N were net mineralized. There was no significant difference between the soil-sand mixtures containing 8% and 16% clay, in which 24% of the manure C and -1% to 4% of the manure N were net mineralized. The higher net mineralization of N in the soil-sand mixture with the lowest clay content was probably caused by a higher remineralization of immobilized N in this soil-sand mixture. Anaerobic storage of the manure reduced the CO₂ evolution rates from the manure C in the three soil-sand mixtures during the initial weeks of decomposition. However, there was no effect of storage on net mineralization of N at the end of the incubation period. Hence, there was no apparent relationship between net mineralization of manure N and C.     

Nitrogen Pollution from Swedish Beef Production based on Suckle-Cows

Measures to improve N-use efficiency and thus reduce N-pollutionare scrutinized in beef production based on suckle-cows. Measures in feed production, animal feed conversion and the use of animal manure are included and their economic opportunities are analysed. The resultssuggest that production based on non-N-fertilized grassgives very low losses of NO₃, NH₃ and N₂Oper ha. Production based on pastures and leys given 100 kgN ha^-1 results in considerably higher losses, especially perha but also per kg of produced beef. Beef productionwithout input of mineral fertilizers might be profitablein regions abundant in land with low opportunity cost,especially if environmental support is provided. Clover-basedbeef production gives relatively high N losses bothper ha and per kg of beef. The reason is unnecessarilyhigh N-content in the clover, resulting in high N-level inexcreta and increased losses from manure and pastures. Achange from a deep straw bed manure system to slurryspread only in spring and immediately incorporated canreduce N-losses considerably but is unprofitable insuckle-cow-production. Beef production has lower N-lossesthan pork production per ha but higher per kg of produced meat.     

Dairy manure treatment effects on manure phosphorus fractionation and changes in soil test phosphorus

In this research, a sequential fractionation procedure coupled with enzyme hydrolysis was used to categorize the phosphorus (P) forms of 18 manure samples collected from in-barn composted bedded pack (beef manure), anaerobic digestion with liquid–solid separation (dairy manure), and liquid–solid separation systems (dairy manure). This research also determined the effects of those P forms on the increase in soil test P (STP) of five soil series. The soils used had initial Bray-1 P ranging from 16 to 43 mg P kg^?1. Total dry-ash P (P_t) of the manures ranged from 1.4 to 15.0 g P kg^?1; total inorganic P (P_it) accounted for 20 to 81 % of P_t; and enzymatically hydrolysable P (P_et) accounted for 5 to 26 % of P_t. Liquid–solid separation tended to concentrate the manure P in the liquid fractions. In contrast, anaerobic digestion did not affect the manure P distribution compared with the undigested raw manure from the same system. No differences in P distribution were found for the compost bedded pack manure. In the soil incubation study, manure and fertilizer were applied at 40 mg total P kg^?1. Separated liquid manure from two systems tended to increase STP more than the separated solid manures from the same systems. Although anaerobic digestion modified some of the physical and chemical properties of the treated manures, it did not clearly impact how digested manure increased STP compared with the raw manures. Overall, the increase in STP after treated manure application was found to be a function of soil clay content and manure P_it?+?P_et applied.     

动物农家肥的应用与环境化学研究进展

Animal manure consists of predominantly urine and feces,but also may contain bedding materials,dropped feed,scurf,and other farming wastes.Manure is typically applied to soils as fertilizer for agricultural production.The estimated amount of manure produced in 12 major livestock-producing countries is 9 × 10~9 Mg of manure annually.Manure is rich in plant nutrients.However,manure is also considered as an environmental pollutant when it is over-applied to cropland or following runoff into surface water.Manure can also in?uence global climate change via emissions of methane(CH_4) and nitrous oxide(N_2O).Thus,increased and updated knowledge of applied and environmental chemistry of animal manure is needed to shed light on the research and development of animal manure utilization and minimization of its adverse environmental concerns.The advances in basic and applied studies of manure major components,organic matter,phosphorus,and nitrogen,primarily related to US livestock production are summarized in this review.Detailed focus was placed on three notable challenges for future manure research:1) soil application of animal manure,2)manure phytate phosphorus,and 3) manure nitrogen availability.This review may contribute to the global effort in sustainable and environmentally sound agriculture by stimulating new ideas and directions in animal manure research,and promoting application of knowledge and insight derived from manure research into improved manure management strategies.     

Response of nectarines to organic fertilization under the rain-fed ecosystem of Northwest Himalayas

The comparative efficacy of organic sources on cropping behavior, nutrient dynamics, physico-chemical and biological properties of soil and fruit quality under rain-fed agroecosystem on “Silver King” nectarines was investigated. Bio-organic nutrients, namely vermi-compost (VC), biofertilizer (BF), farmyard manure (FYM), compost (comp), vermiwash (VW) and cow urine (CU) were evaluated in 11 different treatment combinations. The treatment application of VC at 25 kg tree^?1, BF at 40 g tree^?1, FYM at 30 kg tree^?1, comp at 15 kg tree^?1, VW_1:10 and CU_1:10 significantly improved plant growth and fruit quality characteristics of nectarine trees. This superior combination also enhanced physico-chemical and biological properties of the rhizosphere soil when compared to control as conventional chemical fertilizer application nitrogen, phosphorus and potassium (NPK) fertilizers. Different treatments of bio-organic sources changed pH of the soil to neutral. Available macronutrient contents of soil (viz. N, P, and K) increased by 57.8%, 27.7%, and 16.4%, respectively. Microbial biomass of soil fungi, total bacteria, actinobacteria, and arbuscular mycorrhizal fungi improved 66.0%, 73.8%, 133.3% and 350.0%, respectively, over control. Considerably, a higher amount of leaf macronutrients, N (3.53%), P (0.23%), and K (3.2%), was also recorded over control.     

How are soil use and management reflected by soil organic matter characteristics: a spectroscopic approach

We studied the quantitative and qualitative changes of soil organic matter (SOM) due to different land uses (arable versus grassland) and treatments (organic manure and mineral fertilizer) within an agricultural crop rotation in a long‐term field experiment, conducted since 1956 at Ultuna, Sweden, on a Eutric Cambisol. The organic carbon (OC) content of the grassland plot was 1.8 times greater than that of the similarly fertilized Ca(NO₃)₂ treated cropped plots. The comparison of two dispersion techniques (a low‐energy sonication and a chemical dispersion which yield inherent soil aggregates) showed that increasing OC contents of the silt‐sized fractions were not matched by a linear increase of silt‐sized aggregates. This indicated saturation of the aggregates with OC and a limited capacity of particles to protect OC physically. Thermogravimetric analyses suggested an increase of free organic matter with increasing OC contents. Transmission FT‐IR spectroscopy showed relative enrichment of carboxylic, aromatic, CH and NH groups in plots with increasing OC contents. The silt‐sized fractions contained the largest SOM pool and, as revealed by ¹³C NMR spectroscopy, were qualitatively more influenced by the plant residue versus manure input than the clay fractions. Alkyl and O‐alkyl C in the silt‐sized fractions amounted to 57.4% of organic carbon in the animal manure treated plots and 50–53% in the other treatments.     

Long‐term effects of copper rich swine manure application on continuous corn production

Abstract

Three long‐term field experiments were established in the spring of 1978 and continued through 1988 to evaluate corn (Zea mays L.) response to high Cu levels from Cu rich swine manure and CuSO₄ applications. The field research was conducted on soils with diverse properties, i.e., on a Bertie fine sandy loam (fine‐loamy, mixed, thermic, Aquic Hapludults), a Guernsey silt loam (fine, mixed, mesic, Aquic Hapludalfs), and a Starr‐Dyke clay loam (fine‐loamy, mixed, thermic Fluventic Dystrochrepts‐clayey, mixed, mesic, Typic Rhodudults). Three treatments in the long‐term field experiments on the three soils were i) a control, ii) annual applications of Cu as Cu rich swine manure, and iii) annual applications of Cu as CuSO₄ equivalent to that in the manure. After the 11 years, 1109 mt ha^‐1 of wet Cu rich swine manure were applied for the manure treatment. The Cu rich manure, which contained an average of 1316 mg Cu kg^‐1, was produced by swine fed diets supplemented with an average of 251 mg Cu kg^‐1 as CuSO₄. An average of 325 kg Cu ha^‐1 added to the soils from the manure application over the 11 years exceeded U.S.E.P.A. guidelines for safe copper loading levels for cropland by 45 kg ha^‐1. Copper concentrations in corn ear leaves were within the normal range of 3 to 15 mg kg^‐1 where the 325 kg Cu ha^‐1 were applied to the soils as either Cu rich manure or CuSO₄ over the 11 years. Concentrations of Cu in the grain also were in the normal range of 1 to 5 mg kg^‐1 where the high level of the two Cu sources were applied to the soils. There was no decrease in corn yield on the three soils from application of either Cu source. The lack of yield decrease from the Cu rich manure and CuSO₄ applications may reflect decreased Cu availability at the near neutral pH in the soils under study.     

Measurement of the maximum amount of water-extractable phosphorus in animal manure compost by continuous and sequential water extraction

Measuring the phosphorus (P) solubility in animal manure compost (AMC) is important to estimate both the risk of P loss from agricultural land and the P availability for crops in agriculture that use AMC as fertilizer. Water-extractable phosphorus (WEP) has most often been used to estimate P solubility in AMC. A single water extraction with a high ratio of compost to water is usually used to determine WEP, but in many cases, this may not evaluate the maximum WEP. In this study, we extracted the P included in AMC by using a continuous extraction method with a large amount of water, and tested this approach for 16 AMCs: four cattle manure composts, five swine manure composts, five layer (chicken) manure composts, and two broiler (chicken) litter composts. The P dissolution patterns were fitted to kinetic models, and the maximum WEP (WEP_max) was determined by the coefficient of the non-linear regression equation. The WEP_max values corresponded to the sum of H₂O- and sodium bicarbonate (NaHCO₃)-extractable P measured using the modified Hedley sequential extraction method. The result also suggests that the maximum amount of WEP from AMC can be estimated rapidly using a sequential extraction (the Hedley method) that has been widely used to characterize P in manure or AMC. The maximum water-extractable magnesium (Mg) (WEMg_max) was significantly positively correlated with WEP_max (r = 0.854, P < 0.01). This suggests that WEP_max in the AMCs is affected by water-soluble magnesium compounds.     

Mitigating nitrous oxide emissions from a maize-cropping black soil in northeast China by a combination of reducing chemical N fertilizer application and applying manure in autumn

Abstract

Nitrous oxide (N₂O) emissions from agricultural soils, mainly caused by chemical nitrogen (N) fertilizer inputs, are major sources of N₂O in Chinese terrestrial ecosystems. Thus, attempts to reduce N₂O emissions from agricultural soils by optimizing N applications are receiving increasing attention. Further, organic fertilizers are being increasingly used in China to improve crop production/quality and prevent or reduce soil degradation. However, organic and chemical fertilizers are often both applied in spring in northeast China, which promotes N₂O emissions and may be sub-optimal. Therefore, we hypothesized that reducing applications of chemical fertilizer N and applying manure in autumn could be an effective strategy for mitigating N₂O emissions from cropped soils in the region. To test this hypothesis, we established a field trial to investigate the effects of different combinations of chemical N fertilizer applications and animal manure in autumn on both N₂O emissions and maize (Zea mays L.) grain yields in northeast China. The treatments, expressed as NxMy (where Nx and My denote the total amounts of chemical fertilizer nitrogen (N) and manure (M) applied in kg N ha^?1 and m³ M ha^?1, respectively), were N₀M₀, N₂₃₀M₀, N₂₇₀M₁₂, N₂₃₀M₁₅, N₃₂₀M₁₈ in 2010 and N₀M₀, N₂₃₀M₀, N₂₀₀M₁₂, N₂₀₀M₁₅, N₂₈₀M₁₈ in 2011. Measurements of the resulting N₂O emissions showed that pulse fluxes occurred after each chemical N fertilizer application, but not after manure inputs in autumn or during soil-thawing periods in the following spring. Emission factors for the chemical fertilizer N were on average 1.07% (1.00?1.10%) and 1.14% (0.49?1.83%) in 2010 and 2011, respectively. Furthermore, by comparing the nine pairs of fertilization treatments, the relative increase in cumulative nitrous oxide-nitrogen (N₂O-N) emissions was found to be proportional to the relative increase in urea application, but independent of the amount of autumn-applied manure. These findings imply that N₂O emissions from fertilized agricultural soils in northeast China could be mitigated by supplying manure in the autumn and reducing the total amount of chemical N fertilizer applied in the following year. Although no significant difference in maize grain yield was found among the fertilization treatments, the grain yield-scaled N₂O emissions for the treatments with a lower chemical N application (e.g., N₂₃₀M₁₅ and N₂₀₀M₁₅ treatments) were significantly lower than those with a higher chemical N application (e.g., N₃₂₀M₁₈ and N₂₈₀M₁₈ treatments). Meanwhile, under the condition of the same application amount of chemical fertilizer N, the grain yield-scaled N₂O emission decreased with the increase of manure application rate. Thus, the results support the hypothesis that combining reductions in chemical N fertilizer and applying manure in autumn could be an effective strategy for mitigating N₂O emissions from N-fertilized soils in northeast China.     

Carbon and nitrogen mineralization and ammonia volatilization from fresh,aerobically and anaerobically treated pig manure during incubation with soil

Summary We studied the decomposition of aerobically and anaerobically treated pig manure during a 2-month incubation with soil. The manure samples had not been in contact with straw or with animal urine. The aerobically decomposed manure proved to be the most stable (23% C mineralization), followed by fresh (75%) and anaerobically treated manure (105%, priming effect). The course of mineralization fitted combined first- and zeroorder kinetics. In the anaerobically treated manure, 76% of NH ₄ ⁺ -N was immobilized during the initial incubation phase, followed by a slow linear mineralization. In the aerobically treated manure there was a slow linear mineralization after 5 days, and in the fresh material, a slightly faster linear mineralization after 6 days. Total mineralized N was very similar after 2 months (12%) in all treatments. Total NH₃ losses were highest from the anaerobically treated manure (14%), reflecting a higher NH ₄ ⁺ content with N mineralization following first-order kinetics. Relating NH₃ losses to the initial NH ₄ ⁺ content showed that all NH₃ in the aerobically treated manure was volatilized, whereas only 28% was volatilized from the fresh and the anaerobically treated manure. Present address: Department of Soil Science, Rothamsted Experimental Station, Harpenden Herts, AL5 2JQ, UK     

Comparison of biological and chemical methods to predict nitrogen mineralization in animal wastes

Summary Biological and chemical methods to predict the level of plant-available N in animal manure were investigated under laboratory and growth-chamber conditions. Two biological methods (maize cultivation in pots and incubation of soil-waste mixtures) and four chemical methods (N extraction by autoclaving, 0.5 N KMnO₄, pepsin, and 6 N HCl) were compared for their accuracy in determining the availability of N in 10 samples of animal manure applied to soil. The autoclaving, permanganate, and pepsin methods were able to predict N availability in this group of wastes. Total N mineralized in a soil amended with different samples of animal manure ranged from 0 to 311 mg N kg^-1 soil. Expressed as a percentage of organic N added to the soil, mineralized N range from 0 to 39%. The poultry manure samples gave higher mineralization rates than the other types of manure tested. In general, mineralized N became immobilized during the incubation process, except for the second poultry manure sample, which showed an initially rapid then a a slow release of mineral N, and pig manure sample 2, which showed a slow initial rate, followed by a rapid increase, and then a slow rate of N release. The first-order exponential model used was able to describe the pattern of N mineralization in pig manure sample 2, poultry manure sample 2 but not the other samples.     

Nutrient cycling and greenhouse gas emissions from soil amended with biochar-manure mixtures

Integrating biochar into cattle diets has recently emerged as a potential management practice for improving on-farm productivity.Yet,information concerning the cycling of biochar-manure mixtures is scarce.A 70-d incubation experiment was conducted within two surface(0–15 cm)Mollisols with contrasting textures,i.e.,sandy clay loam(Raymond)and clayey(Lethbridge),to evaluate the effects of biochar(3 Mg ha^-1)on cumulative greenhouse gas(GHG)emissions and related fertility attributes in the presence or absence of cattle manure(120 Mg ha^-1).Five treatments were included:i)non-amended soil(control,CK),ii)soil amended with pinewood biochar(B),iii)soil amended with beef cattle manure(M)(manure from cattle on a control diet),iv)soil amended with biochar-manure(BM)(manure from cattle on a control diet,with pinewood biochar added at 20 g kg^-1of diet dry matter),and v)soil amended with B and M at the aforementioned rates(B+M).A total of 40 soil columns were prepared and incubated at 21℃and 60%–80%water-holding capacity.On average,total CO₂fluxes increased by 2.2-and 3.8-fold under manure treatments(i.e.,M,BM,and B+M),within Raymond and Lethbridge soils,respectively,relative to CK and B.Similarly,total CH4 fluxes were the highest(P<0.05)in Raymond soil under B+M and BM relative to CK and B,and in Lethbridge soil under M and BM relative to CK and B.In Lethbridge soil,application of BM increased cumulative N₂O emissions by 1.8-fold relative to CK.After 70-d incubation,amendment with BM increased(P<0.05)PO_4-P and NO_3-N+NH_4-N availability in Raymond and Lethbridge soils compared with B.A similar pattern was observed for water-extractable organic carbon in both soils,with BM augmenting(P<0.05)the occurrence of labile carbon over CK and B.It can be concluded that biochar,manure,and/or biochar-manure have contrasting short-term effects on the biogeochemistry of Mollisols.At relatively low application rates,biochar does not necessarily counterbalance manure-derived inputs.Although BM did not mitigate the flux of GHGs over M,biochar-manure has the potential to recycle soil nutrients in semiarid drylands.     

Effects of soil-cation composition on reactions of four herbicides in a candler fine sand

Sorption, persistence and transport of herbicides in soils depend on the relative saturation of soils with cations from various soil amendments. Current research was conducted to study the effect of preequilibration of a Candler fine sand (Hyperthermic uncoated typic Quartzipsamments; 0–30 cm depth) with AlCl₃, CaCl₂, CuCl₂, FeCl₃, or KCl salt solutions on sorption in bromacil, simazine, norflurazon, and diuron herbicides commonly used in Florida citrus groves. Preequilibration of the soil with either FeCl₃, or AlCl₃ significantly decreased the sorption and therefore increased internal leaching potential, of all four herbicides as compared to their sorption in untreated soil. This decrease in sorption was much greater for bromacil and simazine (24 to 35%) than for norflurazon and diuron (7 to 8%). The desorption of bromacil and diuron in 1M NH₄OAc was also significantly lower in soils preequilibrated with FeCl₃ or AlCl₃ than the untreated soil. However, the reverse was true in the case of simazine and norflurazon. Preequilibration of the soil with CuCl₂, KCl, and CaCl₂ resulted in a significant decrease in sorption of norflurazon, diuron, and simazine but did not affect bromacil sorption. Accordingly, the species of adsorbed cation had varying effects on the sorption/desorption of each of the herbicides and varied their leaching potential.