不同处理池塘底泥氮矿化机制及有机氮组分矿化特征研究

采用Warning等的淹水培养法,研究了不同处理池塘底泥氮素的矿化特征,并对可矿化氮进行一级动力学方程模拟;采用Bremner法测定了底泥培养前后各有机氮组分含量,并通过通径分析确定了可矿化氮与各有机氮组分之间的关系。研究结果表明,采用不同处理组的底泥氮矿化的强度和容量都小于对照组,其中加入沸石的矿化容量最小,强度也最低,其次是加入微生物的处理,再次是加入脲酶抑制剂的处理;上覆水中氨态氮主要来自底泥酸解氮的矿化,其中氨基酸态氮矿化最大,酰胺态氮和氨基糖态氮次之,水解未知态氮降低最小;通径分析结果表明,在酸解氮中,酸解未知态氮与可矿化氮不相关,而氨基酸态氮、铵态氮、氨基糖态氮和未知态氮与可矿化氮的直接通径系数较大,说明这几种形态氮对可矿化氮皆有贡献。酰胺态氮对可矿化氮有很高的通径系数,表明了它对上覆水氨态氮的贡献最大。     

田间条件下氮的矿化及硝态氮淋溶研究

采用SRC（Soil-Resin-Core）装置，研究了重庆市主要土壤类型的氮矿化差异以及与硝态氮淋溶的关系。研究结果表明，微酸性紫色土（菜地）的氮索矿化量、硝态氮淋失量和有效氮的变幅均较大，而其它两种坡耕地变化的氮素矿化景和硝态氮的淋失量变幅均较小。相关分析表明：在微酸性紫色土中，影响硝态氮淋失的主要因素是矿化量，且二者呈显著正相关；而其它两种坡耕地土壤的矿化量与硝态氮淋失量不表现相关性。这就表明不同土壤矿化、硝态氮淋失的情况有差异。     

黄土区几种土壤培养过程中可溶性有机氮的变化及其与土壤矿化氮的关系

研究了黄土高原12种土壤(农地和林地)35 d好气培养过程中可溶性有机氮(SON)含量及其占可溶性全氮(TSN)的比例,以及SON与土壤矿化氮间的关系。结果表明,随着培养过程的进行,不同类型土壤SON的含量均呈明显增加;土壤SON占TSN的比例在培养的前3 d内明显下降,随后这一比例基本保持在24%左右。根据总可溶性氮确定的供试土壤氮素矿化势No平均为45.8 mg/kg,较由矿化的无机氮确定的土壤氮素矿化势No(平均36.5 mg/kg)高约1/4左右;培养过程中土壤SON含量与利用无机氮拟合得到的土壤氮素矿化势No间的相关性未达显著水平。研究表明,评价土壤氮素矿化特性时仅仅测定矿化的无机氮数量,可能会低估土壤氮素矿化潜力和氮素损失的数量和效应。     

Nitrogen Mineralization in Soils Related to Initial Extractable Organic Nitrogen: Effect of Temperature and Time

An important source of nitrogen (N) for crops is mineralization of soil organic matter during the growing season. Awareness is growing that dissolved organic nitrogen (DON) plays an important role in mineralization and plant uptake. We studied the influence of temperature and time on extractable organic nitrogen (EON) levels, which is a measure of DON, and their relationship with N mineralization. Aerobic incubation experiments were conducted in the laboratory for five soils at different temperatures (4 20, and 30 °C) and different time intervals with optimal water content (60% of its water-holding capacity). Net N mineralization ranged between 14 and 155 mg kg^–1 within 84 days and was correlated with the initial amount of EON. Net N mineralization among the soils, time, and incubation temperatures was linearly related to the square root of time multiplied by temperature, with mineralization rate k being independent of time and temperature. Because initial EON values were also related to these kvalues, we were able to describe the net N mineralization at different temperatures based on an analysis of initial EON. Preliminary validation with results from pot experiments in the literature suggests that the approach is promising, although the proposed model needs to be calibrated with more soils.     

不同培肥措施对采煤塌陷区复垦土壤氮素矿化的影响

为揭示不同培肥措施对采煤塌陷区复垦土壤氮素矿化特征,采用间歇淋洗好气培养法,研究了不施肥(CK)、单施化肥(CF)、单施有机肥(M)、化肥配施有机肥(MCF)和化肥配施生物有机肥(MCFB)5种培肥措施对复垦4年和8年土壤矿质态氮和可溶性有机氮变化及氮素矿化特征的影响。结果表明:间歇淋洗好气培养过程中,复垦8年土壤累积NO_3~-—N产生量较4年增加2.63%~26.83%,NH_4~+—N累积产生量增加12.50%~32.14%,可溶性有机氮(SON)累积产生量在CF和M处理下减少31.59%~62.50%,其他处理增加3.44%~34.69%。同一复垦年限下NO_3~-—N、NH_4~+—N和SON累积产生量均以MCFB最高。从矿化参数来看,5种培肥措施土壤矿化势(N_0)均表现为复垦8年高于复垦4年土壤,增加幅度为MCFB(26.9%)CK(15.9%)CF(15.0%)M(12.7%)MCF(4.8%);CK和CF处理下潜在可矿化有机氮(N_0/N)随复垦年限增加而减少,减少率分别为9.4%和13.8%,其余3种培肥措施N_0/N呈增加趋势,增加率表现为MCF(13.2%)MCFB(7.5%)M(2.8%);MCF处理下矿化率(N_t/N)随复垦年限增加而增加,增加率为13.2%,其余4种培肥措施的矿化率(N_t/N)均表现为复垦8年低于复垦4年土壤,减少幅度为CF(12.1%)CK(9.4%)MCFB(7.5%)M(2.7%)。不同处理间N_0、N_0/N和N_t/N值则均以8年复垦土壤的MCFB处理最高。综合来看,经过连续8年复垦,化肥配施生物有机肥较其他培肥措施更大程度上提高了各项矿化参数值,但随着复垦年限的增加,以化肥配施有机肥处理的N_0、N_0/N的增加幅度最大,以化肥配施生物有机肥处理的N_t/N减少率最低,长期单施化肥有降低潜在可矿化有机氮量(N_0/N)的趋势。     

Nitrogen Mineralization and Nitrification in Two Soils with Different pH Levels

ABSTRACT

Soil pH is one of the properties that mostly influences nitrification rates, and can be used as a tool for controlling this process, seen that depending on its extent it may lead to nitrogen (N) losses and subsequent contaminations. The aims of this study were to evaluate mineralization and nitrification of two soils at different pH levels. The experimental design was factorial with two factors and three replicates, with the first factor referring to two samples of red latosols, one eutrophic (LV1) and the other dystrophic (LV2), and the second factor was soil’s pH, at six levels: 4.0, 4.5, 5.0, 5.5, 6.0, and 6.5. Samples were incubated for 70 days in laboratory conditions. Both nitrate (N-NO₃) and mineral N contents were determined and adjusted to growth models. The eutrophic soil presented higher mineral N and N-NO₃, and the increase of pH levels led to increases of both inorganic N and N-NO₃contents. Increases in pH levels caused N-NO₃levels to increase in both soils, however this occurrence happened because it increased the amount of mineralized N in the soil, seen that in all pH ranges in both soils practically all mineral N was in the form of N-NO₃.     

Sensitivity of Nitrogen Mineralization Indicators to Crop and Soil Management

Abstract

Soil nitrogen (N) mineralization indicators are useful only if they are sensitive to management practices. The precision of measurement and the sensitivity of the following indicators to crop sequence, tillage, and liming effects were compared: (i) mineral N production during a 24‐day incubation under aerobic conditions, (ii) ammonium (NH₄)‐N production under waterlogged conditions, (iii and iv) hot potassium chloride (KCl)–extractable and hydrolyzable NH₄‐N (the latter obtained by subtracting initial NH₄‐N from extracted NH₄‐N), and (v) protease activity. The coefficients of variation decreased in this order: protease activity>KCl‐hydrolyzable NH₄‐N>aerobic incubation>KCl‐extractable NH₄‐N=anaerobic incubation. Most of the test results obtained using the indicators were correlated with each other. Mineralizable N measured by aerobic and anaerobic incubation was sensitive to tillage, liming, and crop sequences, especially when using soil 5‐cm deep. Hot KCl‐extractable NH₄‐N was influenced by tillage but not liming, and less sensitive than the incubation procedures to crop sequence. The protease assay produced no significant test. It was concluded that anaerobic incubation can provide a relatively sensitive assessment of management effects on soil mineralizable N.     

Nationally Coordinated Evaluation of Soil Nitrogen Mineralization Rate using a Standardized Aerobic Incubation Protocol

Abstract

Aerobic incubation methods have been widely used to assess soil nitrogen (N) mineralization, but standardized protocols are lacking. A single silt loam soil (Catlin silt loam; fine‐silty, mixed, superactive, mesic, Oxyaquic Arguidoll) was subjected to aerobic incubation at six USDA‐ARS locations using a standardized protocol. Incubations were conducted at multiple temperatures, which were combined based on degree days (DD). Soil water was maintained at 60% water‐filled pore space (WFPS; constant) or allowed to fluctuate between 60 and 30% WFPS (cycle). Soil subsamples were removed periodically and extracted in 2 M potassium chloride (KCl); nitrate (NO₃) and ammonium (NH₄) concentrations in extracts were determined colorimetrically. For each location, the rate of soil organic‐matter N (SOMN) mineralization was estimated by regressing soil inorganic N (N_i) concentration on DD, using a linear (zero‐order) model. When all data were included, the mineralization rate from four datasets was not statistically different, with a rate equivalent to 0.5 mg N kg^?1 soil day^?1. Soil incubated at two locations exhibited significantly higher SOMN mineralization rates. To assess whether this may have been due to pre‐incubation conditions, time‐zero data were excluded and regression analysis was conducted again. Using this data subset, SOMN mineralization from five (of six) datasets was not significantly different. Fluctuating soil water reduced N‐mineralization rate at two (of four) locations by an average of 50%; fluctuating soil water content also substantially increased variability. This composite dataset demonstrates that standardization of aerobic incubation methodology is possible.     

Nitrogen doses on physiological attributes and yield of sugarcane grown under subsurface drip fertigation

Soil hydric availability and nitrogen fertilization are important environmental factors that influence sugarcane production. In the present study, the physiological attributes SPAD index, maximum photochemical efficiency of photosystem II (F_v/F_m), leaf area index (LAI), chlorophyll and carotenoid content, and sugarcane productivity were assessed under different nitrogen doses (0, 50, 100, 150, and 200 kg N ha^?1) applied in the form of urea via subsurface drip fertigation. The physiological attributes were determined 38, 121, 208, 291, and 381 days after the third harvest (DAH), and stalk and sugar productivity at 381 DAH. The 100 kg N ha^?1 dose has produced better results for the sugarcane physiological attributes. Increasing doses of nitrogen applied via subsurface drip fertigation increased the productivity of stalks and sugar considerably.     

Mineralization of Nitrogen in Soils Amended with Dairy Manure as Affected by Wetting/Drying Cycles

Abstract

Interest in manure management and its effects on nitrogen (N) mineralization has increased in recent years. The focus of this research was to investigate the N‐mineralization rates of different soil types in Coastal Plain soils and compare them to a soil from Illinois. Soils with and without dairy composted manure addition were subjected to different wetting/drying cycles [constant moisture at 60% water‐filled pore space (WFPS) and cycling moisture from 60 to 30% WFPS] under laboratory conditions at three different temperatures (11°C, 18°C, and 25°C). Samples were collected from three different soil types: Catlin (Mollisols), Bama (Ultisols), and Goldsboro (Utilsols). Soil chemical and physical properties were determined to help assess variations in N-mineralization rates. Addition of composted manure greatly impacted the amount of N mineralized. The amount of manure‐derived organic N mineralized to inorganic forms was mainly attributed to the soil series, with the Catlin (silt loam) producing the most inorganic N followed by the Goldsboro (loam) and then Bama (sandy loam). This was probably due to soil texture and the native climatic conditions of the soil. No significant differences were observed between the constant and cycling moisture regimens, suggesting that the imposed drying cycle may not have been sufficient to desiccate microbial cells and cause a flush in N mineralization upon rewetting. Nitrogen mineralization responded greatly to the influence of temperature, with the greatest N mineralization occurring at 25°C. The information acquired from this study may aid in predicting the impact of manure application to help increase N‐use efficiency when applied under different conditions (e.g., climate season) and soil types.     

祁连山东段青海云杉林区土壤氮矿化与土壤因子的相关性

以祁连山东段青海云杉(Picea crassifolia)林分布带土壤为研究对象,采用顶盖埋管的野外取样法和室内分析法,对海拔梯度上土壤铵态氮(NH+4-N)、硝态氮(NO-3-N)净矿化速率、氮净矿化量和净矿化速率进行测定分析,旨在探讨土壤净氮矿化量与气温降水和土壤理化性质的相关关系,以期建立环境变量与土壤氮矿化量和矿化速率模型,进而提高祁连山青海云杉林生产力及水源涵养能力。其结果表明:(1)土壤硝态氮、铵态氮净矿化速率、土壤净氮矿化量和矿化速率随海拔的升高差异性均极显著;土壤氮净矿化量和矿化速率随海拔梯度的升高呈W形变化,与硝态氮净矿化速率随海拔升高的变化规律一致,与铵态氮净矿化速率变化规律相反;在海拔2 800m处,硝态氮净矿化速率、土壤净氮矿化量和矿化速率均达到最大值,为0.372,160.3,0.44 mg/(kg·d),铵态氮净矿化速率出现最低值0.067 mg/(kg·d);在海拔2 900m处出现最低值,为0.155,94.7,0.26mg/(kg·d),在海拔3 100m处,铵态氮的净矿化速率出现最大值0.13mg/(kg·d);(2)回归分析表明,土壤净氮矿化量与年均气温呈极显著负相关(P0.01),R2=0.717 3;与年降水量呈极显著正相关(P0.01),R2=0.383 5;得出气候变化对土壤净氮矿化量的影响程度为:年均气温年降水量;(3)回归分析表明,土壤氮净矿化量与土壤全氮、有机质、含水量、pH值呈极显著正相关(P0.01),其R2依次为0.910 1,0.906 0,0.842 8,0.797 9;与土壤容重呈极显著负相关(P0.01),其R2为0.222 4;由R2值大小可知土壤养分对土壤净氮矿化量的影响程度为:土壤全氮土壤有机质土壤含水量土壤pH土壤容重。     

添加凋落物对杨树人工林土壤氮、磷矿化的影响初探

采用室内培养方法,在30℃和土壤含水量为田间持水量的70％的条件下研究杨树人工林的枯叶或枯枝、枯地被植物、杨树根系以及混合凋落物的添加对土壤氮和磷矿化的影响.结果表明:(1)培养42 d后,不同处理间的土壤有效磷含量存在一定差异,呈现枯叶+土＞枯地被植物+土＞混合凋落物+土＞根+土＞枯枝+土＞对照的趋势;(2)不同处理间的土壤铵态氮含量差异比较小;(3)各种处理的硝态氮含量占总无机氮的78％以上;(4)在培养初期,除添加枯枝处理外,添加其他凋落物处理的土壤硝态氮和总无机氮含量明显下降,后期逐渐升高;(5)土壤无机氮、磷含量及其矿化速率与土壤和凋落物的性质密切相关.     

秸秆和生物质炭添加对陇中黄土高原旱作农田土壤氮素矿化的影响

通过采集2014年设置于甘肃省定西市李家堡镇的不同碳源配施氮素田间定位试验土壤进行120天的室内培养试验,利用Stanford间歇淋洗培养法研究了无碳素和氮素添加(N0)、只施氮素(N100)、秸秆配施氮素(SN100)和生物质炭配施氮素(BN100)4种施肥方式对陇中黄土高原旱作农田土壤氮素矿化的影响.结果表明:秸秆...     

Nitrogen Fractions in Arable Soils in Relation to Nitrogen Mineralization and Plant Uptake

Abstract

Nitrogen (N) as a major constituent of all plants is one of the most important nutrients. Minimizing input of mineral nitrogen fertilizer is needed to avoid harm to the environment. Optimal input of mineral nitrogen should take the nitrogen supply of the soil into account. Many different soil tests have been proposed for determining soil nitrogen availability. In this article we present a new approach that is based on the measurement of nitrate, ammonium, and dissolved organic nitrogen (DON) in a 0.01 M CaCl₂ soil extract. Eighteen agricultural soils, differing widely in the availability of nitrogen were used, fertilized and unfertilized. It is shown that the nitrogen uptake by maize plants (Zea Mays L.) in both “N‐fertilized” and “N‐unfertilized” soils as measured in a pot experiment can be described with a simple model using the measured nitrogen fractions in the extract. The main source of nitrogen uptake by the plants is the mineralized organic nitrogen during the growing period. It is shown that the initial measured DON fraction is a good indicator of the nitrogen mineralized during plant growth.     

Nitrogen Mineralization as Influenced by Different Organic Manures in an Inceptisol in the Foothill Himalayas

Nitrogen-use efficiency can be enhanced through an understanding of the nitrogen (N) mineralization behavior of organic sources. An incubation study was conducted to assess the impact of organic manures on N mineralization. The manures, farmyard manure (FYM), Leucaena leucocephala, and poultry manure, were applied to the soil alone or along with urea. There was a rapid increase in the amount of mineral N released with a peak appearing either at 14 days (+urea treatments) or 21 days (manure only) of aerobic incubation. Thereafter the net N mineralized decreased gradually and levelled off beyond day 56. Overall the cumulative net N mineralized after 98 days of incubation was in the order urea > Leucaena + urea > poultry manure + urea _> FYM + urea > Leucaena > poultry manure > FYM > zero N. The potentially mineralizable N (N₀) was lower in treatments where urea was not applied.     

Nutrient Mineralization from Nitrogen- and Phosphorus-Enriched Poultry Manure Compost in an Ultisol

The combination of inorganic fertilizers and compost is a technique aimed at improving crop growth and maintaining soil health. Understanding the rate of nutrient release from enriched compost is important for effective nutrient management. A laboratory incubation study was conducted for 112 days to study the nutrient mineralization pattern of poultry manure compost enriched with inorganic nitrogen (N) and phosphorus (P) fertilizer nutrients in an Ultisol. Compost applied at the rate of either 5 or 10 g kg^?1 was blended with N (50 kg N ha^?1) and P (30 kg P ha^?1). Carbon dioxide evolution and N and P mineralization were measured fortnightly. The bacterial and fungal populations were determined at the mid and end of the experiment. The combination of compost and inorganic N and P increased carbon (C) and P mineralization by 4?8% and 56?289%, respectively, over the application of either compost or inorganic N and P. However, P addition influenced the amount of C mineralized. Inorganic N and P, on the other hand, were better at increasing N mineralization than compost blended with inorganic N and P over a short time. The addition of compost stimulated bacterial and actinomycete populations, while fungal populations were unaffected. Actinomycetes and bacteria had similar and higher relationship trend with C (R² = 0.24) and P (R² = 0.47) mineralization and were key determinants in nutrient mineralization from compost in this Ultisol. Integrating compost with inorganic fertilizers improves nutrient availability through the growth and activities of beneficial microorganisms.     

横垄覆膜对丹江口库区土壤净氮矿化的影响

以丹江口库区五龙池小流域玉米黄棕壤为例,利用原位矿化试验,通过与横垄无覆膜土壤比较,研究横垄覆膜对土壤净氮矿化的影响。结果表明:玉米苗期中期和拔节期前期,横垄覆膜土壤净氮矿化量与无覆膜土壤相比分别降低7.8%~57.0%和2.2%~52.8%;玉米拔节期后期、抽穗期和成熟期,横垄覆膜土壤净氮矿化量比无覆膜土壤分别提高352.9%~703.3%,52.5%~311.0%和15.2%~334.8%。横垄覆膜土壤净氮矿化量在玉米苗期、拔节期、抽穗期和成熟期与土壤含水量、温度和全氮间均存在较强度关联关系(0.6灰色关联度≤0.8)。逐步回归分析表明,横垄覆膜土壤净氮矿化量在玉米苗期与土壤温度间呈最优线性关系(F=7.205,P=0.023);在玉米拔节期与土壤含水量和温度间呈最优线性关系(F=36.861,P=0.001);在玉米成熟期与土壤含水量间呈最优线性关系(F=42.438,P=0.007)。     

化肥减量配施菌肥对氮素矿化利用的影响

为实现海河流域农田增效减负和氮素利用率的提高,通过设置不同氮磷化肥减量配施菌肥与有机肥处理,即对照(N 200 kg·hm^-2,P₂O₅120 kg·hm^-2,CK)、B₁N₂P₂(菌肥17.5 kg·hm^-2,N、P₂O₅均较CK减量25%)、B₁ON₁P₁(菌肥1为7.5 kg·hm^-2,有机肥为3 t·hm^-2, N、P₂O₅均较CK减量50%)、B₂N₂P₂(菌肥2为7.5 kg·hm^-2,N、P₂O₅均较CK减量25%)、B₂ON₁P₁(菌肥2为7.5 kg·hm^-2,有机肥为3 t·hm^-2,N、P₂O₅均较CK减量50%)。研究夏玉米各生育期的土壤氮素矿化特征和利用情况以及夏玉米产量构成因素。结果表明,菌肥和有机肥配施显著增加了土壤氮矿化量,在拔节期和抽雄期尤为明显,B₁ON₁P₁的氮矿化量较B₁N₂P₂分别高出151.29%、120.09%,B₂ON₁P₁的氮矿化量较B₂N₂P₂分别高出56.28%和245.04%。菌肥与中量化肥组合能促进玉米增产,菌肥1和菌肥2较对照分别增产9.01%和7.94%,B₁N₂P₂的产量和穗粒数最高,产量达9 960.24 kg·hm^-2,穗粒数较CK高出29.99%,B₂N₂P₂的千粒重较CK高出2.28%;菌肥的施用能明显减少玉米的秃尖长度,以B₂N₂P₂的降幅最大,较CK减少了73.29%。菌肥1能提高玉米氮素生理利用率和氮素收获指数,B₁N₂P₂的吸氮总量明显高于B₁ON₁P₁,这与产量构成因素是一致的。综上,化肥减量25%并配施菌肥能维持稳定的氮矿化量并提高产量及其构成因素。本研究为海河流域农田氮素科学管理和减少因过量施肥而造成的农业面源污染提供了理论依据。     

不同生物炭对安徽宣城旱地红壤氮矿化的影响

采用连续间隙淋洗培养法,研究了竹炭、烟草秸秆炭及棉花秸秆炭对安徽宣城旱地红壤氮素矿化作用的影响。结果表明:3种生物炭均可提高土壤p H,但p H增长幅度与生物炭用量相关,最高可增加2个单位;不同用量的生物炭添加都会导致土壤氮素硝化速率及矿化速率的降低,竹炭、烟草秸秆炭及棉花秸秆炭分别使硝化速率最大降幅达49.2%、72.3%与69.2%,矿化速率最大降幅达33.7%、61.9%与61.1%。因此,生物炭实际施用需作谨慎的评估,优化其使用方法。     

Net Nitrogen and Sulfur Mineralization in Mountainous Soils Amended with Indigenous Plant Residues

Abstract

Mineralization of nitrogen (N) and sulfur (S) were examined over a 31‐week incubation period under aerobic conditions in 13 soils selected from the mountainous district of Pertouli, central Greece. The main native plant species are turf, forage crops, forest trees, herbs, and shrubs. Net mineralization and immobilization of N and S by indigenous plants were estimated. Most soils are acidic in this xeric, mesic climatic regime, and organic carbon (C), organic nitrogen (N), and sulfur (S) appreciably varied in soils and plant species. The cumulative net mineralization of N is much higher in comparison to the amount of mineralized S. Release of N is curvilinear with time and associated with a declining mineralization in the later stages of the incubation. Close relationships exist between soil organic S and N and between organic C and N, indicating that these elements are mainly bound in the organic matter. The cumulative net mineralization from soils varies greatly and ranges between 36.6 and 212.8 (average 104.8) mg/kg for N and between 21.4 and 45.2 (average 31.8) mg/kg for S. Immobilization occurs in most soils amended with indigenous plant residues, with the amount of immobilized N varying between 14.8 and 49.5 mg/kg and that of immobilized S ranging from 2.6 to 30.7 mg/kg. However, the estimated rates of N and S mineralization are not negligible and can be taken into account as potential sources in the management of the upland soils.