利用方式和土壤肥力对土壤团聚体和养分的影响

The size distribution of water-stable aggregates and the variability of organic C, N and P contents over aggregate size fractions were studied for orchard, upland, paddy, and grassland soils with high, medium, and low fertility levels. The results showed that > 5 mm aggregates in the cultivated upland and paddy soils were 44.0% and 32.0%, respectively, less than those in the un-tilled orchard soil. Organic C and soil N in different size aggregate fractions in orchard soil with high fertility were significantly higher than those of other land uses. However, the contents of soil P in different size aggregates were significantly greater in the paddy soil as compared to the other land uses. Soil organic C, N and P contents were higher in larger aggregates than those in smaller ones. The amount of water-stable aggregates was positively correlated to their contribution to soil organic C, N and P. For orchard and grassland soils, the > 5 mm aggregates made the greatest contribution to soil nutrients, while for upland soil, the 0.25-0.053 mm aggregates contributed the most to soil nutrients. Therefore, the land use with minimum disturbance was beneficial for the formation of a better soil structure. The dominant soil aggregates in different land use types determined the distribution of soil nutrients. Utilization efficiency of soil P could be improved by converting other land uses to the paddy soil.     

采样密度对中国红壤地区土壤有机碳空间变异研究的影响效应

Spatial variability of soil organic carbon (SOC) of different land use patterns and soil types was examined in a county-wide red soil region of South China,using six sampling densities,14,34,68,130,255,and 525 samples designed by the method of grid sampling in 6 different grid sizes,labeled as D14,D34,D68,D130,D255,and D525,respectively.The results showed that the coefficients of variation (CVs) of SOC decreased gradually from 62.8% to 47.4% with the increase in soil sampling densities.The SOC CVs in the paddy field change slightly from 30.8% to 28.7%,while those of the dry farmland and forest land decreased remarkably from 58.1% to 48.7% and from 99.3% to 64.4%,respectively.The SOC CVs of the paddy soil change slightly,while those of red soil decreased remarkably from 82.8% to 63.9%.About 604,500,and 353 (P < 0.05) samples would be needed a number of years later if the SOC change was supposedly 1.52 g kg-1,based on the CVs of SOC acquired from the present sampling densities of D14,D68,and D525,respectively.Moreover,based on the same SOC change and the present time CVs at D255,the ratio of samples needed for paddy field,dry farmland,and forest land should be 1:0.81:3.33,while the actual corresponding ratio in an equal interval grid sampling was 1:0.74:0.46.These indicated that the sampling density had important effect on the detection of SOC variability in the county-wide region,the equal interval grid sampling was not efficient enough,and the respective CV of each land use or soil type should be fully considered when determining the sampling number in the future.     

水旱轮作与林地利用方式对中国滨海滩涂土壤微生物生物量碳的影响

Rice-wheat rotation and poplar afforestation are two typical land use types in the coastal reclaimed flatlands of eastern China.This study investigated two rice-wheat rotation lands(one reclaimed from 1995 to 2004 and cultivated since 2005, RW1, and the other reclaimed from 1975 to 1995 and cultivated since 1996, RW2) and a poplar woodland(reclaimed from 1995 to 2004 and planted in2004, PW1) to determine the effects of land use types and years of cultivation on soil microbial biomass and mineralizable carbon(C) in this coastal salt-affected region. The results showed that the soil in PW1 remained highly salinized, whereas desalinization was observed in RW1. The total organic C(TOC) in the top soil of PW1 and RW1 did not show significant differences, whereas at a soil depth of 20–30 cm, the TOC of RW1 was approximately 40%–67% higher than that of PW1. The TOC of 0–30-cm soil in RW2 was approximately 37% higher than that in RW1. Microbial biomass C(MBC) and mineralizable C(MNC) exhibited the trend of RW2 RW1 PW1. Sufficient nutrition with more abundant C substrates resulted in higher MBC and MNC, and soil respiration rates were negatively correlated with C/N in RW1 and RW2. Nutrient deficiency and high salinity played key roles in limiting MBC in PW1. These suggested that rice-wheat rotation was more beneficial than poplar afforestation for C accumulation and microbial biomass growth in the coastal salt-affected soils.     

中国滇池流域土地利用方式对土壤侵蚀和养分状况的影响

Soil erosion and loss of soil nutrients have been a crucial environment threat in Southwest China. The land use and its impact on soil qualities continue to be highlighted. The present study was conducted to compare soil erosion under four land use types(i.e.,forestland, abandoned farmland, tillage, and grassland) and their effects on soil organic carbon(SOC), total nitrogen(TN) and total phosphorus(TP) in the Shuanglong catchment of the Dianchi Lake watershed, China. There were large variations in the erosion rate and the nutrient distributions across the four land use types. The erosion rates estimated by137 Cs averaged 2 133 t km-2year-1under tillage and abandoned farmland over the erosion rate of non-cultivated sites, and the grasslands showed a net deposition. For all sites, the nutrient contents basically decreased with the soil depth. Compared with tillage and abandoned farmland, grassland had the highest SOC and TN contents within 0–40 cm soil layer, followed by forestland. The significant correlations between137 Cs, SOC and TN were observed. The nutrient loss caused by erosion in tillage was the highest. These results suggested that grassland and forestland would be beneficial for SOC and TN sequestration over a long-term period because of their ability to reduce the loss of nutrients by soil erosion. Our study demonstrated that reduction of nutrient loss in the red soil area could be made through well-managed vegetation restoration measures.     

人类活动对太湖地区地表水水质的影响

Taihu Lake region is one of the most industrialized areas in China, and the surface water is progressively susceptible to anthropogenic pollution. The physicochemical parameters of surface water quality were determined at 20 sampling sites in Taihu Lake region, China in spring, summer, autumn, and winter seasons of 2005-2006 to assess the effect of human activities on the surface water quality. Principal component analysis (PCA) and cluster analysis (CA) were used to identify characteristics of the water quality in the studied water bodies. PCA extracted the first three principal components (PCs), explaining 80.84% of the total variance of the raw data. Especially, PC1 (38.91%) was associated with NH₄-N, total N, soluble reactive phosphorus, and total P. PC2 (22.70%) was characterized by NO₃-N and temperature. PC3 (19.23%) was mainly associated with pH and dissolved organic carbon. CA showed that streams were influenced by urban residential subsistence and livestock farming contributed significantly to PC1 throughout the year. The streams influenced by farmland runoff contributed most to PC2 in spring and winter compared with other streams. PC3 was affected mainly by aquiculture in spring, rural residential subsistence in summer, and livestock farming in fall and winter seasons. Further analyses showed that farmlands contributed significantly to nitrogen pollution of Taihu Lake, while urban residential subsistence and livestock farming also polluted water quality of Taihu Lake in rainy season. The results would be helpful for the authorities to take sound actions for an effective management of water quality in Taihu Lake region.     

酸雨对菜地系统氮素收支的影响

分别在酸沉降重污染区、轻污染区和对照区选择代表性的蔬菜样地,对土壤、蔬菜、降水、施肥、渗滤水等的氮素动态进行为时一年的定位、定时监测,研究了不同酸雨影响区氮素在菜地系统中的收支平衡。结果表明:在相同的种植条件下,由于酸雨影响了蔬菜的正常生长,致使酸雨影响区菜地系统中氮素收支失衡,酸沉降重污染区和轻污染区菜地系统中氮素I/O值分别为1.27和1.19;而对照区菜地系统中氮素I/O值为1.08,收支基本平衡。在酸沉降重污染区,降水输入系统的氮远大于轻污染区和对照区(约3~4倍),同时因酸雨危害,蔬菜产量明显低于对照区,仅为对照区产量的60%,使系统中通过作物收获的氮输出减少,结果导致大量氮滞留于土壤中并以硝态氮等形态淋失,给水环境带来了氮污染风险。     

农田氮素管理模式对洱海流域大蒜生长和氮素流失风险的影响

为探求能有效提高洱海流域土壤生产力并降低氮素流失风险的适宜氮素管理模式,采用田间试验方法,研究了5种氮素管理模式对大蒜农艺性状、产量与经济效益、氮素利用率、土壤硝态氮含量及氮素表观平衡的影响。结果表明,与习惯施肥处理相比,优化施肥结合免耕秸秆覆盖可提高大蒜产量7.9%,增加经济效益14.1%,氮肥利用率增加约20个百分点,达42.3%,降低0-30cm土壤无机氮残留44.3%;优化施肥结合秸秆翻埋和优化施肥处理的大蒜产量较习惯施肥处理无显著性差异,但经济效益分别增加5.7%和3.4%,氮肥利用率分别增加约11和13个百分点,分别为32.7%和34.5%,0-30cm土壤无机氮残留分别降低60.9%和41.1%;氮素调控处理产量较习惯施肥无显著性差异,经济效益降低3.2%,氮肥利用率提高18个百分点,为40.3%,0-30cm土壤无机氮残留降低53.0%;与习惯施肥处理相比,单施牛粪处理虽然可降低0-30cm土壤无机氮残留92.4%,但大蒜减产22.8%,经济效益降低19.1%。综合研究结果可知,有机无机配施结合免耕秸秆覆盖或秸秆翻埋是洱海流域氮素管理的优化模式,是保证作物产量、提高经济效益、降低环境风险的重要措施。     

中国洞庭湖区稻田土壤氮素淋溶损失的系统研究

A two-year lysimeter study was conducted to study the effects of different fertilizers and soils on nitrogen leaching loss in a double rice cropping system by considering three major types of paddy soils from the Dongting Lake area. The results showed that N concentration in the leachate did not differ significantly among the treatments of urea, controlled release N fertilizer and pig manure and that all these fertilizers produced higher total nitrogen (TN) concentrations in the leachate compared to the case where no fertilizer was applied. The TN leaching loss following urea treatment accounted for 2.28%, 0.66%, and 1.50% of the amount of N applied in the alluvial sandy loamy paddy soil (ASL), purple calcareous clayey paddy soil (PCC), and reddish-yellow loamy paddy soil (RYL), respectively. Higher TN loss was found to be correlated with the increased leachate volume in ASL compared with RYL, and the lowest TN loss was observed in the PCC, in which the lowest leachate volume and TN concentration were observed. Organic N and NH4+ -N were the major forms of N depleted through leachate, accounting for 56.8% and 39.7% of TN losses, respectively. Accordingly, soil-specific fertilization regimens are recommended; in particular, the maximum amount of fertilizer should be optimized for sandy soils with a high infiltration rate. To avoid a high N leaching loss from rice fields, organic N fertilizers such as urea or coated urea should primarily be used for surface topdressing or shallow-layer application and not for deep-layer application.     

15N标记的包膜尿素在华北平原渗滤系统中的回收和淋失

The effectiveness of polyolefin-coated urea (Meister-5 and Meister-10; CU) in a wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation system was studied in lysimeter plots located in the North China Plain for three consecutive maize- wheat-maize cropping seasons. An isotopic method was used to compare the fate of CU to that of non-coated urea (NCU), and N application rates of 0, 100, 150 and 225 kg N ha-1 were evaluated. The results showed that the nitrogen use effciency (15NUE) of CU was 13.3%–21.4% greater than that of NCU for the first crop. Alternatively, when the difference method was applied (apparent NUE), no significant variations were observed among treatments in all three seasons. Although inorganic N leached from the 1.3 m layer was less than 1% of the total applied N, unidentified losses of 15N (losses of 15N = 15N applied as fertilizer – 15N absorbed by crops – 15N remaining in the 0–0.2 m layer – 15N leached from the 1.3 m layer) in CU-treated plots were 24.2%–26.5% lower than those of NCU-treated plots. The nitrate concentration in the 0–1.3 m layer of CU plots at the end of the experiment was 53% lower than that of NCU-treated plots. Thus, CU increased crop N uptake from fertilizer and reduced unidentified losses of applied N, which can reduce the risk of groundwater pollution.     

蚯蚓活动对土壤氮素矿化的影响

通过室内培养试验和田间长期定位试验,探讨了蚯蚓活动对土壤矿质氮的影响。发现蚯蚓对NH4+-N、NO3--N,以及矿质总氮(NH4+-N+NO3--N)均有显著影响,且加速了土壤氮素矿化。小区试验中,在2001年稻季和2003年麦季,蚯蚓活动显著提高了NO3--N和矿质总氮(p<0.05*),但在其他时期,未有显著影响。室内培养试验中,蚯蚓活动明显加速了氮素矿化。尤其在未施用秸秆时,蚯蚓处理后的硝态氮和矿质总氮明显增加,且累积净矿化量和净矿化率也有显著提高。     

中国农田氮肥投入和生产效率

过去40年,中国氮肥用量增加、氮肥效率下降引起了国内外普遍关注,但中国不同作物氮肥用量及其利用效率缺乏大样本数据研究。本文通过农户调查及文献资料,对1970~2009年,尤其是从2000到2009年,中国主要农作物施氮量(化肥氮)、产量、氮效率(氮肥偏生产力)进行了研究。与2000~2003年相比,2008~2009年粮食、蔬菜、果树平均氮肥用量增加,单产增加,氮效率提高。粮食、蔬菜、果树氮肥用量分别增加26、36、107 kg/hm~2,产量分别增加1 280、5 722、18 802 kg/hm~2,氮效率分别增加2.2、6.6、25.2 kg/hm~2。东北、华北和长江中下游三大粮食作物主产区的氮效率都显著提高,而西北、西南和华南等地没有提高。与2000~2003年相比,2008~2009年中国平均氮效率的上升主要是因为单产大幅提高,而非氮肥用量下降。中国粮食作物单产较低,而氮肥用量高,未来在稳定氮肥投入的情况下继续提高单产是增效的主要途径。中国蔬菜和果树氮投入量太高,应该加强管理降低氮肥用量。     

土壤高残留氮条件下施氮对夏玉米氮素平衡、利用及产量的影响

土壤残留氮是不容忽视的土壤氮素资源.通过田间小区试验研究了土壤高残留氮下不同施氮量(0、80、160、240和320 kg/hm2)对夏玉米土壤硝态氮积累、氮素平衡、氮素利用及产量的影响,分析了夏玉米的经济效益.结果表明,土壤剖面硝态氮积累量随施氮量的增加而增加,且施氮处理硝态氮积累量显著高于不施氮处理;各施氮处理土壤硝态氮在0-60 cm土层含量最高,在0--180 cm剖面呈先减少后增加的变化趋势.不施氮处理夏玉米收获后土壤无机氮残留量高达378 kg/hm2,随施氮量的增加,无机氮残留和氮表观损失显著增加.作物吸氮量、氮表观损失量与总氮输入量呈显著正相关,总氮输入量每增加l kg作物吸氮量增加0.156 kg,而表观损失量增加0.369 kg,是作物吸氮量的2.4倍.高残留氮土壤应严格控制氮肥用量,以免造成氮素资源的大量浪费.夏玉米籽粒吸氮量随施氮量的增加呈增加的趋势,氮收获指数呈降低的趋势.氮肥农学效率、氮肥生理利用率、氮肥利用率和氮素利用率在施氮量80 kg/hm2时最高,随施氮量的增加降低;增施氮肥能降低高残留氮土壤中氮肥的增产效果和利用率.综合考虑产量、氮素利用和环境效应,N 80 kg/hm2是氮素高残留土壤上玉米的合理施氮量.     

Recent trends in nitrogen and phosphate use and balance on Japanese farmland

Abstract

We estimated recent trends in nitrogen (N) and phosphate (P₂O₅) application, crop production and surpluses on Japanese farmlands, and calculated the N and P₂O₅ and balances in kind in crop types for 2002. Overall, chemical N and P₂O₅ fertilizer application peaked in 1985 and then decreased. Crop N production was reduced after 1985 and crop P₂O₅ production was reduced after 1990. This lag in crop P₂O₅ decline may have resulted from the accumulation of P₂O₅ in farmland soils before 1990. Nitrogen and P₂O₅ balances in 2002 indicated large surpluses in vegetables and industrial crops, despite the reduction in chemical fertilizer application, although chemical fertilizer and manure application levels were still higher than in other crops. The reduction in chemical fertilizer and manure application eventually reduced the N and P₂O₅ surplus. Substitution of currently non-utilized livestock excreta in place of chemical fertilizers would be worthwhile.     

氮肥对吉林春玉米产量、农学效率和氮养分平衡的影响

为解决东北地区玉米合理施用氮肥问题,于2014年在吉林省中部地区通过田间试验,研究了不同施氮量(0、70、140、210、280 kg/hm2)对玉米产量、氮素吸收利用、土壤无机氮积累变化规律及氮素平衡的影响。结果表明,施氮量在70~210 kg/hm2范围内玉米产量随施氮量的增加而增加,当施氮量增加至280 kg/hm2产量下降,根据玉米产量(y)和施氮量(x)拟合得出线性加平台关系式:y=14.63x+8 734.11(R2=0.924**),得出最佳施氮量为184.0 kg/hm2。氮素利用率、农学利用率和偏生产力随施氮量的增加而下降;氮收获指数随施氮量的增加先增后降,以施氮量210 kg/hm2处理最高,为64.9%。土壤无机氮积累量在玉米整个生育期呈现先快速下降后小幅升高的趋势。玉米成熟期施氮处理各层土壤无机氮积累量均高于不施氮肥处理,且基本随施氮量的增加而增加。玉米收获后土壤无机氮残留量在施氮量70~210 kg/hm2范围内显著增加,施氮量增加至280 kg/hm2不再显著增加;氮表观损失量随施氮量的增加显著增加。玉米氮吸收量、土壤无机氮残留量和氮表观损失量与施氮量呈显著的正向相关性,玉米氮吸收量、土壤无机氮残留量和氮表观损失量分别占增加氮量的21.84%、41.19%和36.97%。综上所述,在本试验条件下,最佳施氮范围为184~210 kg/hm2。     

Recent approaches in nitrogen management for sustainable agricultural production and eco-safety

Among plant nutrients, nitrogen (N) is the most important. Its importance as a growth- and yield-determining nutrient has led to large and rapid increases in N application rates, but often with poor use efficiency. Nitrogen management requires special attention in its use so that the large losses can be minimized and the efficiency maximized. Site-specific nutrient management (SSNM) has been found especially useful to achieve the goals of improved productivity and higher N use efficiency (NUE). Leaf color charts and chlorophyll meters assist in the prediction of crop N needs for rice and wheat, leading to greater N-fertilizer efficiency at various yield levels. Crop simulation models can be used in combination with field information and actual weather data to make recommendations to achieve higher NUE. Remote sensing tools are also used to predict crop N demands precisely. At the same time, traditional techniques like balanced fertilization, integrated N management (INM), use of nitrification inhibitors and slow-release nitrogenous fertilizers (SRNF), split application and nutrient budgeting, among others, are also used to supplement recent N management techniques to attain higher productivity and NUE, and reduce environmental pollution through the leakage of fertilizer N.     

施氮与灌水对夏玉米土壤硝态氮积累、氮素平衡及其利用率的影响

通过田间裂区试验研究了不同施氮量(N 0、150、210和270 kg/hm2)和灌水量(900、1200、和1500 m3/hm2)对夏玉米土壤硝态氮分布累积、氮素平衡以及氮肥利用率的影响。结果表明,夏玉米收获期各处理土壤硝态氮在表层(0—20 cm)含量最高,在0—200 cm剖面均呈现先减少后增加再减少的变化趋势;土壤剖面NO3--N累积量随施氮量的增加而增加,且施氮处理硝态氮积累量显著高于不施氮处理。作物吸氮量、氮素表观损失量均与施氮量和总氮输入量呈显著相关,氮素输入量每增加1 kg,作物吸氮量仅增加0.301 kg,而表观损失量增加0.546 kg,是作物吸氮量的1.8倍左右。随施氮量的增加土壤剖面中NO3--N的损失量逐渐减少。夏玉米子粒吸氮量和收获指数随施氮量的增加有增加的趋势;氮肥回收效率和氮肥农学效率均以处理W1500N150最高,分别为46.15%和12.98kg/kg;氮肥生理效率以处理W1200N150最大,为34.49 kg/kg。本试验条件下,以水氮处理W1500N150的土壤硝态氮残留量、表观损失量较低,夏玉米氮肥回收效率和农学效率较高。     

碱性长效缓释氮肥对蕉园土壤pH和香蕉氮肥利用效率的影响

【目的】近年来由于超量施用化肥导致蕉园土壤严重酸化,土壤生产力逐年明显下降,香蕉产量骤降,传统产区栽培面积锐减。为此本试验在超高密度栽培条件下,以碱性长效缓释氮肥（ALNF,N 22%）作为供试肥料,研究其降低土壤酸度的效果及对香蕉产量和氮肥利用率的影响,并进一步探讨肥料的碱性能否造成氮素的损失。 【方法】本研究包括两个试验,分别为肥料种类和肥料用量对比试验,香蕉栽培密度均为3333 plant/hm2。试验1为碱性长效缓释肥料（ALNF）、控释配方BB肥料（CRF_BB）、常规肥料（CCF）三因素对比试验,以无氮处理（CK）为对照。试验2为完全ALNF（N 337.5 g/plant）,ALNF+60 g尿素N（ACF1,397.5 g/plant）,ALNF+90 g尿素N（ACF2,427.5 g/plant）,以不施氮肥（CK）为对照。 【结果】超高密度栽培条件下,ALNF处理收获期土壤pH值分别比CRF_BB、CCF、CK、ACF1和ACF2处理提高了1.2、1.2、1.1、0.6和0.3个单位。ALNF和CRF_BB处理香蕉单株产量分别比CCF处理增加了43.4%和35.1%,ALNF和ACF1处理香蕉单株产量分别比ACF2增加了50.6%和40.0%。就氮素平衡而言,CRF_BB和ALNF处理作物携出氮量分别比CCF处理提高了48.9%和24.8%;CCF的氮素表观损失量最多,是ALNF处理的2.3倍;ALNF处理的土壤氮素残留量最多,分别是CRF_BB、CCF处理的1.6倍、2.4倍;ALNF处理香蕉的携氮量分别比ACF1、ACF2处理提高了5.0%、31.9%,土壤残留氮量增加了60.8%、162.6%,ALNF的氮素表观损失最少,并随着尿素添加量的增加而增加,ALNF处理的氮素表观损失量仅为ACF2的1/4。CRF_BB和ALNF处理的氮肥利用率分别比CCF的提高了66.7%、33.7%,ALNF处理比ACF1、ACF2处理提高了27.8%、87.7%,ACF1处理的比ACF2处理提高了46.9%。 【结论】碱性长效缓释氮肥能够显著降低土壤酸度,土壤pH提高了0.3~1.2个单位,提高香蕉产量35%~50%,增加香蕉氮素吸收量24%~50%,增加土壤氮素残留量,减少氮素表观损失,提高氮肥利用率27%~67%。单独施用碱性长效缓释氮肥不会造成氮素损失,但是碱性长效缓释氮肥与尿素混合使用会造成氮素损失并降低氮肥利用率。     

农业土地利用系统氮足迹与灰水足迹综合评价

氮足迹和灰水足迹作为定量分析人类活动对活性氮排放及水资源影响的指标,为农业土地利用系统环境效应评价提供了新的理论与途径。该文在氮足迹和灰水足迹理论的基础上,构建了县域尺度农业土地利用系统氮足迹与灰水足迹理论分析框架,以湖南桃江县为研究区,计算了农业土地利用系统氮足迹与灰水足迹。结果表明:1)1980-2010年氮足迹与灰水足迹、单位土地利用面积氮足迹与灰水足迹均呈逐年增加的趋势。2010年氮足迹和灰水足迹分别是1980年的2.02倍和2.36倍,单位土地利用面积氮足迹和灰水足迹分别是1980年的2.00倍和2.31倍;2)1980-2010年输入氮足迹和污染氮足迹分别增长了102.54%、128.79%。2010年肥料氮投入占输入氮足迹的72.72%,污染氮足迹占总氮足迹的32.79%;3)1980-2010年,每年氮肥灰水足迹均高于磷肥灰水足迹。活性氮流失的增长造成的稀释水量增加是农业土地利用系统灰水足迹增长的关键因素。评价结果显示,桃江县农业土地利用系统在足迹总量与单位土地利用足迹对大气和水资源的负面影响正在持续上升。氮足迹与灰水足迹综合评价方法能有效地识别区域农业土地利用过程对环境的负面效应,研究成果为降低农业土地利用过程的环境风险、制定农业土地利用系统优化方案提供参考。