间作及伴随阴离子肥料对油菜吸收积累镉的影响     

谭国湛  王甜  韩国君  李金霞  陈年来 《中国生态农业学报》2013,21(10):1264-1270

为提高Cd污染土壤植物修复效率, 采用盆栽方法研究了Cd含量为10.0 mg·kg^-1的土壤中, 伴随阴离子肥料和间作鹰嘴豆对油菜生长与吸收积累Cd的影响。结果表明: 单作下, 不同肥料处理土壤DTPA提取态Cd含量为Cl^->NO₃^->SO₄^2- >无伴随阴离子; 间作鹰嘴豆提高土壤DTPA提取态Cd含量, 且伴随C₁^-、SO₄^2- 或NO₃^- 条件下达显著水平。单作下, 油菜主根长为NO₃^- >C₁^- >SO₄^2- >无伴随阴离子, 根系体积为SO₄^2->NO₃^- >C₁^- >无伴随阴离子, 根系活力NO3 >SO42 >Cl >无伴随阴离子; 间作鹰嘴豆在无肥处理下可显著提高油菜的主根长与根系体积, 在无肥处理、SO₄^2- 、NO₃^- 处理下显著提高根系活力。单作下, 油菜地上部Cd含量表现为C₁^- >SO₄^2- >NO₃^- >无伴随阴离子, 间作鹰嘴豆可显著降低无肥处理地上部Cd含量, 但显著提高施肥处理地上部的Cd含量。单作下, 施肥可显著增加油菜的Cd积累总量, 以伴随C₁^-处理最大, 达470.4 μg·plant^-1; 间作鹰嘴豆也可提高油菜的Cd积累总量, 且伴随C₁^- 处理最大, 达783.7 μg·plant^-1。除伴随C₁^- 处理外, 施肥处理均可显著提高油菜的Cd转移系数, 施肥处理的Cd转移系数均大于1; 间作鹰嘴豆也可提高油菜的Cd转移系数, 且施肥条件下达显著水平。因此, 如果把油菜用作Cd污染土壤植物修复作物, 可选择施用含Cl 肥料和间作鹰嘴豆, 以提高修复效率。  相似文献   

黄河流域农业灰水足迹效率时空格局演变与驱动因素     

郭玮  胡西武 《水土保持通报》2024,44(2):437-445

[目的] 探讨农业灰水足迹效率时空格局演变与驱动因素,为协同推进农业用水节约集约和水污染综合治理、实现黄河流域农业高质量发展提供科学参考。 [方法] 以黄河流域9省区为研究对象,利用灰水足迹模型、泰尔指数和对数平均迪氏指数等研究方法对2000—2021年农业灰水足迹效率进行测算,并探讨其时空演变格局和驱动因素。 [结果] ①2000—2021年黄河流域农业灰水足迹效率呈上升趋势,年均效率为0.235 8元/m³,内蒙古效率最高为0.467 0元/m³,青海效率最低为0.026 3元/m³。 ②农业灰水足迹效率地区内部差距多年平均贡献率为80.11%,上游地区差距年均贡献率为75%,是造成黄河流域农业灰水足迹效率差距较大的主要原因。 ③黄河流域农业灰水足迹效率总效应为正向效应0.202 4元/m³,耕地资源效应和农业环境效应分别是促进和抑制农业灰水足迹效率的主要因素,二者贡献值分别为0.442 7和-0.440 6元/m³。 ④黄河流域农业灰水足迹效率驱动效应可分为4种模式,不同模式地区提升农业灰水足迹效率的方式不同。 [结论] 黄河流域9省区应采用因地制宜的发展策略,优化农业结构,减少化肥农药的高强度使用,加强农业水环境治理,提升农业灰水足迹效率。  相似文献   

供水条件对温室番茄根系分布及产量影响   总被引：8，自引：4，他引：4  

李波  任树梅  杨培岭  孔清华 《农业工程学报》2007,23(9):39-44

通过田间试验,分析了不同生育期供水条件对番茄灌水量、光合作用、根系分布、产量和水分利用效率的影响。结果表明：番茄开花坐果期控制灌水下限为60%f_C(田间持水量),结果盛期控制灌水下限为75%f_C,控制灌水上限为90%f_C,番茄产量最高,达到91.7 t/hm²,水分利用效率达到27.51 kg/m³,整根的根长、根表面积、根体积、根干重都明显增加。叶片净光和速率在75%f_C条件下最高,有利于光合产物的形成。随土层深度的增加,根长密度呈指数下降。不同土壤水分条件对番茄根系生长影响主要体现在直径小于1 mm的根系上,而且直径小于1 mm的根长和产量之间存在很好的相关关系。  相似文献   

黄土高原玉米坡耕地C因子的估算研究     

余倩  姚冲  付世琳  吴发启 《水土保持学报》2022,36(6):49-54

C因子作为土壤侵蚀预报模型中人为可控制的一个重要的因子,对减少土壤侵蚀和控制水土流失有很大的影响。因此以黄土高原坡耕地典型作物玉米为研究对象,通过进行人工降雨模拟试验,研究了玉米5个不同生育期近地表状况的变化特征,根据玉米不同生育期产沙量计算C值。结果表明,植被覆盖度、株高和结皮厚度均随着玉米生育期的延长而逐渐增加,地表粗糙度随着生育期延长呈现先减小后增加的趋势。产沙量随着玉米的生长逐渐减小,减沙效益随着玉米生育期的延长不断增加。在前人以植被覆盖度计算C值模型的基础上,以植被覆盖度作为关键因子,将株高、土壤结皮、地表粗糙度作为调节因子建立当地C值模型,得到较好的玉米坡耕地的C值模型(模型R²=0.94,RMSE=0.017,MAE=0.014,NSE=0.992)。研究结果根据近地表状况变化特征建立C值计算公式,提高了C值估算的准确性和其在黄土高原的适用性,为提高黄土高原土壤侵蚀预报模型精度提供科学依据。  相似文献   

甘蔗等高种植与新植配置比例对坡面沟蚀引起的氮磷养分流失的影响     

杨翠红  李勇  王旭  陈婷婷  郭豪  杨江怡  吴宗猛  周小淇  黄智刚 《水土保持通报》2023,43(5):69-78

[目的] 探讨甘蔗等高种植与新植适宜的配置比例,为甘蔗种植区减少坡面沟蚀和养分流失、提升耕地质量和合理种植甘蔗提供技术支撑。[方法] 通过野外测量与试验分析相结合,确定苗期、分蘖期、伸长期和成熟期4个甘蔗生长时期内低、中、高3种等高种植和新植比例的甘蔗坡面沟蚀量和养分流失量,并明确其影响因素。[结果] ①整个甘蔗生育期,那辣流域甘蔗种植坡面沟蚀及其导致的全氮、全磷流失量分别在31.3～66.3 t/hm²,39.0～82.5 kg/hm²,18.0～38.4 kg/hm²之间; ②苗期是那辣流域沟蚀和养分流失的主要时期,其贡献量占甘蔗全生育期的比例为47.7%～57.7%。③全生育期,高比例等高(H_C)的坡面沟蚀和养分流失比低比例新植坡面(L_C)低33.03%～35.42%(p＜0.05),但中比例等高(M_C)和H_C,L_C的流失量均不显著;低比例新植(L_Rp)坡面沟蚀和养分流失量比高比例新植(H_Rp)低27.41%～32.98%,比中比例新植(M_Rp)低21.02%～25.86%(p＜0.05),凋落物覆盖度和根系密度是影响沟蚀与养分流失的重要因素。④全生育期,坡面全氮和全磷流失量分别占年氮肥和磷肥施用量的24.1%～39.5%和107.0%～156.7%。[结论] 在甘蔗种植时,60%以上的等高种植比例和30%以下新植比例,可以有效减少坡面土肥流失。  相似文献   

灌溉对大麦/玉米带田土壤硝态氮累积和淋失的影响   总被引：7，自引：3，他引：7  

叶优良  李隆  张福锁  孙建好  刘生战 《农业工程学报》2004,20(5):105-109

以甘肃省河西走廊灌区为试验地点，分别在0、150、300 kg/hm²氮水平和816、1632 m³/hm²灌水量下，对3次灌水前、后大麦/玉米带田0～200 cm土壤NO^-₃-N含量变化和灌水后135 cm处渗漏液NO^-₃-N浓度进行了测定。结果表明：灌水明显影响土壤硝态氮累积量，随灌水次数增加，土壤硝态氮累积量降低，而且在高灌水条件下土壤硝态氮累积量变化比低灌水量时大。从渗漏液硝态氮浓度来看，大麦带和玉米带都是以第1次灌水最高，浓度分别为8.04～17.21和3.30～14.57 mg/L。3次灌水土壤硝态氮淋失量，玉米带以N 150 kg/hm²和灌水量1632 m³/hm²最高，平均为4.31 kg/hm²；大麦带以N 150 kg/hm²及灌水量1632 m³/hm²和N 150 kg/hm²及灌水量816 m³/hm²比较高，平均为6.82 kg/hm²。  相似文献   

NO^-₃胁迫下K⁺、Ca²⁺对黄瓜幼苗膜质过氧化及活性氧清除酶系统的影响     

杨凤娟  王秀峰  魏珉  闫童 《农业工程学报》2005,21(14):155-158

通过水培试验探讨了NO^-₃胁迫下K⁺、Ca²⁺对黄瓜幼苗膜质过氧化及活性氧清除酶系统的影响。结果表明，在相同NO^-₃浓度胁迫7d后， Ca²⁺浓度越大，膜脂过氧化产物丙二醛(MDA)含量越高，而K⁺浓度越大，电解质相对渗透率越高，由此说明K⁺、Ca²⁺对细胞膜造成伤害的机理不同。黄瓜幼苗活性氧清除酶系统对K⁺、Ca²⁺的响应亦不同，在一定程度上，K⁺和Ca²⁺ 可提高SOD、POD和CAT活性，保护植物免受自由基伤害，继而可增强植物对逆境的适应能力。  相似文献   

基于稳定同位素和贝叶斯模型的引黄灌区地下水硝酸盐污染源解析   总被引：5，自引：0，他引：5  

张妍  张秋英  李发东  张鑫  毕直磊  张强 《中国生态农业学报》2019,27(3):484-493

地下水硝酸盐（NO₃^-）污染已经成为全球严重的水环境问题之一,由于饮用水中高含量NO₃^-会转化成亚硝酸盐而增加各种疾病和癌症风险,其来源的确定对于NO₃^-污染的预防和控制非常重要。本文以黄河下游第二大灌区——潘庄灌区为例,首次采用NO₃^-的氮氧稳定同位素结合贝叶斯模型追溯地下水NO₃^-的来源并量化各种来源的贡献比例。结果表明,地下水NO₃^-含量分布在0.1~197.0 mg·L^-1,平均值为34.2 mg·L^-1。与《生活饮用水卫生标准》中规定的地下水NO₃^-最大含量[20 mg（N）·L^-1,相当于NO₃^-含量90 mg·L^-1]相比,有10%的样品NO₃^-含量超标。井深<30 m、30~60 m和>60 m的地下水NO₃^-平均含量分别为25.9 mg·L^-1、39.7 mg·L^-1和20.1 mg·L^-1。空间上,宁津县、武城县、平原县和禹城市有大片区域地下水NO₃^-含量较高。地下水NO₃^-的δ¹⁵N组成范围为0.72‰~23.93‰,平均值为11.62‰;δ¹⁸O组成范围为0.49‰~22.50‰,平均值为8.46‰。同位素结果表明粪便和污水、农业化肥是地下水中NO₃^-的主要污染来源。这反映了人类活动是引起地下水NO₃^-污染的主要原因。贝叶斯模型结果显示,粪便和污水对潘庄灌区地下水中NO₃^-平均贡献率高达56.2%,化肥的平均贡献率为19.3%,大气降水和土壤的平均贡献率分别为6.2%和12.3%。由于污水、粪便和化肥是地下水中NO₃^-的主要来源,为保护和改善研究区地下水水质,建议加强污水管道建设,强化畜禽粪便的管理以及提高化肥利用效率。  相似文献   

双针热脉冲测定冻土热特性的数值模拟方法     

张媛媛  刘湘君  赵天悦  赫刘台  何海龙  刘刚 《农业工程学报》2024,40(11):92-99

使用双针热脉冲(dual probe heat pulse, DPHP)测定冻土热特性时施加热脉冲后会导致加热探针周围的冰融化,使用目前常用的仅考虑热传导（忽略融化相变、冰水两相分界面）的解析解处理DPHP温度数据,会导致在-5 ℃至0 ℃温度范围内无法准确测量热导率 (λ) 和比热 (C_v)。为了能够准确测定冻土的 λ 和 C_v,有必要考虑DPHP加热过程中引起的冰融化的相变潜热。该研究基于COMSOL仿真软件模拟了考虑相变潜热、相变区间以及移动冰水界面的DPHP测量过程,采用随温度非线性变化的真实冻土热特性进行模拟,并与真实冻土的DPHP测量数据对比。结果表明：1）COMSOL仿真在不考虑相变条件下与无限线性热源模型结果完全吻合（R² = 0.9989）;2）当土壤初始温度低于-5 ℃时,考虑相变发生的COMSOL仿真能够准确模拟试验结果,表现出较高的相关性（R² > 0.93）,在-2 ～ 0 ℃的土壤初始温度范围内,无限线性热源模型的结果与试验测量显著偏离（R² < 0.0013）;3）在不同土壤初始温度下,相变温度为-1.5 ～ -0.5 ℃的仿真结果与试验数据具有较高的相关性（R² > 0.7）。本研究结果检验了有限元仿真用于真实冻土DPHP研究的可行性,可为准确预测冻土热特性的研究提供方法。  相似文献   

太行山前平原农田基础地力对夏玉米产量的影响及培肥目标          下载免费PDF全文

贾良良  黄少辉  刘克桐  孙彦铭  杨军芳  杨云马  邢素丽  刘孟朝 《中国土壤与肥料》2021,(3):340-346

太行山前平原是河北省重要的夏玉米产区,对2005～2013年在河北省开展的测土配方施肥项目的“3414”试验数据以及山区平原农田基础地力对玉米产量、基础地力贡献率和产量反应进行了分析,并利用边界线分析方法对土壤有机质、全氮、有效磷和速效钾对基础产量的响应进行了评价,确定了太行山前平原农田土壤培肥目标。研究结果发现,太行山前平原夏玉米基础地力产量分布在3222～9672 kg/hm²之间,平均值为6210 kg/hm²,基础地力对玉米产量的贡献率分布范围在32.2%～99.7%之间,平均值为71.7%,在太行山前平原夏玉米基础地力产量范围内,基础地力产量与施肥产量和基础地力贡献率呈显著线性正相关关系,基础地力产量每增加1000 kg/hm²,配方施肥产量则增加585 kg/hm²,基础地力贡献率也提高6.5%。氮磷钾肥的施肥产量反应分别为1614、909和802 kg/hm²,边界线分析方法确定山区平原土壤培肥目标下限是土壤有机质14.3 g/kg,土壤全氮1.20 g/kg,有效磷20.2 mg/kg,速效钾121.9 mg/kg,提高土壤有效磷和速效钾含量对缩减由土壤肥力差异引起的产量差最为明显,是河北省太行山前平原的重点培肥方向。  相似文献   

基于数据包络分析模型的江苏省农业水资源利用效率评价   总被引：1，自引：1，他引：1  

张娜娜  王海涛  吴颖超  闵兴华  曹磊  赵言文 《水土保持通报》2015,35(4):299-303

[目的]研究江苏省2002—2011年农业水资源利用效率,为提高该省农业水资源利用率提供依据。[方法]采用数据包络分析(DEA)模型中C2 R和BC2两种模型,选取的投入指标为农作物播种面积、农田灌溉用水量、农田灌溉耗水量和农业在岗职工人数;产出指标为有效灌溉面积、农村居民人均农业收入、农业生产总值和农作物产量。[结果](1)在2002—2011年期间,江苏省农业水资源利用效率处于较高的水平,DEA有效年份占50%;(2)造成DEA无效既有技术原因也有规模原因,存在投入冗余和产出不足;(3)随着时代发展,江苏省农业水资源利用投入冗余和产出不足整体呈现逐渐降低趋势。[结论]江苏省农业水资源利用情况得到了逐步改善。  相似文献   

Using natural 13C abundances to differentiate between three CO2 sources during incubation of a grassland soil amended with slurry and sugar     

Yakov Kuzyakov  Roland Bol 《植物养料与土壤学杂志》2004,167(6):669-677

This study describes a novel approach to separate three soil carbon (C) sources by one tracer method (here ¹³C natural abundance). The approach uses the temporal dynamics of the CO₂ efflux from a C₃ grassland soil amended with added C₃ or C₄ slurry and/or C₃ or C₄ sugar to estimate contributions of three separate C sources (native soil, slurry, and sugar) to CO₂ efflux. Soil with slurry and/or sugar was incubated under controlled conditions, and concentration and δ¹³C values of evolved CO₂ were measured over a 2‐week period. The main assumption needed for separation of three C sources in CO₂ efflux, i.e., identical decomposition of applied C₃ and C₄ sugars in soil, was investigated and proven. The relative contribution to the CO₂ efflux was higher, but shorter with an increased (microbial) availability of the C source, i.e., sugar > slurry > SOM. The shortcomings and limitations as well as possible future applications of the suggested method are discussed.  相似文献   

Freeze-dried soil extraction method for the measurement of microbial biomass C     

K. R. Islam  R. R. Weil  C. L. Mulchi  S. D. Glenn 《Biology and Fertility of Soils》1997,24(2):205-210

A new method for the measurement of microbial biomass C by direct extraction of freeze-dried soil with either 0.5M K₂SO₄ or 0.5M NaHCO₃ was evaluated. The underlying principle of the method is that rehydrating a freeze-dried soil releases cytoplasmic organic compounds from desiccated and disrupted microbial cells. Nineteen soils under various management regimes were sampled to test the proposed method, in which each soil sample was split into two subsamples. One subsample was kept in the field-moist condition at 4°C. The other subsample was brought to 100% water-holding capacity and frozen at –20°C for 24h. The frozen soil was then freezedried. Both subsamples were extracted with 0.5M K₂SO₄ or 0.5M NaHCO₃ at a soil-to-extractant ratio of 1-to-4 (w/v) and organic C determined in the extract (C_{K2 SO4} or C_NaHCO3). The net freeze-dry stimulated increase in extracted C was correlated (r ²=0.98 for C_{K2 SO4} or 0.93 for <$>\rm C_{NaHCO_3})<$> more closely with microbial biomass C (C_MB) measured as net evolution of CO₂–C by chloroform fumigation incubation (CFI) than with total C (r ²=0.42 for C_{K2 SO4} or 0.47 for C_NaHCO3). Based on linear regression equations, extraction efficiency coefficients (K _EC) were used to calculate C_MB from C_{K2 SO4} or C_NaHCO3 as follows: C_MB=C_{K2 SO4}/0.152±0.004 C_MB=C_NaHCO3/0.257±0.01 The relationship between the C_MB and the flushes of C extracted after rehydration of freeze-dried soil showed that the K _EC values were more consistent for C_{K2 SO4} than C_NaHCO3. The freeze-dried soil extraction was a fast, precise, reliable and safe method for measuring microbial biomass C in soil. Received: 27 May 1996  相似文献   

Long‐Term Changes in Soil Carbon Stocks in the Brazilian Cerrado Under Commercial Soybean     

Eduardo Miranda  Janaina Carmo  Eduardo Couto  Plínio Camargo 《Land Degradation \u0026amp; Development》2016,27(6):1586-1594

The net effect of agriculture on soil carbon is not yet fully understood. While a number of studies on shallow profiles have been published, evidence suggests that carbon stock changes occur in deeper layers. In this study we analyzed the effect of agriculture in the Cerrado soil C looking at changes in seven different profile depths from 0 to 100 cm in a commercial grain farm. We also used isotopic techniques to distinguish between the original Cerrado C₃ carbon and the C₄ carbon derived from the grasses used in agriculture. At 0–5 cm depth C stocks significantly decreased with cultivation time. The C stock did not change significantly when it was calculated using the 0–10, 0–20, 0–30, 0–50 or 0–75 cm profile (p > 0·05) but increased with cultivation time when the profile considered was 0–100 cm (p < 0·05). A two‐source isotope model revealed that there was a significant increase in carbon derived from C₄ grasses for all depths with cultivation time. Annual carbon sequestration rates for the upper 100 cm of soil were 1·1 Mg C ha⁻¹ year⁻¹ for total carbon and 0·8 Mg C₄ C ha⁻¹ year⁻¹ for C₄ carbon. The oldest area, with 23 years of cultivation, had a soil C stock increase compared to the native Cerrado soil of 17·6%. These findings suggest that commercial grain farms practices may increase soil C stock compared to native Cerrado soil, if a more complete soil profile down to 100 cm is used to assess C stocks. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

喀斯特石漠化治理区农业发展驱动因子研究——基于索洛速度增长方程     

李永垚  熊康宁  罗娅 《中国水土保持科学》2013,11(3):47-54

选取贵州关岭—贞丰花江示范区为研究区,采用索洛速度增长方程,测算研究区农业科技进步、劳动力、资金、土地等因子对于农业经济增长的贡献率,分析当前农业发展的推动因素和阻碍因素,同时结合当前石漠化山区几个典型的农业综合开发模式以及国内外现代农业中可持续农业、生态农业、低碳农业、精准农业、自然农业、集约农业发展的理念、特点、关键技术和模式,提出生态恢复重建与农业综合开发并重、农业生产结构调整与农业生态产业化并举、强化科技支撑和提高农业科技进步贡献率等3大策略构想,以促进石漠化综合治理区生态环境改善和农业可持续发展。  相似文献   

Three‐source partitioning of CO2 efflux from maize field soil by 13C natural abundance     

Martin Werth  Yakov Kuzyakov 《植物养料与土壤学杂志》2009,172(4):487-499

A natural‐¹³C‐labeling approach—formerly observed under controlled conditions—was tested in the field to partition total soil CO₂ efflux into root respiration, rhizomicrobial respiration, and soil organic matter (SOM) decomposition. Different results were expected in the field due to different climate, site, and microbial properties in contrast to the laboratory. Within this isotopic method, maize was planted on soil with C₃‐vegetation history and the total CO₂ efflux from soil was subdivided by isotopic mass balance. The C₄‐derived C in soil microbial biomass was also determined. Additionally, in a root‐exclusion approach, root‐ and SOM‐derived CO₂ were determined by the total CO₂ effluxes from maize (Zea mays L.) and bare‐fallow plots. In both approaches, maize‐derived CO₂ contributed 22% to 35% to the total CO₂ efflux during the growth period, which was comparable to other field studies. In our laboratory study, this CO₂ fraction was tripled due to different climate, soil, and sampling conditions. In the natural‐¹³C‐labeling approach, rhizomicrobial respiration was low compared to other studies, which was related to a low amount of C₄‐derived microbial biomass. At the end of the growth period, however, 64% root respiration and 36% rhizomicrobial respiration in relation to total root‐derived CO₂ were calculated when considering high isotopic fractionations between SOM, microbial biomass, and CO₂. This relationship was closer to the 50% : 50% partitioning described in the literature than without fractionation (23% root respiration, 77% rhizomicrobial respiration). Fractionation processes of ¹³C must be taken into account when calculating CO₂ partitioning in soil. Both methods—natural ¹³C labeling and root exclusion—showed the same partitioning results when ¹³C isotopic fractionation during microbial respiration was considered and may therefore be used to separate plant‐ and SOM‐derived CO₂ sources.  相似文献   

信息技术提升农业机械化水平   总被引：13，自引：12，他引：1  

罗锡文  廖娟  邹湘军  张智刚  周志艳  臧英  胡炼 《农业工程学报》2016,32(20):1-14

为适应中国现代农业建设的需要,保持中国农业机械化水平持续增长,实现中国农业可持续发展,该文提出,应将先进的信息技术融入中国农业机械的设计、制造、作业和管理等环节,使农业机械装备实现信息化和智能化,从而整体提升农业机械化水平。文中介绍了参数化设计、基于知识工程的农机产品设计、基于产品数据管理的并行协同设计等农机产品设计的关键技术;柔性制造、计算机集成制造、虚拟与网络制造等农机产品制造的关键技术;农情信息采集、农业机械导航、田间管理等农业机械作业的关键技术;农业机械管理、农业机械调度等关键技术。分析了这些关键技术信息化的不足,总结了世界各国的发展趋势,指出了用信息技术提升中国农业机械化水平应解决的核心问题。为加强农机装备的信息技术创新,该文建议,应突破一批智能农业装备数字化设计技术、自动导航协调控制技术及农业装备现场总线技术等关键技术;研发一批大田和设施农业生产作业系统、果园作业智能装备和畜禽水产精准生产装备等重大技术产品;构建一批水肥药田间精准作业系统、畜禽水产自动饲喂系统和自动化加工生产线等农业机械精准作业系统,从而进一步用信息技术提升农业机械化水平。  相似文献   

利用~(13)C标记和自然丰度三源区分玉米根际CO_2释放   总被引：1，自引：1，他引：0  

孙昭安  张保仁  何敏毅  王开永  胡正江  陈清  孟凡乔 《土壤学报》2021,58(5):1256-1266

石灰性土壤中,根际土壤释放的CO_2有三个来源,即根源呼吸、土壤有机碳(SOC)分解和土壤无机碳(SIC)溶解,三源区分土壤释放的CO_2是量化土壤碳平衡的前提。分别在玉米拔节期、抽穗期和灌浆期进行7 h的~(13)O_2脉冲标记,经过27 d示踪期后破坏性取样,测定~(13)标记与自然丰度处理中,玉米地上部、根系、土壤和土壤CO_2的碳含量和δ~(13)值,利用~(13)示踪并结合自然丰度法区分玉米土壤CO_2的来源。研究结果显示,随着玉米生长,根源呼吸对土壤CO_2的贡献呈降低趋势,从拔节期的66.7%降低至灌浆期的25.8%。整个玉米旺盛生育期内(从拔节期到生育期末),根源呼吸和土壤总碳释放对土壤CO_2具有同等贡献,SOC和SIC释放对土壤总碳释放的贡献率分别为30%和20%。玉米生长对土壤的碳输入(根系+根际沉积物)超过土壤总碳(SIC+SOC)的释放,总体表现为土壤碳汇。研究表明,SIC溶解对全球碳库稳定性和调节CO_2浓度的影响非常重要,若忽视石灰性土壤中SIC溶解,则会高估SOC的分解,进而影响SOC激发效应以及土壤碳平衡的评估。  相似文献   

Trace amounts of O₂ affect NO and N₂O production during denitrifying enzyme activity (DEA) assays     

Robert E Murray 《Soil biology & biochemistry》2004,36(3):513-517

We evaluated the potential of trace amounts of O₂ inadvertently introduced into anaerobic incubations to initiate the C₂H₂-catalyzed NO oxidation reaction and affect NO and N₂O production rates during denitrifying enzyme activity (DEA) assays. We measured the rate of NO production in the presence and absence of 10 kPa C₂H₂ and N₂O production in the presence of 10 kPa C₂H₂ by short-term incubations of slurries of humisol and sandy loam soil. NO production, in the absence of C₂H₂, was similar for both soils (0.73-1.32 ng NO-N g dry soil⁻¹ min⁻¹) and replicate measurements of NO production rates were linear and exhibited small standard deviations. It was not possible to consistently measure NO production in the presence of C₂H₂. Replicate measurements of NO production were always lower and exhibited a wide range of variability when C₂H₂ was present. The rate of NO production in the absence of C₂H₂ was only 2.3-3.0% of the rate of N₂O production in the presence of C₂H₂ in humisol soil but was much larger (31.8-35.0%) in the sandy loam soil. Rates of NO production from sandy loam soil were reduced by 58% when trace amounts (30 μl) of O₂ were added to slurry incubations containing C₂H₂. We conclude that trace amounts of O₂ inadvertently introduced into the slurries during sampling could initiate scavenging of NO by the C₂H₂-catalyzed NO oxidation reaction and cause an underestimate of N₂O production during DEA assays in some soils.  相似文献   

Conversion of forest to agricultural land affects the relative contribution of bacteria and fungi to nitrification in humid subtropical soils     

Jing Wang  Qian Liu  Zucong Cai 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(1):83-88

Land-use and management practices can affect soil nitrification. However, nitrifying microorganisms responsible for specific nitrification process under different land-use soils remains unknown. Thus, we investigated the relative contribution of bacteria and fungi to specific soil nitrification in different land-use soils (coniferous forest, upland fields planted with corn and rice paddy) in humid subtropical region in China. ¹⁵N dilution technique in combination with selective biomass inhibitors and C₂H₂ inhibition method were used to estimate the relative contribution of bacteria and fungi to heterotrophic nitrification and autotrophic nitrification in the different land-use soils in humid subtropical region. The results showed that autotrophic nitrification was the predominant nitrification process in the two agricultural soils (upland and paddy), while the nitrate production was mainly from heterotrophic nitrification in the acid forest soil. In the upland soils, streptomycin reduced autotrophic nitrification by 94%, whereas cycloheximide had no effect on autotrophic nitrification, indicating that autotrophic nitrification was mainly driven by bacteria. However, the opposite was true in another agricultural soil (paddy), indicating that fungi contributed to the oxidation of NH₄⁺ to NO₃^?. In the acid forest soil, cycloheximide, but not streptomycin, inhibited heterotrophic nitrification, demonstrating that fungi controlled the heterotrophic nitrification. The conversion of forest to agricultural soils resulted in a shift from fungi-dominated heterotrophic nitrification to bacteria- or fungi-dominated autotrophic nitrification. Our results suggest that land-use and management practices, such as the application of N fertilizer and lime, the long-term waterflooding during rice growth, straw return after harvest, and cultivation could markedly influence the relative contribution of bacteria and fungi to specific soil nitrification processes.  相似文献