Determinants of annual fluxes of CO2 and N2O in long-term no-tillage and conventional tillage systems in northern France

The greenhouse gases CO₂ and N₂O emissions were quantified in a long-term experiment in northern France, in which no-till (NT) and conventional tillage (CT) had been differentiated during 32 years in plots under a maize–wheat rotation. Continuous CO₂ and periodical N₂O soil emission measurements were performed during two periods: under maize cultivation (April 2003–July 2003) and during the fallow period after wheat harvest (August 2003–March 2004). In order to document the dynamics and importance of these emissions, soil organic C and mineral N, residue decomposition, soil potential for CO₂ emission and climatic data were measured. CO₂ emissions were significantly larger in NT on 53% and in CT on 6% of the days. From April to July 2003 and from November 2003 to March 2004, the cumulated CO₂ emissions did not differ significantly between CT and NT. However, the cumulated CO₂ emissions from August to November 2003 were considerably larger for NT than for CT. Over the entire 331 days of measurement, CT and NT emitted 3160 ± 269 and 4064 ± 138 kg CO₂-C ha⁻¹, respectively. The differences in CO₂ emissions in the two tillage systems resulted from the soil climatic conditions and the amounts and location of crop residues and SOM. A large proportion of the CO₂ emissions in NT over the entire measurement period was probably due to the decomposition of old weathered residues. NT tended to emit more N₂O than CT over the entire measurement period. However differences were statistically significant in only half of the cases due to important variability. N₂O emissions were generally less than 5 g N ha⁻¹ day⁻¹, except for a few dates where emission increased up to 21 g N ha⁻¹ day⁻¹. These N₂O fluxes represented 0.80 ± 0.15 and 1.32 ± 0.52 kg N₂O-N ha⁻¹ year⁻¹ for CT and NT, respectively. Depending on the periods, a large part of the N₂O emissions occurred was probably induced by nitrification, since soil conditions were not favorable for denitrification. Finally, for the period of measurement after 32 years of tillage treatments, the NT system emitted more greenhouses gases (CO₂ and N₂O) to the atmosphere on an annual basis than the CT system.     

氮钾配施对大蒜增产效应的研究

1999～2001年连续三年多点试验结果表明:在安徽省来安县大蒜产区水稻土上氮钾配施对大蒜产量及品质都有明显的正效应,蒜苔增产24.2%～29.2%,蒜头增产17.3%～18.9%。氮钾肥的产量效应与土壤的氮钾水平和氮钾比例密切相关。氮肥的适宜用量为N300～375kg/hm2,钾肥为K2O150kg/hm2。回归方程计算显示,大蒜产区的土壤临界钾素含量为101μg/ml,氮素临界含量为46μg/ml(ASI法测定)。氮钾配施并能提高蒜苗、蒜苔维生素C及可溶性糖含量。增施钾肥对大蒜的经济效益明显提高,产投比为11.07～13.26。     

枣树专用叶面肥施肥技术及其肥效

采用正交试验设计对枣树专用叶面施肥技术及其肥效进行了研究。对不同时期果吊比和单果重分析结果表明,花明喷施枣树专用叶面肥可显著提高红枣座果率,喷肥1次较对照（喷水）果吊比提高59.3%;幼果期喷施具有保果、促进幼果生长发育之功效,喷肥1次较对照果吊比提高19.2%,单果重增加12.7%;膨个期喷施可促进枣果膨大,喷肥1次较对照单果重增加6.4%。单株产值多重比较分析结果表明,枣树专用叶面肥的最佳施肥方案为花期1次,幼果期1次,膨个期2次。最佳施肥方案与对照相比,单株产量提高53.6%,单株产值提高64.3%。     

香蕉茎叶对母牛繁殖性能影响的研究

[目的]为研究香蕉茎叶对母牛繁殖性能的影响,[方法]采用比较法,对饲喂香蕉茎叶和玉米秸秆青贮能繁母牛间的繁殖性能及犊牛的生长发育的差异进行了对比。[结果]研究结果表明,在相同的饲养管理条件下两组母牛的繁殖性能和犊牛的生长发育情况无明显差异。[结论]与肉牛常规饲料——玉米秸秆青贮相比,长期饲喂香蕉茎叶青贮饲料对能繁母牛繁殖性能、对胎儿和犊牛的生长发育不会产生不良影响,可以部分或完全替代玉米秸秆饲料,来降低母牛的生产成本,提高母牛的养殖效益。     

冬季青菜无纺布覆面效果试验初报

[目的]探索无纺布在冬季青菜上的应用效果。[方法]采用随机区组小区试验设计进行试验。[结果]在不使用农药的情况下,使用无纺布覆盖有较好的增产效果,不同的覆面栽培方式在增产上有较大的差异。定植后覆盖无纺布对青菜的增产效果最好,增产率达到36.0%;播种时随即覆面,反而使产量降低12.1%。[结论]无纺布覆盖的效果良好,可以在蔬菜的生产中推广应用。     

10%溴氟菊酯乳油防治甘蓝蚜试验

本文用１０％溴氟菊酯乳油对甘蓝蚜进行了室内毒力测定和田间药效试验。试验结果表明：１０％溴氟菊酯乳油对甘蓝蚜的室内触杀ＬＣ５０为１１．７４２０ｍｇ／ｋｇ，而对比药剂２０％甲氰菊酯乳油的ＬＣ５０为２２．１２０８ｍｇ／ｋｇ，可见，１０％溴氟菊酯乳油的触杀作用明显高于２０％甲氰菊酯乳油。１０％溴氟菊酯乳油１０００×，２０００×稀释液，药后３天，５天对甘蓝蚜的防效均达到９０％以上，明显高于２０％甲氰菊酯乳油２０００ｘ稀释液８４．１％和８５．１％的防效。因此，建议田间使用１０％溴氟菊酯乳油２０００×稀释液防治甘蓝蚜为宜     

绿色壁垒对我国农产品进出口的影响

介绍了绿色壁垒的主要内容和形式,阐述了绿色壁垒对我国农产品进出口的影响,提出了我国跨越绿色壁垒应采取的措施.     

反坡梯土保水保肥及增产效果研究

连续 6年的试验研究表明 ,在旱坡地上修建反坡梯土 ,具有保水、保土、保肥和增产的作用 ,能够将旱坡地面上的冲刷水变成地下渗透水 ,确保反坡梯土内的肥水肥土不被冲刷流失 ,把“三跑土”变成“三保土” ,从而提高粮食产量     

PBO在杏树上的应用研究

[目的]探讨微量元素叶面肥PBO在杏树上的增产效果。[方法]2004～2007年于杏树花前1周、新梢长出7～8片叶、6月初、7月中旬各喷施1次150～300倍液的PBO,喷洒清水为对照。[结果]与不喷施PBO对照比较,喷施4次PBO的杏树,4年平均短果枝率比对照提高25.1个百分点,成花率提高34.4个百分点,坐果率提高21.0个百分点,单果重提高18.8 g,优质果率提高15.9个百分点;4年平均每株产量提高7.86 kg,平均每公顷产量提高12 900 kg,增产260.8%,增产效果显著。[结论]杏树喷施PBO可抑制新梢的旺长,增加贮藏营养积累,增强保水力,提高短果枝率比例,促进花芽分化和形成,提高成花率、坐果率和单果重,是取代环剥、扭梢和多效唑的有效途径。     

油菜的钾肥效应研究

针对安徽省南部地区土壤有效钾含量逐年下降和高产油菜需钾较多的矛盾 ,开展了油菜钾肥效应试验研究。试验结果表明 :施用钾肥能显著提高油菜产量和经济效益 ,该地区钾肥的适宜用量为 12 0kg/hm2 。