不同自然植被管理措施对红壤丘陵果园水土流失的影响

丘陵是“山—丘—谷”的过渡地带，生态系统脆弱，一旦植被遭破坏，极易水土流失。在红壤丘陵园地应用除草剂调控水土流失试验结果表明：与传统的清耕法相比，克无踪、草甘膦、草草克、克克草和生草法可使地表径流量分别减少47.7%，20.8%，31.4%，41.3%和45.5%；可使土壤侵蚀量分别减少52.4%，39.0%，48.1%，50.7%和55.2%；可使土壤养分分别减少50.2%，37.0%，41.8%，45.8%和60.3%。除草剂对杂草再生率影响，与生草法比较，克无踪可达67.2%，草甘膦达30.3%，草草克36.8%，克克草51.2%和清耕法55.1%；克无踪调控杂草效果分别是草甘膦的2.2倍，清耕法的1.2倍。克无踪调控杂草效果显著，有望成为红壤丘陵园地培肥与水保相得益彰的有效措施。     

不同除草处理对经济林果园地水土保持作用的初步研究

丘陵、中低山区(海拔<1 500 m)是经济林果木发展的主要适生区域,亦是人类活动最频繁的区域,生态系统脆弱,一旦土壤地被物遭破坏,极易引起严重的水土流失.通过在四川盆地紫色土桃园地和盆边山地黄壤茶园地设置16个径流场,进行4种除草处理,应用不同除草方式调控水土流失试验1年,结果表明(1)除草试验处理的土壤侵蚀量和养分(N,P,K,OM)流失量排序是耕作除草＞草甘膦除草＞克无踪除草＞割草覆盖(CK).(2)除草试验处理的土壤侵蚀量与传统耕作除草相比较,坡度25°和坡度10°的桃园地应用草甘膦除草、克无踪除草和割草覆盖(CK)土壤侵蚀量分别减少61.7%,67.6%,85.7%和 12.6%,24.2%,50.4%;坡度18°和坡度8°的茶园地土壤侵蚀量分别减少71.2%,84.3%,89.3%和16.2%,52.3%,82.8%.(3)桃园地应用草甘膦除草,土壤养分N,P,K,OM流失量比克无踪除草分别高19.9%,9.2%,23.3%,15.4%(坡度25°)和16.2%,15.3%,17.0%,20.6%(坡度10°);茶园地应用草甘膦除草土壤养分N,P,K,OM流失量比克无踪除草分别高89.6%,90.7%,80.0%,106.6%(坡度18°)和85.1%,81.4%,76.2%,83.9%(坡度8°).(4)除草试验处理的杂草生物量和盖度 桃园地和茶园地应用草甘膦、克无踪和耕作除草的杂草生物量绝对干重分别是割草覆盖(CK)的16.0%,60.0%,75.0%和5.9%,43.9%,79.5%;桃园地应用草甘膦除草、克无踪除草、耕作除草和割草覆盖(CK)的杂草总盖度分别为40%,80%,65%和95%,茶园地应用草甘膦除草、克无踪除草、耕作除草和割草覆盖(CK)的杂草总盖度分别为25%,80%,95%和95%.     

黄土高原区果园生草覆盖对土壤物理性状、水分及产量的影响

通过试验证明果园生草制是黄土高原地区果园土壤管理的一个行之有效的模式。果园生草覆盖区与对照相比土壤物理性状、水分及产量均有明显提高，直径1．0mm以上的土壤团粒增加了10．2％一12．2％，提高60．4％一72．2％；土壤容重下降0．05—0．13g/cm^3，降低4．2％一10．0％；土壤孔隙度增加2．5％一5．5％，提高4．6％一10．9％；有机质增加0．19％一0．57％，提高24．4％一73．1％；0—20cm土壤水分增加1．7％一3．0％，提高16．7％一29．4％；苹果产量和经济效益，提高幅度分别为12．73％一31．57％和15．17％一36．22％。     

利用小孢子胚离体培养筛选抗除草剂的油菜

选用4个甘蓝型油菜（Brassica napus L．）F、（7039，7040，282和5102）为小孢子培养供体材料，分别对小孢子胚在含草甘膦和盖草能的培养基上进行培养，以筛选出抗草甘膦和抗盖草能的胚状体，进而获得再生植株。其中，基因型7039和7040用于草甘膦筛选，282和5102用于盖草能的筛选。选取子叶期胚状体，在含0．006％的草甘膦及0．01％和0．02％盖草能的MS-2培养基上培养2周，不抗草甘膦和小抗盖草能的胚状体2周内变褐死去，抗草甘膦和抗盖草能的胚状体转绿。随后转绿胚状体转移至正常MS-2培养基中继续培养，直至获得再生植株。再生植株喷施0．25％的草甘膦液表明均抗草甘膦；而对植株喷施0．05％的盖草能液时，0．02％筛选出的植株大部分为抗盖草能，而0．01％筛选出的植株却大部分死去，表明用0．02％浓度筛选抗盖草能植株的方法更有效。用170mg／L秋水仙碱直接处理再生植株20和30h，染色体加倍率分别达到了34％和52％。     

自然生草对渭北旱塬苹果园土壤氮及果实品质的影响

为了减少土壤硝态氮的积累,防止苹果缺钙症状的发生,该研究以果园清耕为对照,探讨渭北旱塬果园自然生草（繁缕和牛繁缕群落,自然生草2、4、6和8 a）对土壤有机质、全氮、硝态氮、铵态氮、水溶性钙含量和苹果果实中的氮、磷、钾、钙含量及果实缺钙症状和果实品质等的影响。结果表明果园自然生草可提高0～40 cm土层土壤有机质、全氮和水溶性钙的含量,略微提高40～60 cm土层土壤水溶性钙含量,且自然生草年限越长,土壤有机质、全氮和水溶性钙含量越高,但对40 cm土层以下的土壤有机质、全氮和60 cm土层以下的土壤水溶性钙含量无显著影响。自然生草2和4 a 0～60 cm土层土壤铵态氮略低于清耕,6和8 a的略高于清耕,自然生草对土壤铵态氮无显著影响。自然生草2、4、6和8 a 0～80 cm土层土壤硝态氮较清耕分别降低16.28%,31.31%,40.13%和47.41%,均极显著低于（P<0.01）清耕;>80～240 cm土层分别降低4.38%,12.41%,16.90%和19.39%,自然生草4、6和8 a的均极显著低于（P<0.01）清耕;但自然生草对240 cm以下土层土壤硝态氮基本无影响。不同生长年限自然生草的生物量、全碳、全氮、全磷、全钾和全钙均基本相同。自然生草提高了果实中的钙含量,降低了果实中的氮钙比、磷钙比和钾钙比,降低了果实缺钙症状的发生率,提高了果实着色面积、果实硬度和果实可溶性固形物含量。渭北旱塬果园自然生草,可有效提高果园土壤有机质,减少硝态氮积累,减少缺钙症状发生,提高果实品质。     

草甘膦的土壤酶效应研究

为了探讨当今世界使用量最大的除草剂——草甘膦的土壤环境效应,本文采用室内模拟方法,较为系统地研究了我国4类土壤：褐土、黄绵土、风沙土和红壤,共11个土样中4种主要酶类（脲酶、转化酶、磷酸酶以及脱氢酶）活性与草甘膦间的关系,计算并得到了能够表征土壤轻度污染的生态剂量值ED10。结果表明：非缓冲液法较好地反映了土壤酶的实际情况;草甘膦总体上激活土壤脲酶、转化酶和脱氢酶活性,最大增幅分别为190％、1372％和42％;抑制磷酸酶活性,最大幅度为35％;磷酸酶与草甘膦间为完．全抑制作用机理;激活脱氢酶活性揭示出草甘膦导致了土壤中微生物活性增强,从侧面反映出草甘膦是一种毒性较低的农药。计算获得4类供试土壤褐土、黄绵土、风沙土和红壤ED10值分别为168．3、438．5、35．1和141．4mg·kg^-1;在一定程度上用土壤酶活性比生物来表征土壤污染程度更敏感。土壤性质对草甘膦的毒性有重要影响。     

模拟酸雨对红壤重金属元素释放的影响研究

经过9150～10650mm的模拟酸雨淋溶以后，与对照相比，pH4．5的酸雨使红壤Cr累积释放量增加4．02％～88．54％，Co增加-2．35%～56．14％．Ni增加5．82％～79．53％．Cu增加-3．45％～82．23％．Cd增加4．87％～83．14％．Pb增加10．64％～99．19％；pH3．5的酸雨使Cr累积释放量增加6．72％～308．42％，Co增加14．17％～134．81％，Ni增加10．06％～140．32％，Cu增加-3．11％～258．89％．Cd增加8．44％～630．84％，Pb增加17．02％～483．15％。几种重金属元素释放对酸雨的敏感性依次是：Pb和Cd释放对酸雨较敏感．其次为Cr和Cu，而Ni和Co的释放对酸雨较不敏感。红壤中Cr，Co．Ni，Cu．Cd，Pb累积释放量差别较大，但不同土壤之间其分布表现出基本一致的特点，释放量大小依次是：Pb〉Co〉Ni〉Cu〉Cr〉Cd。红壤中Cr，Co，Ni，Cu，Cd．Pb的累积释放量（Q）随淋溶量（H）的变化符合二次模型。     

不同激活方法对水牛ICSI介导转基因效果的影响

本研究探讨了不同激活方法对水牛ICSI介导转基因效果的影响。水牛体外成熟卵进行ICSI介导转基因（ICSI—mediatedgenetransfer。ICSI．Tr）操作后，先用5ixmol／L的离子霉素（ionomycin，Ion）激活处理5min，然后分成3组，再分别用10μg／mL放线菌酮（cycloheximide，CHX）培养5h（CHX5h组）、10μg／mLCHX培养3h后再用2mmol／L的二甲氨基嘌呤（6-DMAP）培养2h（CHX3h-DMAP2h组）或用培养液（CM）培养3h后再用2mmol／L6-DMAP培养2h（CM3h．DMAP2h组）。结果显示，CHX5h组的分裂率、早期胚胎基因表达率和囊胚发育率最高，且显著高于CM3h．DMAP2h组（66．7％比49．5％，p〈0．05；66．7％比40．0％，p〈0．01；22．2％比9．9％，p〈0．05）。ICSI18h后检查原核形成率，发现CHX5h和CHX3h．DMAP2h处理组的完整精子头百分率显著低于CM3h-DMAP2h处理组（p〈0．05），2原核（pronucleus，PN）百分率则显著提高（42．4％比23．8％，p〈0．05；44．6％比23．8％，p〈0．01）。以上结果表明，在水牛ICSI介导转基因时，Ion联合CHX较Ion联合6-DMAP激活重构胚效果好。     

玉米不同间作方式对坡耕地水土流失的影响

针对云南山地种植措施不合理、水土资源流失严重的现状，进行了玉米间作蔬菜和草带等不同种植方式对坡耕地水土流失影响的研究。结果表明：8月份玉米间作马铃薯的径流量比玉米裸地单作减少37．4％；7月、8月份玉米间作白菜的土壤侵蚀量比玉米裸地单作分别减少46．7％和58．2％；7，8，9，10月份玉米间作混播草带（处理G）侵蚀量分别比玉米裸地单作显著减少68．9％，74．6％，84．5％和82．1％（P〈0．01）；玉米间作白菜、间作马铃薯、间作辣椒总侵蚀量分别比玉米裸地单作显著减少47．O％，43．8％和10．2％（P〈O．01）；玉米间作草带（处理D，G）总侵蚀量分别比玉米裸地单作显著减少60．8％和70．0％（P〈0．01），玉米间作马铃薯的总径流量比玉米盖膜单作减少21．0％；在低雨强、中雨强和高雨强下，玉米间作处理的平均侵蚀量分别比玉米裸地单作减少35．7％，61．4％和70．2％。说明玉米间作蔬菜和牧草能有效减轻坡耕地水土流失，在高强度降雨中，其水土保持效果更明显。     

六堡茶茶园间种黑麦草抑制杂草效果试验初报

为减少茶园草害,解决有机茶园人工除草难问题,通过在六堡茶茶园行间间种黑麦草,研究黑麦草对杂草生长的影响,同时设置清耕对照,采用小样方调查法,调查茶园杂草种群数量、生物量、株高等指标。结果表明:1)在黑麦草组中调查到7个科12种杂草,对照组共调查到13个科22种杂草,黑麦草组比对照组杂草少6个科10种杂草。2)从杂草密度、株高、盖度、干重、发生频率比较,黑麦草能有效抑制茶行间杂草的生长。     

丘陵红壤橘园不同地面管理措施的经济生态效益研究

A three-year experiment was conducted to investigate and compare the economic and ecological benefits of six types of vegetation management measures in citrus orchards of the hilly red soil region of the eastern part of China. Six vegetation treatments, including tillage without herbicide （clean tillage） and no tillage without herbicide （sod culture） and with herbicide paraquat （paraquat）, glyphosate （glyphosate）, glyphosate-glyphosate-paraquat （G-G-P）, and paraquatparaquat-glyphosate （P-P-G）, were applied in the citrus orchards on a clayey red soil with slopes of 8° and 13°and a sandy soil with slope of 25°. The results showed that the sod culture, paraquat, glyphosate, G-G-P, and P-P-G treatments reduced surface runoff by 38.8%, 42.5%, 18.7%, 28.7%, and 37.5%, then the soil-water losses by 55.5%, 51.7%, 39.9%, 46.8%, and 50.0%, and the N, P, and K nutrient losses by 60.3%, 50.2%, 37.0%, 41.8%, and 45.4%, respectively, as compared with the clean tillage treatment. The weed regeneration ratios with the treatments of clean tillage without herbicide, paraquat, glyphosate, G-G-P, and P-P-G were reduced by 55.1%, 67.2%, 30.3%, 36.8%, and 51.2%, respectively, as compared with the sod culture. The sod culture, paraquat, glyphosate, G-G-P, and P-P-G treatments could increase the soil fertility （annual accumulation of N, P, K, and OM） by 7.1%, 6.9%, 5.3%, 6.2%, and 6.6%, respectively, whereas the clean tillage treatment without herbicide reduced soil fertility by 4.4% after the three-year experiment. The citrus fruit yields in the treatments of paraquat, glyphosate, G-G-P, and P-P-G increased by 7%-10%; the soluble solid, total sugar, total acidity, sugar-acid ratio, and single fruit weight of citrus fruits of all treatments except sod culture significantly （P 〉 0.05） exceeded that of the clean tillage treatment. In general, the paraquat treatment showed the best economic and ecological benefits among the six treatments; therefore, it could be regarded as the best available vegetation     

Effects of incorporated corn residues on glyphosate mineralization and sorption in soil

In modern agricultural systems employing conservation tillage practices, glyphosate is widely used as a preplant burndown herbicide in a wide range of crops. Conservation tillage systems are characterized by a significant presence of crop residues at the soil surface so that glyphosate is applied to a soil matrix rich in poorly decomposed crop residues. Incorporation of corn residues in the range from 0.5 to 4% caused different effects on mineralization and sorption of [14C]glyphosate in sandy and sandy loam soils. More specifically, low levels of incorporated corn residues did not affect or slightly stimulated herbicide mineralization in the sandy and sandy loam soils, respectively. In the sandy soil, incorporation of the highest level of corn residues (4%) caused a decrease in [14C]glyphosate mineralization. [14C]Glyphosate sorption on both soil types was reduced in samples receiving high amounts of incorporated corn residues.     

典型水土保持措施对红壤坡地柑橘园水土保持效益的影响

为研究红壤坡地果园不同水土保持措施的水土保持综合效益,该研究采用野外标准径流小区试验方法,通过对江西水土保持生态科技园柑橘园小区长期定位观测,分析了植物措施、耕作措施、工程+植物措施和工程措施等4种不同水土保持措施的径流、泥沙、养分流失情况以及对土壤理化性质的影响。结果表明:1)各项水土保持措施的年均减流效益依次为,工程措施耕作措施工程+植物措施植物措施;减沙效益依次为,工程措施耕作措施植物措施工程+植物措施。植物措施减流效益最佳,为71.43%;工程+植物措施减沙效益表现最优,为95.88%。减氮效益为工程措施工程+植物措施耕作措施植物措施。减磷效益趋势与减沙效益一致。植物措施减氮效益最佳,为19.84%;工程+植物措施减磷效益最佳为68.94%。2)各项水土保持措施土壤理化指标,田间持水量依次为:工程措施工程+植物措施植物措施耕作措施。其中耕作措施田间持水量提高幅度最大,为14.60%;植物措施其次,提高7.19%。土壤含水率依次为,耕作措施工程+植物措施工程措施植物措施。其中植物措施土壤含水率提高幅度最大,为18.94%。土壤≥0.5mm水稳性团聚体(WSA,water-stable aggregates)质量分数值依次为,工程措施工程+植物措施耕作措施植物措施。其中植物措施WSA值提高幅度最大,为4.42%。土壤养分综合趋势与WSA值一致。土壤养分以植物措施中的百喜草全园覆盖提高最大,有机质、全氮和全磷分别增加34.53%,78.26%,12.24%。由此可知,植物措施稳定后,在减流减沙、减少养分流失及土壤改良等水土保持综合效益方面表现最优。该研究可为南方红壤丘陵区果园开发选择适合的水土保持治理措施,以及提高果园土壤质量、解决水土流失与环境问题提供参考。     

Losses of 15N-nitrogen by plant–soil system after herbicide application on black oat

Recent studies have demonstrated that the use of glyphosate or glufosinate-ammonium herbicides for some cover crop desiccation in conservationist systems could favor nitrogen (N) losses from the soil–plant system. In this context, the objective of this study was to evaluate the losses of N by the plant–soil system after the desiccation of black oat (Avena strigosa Schreb.) with the application of herbicides glyphosate, glufosinate-ammonium, or paraquat. Two greenhouse experiments were implemented using black oat plants fertilized with labeled (¹⁵N) ammonium nitrogen, and the N loss of the plant–soil system was quantified. The desiccation of black oat with glyphosate caused a reduction in root dry mass by approximately 60% in both experiments. The glyphosate and glufosinate-ammonium reduced the amount of N present in the aboveground portion; however, the paraquat herbicide did not modify it. None of the herbicides applied affected N losses in the black oat plant–soil system. However, 5–15% of the N applied as fertilizer was lost up to harvest. The results suggest that black oat can be used as a cover crop in direct sowing in order to avoid nitrogen losses in the soil–plant system.     

Nitrogen availability from alfalfa suppressed or killed for no‐till production

Abstract

There is interest in intercropping perennial legumes with com (Zea mays L.) under no‐tillage soil management. Evaluation of N availability by measuring plant N uptake in field research trials with such systems is often complicated by competition for water. We monitored soil inorganic N (ammonium and nitrate) levels at 14‐day intervals for 42 days at 0–10 cm and 10–20 cm soil depths after an alfalfa (Medicago sativa L.) sod was subjected to four different suppression treatments: a) cut and remove, b) cut and return, c) above‐ground kill with paraquat, and d) complete kill with glyphosate. The initial (14 day) release of N was similar in all treatments where residues were left or returned, but alfalfa regrowth immobilized much of the N mineralized in all treatments, except where alfalfa was killed. The greatest quantity of soil inorganic N was found on day 28 where alfalfa was killed, equal to nearly 72% of the N contained in the alfalfa topgrowth. Soil nitrate N concentrations, averaged to a depth of 20 cm and over the 28 and 42 day sampling times, were 6, 9, 13, and 28 mg N/kg for cut and remove, cut and return, paraquat and glyphosate treatments, respectively. Only where alfalfa was killed did soil nitrate concentrations reach the levels established in recently published work as indicative of no further need for fertilizer N (21–25 mg N/kg). These results suggest that a perennial alfalfa intercrop will compete with corn for available soil N. Measures of inorganic soil N might now permit the evaluation of N adequacy for com in various intercrop systems.     

Modifying profile water storage through tillage,herbicide, chemical evaporation retardent and straw mulch and its effect on rainfed chickpea (Cicer arientinum L.)

The influence of tillage, herbicide (paraquat), evaporation retardents (white opaque polythene and hexadecanol) and straw mulch, applied in the post-monsoon pre-seeding period, on soil moisture conservation and yield of chickpea (Cicer arietinum L.) was studied in a 2-year field experiment. These practices all proved to be useful in conserving more soil moisture in the 180 cm deep soil profile. Opaque polythene conserved most moisture, followed by straw mulch with an average increase of 47 mm (24%) and 32 mm (16%) over the control. Polythene and straw mulch greatly improved moisture in the seeding zone; tillage, hexadecanol and paraquat were also useful. Soil moisture conservation treatments improved plant stand, profile water use, yield and yield components. The effect of treatments varied with crop season rainfall. In the first year, with low rainfall (51 mm), polythene and straw mulch significantly increased the grain yield over other treatments. Hexadecanol, tillage and herbicide also tended to increase yields. In the second, wetter crop season (rainfall 139 mm), the differences in yield between treatments were not significant though the trend was similar to the dry year. Polythene and straw mulch increased yields over the control by 690 and 536 kg/ha in the first year and 399 and 281 kg/ha in the second year. Polythene and hexadecanol being costly, straw mulch, tillage and herbicide offer scope for adoption at field scale.     

生草栽培对南丰蜜橘园土壤微生物群落结构与功能特征的影响

为探究橘园生草对土壤微生物群落结构与功能特征的影响,本研究以南丰蜜橘(Citrus reticulita Blanco cv.Kinokuni)为研究对象,设置行间播种白三叶草(Trifolium repens)、黑麦草(Lolium multiflorum)、自然生草和清耕4个处理,采用荧光定量PCR技术和Illum...     

Herbicide effects on soil arthropod dynamics and wheat straw decomposition in a North Carolina no-tillage agroecosystem

Summary Herbicide combinations of paraquat, glyphosate, alachlor, linuron, fluazifopbutyl, aciflurofen, and bentazon were investigated for their impact on soil arthropod population dynamics and surface wheat straw decomposition (weight loss) within a North Carolina coastal plain agroecosystem. Herbicides were applied twice (preemergence and mid-bloom) at recommended field rates to soybeans no-till planted into wheat residue. Separate measurements were made for surface crop residue and soil-dwelling (0–3 cm depth) arthropods. Decomposition of herbicide (glyphosate) and nonherbicide-treated wheat straw residue was compared using mesh bag techniques. Decay rate constants were estimated for glyphosate and nonherbicide-treated wheat straw residue by fitting a two-component model to the data. Comparison of soil microarthropod numbers from herbicide and nonherbicide treatments showed no consistent trend, suggesting that abiotic factors such as soil temperature and moisture were probably more significant than herbicide effects in regulating soil microarthropod number and activity. Herbicides had no effect on soil macroarthropod number or activity until late in the season when macroarthropods were most abundant under weedy, no-tillage conditions. Moist soil and litter, low soil temperature, floral diversity, and high weed-seed availability probably enhanced macroarthropod numbers in nonherbicide treatments. Decomposition (ash-free weight loss) of nonherbicided, surface crop residues was more rapid than herbicide (glyphosate) treated, indicating that herbicide effects occur at the decomposer as well as producer level of agroecosystems.Paper No. 9957 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601, USA     

除草剂对不同种植年限柑橘园土壤氮转化过程及温室气体排放的影响

为探讨除草剂施用对柑橘园土壤氮转化及温室气体排放的影响,在实验室培养条件下,研究了0年(林地)、种植10年和30年的柑橘园土壤中分别添加除草剂草甘膦和丁草胺后,尿素态氮含量、硝化和反硝化作用以及温室气体排放的变化。研究结果表明,橘园土壤中尿素第1 d的水解率、氮肥硝化率、反硝化作用损失总量以及N_2O和CO_2排放量显著高于林地土壤(P0.05)。与10年橘园土壤相比,30年橘园土壤显著增加了尿素的水解速率、氮肥硝化率和CO_2排放量(P0.05),但二者的反硝化损失量没有显著差异。施用草甘膦和丁草胺都显著促进了林地土壤的尿素水解(P0.05),第1 d尿素态氮含量分别降低11.20%和12.43%;但对3种土壤氮肥的硝化率均没有明显影响。施用丁草胺显著降低了林地土壤的CO_2排放量(P0.05),对两种橘园土壤的CO_2排放没有明显影响,但明显增加了两种橘园土壤的N_2O排放总量(P0.05),分别比不施除草剂增加56.27%和85.41%;施用草甘膦对3种土壤的N_2O和CO_2排放均没有明显影响。可见,草甘膦和丁草胺的施用不会对柑橘园土壤的氮转化过程产生影响,但丁草胺显著增加了柑橘园土壤的N_2O排放。