耕作和养分管理方式对冬小麦-夏玉米轮作农田春季杂草群落的影响

保护性耕作和杂草多样性是现代生态农业关注的热点问题.尽管保护性耕作下农田杂草多样性有所提高,但耕作方式与养分管理方式对农田杂草群落多样性的交互影响尚未探明.本研究以山东省济南市一块连续3年施行不同耕作方式(免耕、深松、旋耕、深耕)和不同养分管理措施(农户常规:年施氮肥480 kg·hm^-2,高产高效:年施氮肥360 kg·hm^-2,优化管理:年施氮肥300 kg·hm^-2)的冬小麦-夏玉米轮作农田为研究样地,调查并比较了不同管理模式下农田春季杂草群落特征.结果表明: 该冬小麦-夏玉米农田春季杂草群落共发现杂草15种,其中优势物种为马唐和稗;与深耕和旋耕相比,免耕和深松下杂草密度较高.在群落多样性方面,深耕处理下的物种丰富度和均匀度最低,而群落优势度高于其余3种耕作方式;在养分管理中,随着施肥量的增加,物种丰富度和均匀度均升高;深耕和旋耕处理下,随着施肥量的增加,群落优势度升高;而在免耕深松处理下,群落优势度会随着施肥量的增加而减少.在杂草群落生物量方面,免耕和深松的生物量显著高于深耕和旋耕,农户常规处理均高于其余两种养分管理方式,杂草生物量最高的组合是免耕+农户常规.免耕和施肥将提高农田春季杂草群落丰富度、均匀度和生产力.     

耕作方式对华北寒旱区燕麦田杂草群落结构的影响

为了明确不同耕作方式对燕麦田杂草群落结构及作物生产的影响,依托华北寒旱区定位10年的免耕、深松、翻耕田间试验,并设置10年免耕后翻耕和10年深松后翻耕处理,监测了2种土壤类型下燕麦田不同耕作方式的杂草总密度、优势杂草种类、杂草多样性指数和生物量以及燕麦产量.结果表明: 区域杂草群落结构以狗尾草为主;长期免耕下燕麦田不同生育期杂草密度为翻耕的2.20～5.14倍,而长期免耕或深松后翻耕处理的杂草密度与翻耕差异不显著.免耕下砂质栗钙土与壤质草甸栗钙土燕麦田的杂草Shannon多样性指数分别达0.429和0.531,免耕下杂草生物量是翻耕处理的1.35和2.26倍,而燕麦生物产量较翻耕处理减少22.3%和46.2%.表明耕作方式与土壤类型共同决定杂草群落特征.华北寒旱区长期免耕具有促进农田植物群落自然演化、容蓄多年生宿根类杂草的特征,而翻耕具有降低一年生杂草密度、灭除浅位性宿根杂草、激发深位性宿根杂草的特征;杂草多样性与作物高产性相悖演化.     

不同施肥方式对稻麦轮作田土壤杂草种子库的影响

为揭示不同施肥方式(纯施化肥、有机肥配施化肥、秸秆还田配施有机无机肥、有机无机复合肥)对稻麦两熟制地区农田土壤杂草种子库的影响, 在江苏常州金坛区进行了固定施肥试验。经过连续4年试验处理后, 对不同施肥处理下农田土壤杂草种子库杂草种子种类及密度进行了调查, 并对杂草种子多样性、数量、分布与施肥措施的关系进行了分析。结果表明, 与不施肥相比, 施肥有减少稻麦轮作田土壤杂草种子库杂草种子种类数、杂草种子群落均匀度指数和物种多样性指数的趋势, 并使稻麦轮作田土壤杂草种子库杂草种子总密度明显降低。施肥明显提高了土壤杂草种子库菵草(Beckmannia syzigachne)、日本看麦娘(Alopecurus japonicus)、看麦娘(A. aequalis)种子的密度, 施用猪粪堆肥配施化肥处理提高程度更为显著; 秸秆还田配施化肥、秸秆还田配施有机肥化肥、有机无机复合肥施用处理有减少菵草、日本看麦娘、看麦娘杂草种子密度的趋势。施肥明显降低了土壤杂草种子库阔叶杂草种子密度; 施用有机肥有增加土壤杂草种子库水苦荬(Veronica undulata)、蛇床(Cnidium monnieri)种子密度的趋势; 施用猪粪堆肥有增加土壤杂草种子库鸭舌草(Monochoria vaginalis)种子密度的趋势。因此, 不同种类杂草对不同肥料存在偏好性差异, 不同施肥方式造成了土壤杂草种子库优势物种组成的差异。     

不同施肥条件下黄土麦地杂草生物多样性

采用倒置“W”9点取样法,研究了黄土区9种不同施肥处理长期肥料定位试验小麦田间杂草的生物多样性.结果表明,不同施肥条件下小麦田间杂草组成有一定差异,试验区共有杂草16种,隶属10科16属,约占陕西省麦田杂草种数的34%.随着土壤养分状况的改善,杂草的物种多样性逐渐减少,氮磷钾及其与有机物料配合施用处理（NPK、SNPK、M1NPK、M2NPK）的杂草种群为3～5个,对照及氮、氮磷、氮钾处理(CK、N、NP、NK)杂草种群为6～8个;不同施肥处理杂草相对丰度为0～73%,Shannon多样性指数为0.2～1.08,Shannon均匀度指数为0.05～0.26,Margalef物种丰富度指数为0.26～1.26.不平衡施肥处理的3个多样性指数都高于平衡施肥处理,且大部分达到显著水平.     

土壤耕作及秸秆还田对夏玉米田杂草生物多样性的影响

于2008年夏玉米(Zea mays)生长期间,在连续5a秸秆全量还田的免耕、旋耕、耙耕、深松和常规耕作试验地中,研究了杂草总密度、优势杂草种类、生物多样性指数、杂草生物量和夏玉米产量。调查共记录杂草种类13种,秸秆全量还田时,免耕显著提高杂草的总密度;无秸秆还田时,常规耕作的杂草密度高于免耕、旋耕、耙耕和深松。秸秆全量还田后,免耕和深松条件下,杂草优势种为马唐和旱稗,旋耕和耙耕条件下为马唐、旱稗和牛筋草;常规耕作条件下,优势杂草为马唐、苘麻、旱稗和香附子。无秸秆还田条件下,免耕和常规耕作增加了杂草优势种的数量。秸秆全量还田后,免耕、耙耕和深松等耕作措施导致杂草群落的物种丰富度及均匀度均较高。无论哪种耕作条件,5a连续秸秆还田能够显著提高夏玉米籽粒产量和生物学产量,其中尤以常规耕作秸秆全量还田处理产量最高,且田间杂草的生物学产量与夏玉米的生物学产量呈显著负相关关系。     

保护性耕作对陇东黄土高原轮作田杂草的影响

以陇东黄土高原旱地连续12年保护性耕作为基础,通过田间取样调查,研究了4种耕作措施下冬小麦-箭筈豌豆-玉米轮作田中杂草的组成和群落特征.结果表明： 不同作物生长期的杂草种类、密度和群落特征各异.免耕使冬小麦生长期杂草密度显著增大,轮作箭筈豌豆后免耕处理的杂草密度变小;秸秆覆盖显著降低了玉米生长期的杂草密度,玉米生长期免耕+秸秆覆盖处理的杂草密度最低.冬小麦和箭筈豌豆轮作前后杂草的群落多样性特征完全相反,从冬小麦生长期到箭筈豌豆生长期,免耕处理杂草群落的多样性指数先高于常规耕作处理,后期低于常规耕作处理;玉米生长期免耕处理的多样性指数均大于其他3种处理.因此,免耕和秸秆覆盖在一些作物生长期能抑制杂草的发生和分布,3种作物轮作对杂草防治具有明显作用.     

耕作措施和施肥方式对麦田杂草密度和生物量的影响

为明确我国华北地区麦玉轮作系统小麦免耕的推广和施肥方式的改变对麦季杂草生长的影响,在免耕实施5年后,调查了麦田杂草密度、单株质量和生物量。结果表明:华北地区小麦生长早期,免耕有降低麦田杂草总密度和优势种播娘蒿密度趋势,但差异并不显著;相对于传统耕作,免耕秸秆覆盖和不覆盖处理总杂草生物量显著降低,其中播娘蒿生物量分别降低了57%和73%;免耕也使播娘蒿单株质量降低了27%～53%;免耕秸秆覆盖和不覆盖处理播娘蒿的株高分别比传统耕作降低了25%和19%;但一般情况耕作方式并没有显著影响离子草和麦家公生长;相对于分次施肥,集中施肥杂草生物量降低了21%～68%,播娘蒿生物量降低了58%～65%,麦家公降低91%;免耕在一定程度上抑制了某些杂草的生长,但追肥促进了杂草的快速生长。     

陕北黄土丘陵沟壑区水土保持耕作及施肥下农田土壤种子库特征

为了探明多年免耕下农田恶性杂草发生的机理,提高保护性耕作下作物对农田恶性杂草持久稳定的抑制效果,依据陕西安塞田间4a的定位试验, 采用小区调查取样和室内实验相结合的方法,从物种组成、密度特征、多样性以及相似性特征等方面,研究了黄土丘陵旱作农区大豆(Glycine max)、玉米(Zea mays)、红小豆(Semen Phaseoli)、马铃薯(Solanum tuberosum)在翻耕化肥(CF)、翻耕有机肥(CM)、翻耕无肥(CN)、免耕化肥(NF)、免耕有机肥(NM)、免耕无肥(NN)等水平下的农田土壤种子库.结果表明: (1) 4种作物24种土样中共萌发出12个物种1965株幼苗,隶属于7科12属.1年生杂草占94%,棒头草(fugax nees ex steud)、苋菜(Acalypha australis)、马唐(Digitaria sanguinalis)、早熟禾(Poa sphondylodes)为优势种,占87%.(2)在0～20cm土层不同处理间,土壤种子库的密度变动于(282.9±63.4)～(7482.5±1078.3)粒·m- 2,其中,红小豆小区＞马铃薯小区＞大豆小区＞玉米小区;翻耕小区＞免耕小区;有机肥小区＞化肥小区＞无肥小区,差异极显著. (3)土壤种子库密度NM红小豆最高,NN玉米最低;丰富度指数CF大豆为2.30;NN红小豆为0.29;多样性指数NN大豆为5.56,CF红小豆为0.45;生态优势度NF玉米为1.35,CF大豆为0.17.玉米、大豆是黄土丘陵沟壑旱作农区免耕下农田抑制杂草最为适宜的作物, NM玉米、NF大豆和NM大豆是黄土丘陵沟壑旱作农区较优的耕作管理方式,其农田的生态效应是能够竞争性抑制恶性杂草的蔓延,优化土壤环境,杂草的多样性高且比较均衡,杂草的土壤种子库密度低.     

长期施肥对早稻产量和杂草群落的影响

利用1982年布置的双季稻红壤稻田长期施肥定位试验,于2011年研究了在无机肥(化肥NPK)与有机肥(M)氮磷钾养分等量条件下,长期施用有机肥、无机化肥和有机无机肥配施模式下早稻生长发育、早稻产量及稻田杂草群落变化。结果表明:施肥能促进早稻生长发育,显著提高早稻产量,增加施肥用量和均衡肥料及养分种类在一定程度上能促进早稻生长发育和稻谷增产;在施用有机肥的基础上,优先考虑施用氮肥,其次是磷肥,才能使红壤稻田早稻增产。施肥处理中,单施有机肥最能提高早稻杂草密度和促进早稻杂草生长,配施处理中,有机无机均衡配施最能促进早稻杂草生长,还能遏制恶性杂草繁殖;与单施有机肥或化肥相比较,有机无机肥配施能普遍降低早稻杂草群落多样性、优势度和均匀度,在施用有机肥的基础上,化肥尤其是化肥氮的施用对早稻杂草群落的多样性、优势杂草和均匀度起着决定性作用;早稻分蘖盛期杂草生物量一定程度上还能表征早稻稻谷产量。     

施肥对玉米田大型土壤动物群落的影响

采用手捡法对玉米田秸秆回填及施肥处理条件下大型土壤动物群落组成及多样性进行研究。结果表明,玉米田内土壤动物数量与施肥情况有关。不同施肥处理玉米田内土壤动物个体总数从多到少依次为：NPK正常施肥秸杆不回田处理〉不施肥处理;全部秸杆回田处理〉CK对照处理（秸杆不回田、不施肥）。土壤动物类群数依次为：NPK正常施肥秸杆不回田处理=不施肥处理（全部秸杆回田）〉CK对照处理（秸杆不回田,不施肥）。生物多样性指数分析表明,不同处理之间生物多样性无明显差异,但在玉米生长不同时期内,生物多样性有明显差异。     

Effects of tillage systems on wheat and weed water relationships over time when growing together,in semiarid conditions

Water availability directly influences interactions and competition between weeds and crops. This article is based on the idea that relative water content (RWC) indicates the water uptake within plants and that it is possible to explain the water relationships between plants that are growing together. A field experiment carried out for 3 years (2013–2014, 2014–2015 and 2015–2016) compared the short-term effects of years and tillage systems on wheat grain yield, weed density, wheat-RWC, weed-RWC and soil water content (SWC), at tillering and flowering stages in a winter wheat monoculture system. The three tillage treatments were conventional tillage (CT), minimum tillage (MT) and no-tillage (NT). Wheat grain yield was low all years of study, because of low interannual rainfall, and we did not observe differences between tillage systems. Weed density was also affected by year and not by tillage systems. Lowest winter rainfall (73.4 mm from Nov to Feb) in the last year of the study (2015–2016), decreased the weed density in all tillage systems. Despite the rainfall variability over the 3 years of study, the NT system presented higher weed density (73 plants/m²) than MT and CT systems (39.83 and 46.33 plants/m²). We also observed a higher number of weed species for the NT system, facilitated by a high soil water storage in this system. The wheat-RWC, at tillering stage, varied with years and tillage systems; we found that high winter rainfall (2013–2014) led to higher values in CT (64.5%) compared with MT (52.9%) and NT plots (52.9%). Weed-RWC values did not vary and SWC was greater in NT than in CT and MT. At flowering stage, the year (2015–2016) with highest spring rainfall favoured higher wheat-RWC in NT (56.9%) compared with CT (48.3%). However, the lowest spring rainfall coincided with the lowest weed-RWC, (18% in NT plots) and SWC was always higher in NT soils. The results showed that climatic conditions affected the water competence dynamics between weeds and wheat in different ways. Seemingly, weeds can tolerate a lack of water availability until crop tillering stage independently of tillage system; however, the competition for water was not a problem as crops overcame the high weed density by flowering stage.     

玉米田养鹅措施对杂草群落生态特征的影响

探索如何在利用和控制农田杂草的同时又能维持较高的杂草群落多样性的生产方式, 是当前农业发展的重要方向。作者以“农牧一体化”生产方式下的“玉米(Zea mays)田养鹅”处理和常规玉米种植处理为研究对象, 探讨了玉米田养鹅处理放牧前后及同期常规玉米种植处理下杂草生态位、功能群结构和杂草群落生物多样性的变化。结果表明: (1)在玉米田养鹅模式下, 黑麦草(Lolium multiflorum)、紫花苜蓿(Medicago sativa)和灰绿藜(Chenopodium glaucum)在放牧前的生态位宽度较大, 但放牧后黑麦草、紫花苜蓿的生态位宽度减小, 而灰绿藜、尼泊尔蓼(Polygonum nepalense)、西南草莓(Fragaria moupinensis)和老鹳草(Geranium sibiricum)等物种的生态位宽度则有不同程度的增大, 放牧后群落内新增加了7种杂草; 对照中, 前期丝叶球柱草(Bulbostylis densa)的生态位宽度最大, 而后期鼠麹草(Gnaphalium affine)的生态位宽度变为最大, 新增2种杂草。(2)放牧前玉米田养鹅处理下的黑麦草和紫花苜蓿的重叠度最大, 而放牧后黑麦草和西南草莓的重叠度变为最大; 在常规玉米种植模式下, 前期丝叶球柱草和马唐(Digitaria sanguinalis)的重叠度最高, 而后期丝叶球柱草和鼠麹草的重叠度最高。(3)两种模式下放牧前后均是一年生双子叶(DA)杂草功能群占据最大优势, 但玉米田养鹅处理模式下放牧后多年生功能类群所占的比例较放牧前增加, 且分配更均匀。(4)放牧前, 玉米田养鹅处理的Shannon-Wiener多样性指数、Margalef物种丰富度指数和Simpson多样性指数均高于对照, 其中Shannon-Wiener多样性指数和Margalef物种丰富度指数差异显著(P<0.05, n=3), 而Pielou均匀度指数低于对照, 但差异并不显著(P>0.05, n=3); 放牧后玉米田养鹅处理的Shannon-Wiener多样性指数和Margalef物种丰富度指数仍显著高于对照(P<0.05, n=3), 而Pielou均匀度指数和Simpson多样性指数则分别显著低于对照 (P<0.05, n=3)。放牧前后, 玉米田养鹅处理杂草群落的地上总生物量均高于对照, 但差异不显著(P>0.05, n=3)。(5)玉米田养鹅处理的玉米产量与对照相比减产4.0%, 但并未达到显著差异(P>0.05, n=12)。总的来看, 玉米田养鹅生产方式维持了较高的农田生态系统生物多样性, 虽然造成了一定的减产, 但可通过鹅的产出获得更高的经济效益。     

The conservation of arable weeds at crop edges of barley fields in northeast Spain

The effects of weed control practices and fertilisation on weed flora and crop yield were evaluated in crop edges of barley fields in northeastern Spain. The study was carried out in four organic and four conventional barley fields. In each field, four permanent plots were delimited at the crop edge, and fertilisation and weed control treatments in a factorial design were applied over 3 years. Weed composition and the aboveground biomass of weeds and barley were recorded before the crop harvest in the first and the third year. We found relatively low values of species richness per field, as well as low values of weed biomass, especially in the organic crop edges (3.9% of total biomass). Weeds were significantly reduced by herbicide applications on conventional fields and were not affected by weed harrowing on organic fields or fertilisation. These results demonstrate that specific measures are needed to enhance biodiversity at crop edges both in organic and conventional fields. Our results also suggest that under Mediterranean conditions and among impoverished weed communities, limiting the use of herbicides is crucial to enhancing arable diversity and that, contrary to findings found in previous studies in temperate climates, fertilisation and weed harrowing have little effect on weeds.     

保护性耕作和杂草管理对冬小麦农田土壤水分及有机碳的影响

在秸秆全量还田的试验田中(从2004年起),于2008-2009年及2009-2010年冬小麦生育期间,研究了不同耕作措施(旋耕、耙耕、免耕、深松和常规耕作)和杂草管理对冬小麦田土壤水分及有机碳的影响.结果表明:在未除草条件下,免耕、深松的杂草总密度显著提高;而在除草条件下,杂草密度显著下降.小麦从拔节期到灌浆期0～60 cm土层水分含量呈明显波动变化,田间保留一定量的杂草可增加不同耕作方式0～20 cm的土壤水分含量,表现出一定的土壤水分保持效应.保留杂草仅提高了拔节期0～20 cm土层的土壤有机碳含量;而在抽穗期和灌浆期,0～20、20～40和40～60 cm土层有机碳含量均低于去除杂草处理.去除杂草条件下,深松显著提高了冬小麦籽粒产量;保留杂草条件下,旋耕的籽粒产量最高,常规耕作产量最低.     

不同方式处理牛粪对大豆生长和品质的影响

大型养殖场粪便堆积造成严重的环境污染,对这类废弃物开展资源化利用研究具有重要生态学和经济学意义。以不施肥料处理(CK)为对照,研究了生态养殖场牛粪经腐熟(DD)和蚯蚓处理(RD)后对大豆生长与品质的影响。研究表明:生态养殖场牛粪经过两种处理后,在一定施用量范围(DD≤30 t/hm2,RD≤45 t/hm2)内,可显著增加大豆株高、分株数、干物质积累,促进植株生长,增加单株荚数、籽粒数、籽粒重,提高大豆产量(P<0.01)。施入腐熟牛粪30 t/hm2株高和单株结荚数比CK分别增加24.2 cm、63%;经蚯蚓处理后,可以提高牛粪施用量的上限,施入蚯蚓处理过的牛粪45 t/hm2时产量最高、单株结荚数最多,比CK分别增加72%和75%(P<0.01);施入蚯蚓处理过的牛粪15 t/hm2时,粗蛋白含量、蛋脂总量最高,比CK分别增加7%和6%(P<0.01)。本研究可为大型养殖场牛粪资源化利用提供科学依据。     

Developing a set of simulation-based indicators to assess harmfulness and contribution to biodiversity of weed communities in cropping systems

Weeds are both harmful for agricultural production and an essential component of biodiversity in agricultural landscapes. Therefore, new cropping systems aiming at both maximising weed-related biodiversity and minimising weed harmfulness are needed. New cropping systems are now increasingly designed with weed dynamics models but these usually only consider weed densities or crop yield losses. The present paper proposed a set of indicators for assessing the impact on crop production and biodiversity of weed communities simulated with a cropping system model. Five harmfulness indicators were developed to take account of the criteria most frequently listed by farmers via an internet survey: (1) crop yield loss, (2) harvest pollution by weed seeds, stems and leaves, (3) harvesting problems due to green weed biomass blocking the combine, and (4) field infestation represented by weed biomass averaged over cropping seasons. A fifth indicator was added, i.e. (5) the increase in crop disease (i.e. take-all disease of cereals) in the presence of weeds. The biodiversity indicators were chosen in collaboration with ecologists. Two indicators reflect the weed contribution to vegetal biodiversity: (1) species richness and (2) Pielou's index for species equitability. Three other indicators were developed to assess weeds as a trophic resource for other organisms in the agro-ecosystems: (3) the number of weed seeds present on soil surface in autumn and winter to feed field birds, (4) lipid-rich seeds on soil surface in summer to feed insects such as carabids, and (5) weed flowers in spring and summer to feed domestic bees. These indicators were tested in a series of contrasted cropping systems identified in farm surveys and simulated with FlorSys. Analyses of variance showed that the cropping system and the crop sequence presented the highest impact on indicator values. Weather scenario and pedoclimate had little effect. Antagonisms and synergies between weed-related harmfulness and biodiversity were identified with Spearman correlations. Harmfulness indicators were all positively correlated, except for additional disease risk which was at best poorly correlated with other indicators. Most weed-related biodiversity indicators were also positively correlated, except species richness which was negatively correlated with species equitability, bird resource and insect resource. Weed harmfulness generally increased with increasing weed-related biodiversity. These correlations were though weak, and others were negative, showing that increased biodiversity could occur with decreased harmfulness (e.g. trophic resource for insects vs. yield loss or field infestation). Consequently, there are cropping systems that reconcile agricultural production and biodiversity.     

Weed development in spring wheat after contrasting soil tillage and nitrogen management

Soil tillage and nitrogen (N) management effects on weed species composition were evaluated in 2013 and 2014 on a clayey soil after 5‐years of organic management at the Royal Agricultural University's Harnhill Manor Farm, UK. Three tillage systems – Conventional Tillage (CT), and High and Low Intensity Non‐inversion Tillage (HINiT & LINiT) – were compared at four N fertiliser rates of 0, 70, 140 and 210 kg N ha^?1. Broad‐spectrum herbicide was applied before soil operations across the site in both years. Previous organic management legacy of high weed biomass promoted greater weed prevalence in 2013 while 2‐years of herbicide inclusion reduced weed biomass. Contrasting weather conditions across the seasons affected weed incidence. In the 2014 wet season, early weed dry weight (DM) was higher under HINiT than CT and LINiT, while no differences were observed in the 2013 dry year. At midseason, weed DM was higher under HINiT than CT and LINiT in both years, which was related to higher DM of the dominant weeds Stellaria media (L.) Vill. and Sinapis arvensis L. Grass weed DM was higher under non‐inversion tillage than CT. N fertilisation increased midseason total weed DM and weed prevalence at harvest. Spring wheat yield was the highest under CT while LINiT produced 17% higher yields than HINiT. Despite higher but still tolerable weed prevalence under both non‐inversion tillage systems and with the application of N, weeds alone was not the only yield‐limiting factor. However, results show that CT is the most reliable option for weed control in changing weather, while N fertilisation rates needs to be considered.