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1.
ABSTRACT Soil fertility amendments, including composted cotton-gin trash, swine manure, a rye-vetch green manure, or synthetic fertilizers, were applied to subplots and tillage on bare soil; or tillage followed by surface mulch with wheat straw were applied to main plots to determine the effect on the incidence of southern blight caused by Sclerotium rolfsii, yield of processing tomato, and soil microbial communities. The amendment-tillage interaction was significant in 1997 and disease incidence was 67% in tilled bare soil receiving synthetic fertilizers; whereas disease incidence was 3, 12, and 16% in surface-mulched plots amended with a composted cotton-gin trash, swine manure, or a rye-vetch green manure. The amendment effect was significant in 1998, and disease incidence was 61% in plots receiving synthetic fertilizer and was 23, 44, and 53% in plots receiving cotton-gin trash, swine manure, or rye-vetch green manure, respectively. In 1997, yields were highest in tilled surface-mulched plots amended with synthetic fertilizers, cotton-gin trash, or swine manure, respectively. In 1998, yields were low in all plots and there were no significant differences in yield due to treatment. Propagule densities of antagonistic soil fungi in the genus Trichoderma were highest in soils amended with composted cotton-gin trash or swine manure in both years. Propagule densities of fluorescent pseudomonads in soil were higher in plots amended with organic amendments than with synthetic fertilizers in both years. Propagules densities of enteric bacteria were elevated in soils amended with raw swine manure biosolids in both years. Our research indicates that some organic amendments, such as cotton-gin trash, reduced the incidence of southern blight in processing tomato and also enhanced populations of beneficial soil microbes.  相似文献   

2.
Weed flora in a crop rotation of soybean, sugar beet, and spring wheat were studied under combinations of conventional and reduced tillage, biocide application, and chemical fertilization to investigate whether any combination of conservational practices offers the potential to increase weed community diversity while maintaining weed biomass at an acceptable level. Weed density increased under reduced biocide application. Weed density and size increased under manure compost application (with reduced chemical fertilization) because of weed seed introduction. Weed emergence from seeds dispersed in the previous year was greater under reduced tillage. Two-year individuals increased under a combination of reduced tillage, reduced biocide application and manure compost application. These increases in weed population density and size under conservational practices were yet not consistent; rather, they showed an annually fluctuating trend. In terms of weed diversity, species richness and Shannon's diversity index were higher under manure application because of the introduction of new species and probably as a result of suppression of weed growth and reproduction, which can reduce the chance of dominance by certain species. When combined with manure application, reduced tillage may offer the potential for increasing diversity by reducing the competitiveness of dominant species and facilitating establishment of new or minor species.  相似文献   

3.
不同施肥方式对稻麦轮作制稻田杂草群落的影响   总被引:1,自引:0,他引:1  
为揭示不同施肥(纯施化肥、有机肥配施化肥、秸秆还田配施有机无机肥、有机无机复混肥)对稻—麦两熟制区稻田杂草的影响,以南京农业大学连续4年固定施肥金坛试验田为材料,于2014年水稻收获前进行了杂草群落调查,研究不同施肥、秸秆还田水稻田间杂草种类、密度、高度和杂草多样性指数的差异。结果表明:试验水稻田共记录杂草16种,分属7科、11属。稗草(Echinochloa crusgalli)、鸭舌草(Monochoria vaginalis)、多花水苋(Ammannia multiflora)、水苋菜(A.baccifera)、陌上菜(Lindernia procumbens)广泛分布于各试验田块。长期施肥可减少稻田杂草种类及发生密度。其中阔叶杂草和莎草科杂草在试验设定的各施肥措施下其种类和密度均显著下降,但株高显著增加;禾本科杂草种类、密度和株高几乎不受影响。秸秆还田配施化肥、有机肥配施化肥、有机无机复混肥+穗肥尿素和纯施化肥的田块中,杂草群落多样性指数低、均匀度指数相对较低,优势度指数较高,容易使单一优势杂草种类暴发,造成较严重危害;秸秆还田配施有机肥化肥、有机无机复混肥一次施用的稻田环境中,杂草群落多样性指数较高,均匀度指数较高,优势度指数较低,杂草群落结构较复杂,群落相对较稳定,且杂草密度较低,对水稻的生长危害较轻。  相似文献   

4.
Organic soil amendments including composted cotton gin trash, composted poultry manure, an incorporated rye-vetch green manure, or synthetic fertilizer were applied to subplots, and main plots were either tilled frequently or surface-mulched in experimental field plots between 1997 and 2004. Soil from each replication of the tillage and fertility treatments was sampled in August of 2001, 2002, and 2003, brought to the greenhouse, and infested with Phytophthora capsici to study the effect of previous soil treatments on disease incidence and dispersal of the pathogen. Both the previous tillage and fertility amendments affected the incidence of disease and dispersal of the pathogen. Final disease incidence, AUDPC and the distance of pathogen spread were significantly greater in soils with previous surface mulch applications than in frequently tilled soils. Final disease incidence, AUDPC and the distance of pathogen spread were also significantly higher in soils amended with cotton gin trash, than rye-vetch green manure, poultry manure, or synthetic fertilizer. Soils amended with cotton gin trash had higher soil water content, lower bulk density, higher humic matter content, higher porosity and higher levels of mineralizable N, than soils with other fertility amendments. Soil water content, soil porosity, humic matter content, and net mineralizable levels nitrogen were positively correlated and bulk density was negatively correlated with final incidence of disease.  相似文献   

5.
The vegetation cover during the non‐cropping season could have important implications for the maintenance and recovery of soil fertility, as well as for biodiversity conservation in croplands. In this study, five fertilization regimes (control: non‐fertilization; N: inorganic N fertilization; P: inorganic P fertilization; NPK: balanced fertilization with inorganic N, P and K; NPKM: balanced NPK plus farmyard manure) were conducted from 1981 in a double‐rice (Oryza sativa L.)‐cropping system in subtropical China. The effects of long‐term fertilization were investigated on the weed growth, diversity and community structure during the fallow period. The results showed that, relative to the control, both inorganic fertilization alone (N, P and NPK) and NPKM in the rice‐growing season significantly increased the weed density and biomass during the fallow period in the paddy field. There was no significant difference in the weed species richness (the number of species) among the treatments. Compared with the control, fertilization tended to reduce the weed diversity (Shannon's H′) and evenness (Shannon's E), especially in the N treatment. Long‐term fertilization resulted in a significant shift in weed community's composition during the fallow period. The weed community's structure was affected by soil nutrients in the order P > N > K.  相似文献   

6.
长期施肥对土肥力及作物产量的影响   总被引:2,自引:0,他引:2  
对陕西关中典型土壤———土进行了连续25 a的定位施肥试验。通过对25年来不同施肥小区土壤肥力差异的分析研究表明:多年连续施肥,可以明显提高土壤中有机质、全氮、全磷、碱解氮、速效磷含量以及作物产量,即单施化肥或有机—无机肥料配合施用,都可以增强土壤养分容量及其供应强度,有利于培肥土壤,提高作物产量,其中又以有机—无机肥料配合施用的效果更好。  相似文献   

7.
A minimal amount of information is currently available concerning arbuscular mycorrhizal (AM) fungal associations with crops in semi-arid zones on Leptosols in Turkey. Therefore, using molecular ecological techniques, we studied the effects of different management practices (without fertilization, chemical fertilization, farmyard manure, and plant compost amendments) on AM fungal communities associated with wheat roots. Experiments were conducted in a field established in 1996 in southern Mediterranean Turkey where soil productivity is low owing to unfavorable climatic effects and soil characteristics. We determined 201 partial sequences of AM fungal nuclear ribosomal large subunit genes. The higher AM fungal richness was found in the control treatment without fertilization and plant compost treatments compared with the chemical fertilization and farmyard manure treatments. Clones related to Rhizophagus were found in all treatments and accounted for 37% of the total AM fungal clones, whereas those of Funneliformis were dominant under chemical fertilization. Redundancy analysis based on the frequency of operational taxonomic units revealed that AM fungal communities were divided into three groups, namely, the control treatment, the chemical fertilization treatment, and the organic treatments (farmyard manure and plant compost treatments). Although different organic amendments supported relatively similar AM fungal communities, plant compost induced higher AM fungal richness than farmyard manure fertilization.  相似文献   

8.
Changes in both soil organic C storage and soil respiration in farmland ecosystems may affect atmospheric CO2 concentration and global C cycle. The objective of this field experiment was to study the effects of three crop field management practices on soil CO2 emission and C balance in a cotton field in an arid region of Northwest China. The three management practices were irrigation methods(drip and flood), stubble managements(stubble-incorporated and stubble-removed) and fertilizer amendments(no fertilizer(CK), chicken manure(OM), inorganic N, P and K fertilizer(NPK), and inorganic fertilizer plus chicken manure(NPK+OM)). The results showed that within the C pool range, soil CO2 emission during the whole growing season was higher in the drip irrigation treatment than in the corresponding flood irrigation treatment, while soil organic C concentration was larger in the flood irrigation treatment than in the corresponding drip irrigation treatment. Furthermore, soil CO2 emission and organic C concentration were all higher in the stubble-incorporated treatment than in the corresponding stubble-removed treatment, and larger in the NPK+OM treatment than in the other three fertilizer amendments within the C pool range. The combination of flood irrigation, stubble incorporation and application of either NPK+OM or OM increased soil organic C concentration in the 0-60 cm soil depth. Calculation of net ecosystem productivity(NEP) under different management practices indicated that the combination of drip irrigation, stubble incorporation and NPK+OM increased the size of the C pool most, followed by the combination of drip irrigation, stubble incorporation and NPK. In conclusion, management practices have significant impacts on soil CO2 emission, organic C concentration and C balance in cotton fields. Consequently, appropriate management practices, such as the combination of drip irrigation, stubble incorporation, and either NPK+OM or NPK could increase soil C storage in cotton fie  相似文献   

9.
Effects of Azolla species on weed emergence in a rice paddy ecosystem   总被引:1,自引:1,他引:1  
The effects of Azolla pinnata R. Br. on weed emergence were evaluated in terms of plot area coverage by an A. pinnata mat, its biomass production and the amount of weed emergence, using fresh and dry weights, in a rice paddy field experiment. The experiment was conducted following a randomized block design with five combinations of fertilizer and A. pinnata treatments (control, A. pinnata  + superphosphate, A. pinnata  + urea, A. pinnata  + compound fertilizer, A. pinnata  + cow manure). The results revealed that after 18 days of inoculation, all superphosphate (T1) and cow manure (T4)-treated plots were fully covered by the A. pinnata mat. However, coverage of the urea (T2) and compound fertilizer (T3)-treated plots were only 80% and 70%, respectively. The full plot area coverage by the A. pinnata mat and the highest biomass production with superphosphate and cow manure-treated plots were able to completely inhibit two weed species ( Scirpus juncoides Roxb. var. hotarui Ohwi and Monochoria vaginalis Burm. f. Presl var. plantaginea (Roxb.) Solms-Laub) and significantly suppressed four other weeds ( Cyperus serotinus Rottb, Echinochla oryzicola Vasing, and Eclipta prostrata L.). In all the treatments, the fresh weight of weeds significantly reduced to 13, 29, 34, and 9%, respectively, for treatments T1, T2, T3, and T4. The dry weights also were significantly reduced to 10.00, 16.00, 22.00, and 7.26%, respectively, for treatments T1, T2, T3, and T4 over the control. The results revealed that there was a significant correlation among plot area coverage by the A. pinnata mat, its biomass production and weed emergence in a rice paddy field over the control. Azolla pinnata did not have any detrimental effect on the growth of rice plants.  相似文献   

10.

Speargrass, Imperata cylindrica (L.) Raeuschel, is a serious weed, threatening crop productivity in smallholder farms in West Africa. Since the use of more effective practices such as deep tillage and chemical control is beyond the means of resource-poor farmers who carry out most agricultural activities in this region, low-input alternative technology needs to be developed. Field studies were conducted during the 1993/1994 and 1995/1996 growing seasons to investigate the influence of three velvetbean accessions and two levels of fertilizer on the control of speargrass during the year of cover crop planting and one year later. The velvetbean accessions in 1993 were: Mucuna cochinchinensis and M. pruriens var. utilis. In 1995, M. pruriens var. IRZ was included in the study. M. cochinchinensis in 1993 and M. pruriens var. IRZ in 1995 had the highest ground cover rating early in the growing seasons whereas M. pruriens var. utilis had the lowest ground cover rating in both years. Inorganic fertilizer at30 kg ha- 1 each of N, P and K increased velvetbean ground cover by 2-22%, with M. cochinchinensis (14-22%) and M. pruriens var. IRZ (5-15%) showing the highest response in 1993 and 1995, respectively. M. pruriens var. utilis showed the least response in both years. After one growing season M. pruriens var. utilis, M. cochinchinensis, and M. pruriens var. IRZ reduced speargrass shoot density by 50, 76, and 68%, and shoot dry matter by 72, 92, and 79%, respectively. Fertilizer reduced speargrass growth in velvetbean plots, while the opposite occurred in plots without velvetbean. Velvetbean residue effectively suppressed speargrass until the beginning of the subsequent cropping season. Maize grown 1 year after velvetbean required 50% less weeding than plots without velvetbean. Maize shade reduced speargrass shoot growth by 30-80% but regrowth of the weed occurred 4 weeks before maize harvest. Maize grain yield was higher in plots previously seeded to velvetbean than in plots without velvetbean. Speargrass shoot density and dry matter were negatively correlated with maize grain yield (r =-0.42 and r =-0.32, respectively, P < 0.01). Although velvetbean may effectively reduce speargrass during the year of establishment and the subsequent cropping phase it has a limited effect on rhizomes and, as such, does not provide a long term control.  相似文献   

11.
This study evaluated the effect of different organic amendments on lettuce fusarium wilt caused by Fusarium oxysporum f. sp. lactucae in pots under controlled conditions. Their effects on the density of the pathogen, on the total fungi and on fluorescent Pseudomonas spp. were also evaluated after two subsequent lettuce crops. A significant reduction in the severity of the symptoms of F. oxysporum f. sp. lactucae was found after the use of Brassica carinata pellets (52–79% reduction) and compost (49–67% reduction), while Brassica green manure and cattle and chicken manure only provided partial control of fusarium wilt. However, variations in effectiveness were observed for the same treatment in repeated trials. In general, an increase was observed in Pseudomonas and a decrease in fungal populations in the growing medium, which was obtained by mixing a blonde sphagnum peat and a sandy loam soil with B. carinata pellets and compost after two consecutive cropping cycles. Prolonging the Brassica and compost treatments from 30 to 60 days did not significantly affect disease severity, plant growth or the microbial population of the total fungi or Pseudomonas. The largest lettuce biomass was obtained in the non‐inoculated growing medium amended with brassica flour, chicken manure, B. carinata pellets and compost, as a consequence of fertilization. The treatment with B. juncea green manure, B. carinata (pellets and flour) and compost applied 30 days before planting led to promising results and merits further investigation for use under field conditions.  相似文献   

12.
Losses of crop yield due to weed competition in unweeded plots averaged nearly 60% of weed-free yields in cotton and 70% in groundnuts. Weed competition was not directly related to weed groundcover but was dependent on the seasonal growing conditions. The critical period of weed competition in both crops was the 6 weeks between 4 and 10 weeks after crop emergence. During this period cotton could tolerate up to 25% weed groundcover without appreciable loss in crop yield. Groundnuts could tolerate not more than 10% weed cover before yield loss occurred. A main factor in achieving standards of weed control within these limits was preventing the early growth of monocotyledonous weed species: pre-sowing application of trifluralin and benfiuralin provided this over a wide range of growing conditions.  相似文献   

13.
The effects of tillage system and fertilization regimes on weed flora in quinoa (Chenopodium quinoa Willd.) were evaluated by means of two field experiments in 2011 and 2012. The experiments were laid out in a split-plot design with two main plots (conventional and minimum tillage) and four sub-plots (fertilization regimes). The results indicated that weed biomass and density in quinoa were influenced by the different fertilization and tillage treatments. Moreover, seed yield in conventional was 5%–13% higher than that of minimum tillage, probably due to the lower weed density and biomass. Concerning fertilization treatments, total weed density and biomass increased under manure application and inorganic fertilization. Tillage effects on weeds were species specific. The density of perennial weeds such as purple nutsedge (Cyperus rotundus L.) and the density of small-seeded weeds such as redroot pigweed (Amaranthus retroflexus L.) and common purslane (Portulaca oleracea L.) were significantly lower under the conventional tillage than under the minimum tillage system.  相似文献   

14.
Weed species diversity may benefit from organic farming due to enhanced temporal diversification of crop species in a rotation and omission of herbicide applications. However, in intensively managed conventional systems, little evidence exists as to what extent diversified crop rotations contribute to higher weed species richness. Using an on-farm approach, the effect of crop rotation (organic, conventional diverse (CD) and conventional simple (CS) crop rotations) and weed control (with vs. without) on weed species richness, cover, community composition and crop biomass, was analysed in 24 winter wheat fields. Weed species with beneficial functions for invertebrates and birds were analysed separately. Weed species richness was higher in the organic crop rotation, but did not differ between CD and CS crop rotations. Weed control treatment reduced species richness in both conventional rotations, but not in the organic one. Redundancy analyses revealed that crop rotation intensity accounted for the largest part of the explained variation in weed species composition. Results from the study indicate that the maintenance of weed species richness and conservation of species with important ecological functions requires not only temporal diversification of crop species in the rotation, but also an adjustment of weed control strategies.  相似文献   

15.
Liebman  & Davis 《Weed Research》2000,40(1):27-47
Greater adoption and refinement of low-external-input (LEI) farming systems have been proposed as ways to ameliorate economic, environmental and health problems associated with conventional farming systems. Organic soil amendments and crop diversification are basic components of LEI systems. Weed scientists can improve the use of these practices for weed management by improving knowledge of four relevant ecological mechanisms. First, multispecies crop rotations, intercrops and cover crops may reduce opportunities for weed growth and regeneration through resource competition and niche disruption. Secondly, weed species appear to be more susceptible to phytotoxic effects of crop residues and other organic soil amendments than crop species, possibly because of differences in seed mass. Thirdly, delayed patterns of N availability in LEI systems may favour large-seeded crops over small-seeded weeds. Finally, additions of organic materials can change the incidence and severity of soil-borne diseases affecting weeds and crops. Our research on LEI sweetcorn and potato production systems in central and northern Maine (USA) suggests that these mechanisms can reduce weed density and growth while maintaining crop yields. Low-external-input farming systems will advance most quickly through the application of interdisciplinary research focused on these and other ecological mechanisms.  相似文献   

16.
Herbicides contribute significantly to agricultural intensification, but some negatively impact non‐target organisms. Much research has focused on reducing herbicide use through technological improvements in application and herbicide selectivity, but impacts on non‐target organisms are less well understood. Using experimental plots in silage systems, we investigated impacts of herbicides (both narrow spectrum targeting broad‐leaved plants and selective and non‐selective broad spectrum) applied using traditional techniques (blanket‐ and manual spot‐spraying) and a novel application technique (automated spot‐spraying) on non‐target plant richness/diversity, target weed presence (Rumex species) and production (DM yield). All herbicides reduced non‐target plant richness/diversity and sometimes target weeds (when applied using traditional methods). Automated spot‐spraying had fewer negative effects on non‐target organisms, but did not reduce target weeds. No differences in production levels among treatments were observed. The automated spot‐spraying technique requires further research and development. Our results indicate that 20–30% weed cover does not significantly alter production and so, as herbicides are expensive, their effects on non‐target organisms and the environment can be more significant than their benefits to production. We advocate more research into the relationships between weed infestation and production in grasslands, so that the propensity to overuse herbicides is reduced.  相似文献   

17.
Weed competition and nutrient scarcity often restrict organic cereal production, especially where the availability of livestock manure is limited. While harrowing of annual weeds and legume cover crops can be used, these methods are both executed in early spring and may hinder each other. Two cycles of a 2‐year crop rotation were carried out in south‐east Norway (60°42′N, 10°51′E, altitude 250 m) with weed harrowing and undersown cover crops (WHCC) at two fertiliser rates (40 and 100 kg nitrogen ha?1). The effect of the WHCC treatments was measured by weed density and species, weed biomass, changes in weed seedbank and grain yield. The weed density depended on the interaction between WHCC, fertiliser and year. On average, pre‐emergence weed harrowing reduced weed density by 32% and weed biomass by 49%, while pre‐ and post‐emergence weed harrowing reduced weed density by 59% and weed biomass by 67% compared with the untreated control. Spergula arvensis became more abundant at low rather than at high fertiliser rates. On average, white clover cover crop sown after pre‐emergence weed harrowing resulted in the highest yields for both oat (+12.1%) and wheat (+16.4%) compared with the untreated control. Despite differences in weed population density and biomass among WHCC treatments within years, the weed biomass, weed density and seedbank increased for all WHCC treatments over the 4‐year period. More research is required into improving the efficacy of mechanical and cultural weed suppression methods that organic systems rely on.  相似文献   

18.
有机改良剂在防治植物土传病害中的应用   总被引:22,自引:0,他引:22  
 本文综述了有机改良剂的类型及其在防治作物土传病害的应用情况,包括壳质粗粉、植物残体、绿肥、饼肥、堆肥和粪肥;概括了有机改良剂的防病机制,如直接的抑菌作用、对土壤微生物区系的调节、诱导抗病性、改良土壤结构和促进植物生长等;讨论了当前有机改良剂防治作物土传病害研究存在的一些问题及今后应重点研究的课题,并对有机改良剂防治植物病害在未来的发展前景提出了自己的看法。  相似文献   

19.
The objective of this study was to obtain detailed information on the long‐term weed suppression potential of four winter soil cover types included in an arable crop system managed at various input levels. We used weed seedbank size and composition to assess weed suppression potential. A field experiment was established in 1993 as a split‐split‐plot design with four replications, including two tillage systems [a conventional system (CS) including ploughing in the cover crops and a low‐input system (LIS) including no tillage with surface mulching of the cover crops] in the main plots, three mineral nitrogen fertilization rates for the main crop in the sub‐plots and four soil cover types (main crop residue, rye, crimson clover and subterranean clover) in the sub‐sub‐plots. Seedbank sampling took place in winter 2000/01. The weed seedbank was analysed with the seedling emergence method. Data were analysed using anova and multivariate techniques. Results indicated that the seedbank density in the LIS was about five times higher than in the conventional input system. In the CS, use of a rye cover crop resulted in a lower seedbank density with respect to the crop residue treatment (?25%), whereas in the LIS the subterranean clover cover crop decreased weed seedbank density as compared with the other cover crops and the crop residue treatment (?22% on average). Differences in species composition were mainly related to tillage system. Implications for cover crop management and the development of sustainable cropping systems are discussed.  相似文献   

20.
Strawberry (Fragaria?×?ananassa) is one of the most important berry crops worldwide. Fusarium wilt poses a serious threat to commercial strawberry production worldwide and causes severe economic losses. Our previous surveys suggested that soil pH, soil amendment with organic matter and/or crop rotation could offer opportunities for improved management of strawberry disease. Studies were conducted for the first time to determine the effects of soil pH, soil amendments with manure compost and crop residue, and crop rotation on the severity and impact of Fusarium wilt on strawberry. At soil pH 6.7, plants showed the least severe disease and the lowest reductions in shoot and root dry weight (DW) of plants from disease, significantly lower than those of plants in acidic soil at pH 5.2 or 5.8. In soil amendment with manure compost at 5.0?%, plants showed the least severe disease and the lowest reductions in shoot and root DW of plants from disease, significantly lower than those of plants in the other three levels of manure compost. In soil amendment with crop residue at 2.5?% or 5.0?%, shoot and root disease of plants and reductions in shoot and root DW of plants from disease were significantly lower than those of plants in soil without crop residue or excessive crop residue amendment at 10.0?%. Plants in soil rotated with tomato not only showed the least severe disease but also showed the lowest reductions in shoot and root DW of plants from disease, significantly lower than those of plants in soil continuously planted with strawberry without rotation or rotated with capsicum. Soil pH, soil amendment with manure compost or crop residue, and crop rotation, all significantly reduced the severity and impact of Fusarium wilt on strawberry. There is great potential for manipulating soil pH, adding soil organic amendments and utilizing crop rotation, not only to successfully manage Fusarium wilt on strawberry, but to do so in a sustainable way without current reliance upon chemical fumigants.  相似文献   

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