Weed Seed Populations in Ridge and Conventional Tillage

Weed Science ◽  
1988 ◽  
Vol 36 (4) ◽  
pp. 500-503 ◽  
Author(s):  
Frank Forcella ◽  
Michael J. Lindstrom

Weed seed and seedling populations, and weed competition were compared in plots of continuous corn and corn/soybean rotation under ridge and conventional tillage. After 7 to 8 yr of standard chemical and mechanical weed control, from 1500 to 3000 weed seeds/m2(to a 10-cm depth) were found in continuous corn with ridge tillage whereas about two-thirds fewer seeds were found in conventionally tilled corn. Soil from a corn/soybean rotation had from 200 to 700 seeds/m2in both tillage systems. Annual loss of weed seeds from the soil through germination was from 3 to 12% in ridge tillage and 11 to 43% in conventional tillage. Additions to the seed pool were supplied by small weeds whose germination was stimulated by “layby” cultivation, with up to 10 times more emergence and 140 times more seed production in ridge than in conventional tillage. Withholding herbicides for 1 yr reduced yields of continuous corn by 10 to 27% in ridge tillage, only 2 to 4% in conventional tillage, and negligibly in corn/soybean rotations regardless of tillage. Reducing seed production of small layby weeds in ridge tillage may aid in solving the weed problem in this conservation tillage system.

Weed Science ◽  
1999 ◽  
Vol 47 (2) ◽  
pp. 175-183 ◽  
Author(s):  
George O. Kegode ◽  
Frank Forcella ◽  
Sharon Clay

Approaches to crop production that successfully reduce weed seed production can benefit farming systems by reducing management inputs and costs. A 5-yr rotation study was conducted in order to determine the effects that interactions between crop rotation, tillage, and amount of herbicide and fertilizer (management inputs) have on annual grass and broad-leaved weed seed production and fecundity. There were 10 crop rotation and tillage system combinations and three levels of management inputs (high, medium, and low). Green and yellow foxtail were the major weed species, and together they yielded between 76 and 93% of collected weed seeds. From 1990 to 1994, average grass weed seed productions were 7.3 by 103, 3.7 by 1036.1 by 103and 5.7 by 103seeds m−-2, whereas average broad-leaved weed seed productions were 0.4 by 103, 0.4 by 103, 1.4 by 103, and 0.4 by 103seeds m−-2in crop rotations using conventional tillage (moldboard plow), conservation tillage, no tillage, and ridge tillage, respectively. Crop rotations using conventional or ridge tillage consistently produced more grass and broad-leaved weed seeds, especially in low-input plots. There was little difference in weed seed production among input levels for crop rotations using conservation tillage. Comparing rotations that began and ended with a corn crop revealed that by increasing crop diversity within a rotation while simultaneously reducing the amount of tillage, significantly fewer grass and broad-leaved weed seeds were produced. Among the rotations, grass and broad-leaved weed fecundity were highly variable, but fecundity declined from 1990 to 1994 within each rotation, with a concomitant increase in grass and broad-leaved weed density over the same period. Crop rotation in combination with reduced tillage is an effective way of limiting grass and broad-leaved weed seed production, regardless of the level of management input applied.


2009 ◽  
Vol 89 (2) ◽  
pp. 273-280 ◽  
Author(s):  
M. R. Carter ◽  
J. B. Sanderson ◽  
R. D. Peters

Conservation tillage in combination with mulches in potato (Solanum tuberosum L.) farming systems can maintain crop productivity and improve soil properties, in comparison with conventional tillage systems. However, information is needed on the long-term influence of such practices on potato crop parameters. A study was initiated in 1994 on a Charlottetown fine sandy loam (Orthic Podzol) in Prince Edward Island to assess the feasibility of using conservation tillage practices in combination with crop residue mulches (after the potato harvest) on potato production in two different potato rotations: a 2-yr barley-potato rotation and a clover-based 3-yr (barley-red clover -potato) rotation. In the conservation tillage system, the primary tillage event was moved from the autumn to spring and the degree and depth of tillage were reduced by replacing the conventional mouldboard plough (20 cm depth) with a shallow (15 cm depth) one-pass chisel plough just prior to potato planting. Potato yield and tuber quality, surface residue levels after potato planting, and tuber mineral content were evaluated from 2000 to 2007. Adoption of conservation tillage over the long-term did not adversely influence total or marketable potato yield, or tuber quality. The clover-based 3-yr rotation, compared with the 2-yr rotation, had little effect on total potato yield (42 vs. 44 Mg ha-1), but produced significantly higher marketable tuber yields (38 vs. 32 Mg ha-1), for four of the eight yrs of the study. The conservation tillage system, for both rotations, provided relatively high surface residue levels (>30%) after potato planting, compared with the bare soil surface in the conventional tillage system. Nutrient and trace element contents in tuber dry matter were similar between conservation and conventional tillage. Tuber uptake of nitrogen and other nutrients were slightly greater under the 3-yr, compared with the 2-yr rotation, and associated with tuber dry-matter yield differences. The results of the 14-yr study confirm the conclusions of previous short-term studies that a reduction in depth and intensity of tillage for potato culture is yield neutral, and a viable alternative to conventional tillage systems for potato production on sandy loams in eastern Canada. Key words: Conservation tillage, potato, crop rotation, fine sandy loam, crop yield, surface residue, eastern Canada


Weed Science ◽  
1994 ◽  
Vol 42 (2) ◽  
pp. 184-194 ◽  
Author(s):  
Douglas A. Derksen ◽  
A. Gordon Thomas ◽  
Guy P. Lafond ◽  
Heather A. Loeppky ◽  
Clarence J. Swanton

Continuous-cropping conservation tillage systems may provide a viable alternative to the practice of summer fallow; however, concerns have been raised regarding potentially negative changes in weed communities in continuous cropping. Field experiments were established in Saskatchewan at three locations to determine the nature of weed community differences between a crop sequence with and without fallow in zero-, minimum-, and conventional-tillage systems from 1986 to 1990. Weed communities in continuous-cropping treatments tended to have greater total densities and were more similar in composition than crop-fallow treatments. Inclusion or exclusion of fallow within the rotation had a greater impact on weed community composition than did tillage system at Ituna and Waldron, but the reverse was true at Tadmore due to poor crop growth in all tillage systems. Differences in weed community composition were generally characterized by fluctuational changes in species associations. Volunteers of summer-annual crops, such as canola, flax, and barley, were associated with continuous cropping, but other species including perennial weeds, such as Canada thistle, perennial sowthistle, and quackgrass, were not strongly associated with the presence or absence of fallow. The practice of fallowing land to manage weeds may not be necessary.


Weed Science ◽  
1984 ◽  
Vol 32 (1) ◽  
pp. 84-89 ◽  
Author(s):  
Edward E. Schweizer ◽  
Robert L. Zimdahl

The impact of two weed management systems on the weed seed reserves of the soil, on the yearly weed problem, and on barley (Hordeum vulgareL. ‘Steptoe’), corn (Zea maysL. ‘Pioneer 3709′), and sugarbeet (Beta vulgarisL. ‘Mono Hy D2′) production was assessed where these crops were grown in rotation for 6 consecutive years. Weeds were controlled in each crop with a moderate (system I) or intensive (system II) level of herbicides, plus conventional tillage. Weed seeds from seven annual genera were identified, with redroot pigweed(Amaranthus retroflexusL. ♯3AMARE) andChenopodiumcomprising 56 and 30%, respectively, of the initial 1377 million weed seeds/ha that were present in the upper 25 cm of the soil profile. After the sixth cropping year, the overall decline in the total number of weed seeds in soil was 96% in system I and 97% in system II. Over the 6-yr period, about 1.3 times more weeds escaped control in system I than in system II; and within a crop, the fewest number of weeds escaped annually in sugarbeets, and the most in barley. Yields of barley grain, corn silage, and recoverable sucrose were similar each year in the two weed management systems.


2006 ◽  
Vol 46 (12) ◽  
pp. 1557 ◽  
Author(s):  
B. S. Chauhan ◽  
G. S. Gill ◽  
C. Preston

In the past few years, there has been a growing trend towards reducing tillage in cropping systems to allow stubble retention, earlier planting and improved soil structure. However, the adoption of conservation tillage systems will change weed control practices. Different tillage systems interact with the micro-environment of weed seeds and can influence the pattern of recruitment from the weed seed bank. Here, we present a review of the effect of different tillage systems on weed ecology, herbicide activity and herbicide persistence. Tillage systems can have a major influence on the vertical distribution of weed seeds in the soil seed bank. However, the impact of the changes in the vertical seed distribution on weed seedling recruitment is not well understood. Usually weed seedling recruitment increases if tillage equipment brings buried seed to, or close to, the soil surface, and seedling recruitment decreases if surface seed is buried deeper in the soil. However, tillage responses have a tendency to be species specific and can also be influenced by the intensity of tillage. Any weed species in which germination is stimulated by exposure to light is likely to become more prevalent under reduced tillage systems. Similarly, species that require burial for germination may become less prevalent. Crop residue present on the soil surface can also influence weed seedling recruitment by modifying the physical environment (mainly temperature) of weed seeds. Weed responses to plant residue could also be influenced by the allelopathic activity of the residue and the sensitivity of the weed species present. Few studies have investigated the fate of weed seeds that fail to germinate under any tillage system. Further research is needed to determine whether the weed seeds that fail to germinate decay before the start of the next growing season or become part of a persistent seed bank. Crop residues present on the soil surface can intercept a considerable amount of the applied herbicide and, depending on the herbicide, this intercepted component is susceptible to losses. Therefore, conservation tillage systems are expected to have lower efficacy of soil active herbicides. However, there has been little investigation of rate of loss of soil active herbicides under reduced tillage systems and the results reported have been inconsistent. Much of the research on these effects is from overseas and may not be true in Australian conditions. Therefore, further work is needed to clearly understand the impact of changing tillage systems on weed ecology, herbicide performance and persistence.


2004 ◽  
Vol 52 (3) ◽  
pp. 211-220 ◽  
Author(s):  
P. László ◽  
C. Gyuricza

Within the framework of cooperation between Szent István University and the Vienna University of Agricultural Sciences, a soil cultivation experiment in a maize (Zea mays L.) monoculture was set up for the first time in Austria near Pyhra (Lower Austria) in 1996. A study was conducted to evaluate the effects of ridge tillage (RT) in comparison with conventional mouldboard ploughing in autumn (CT) and no-tillage (NT) on the penetration resistance (PR), soil bulk density (BD) and porosity (P) of sandy loam soil (Typic Agriudoll). Analyses were made for each treatment and for different parts of the ridge (top and side of the ridge, and interrow) in 1998, 2000 and 2002. The average PR and BD values were greatest in the no-tillage plot, being 3.42 MPa and 1.56 g·cm-3, respectively. After six years, ridge tillage resulted in lower penetration resistance and bulk density values in the upper 20 cm than conventional tillage and no-tillage. Ridge tillage appears capable of reducing compaction in this soil. It can be concluded from the results that ridge tillage is capable of maintaining and improving favourable physical conditions in the soil.


Weed Science ◽  
2011 ◽  
Vol 59 (3) ◽  
pp. 398-403 ◽  
Author(s):  
Marie-Josée Simard ◽  
Sébastien Rouane ◽  
Gilles D. Leroux

The effect of herbicide rates on weed control and crop yield is the subject of countless and ongoing research projects. Weed seed banks receive very little attention in comparison. The seed bank resulting from 3 yr (2006 to 2008) of single herbicide rates in a cropping system where glyphosate/glufosinate and corn/soybean were rotated or not was evaluated in a field located in St-Augustin-de-Desmaures, Québec, Canada. Field plots under conventional tillage were seeded in corn every year, or corn and soybean (1 yr). These plots received the same herbicide every year or various glyphosate/glufosinate 3-yr sequences. Subplots were sprayed with a single POST application of the recommended rate of glyphosate (900 g ae ha−1) or glufosinate (500 g ai ha−1) or lower rates. Subplots received the same full (1.0×, recommended) or reduced (0.5×, 0.75×) rate every year. After crop harvest in 2008, soil cores were extracted and the weed seed bank was evaluated. Including soybean in the cropping system resulted in lower seed banks compared to those under continuous corn cropping. Including glufosinate in a glyphosate herbicide sequence increased weed seed banks due to the lower efficacy of the glufosinate rates tested at reducing the seed bank of annual grasses. Higher herbicide rates translated into lower seed banks, up to a certain rate. After 3 yr, the lowest seed bank (full glyphosate rates every year) still had 4,339 ± 836 seeds m−2and was higher than the initial seed bank (2,826 ± 724 seeds m−2).


Weed Science ◽  
2017 ◽  
Vol 66 (1) ◽  
pp. 109-120 ◽  
Author(s):  
Bryan Brown ◽  
Eric R. Gallandt

Weed management strategies differ in their ability to control weeds, and often have unique agroecological implications. To provide growers with an improved sense of trade-offs between weed control and ecological effects, we implemented several prominent organic weed management strategies in yellow onion in 2014 and 2015. Strategies included cultivation of weed seedlings during the early, weed-sensitive “critical period” of the crop; frequent cultivation events to ensure “zero seed rain”; and weed suppression with polyethylene or natural mulches. As expected, end-of-season weed biomass and weed seed production were greatest in the critical period system and nearly zero for the zero seed rain system. Weeds were also well controlled in natural mulch systems. Average onion yield per treatment was 50.7 Mg ha−1. In 2014, the critical period system and the polyethylene mulch systems demonstrated yield loss, likely due to weed competition and excessive soil temperature, respectively. Onion soluble solids content was also diminished in these systems in 2014, but bulb firmness was greatest in unmulched systems. Carabid beetles, earthworms, soil compaction, soil nitrate, and microbial biomass were affected by weed management strategy, with natural-mulched systems generally performing most favorably. However, these effects were not substantial enough to affect yield of a subsequent sweet corn crop grown in weed-free conditions. In contrast, sweet corn managed with only early-season cultivations demonstrated yield loss (P=0.004) in plots where the critical period treatment was implemented the prior year, indicating that weed competition resulting from abundant weed seed production in that system was the most influential legacy effect of the weed management strategies.


2017 ◽  
Vol 43 (1) ◽  
pp. 14-19 ◽  
Author(s):  
Camila Ranzi ◽  
Juliane Nicolodi Camera ◽  
Carolina Cardoso Deuner

ABSTRACT The objective of this study was to evaluate the influence of two tillage programs (conventional and no-tillage) and different rotations with soybeans and corn on the occurrence of Fusarium species. The work was conducted in the experimental field and Seed Laboratory at Iowa State University. The treatments were: tillage (no-tillage and conventional tillage), crop (corn and soybeans) and three different cropping sequences for corn and soybeans, respectively. Treatment with corn: (1) the first year after four years of soybeans (1C); (2) alternating corn and soybeans each year (C / SB); (3) Continuous corn (C). Treatment with soybeans; (1) the first year after four years of corn (1S); (2) alternating soybeans and corn each year (SB / C); (3) Continuous soybeans (S). Two plant counts were performed in two stages in soybean (VC and V3) and corn (V1 and V3). The root system of ten plants were collected in the vegetative stages V2 and V5 for soybeans and corn. The fungi were isolated from the roots, and the Fusarium species were identified based on the most distinctive morphological characteristics. Nine species were identified in both soybeans and corn, namely F. acuminatum, F. equiseti, F. graminearum, F. oxysporum, F. proliferatum, F. solani, F. subglutinans, F. verticillioides and F. virguliforme. There were no significant differences among the treatments concerning the Fusarium species composition, for both soybeans and corn. In soybeans Fusarium oxysporum was the most frequently observed saprophyte species, followed by F. solani. For corn the main trends in the data was the predominance in all treatments of F. solani, whose highest frequency was in the no-tillage system.


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