Winter-killed Cereal Rye Cover Crop Influence on Nitrate Leaching in Intensive Vegetable Production Systems

High levels of residual soil nitrate are typically present in cool-season vegetable fields in coastal regions of California in the fall, after the production of multiple crops over the course of the growing season. This nitrate is subject to leaching with winter rains when fields are left fallow. Although the benefits of growing nitrate scavenging cover crops on soil and water quality are well documented, the portion of vegetable production fields planted to winter cover crops in this region is low. Most growers leave their fields unplanted in bare-fallow beds because the risk of having too much cover crop residue to incorporate may delay late winter and early spring planting schedules. A possible strategy to derive benefits of a cover crop yet minimize the amount of residue is to kill the cover crop with an herbicide when biomass of the cover crop is still relatively low. To evaluate whether this strategy would be effective at reducing nitrate leaching, we conducted field studies in Winter 2010–11 (Year 1) and Winter 2011–12 (Year 2) with cereal rye (Secale cereale). Each trial consisted of three treatments: 1) Fallow (bare fallow), 2) Full-season (cover crop allowed to grow to full term), and 3) Partial-season (cover crop killed with herbicide 8 to 9 weeks after emergence). In Year 1, which received 35% more rainfall than the historical average during the trial, the Full-season cover crop reduced nitrate leaching by 64% relative to Fallow, but the Partial-season had no effect relative to Fallow. In Year 2, which received 47% less rainfall than the historical average during the trial, the Full- and Partial-season cover crops reduced nitrate leaching by 75% and 52%, respectively, relative to Fallow. The Full-season cover crop was able to reduce nitrate leaching regardless of yearly variations in the timing and amount of precipitation. Although the Partial-season cover crop was able to reduce leaching in Year 2, the value of this winter-kill strategy to reduce nitrate leaching is limited by the need to kill the crop when relatively young, resulting in the release of nitrogen (N) from decaying residues back into the soil where it is subject to leaching.

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Fall Cover Crops for Reducing Nitrate Leaching in Cool Season Vegetable Production in the Salinas Valley

HortScience ◽

10.21273/hortsci.40.4.1110b ◽

2005 ◽

Vol 40 (4) ◽

pp. 1110B-1110

Author(s):

Richard F. Smith ◽

Louise E. Jackson ◽

Tiffany A. Bensen

Keyword(s):

Nitrate Leaching ◽

Cover Crops ◽

Cover Crop ◽

Production Systems ◽

Indian Mustard ◽

Vegetable Production ◽

Land Rent ◽

Cereal Rye ◽

Salinas Valley ◽

Bare Fallow

Lettuce growers in the Salinas Valley are often not able to rotate to other crops due to economic pressure, such as high land rent. Winter-grown cover crops (October to March) provide a short-term rotation from lettuce and have been shown to reduce nitrate leaching by 75%. However, the use of winter-grown cover crops is low due to the extended time these cover crops tie up the ground. As a result, growers are interested in the potential of fall-grown cover crops (September to October) to reduce nitrate leaching through the winter. Fall-grown cover crops are incorporated into the soil prior to the onset of winter rains and leave the soil bare over the winter; however, during fall growth, the cover crop has the potential to capture excess nitrate that may leach during the fallow period, but how much has not been previously measured. A long-term trial was established in Fall 2003 using treatments of Indian mustard (B. juncea) `ISCI 61', White mustard (S. alba) `Ida Gold', Cereal rye (Secale cereale) `Merced', and a no cover crop control. All cover crops contained ≈224 kg·ha-1 N upon incorporation. Anion resin bags were installed 90 cm deep in the soil following incorporation to trap leaching nitrate; they were left in place until planting of the lettuce the following spring. First-year results indicated that the mustard cover crops and `Merced' rye all reduced nitrate leaching to the 90-cm depth by 67% to 82% over the bare fallow treatment. These results indicate that fall-grown cover crops have the potential to reduce nitrate leaching in lettuce production systems in the Salinas Valley.

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Carryover of Common Corn and Soybean Herbicides to Various Cover Crop Species

Weed Technology ◽

10.1614/wt-d-16-00062.1 ◽

2017 ◽

Vol 31 (1) ◽

pp. 21-31 ◽

Cited By ~ 19

Author(s):

Cody D. Cornelius ◽

Kevin W. Bradley

Keyword(s):

Cover Crops ◽

Cover Crop ◽

Production Systems ◽

Italian Ryegrass ◽

Hairy Vetch ◽

Crop Species ◽

Cereal Rye ◽

Crimson Clover ◽

Crop Establishment ◽

Biomass Reduction

The recent interest in cover crops as component of Midwest corn and soybean production systems has led to the need for additional research, including the effects of residual corn and soybean herbicide treatments on fall cover crop establishment. Field studies were conducted in 2013, 2014, and 2015 in Columbia, Missouri to investigate the effects of common residual herbicides applied in corn and soybean on establishment of winter wheat, tillage radish, cereal rye, crimson clover, winter oat, Austrian winter pea, Italian ryegrass, and hairy vetch. Cover crops were evaluated for stand and biomass reduction 28 d after emergence (DAE). Rainfall from herbicide application to cover crop seeding date was much greater in 2014 and 2015, which resulted in less carryover in these years compared to 2013. When averaged across all herbicides evaluated in these experiments, the general order of sensitivity of cover crops to herbicide carryover, from greatest to least was Austrian winter pea=crimson clover>oilseed radish>Italian ryegrass>hairy vetch>wheat >winter oat>cereal rye. Cereal rye had the fewest instances of biomass or stand reduction with only four out of the 27 herbicides adversely effecting establishment. Pyroxasulfone consistently reduced Italian ryegrass and winter oat biomass at least 67% in both the corn and soybean experiments. In the soybean experiment, imazethapyr- and fomesafen-containing products resulted in severe stand and biomass reduction in both years while flumetsulam-containing products resulted in the greatest carryover symptoms in the corn experiment. Results from these experiments suggest that several commonly used corn and soybean herbicides have the potential to hinder cover crop establishment, but the severity of damage will depend on weather, cover crop species, and the specific herbicide combination.

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Herbicide Programs for the Termination of Various Cover Crop Species

Weed Technology ◽

10.1017/wet.2017.20 ◽

2017 ◽

Vol 31 (4) ◽

pp. 514-522 ◽

Cited By ~ 5

Author(s):

Cody D. Cornelius ◽

Kevin W. Bradley

Keyword(s):

Cover Crops ◽

Cover Crop ◽

Field Experiments ◽

Crop Yields ◽

Production Systems ◽

Annual Ryegrass ◽

Crop Species ◽

Cereal Rye ◽

Crimson Clover ◽

Herbicide Treatments

The recent interest in cover crops as a component of Midwest corn and soybean production systems has led to a greater need to understand the most effective herbicide treatments for cover crop termination prior to planting corn or soybean. Previous research has shown that certain cover crop species can significantly reduce subsequent cash crop yields if not completely terminated. Two field experiments were conducted in 2013, 2014, and 2015 to determine the most effective herbicide program for the termination of winter wheat, cereal rye, crimson clover, Austrian winter pea, annual ryegrass, and hairy vetch; and cover crops were terminated in early April or early May. Visual control and above ground biomass reduction was determined 28 d after application (DAA). Control of grass cover crop species was often best with glyphosate alone or combined with 2,4-D, dicamba, or saflufenacil. The most consistent control of broadleaf cover crops occurred following treatment with glyphosate +2,4-D, dicamba, or saflufenacil. In general, control of cover crops was higher with early April applications compared to early May. In a separate study, control of 15-, 25-, and 75-cm tall annual ryegrass was highest with glyphosate at 2.8 kg ha−1or glyphosate at 1.4 kg ha−1plus clethodim at 0.136 kgha−1. Paraquat- or glufosinate-containing treatments did not provide adequate annual ryegrass control. For practitioners who desire higher levels of cover crop biomass, these results indicate that adequate levels of cover crop control can still be achieved in the late spring with certain herbicide treatments. But it is important to consider cover crop termination well in advance to ensure the most effective herbicide or herbicide combinations are used and the products are applied at the appropriate stage.

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Effects of Long-Term Cover Cropping on Weed Seedbanks

Frontiers in Agronomy ◽

10.3389/fagro.2020.591091 ◽

2020 ◽

Vol 2 ◽

Author(s):

Virginia Nichols ◽

Lydia English ◽

Sarah Carlson ◽

Stefan Gailans ◽

Matt Liebman

Keyword(s):

Cover Crops ◽

Cover Crop ◽

Production Systems ◽

Early Spring ◽

Weed Suppression ◽

Winter Rye ◽

Maize Crop ◽

Cover Cropping ◽

Crop Biomass

Cool-season cover crops have been shown to reduce soil erosion and nutrient discharge from maize (Zea mays L.) and soybean [Glycine max (L.) Merr.] production systems. However, their effects on long-term weed dynamics are not well-understood. We utilized five long-term research trials in Iowa to quantify germinable weed seedbank densities and compositions after 10+ years of cover cropping treatments. All five trials consisted of zero-tillage maize-soybean rotations managed with and without the inclusion of a yearly winter rye (Secale cereal L.) cover crop. Seedbank sampling was conducted in the early spring before crop planting at all locations, with three of the five trials having grown a soybean crop the preceding year, and two a maize crop. Two of the trials (both previously soybean) showed significant and biologically relevant decreases (4,070 and 927 seeds m−2, respectively) in seedbank densities in cover crop treatments compared to controls. In another two trials, one previously maize and one previously soybean, no difference was detected in seedbank densities. In the fifth trial (previously maize), there was a significant, but biologically unimportant increase of 349 seeds m−2. All five trials' weed communities were dominated by common waterhemp [Amaranthus tuberculatus (Moq.)], and changes in seedbank composition from cover-cropping were driven by changes in this species. Although previous studies have shown that increases in cover crop biomass are strongly correlated with weed suppression, in our study we did not find a relationship between seedbank changes and the mean amount of cover crop biomass produced over a 10-years period (experiment means ranging from 0.5 to 2.0 Mg ha−1 yr−1), the stability of the cover crop biomass production, nor the amount produced going into the previous crop's growing season. We conclude that long-term use of a winter rye cover crop in a maize-soybean system has the potential to meaningfully reduce the size of weed seedbanks compared to winter fallows. However, identifying the mechanisms by which this occurs requires further research into processes such as seed predation and seed decay in cover cropped systems.

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Small grain winter cover crops for conservation of residual soil nitrogen in the mid-Atlantic Coastal Plain

American Journal of Alternative Agriculture ◽

10.1017/s0889189300008948 ◽

2001 ◽

Vol 16 (2) ◽

pp. 66-72 ◽

Cited By ~ 17

Author(s):

F.J. Coale ◽

J.M. Costa ◽

G.A. Bollero ◽

S.P. Schlosnagle

Keyword(s):

Coastal Plain ◽

Cover Crops ◽

Cover Crop ◽

Atlantic Coastal Plain ◽

Residual Soil ◽

Soil N ◽

Cereal Rye ◽

Winter Cover ◽

Winter Cover Crops ◽

Atlantic Coastal

AbstractCereal rye is an effective winter cover crop because it accumulates residual soil N and reduces nitrate leaching. Wheat, barley, and triticale are alternative winter small grain species that may be managed as winter cover crops and yet produce marketable commodities. The objectives of this research were to evaluate N recovery capacity and grain yields of wheat, barley, triticale, and cereal rye grown as winter cover crops. Field plots established in 1996 and 1997 at two different locations on Maryland's mid-Atlantic Coastal Plain were amended with annual spring applications of four rates of broiler litter in a randomized complete block design with four replications. Each manure rate plot was divided into four subplots by planting four winter small grain cover crops: wheat, barley, triticale, and cereal rye. Rye cover crop treatments were killed with herbicide when the plants were 30 to 50 cm tall, while the wheat, barley, and triticale treatments continued to grow until grain maturity. Barley, rye, triticale, and wheat cover crops exhibited similar capacities to accumulate soil N, and therefore, reduce the potential for NO3—N leaching to groundwater. At the time of rye kill-down, aerial biomass N accumulation ranged from 11 to 112 kg N ha−1 and soil NO3—N levels were low (<1.5 mg NO3—N kg−1) and relatively uniform across treatments. Average barley, triticale, and wheat grain yields increased with previous broiler litter application rate and initial soil NO3—N concentration. Potential income derived from the grain and straw produced could partially or completely offset cover crop production costs.

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Evaluation of cover crop sensitivity to residual herbicides applied in the previous soybean [Glycine max (L.) Merr] crop

Weed Technology ◽

10.1017/wet.2019.10 ◽

2019 ◽

Vol 33 (2) ◽

pp. 312-320 ◽

Cited By ~ 1

Author(s):

Derek M. Whalen ◽

Mandy D. Bish ◽

Bryan G. Young ◽

Aaron G. Hager ◽

Shawn P. Conley ◽

...

Keyword(s):

Cover Crops ◽

Cover Crop ◽

Crop Production ◽

Production Systems ◽

Ground Cover ◽

Crop Species ◽

Cereal Rye ◽

Crimson Clover ◽

Crop Establishment ◽

Study Results

AbstractIn recent years, the use of cover crops has increased in U.S. crop production systems. An important aspect of successful cover crop establishment is the preceding crop and herbicide program, because some herbicides have the potential to persist in the soil for several months. Few studies have been conducted to evaluate the sensitivity of cover crops to common residual herbicides used in soybean production. The same field experiment was conducted in 2016 in Arkansas, Illinois, Indiana, Missouri, Tennessee, and Wisconsin, and repeated in Arkansas, Illinois, Indiana, Mississippi, and Missouri in 2017 to evaluate the potential of residual soybean herbicides to carryover and reduce cover crop establishment. Herbicides applied during the soybean growing season included acetochlor; acetochlor plus fomesafen; chlorimuron plus thifensulfuron; fomesafen; fomesafen plus S-metolachlor followed by acetochlor; imazethapyr; pyroxasulfone; S-metolachlor; S-metolachlor plus fomesafen; sulfentrazone plus S-metolachlor; sulfentrazone plus S-metolachlor followed by fomesafen plus S-metolachlor; and sulfentrazone plus S-metolachlor followed by fomesafen plus S-metolachlor followed by acetochlor. Across all herbicide treatments, the sensitivity of cover crops to herbicide residues in the fall, from greatest to least, was forage radish = turnip > annual ryegrass = winter oat = triticale > cereal rye = Austrian winter pea = hairy vetch = wheat > crimson clover. Fomesafen (applied 21 and 42 days after planting [(DAP]); chlorimuron plus thifensulfuron and pyroxasulfone applied 42 DAP; sulfentrazone plus S-metolachlor followed by fomesafen plus S-metolachlor; and sulfentrazone plus S-metolachlor followed by fomesafen plus S-metolachlor followed by acetochlor caused the highest visual ground cover reduction to cover crop species at the fall rating. Study results indicate cover crops are most at risk when following herbicide applications in soybean containing certain active ingredients such as fomesafen, but overall there is a fairly low risk of cover crop injury from residual soybean herbicides applied in the previous soybean crop.

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001 COLLABORATIVE LEARNING AND PARTICIPATORY ON-FARM RESEARCH: COVER CROPS AND VEGETABLE PRODUCTION SYSTEMS

HortScience ◽

10.21273/hortsci.29.5.427a ◽

1994 ◽

Vol 29 (5) ◽

pp. 427a-427

Author(s):

John M. Luna ◽

Daniel Green-McGrath ◽

Ray William ◽

Stefan Seiter ◽

Tom Tenas

Keyword(s):

Collaborative Learning ◽

Cover Crops ◽

Cover Crop ◽

Crop Yields ◽

Production Systems ◽

Nitrogen Accumulation ◽

Vegetable Production ◽

Economic Returns ◽

Crop Species ◽

On Farm

A participatory, on-farm research project was initiated in 1992 in an effort to enhance mutual learning, knowledge, and experience of integrating cover crops into western Oregon vegetable production systems. A major goal of the project was to include growers, agribusiness representatives, governmental agency, Extension and university researchers in a collaborative learning process, emphasizing grower participation in the design and implementation of on-farm research and demonstration projects. To facilitate this participation from the planning stage forward, four “focus sessions” were hosted by lead farmers in different areas of the Willamette Valley to define growers' needs and interests relating to on-farm research and demonstration trials. Based on individual growers' specific experimental objectives, cover crop evaluation trials were established on ten farms. Typically on each farm, 5 to 10 cover crop species or mixtures (grain and legume) were planted in large plot strips. Twenty five different cover crop species, varieties, and mixtures were planted. Seasonal cover crop biomass and nitrogen accumulation rates were determined, with cover crop impacts on crop yields and economic returns evaluated at selected sites.

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Cover Crop Benefits for South Florida Commercial Vegetable Producers

EDIS ◽

10.32473/edis-ss461-2006 ◽

2006 ◽

Vol 2006 (11) ◽

Author(s):

Yuncong Li ◽

Edward A. Hanlon ◽

Waldemar Klassen ◽

Qingren Wang ◽

Teresa Olczyk ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Cover Crops ◽

Cover Crop ◽

Production Systems ◽

South Florida ◽

Vegetable Production ◽

Science Department ◽

Nutrient Conservation ◽

Soil And Water

SL-242, an 8-page illustrated fact sheet by Y. Li, E. A. Hanlon, W. Klassen, Q. Wang, T. Olczyk, and I. V. Ezenwa, describes how and why to use cover crops in South Florida vegetable production systems, and identifies several cover crops that work in Florida's climate, that contribute to nutrient conservation, and whose biomass can be incorporated to improve soil organic matter. Published by the UF Soil and Water Science Department, June 2006. SL-242/SS461: Cover Crop Benefits for South Florida Commercial Vegetable Producers (ufl.edu)

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2,4-D deposition is reduced and more variable immediately adjacent to cereal rye cover crop rows

Weed Technology ◽

10.1017/wet.2019.82 ◽

2019 ◽

Vol 34 (1) ◽

pp. 147-152 ◽

Cited By ~ 1

Author(s):

Erin R. Haramoto ◽

Austin D. Sherman ◽

Jonathan D. Green

Keyword(s):

Cover Crops ◽

Cover Crop ◽

Spray Deposition ◽

Late Summer ◽

Soil Surface ◽

Biomass Accumulation ◽

Early Spring ◽

Complete Control ◽

Cereal Rye ◽

Spray Solution

AbstractHorseweed, also known as marestail, is a problematic weed for no-till soybean producers that can emerge from late summer through the following spring. Overwintering cover crops can reduce both the density and size of fall-emerged weeds such as horseweed and reduce further spring emergence, although typically cover crops do not provide complete control. Cover crops may be integrated with additional spring herbicide applications to control emerged horseweed, and selective herbicides such as 2,4-D may be used to target horseweed while maintaining small grain cover crop growth. However, cover crops may affect herbicide deposition, which could reduce their efficacy to control weeds. The objective of this study was to determine how the amount and variability of 2,4-D ester spray solution deposition, measured with water-sensitive paper, was affected by a cereal rye cover crop and fall-applied saflufenacil. We also examined deposition at the soil surface relative to the cereal rye row position. In a year with greater cereal rye biomass accumulation, there was 44% less coverage and average deposit size was 45% smaller immediately adjacent to cereal rye rows compared with between rows and areas without cereal rye. Greater variability in these measurements was also noted in this position. Percent spray solution coverage was also 22% greater in plots that received saflufenacil in the fall, and deposits were 28% larger. In a year with less cover crop and winter weed biomass, no differences in spray deposition were observed. This suggests that small horseweed plants and other weeds immediately adjacent to cereal rye cover crop rows may be more likely to survive early spring herbicide applications, though the suppressive effects of cover crops may mitigate this concern.

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Horseweed (Conyza canadensis) Suppression from Cover Crop Mixtures and Fall-Applied Residual Herbicides

Weed Technology ◽

10.1017/wet.2018.111 ◽

2019 ◽

Vol 33 (2) ◽

pp. 303-311 ◽

Cited By ~ 4

Author(s):

Kara B. Pittman ◽

Jacob N. Barney ◽

Michael L. Flessner

Keyword(s):

Cover Crops ◽

Weed Management ◽

Cover Crop ◽

Field Experiments ◽

Late Spring ◽

Integrated Weed Management ◽

Management Approach ◽

Late Winter ◽

Cereal Rye ◽

Crimson Clover

AbstractHorseweed is a problematic weed to control, especially in no-tillage production. Increasing cases of herbicide resistance have exacerbated the problem, necessitating alternative control options and an integrated weed management approach. Field experiments were conducted to evaluate horseweed suppression from fall-planted cover crop monocultures and mixtures as well as two fall-applied residual herbicide treatments. Prior to cover crop termination, horseweed density was reduced by 88% to 96% from cover crops. At cover crop termination in late spring, cereal rye biomass was 7,671 kg ha–1, which was similar to cereal rye–containing mixtures (7,720 kg ha–1) but greater than legumes in monoculture (3,335 kg ha–1). After cover crops were terminated in late spring using a roller crimper, corn and soybeans were planted and horseweed was evaluated using density counts, visible ratings, and biomass collection until harvest. Forage radish winterkilled, offering no competition in late winter or biomass to contribute to horseweed suppression after termination. Excluding forage radish in monoculture, no difference in horseweed suppression was detected between cereal rye–containing cover crops and legumes (crimson clover and hairy vetch) in monoculture. Likewise, horseweed suppression was similar between monocultures and mixtures, with the exception of one site-year in which mixtures provided better suppression. In this experiment, the cover crop treatments performed as well as or better than the fall-applied residual herbicides, flumioxazin+paraquat and metribuzin+chlorimuron-ethyl. These results indicate that fall-planted cover crops are a viable option to suppress horseweed and can be an effective part of an integrated weed management program. Furthermore, cover crop mixtures can be used to gain the benefits of legume or brassica cover crop species without sacrificing horseweed suppression.

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