Elson Shields, Entomology Department, Cornell University
The increased adoption of cover crops as a soil conservation and soil health building strategy is not without increased risk from insect pest problems. Increased insect pest risk can be managed with a combination of timely killing of the cover crop, pest scouting, and additional timely application of insecticide.
The best-case scenario for the management of the cover crop to reduce insect risk is to kill the cover crop far enough in advance that the cover crop is completely dead prior to the planting of the crop. Foliar feeding insects often can survive on the dying cover crop, and if the new crop emerges before the cover crop is completely dead, the foliage feeding insects simply move from the dying cover crop onto the newly emerged and tender crop plants. This is termed a green bridge.
The worst-case scenario for insect risk is to plant into a green cover crop which has been rolled prior to planting and then sprayed with an herbicide to kill it after the crop has been planted. This provides an excellent green bridge for the insects, like black cutworm larvae and armyworm larvae, to move directly onto the newly emerging crop.
Cover Crop Bridging Insects:
Black cutworm: Black cutworm is a long-ranged migrant which overwinters in the southern US. Moths typically arrive in NY during mid-April to early-May on the early weather systems. Moths are attracted to grassy areas, grassy cover crops, grass waterways, and fields with grassy weed problems. Eggs are laid on these plants and larvae begin feeding on these plants. In the situations where producers kill the cover crops or grassy weed areas with herbicide or tillage, the black cutworm larvae continue to feed on the dying plants for 1-2 weeks. When corn seedlings start emerging, the existing larvae then move from the dying plants onto the growing corn. Since black cutworm larvae do not start their cutting behavior until mid-size (L-4), the early larval development on the grassy weeds is a critical association with the economic association of black cutworm to seedling corn. In the situations where eggs are laid on emerging corn, corn development to V6, a stage where black cutworm has difficulty cutting occurs before the black cutworm develops to the larval stage where they begin cutting (L4).
Since black cutworm larval development on existing plants in the field prior to the planting and emergence of the corn is a critical component in the development of economic infestations, the management of the green plants prior to corn planting is important. Elimination of the green bridge between the cover crop and/or grassy weed cover at least 2 weeks before the emergence of corn seedling dramatically reduces the risk of a black cutworm infestation in NY corn fields. If the separation between the killing of the cover crop/grassy weeds and the emergence of the corn crop cannot be at least 14 days, the corn seedlings need to be scouted for the presence of foliar feeding, early cutting and the presence of larvae. To the trained eye, pre-cutting foliar feeding is very obvious and easily detected.
Armyworm: Armyworm is a long-ranged migrant similar to black cutworm, but often arrives 15-30 days later in NY. It overwinters in the southern US, and the moths emerging in April in the south use the weather systems to move long distances. When the moths arrive, they are attracted to grass hay fields or grassy cover crops. If the eggs are laid in the hay field, larvae will feed on the grass and only move when the field has been stripped, thus the name armyworm. Neighboring corn fields are then attacked by the larger marching larvae. When eggs are laid in a grassy cover crop, the larvae will feed on the cover crop until it is stripped before moving. If corn is emerging in the cover crop, they will simply move onto the young corn plants. Armyworm larvae are totally foliage feeders and do not cut plants like black cutworm. With timely scouting, this insect is easily controlled with an application of foliar insecticide. Usually, the infestation is missed until the field is stripped and the larger larvae are moving into a neighboring field.
Seed corn maggot: Seed corn maggot (SCM) adults (flies) are attracted to decomposing organic material. This organic matter can range from animal manures to decomposing plant material/killed cover crop. Fresh decomposing organic matter is more attractive to the flies for egg deposition than composted organic matter; although, SCM will also lay eggs in composted organic matter. Adult flies are present for egg laying from early May until late September. The highest risk fields for SCM problems would be a green manure crop covered with a thick layer of animal manure prior to planting the crop. High manure application rates without thorough incorporation before planting of large seed crops is a high SCM risk field. Damage from SCM is plant stand reduction, and without insecticide protection, plant stands can be reduced 30%-80%. The primary reason for insecticide treatment (Poncho, Cruiser, etc) on large seed crops (corn, soybeans) is protection against SCM-related plant stand loss. Under extremely heavy SCM pressure, the insecticide seed treatment can be overwhelmed, resulting in corn/soybean stand losses.
To reduce risk from SCM, cover crops should be killed and allowed to turn brown before planting the season’s crop. In addition, applications of manure should be subsurface rather than surface applied.
Wireworms: Adult wireworms (click beetles) are attracted to small grains, grass fields, run-out alfalfa fields which are mostly grass, and grass-based cover crops. Adult beetles search out these hosts during the growing season (June-August) and lay eggs. The larvae (wireworms) hatch and feed on a wide array of roots for multiple years. In cropping sequences where grassy/small grain/cover crops are present in the field during the June-August period, wireworms feeding on new seedlings and root crops can become an economic problem. While corn is technically a grass, wireworms do not find corn fields attractive for egg laying. However, small grains are very attractive. Generally, spring planted grains are more attractive than fall planted grains which mature in early summer. In conventional production systems, the insecticide seed treatment generally is effective at reducing the impact of wireworm feeding. However, in the organic production system, there are no effective rescue treatments for wireworm infestations/feeding damage. If grassy cover crops are the only grass in the cropping sequence, timely crop termination before June will reduce the attractiveness to wireworms for egg laying.
White grubs: In NYS, there are two different groups of white grubs which can be problematic. The first group is the native white grubs which have multi-year life cycles and the second group is the invasive annual white grubs (Japanese Beetle, European Chafer). Adults from both groups are attracted to grassy habitats to lay their eggs during mid-June to mid-July. Eggs hatch during August, and the larvae begin to feed on grass roots. In the case of the invasive annual white grubs, the larvae grow quickly and achieve more than 50% of development before winter. In the spring, the larvae resume development and are quite large when the grassy field is rotated to corn or soybeans and the new plants are quite small. Plant death is caused by these large larvae feeding on plant roots faster than the plant can generate roots. Larvae become adults in June and the cycle repeats. In the case of the native multiyear white grubs, the life cycle is similar but larval development requires 2-4 years depending on the species. Subsequent crops following the grassy/cover crop/small grain field are then impacted differently. With annual white grubs, the damage to the subsequent crop is confined to the following year only. In the case of native white grubs, subsequent crops could be impacted up to 4 years with declining damage levels each year.
The following two different cropping scenarios seem to place subsequent crops at higher risk. The most common case is the alfalfa field which has become mostly grass or a grass hay field which is then rotated into a large seed crop like corn or soybeans. The second scenario is the field which has been planted to a grass-based cover crop and not killed during the June-July egg laying period. In most cases, the insecticide seed coating on all corn and some soybean seeds reduce the impact of white grubs on subsequent crops. High white grub populations can overwhelm the insecticide, however.
Slugs: Increasing the organic soil cover with either the use of cover crops or last year’s crop waste increases the slug problem. In cool wet springs, which slow plant emergence and growth, damage from slug feeding can be severe. There is a little anecdotal evidence to suggest the presence of green cover reduces the slug damage because of the surplus of green tissue. In these cases, slugs miss the newly emerging plants and feed on the green cover crop.
By Brian Caldwell, Jeff Liebert, and Matthew Ryan
Soil and Crop Sciences Section, School of Integrative Plant Science, Cornell University
Interest in no-till planting soybeans into a rolled-crimped winter cereal cover crops is increasing among New York State organic grain farmers. This approach is also called “organic rotational no-till” because tillage is used to establish the cover crop in the fall. The rolled-crimped cover crop acts as mulch and helps suppress weeds in the summer. In addition to soil health benefits, this system has potential to save time and fuel by eliminating mechanical inter-row cultivation for weeds in organic soybean production.
In September of 2013, cereal rye, winter barley, and triticale were planted at an organically managed farm in Penn Yan, NY in anticipation of rolling-crimping them for no-till soybean planting the following spring. Two cultivars were planted per species: ‘Aroostook’ and a variety not stated (VNS) rye, ‘McGregor’ and ‘Verdant’ barley, and ‘TriCal 718’ and ‘TriCal 815’ triticale. The six cultivars across three species were arranged in a randomized complete block design with four replications, and plots were 15 x 15 feet to accommodate farm-scale equipment. Immediately prior to rolling-crimping, cover crop biomass was sampled from each plot. Cover crop biomass was determined by clipping the plants at the soil surface within a 5.4-ft2 (0.5-m2) quadrat, oven-drying the vegetation at 122°F for one week, and then weighing the dried samples. Weed biomass samples were collected approximately 15 weeks after soybean planting, which corresponds to the maturation of one of the most dominant weeds in the experiment, common ragweed (Ambrosia artemisiifolia L.). Weed biomass samples were collected, dried, and weighed as described for the cover crops, except 2.7-ft2 (0.25-m2) quadrats were used.
Soil types in this field were Cayuga silt loam and Honeyoye silt loam with 3-8% slopes. Soil test results showed the field was low in pH (5.7), P (3.8 lb/acre), and soil organic matter (2.0%).
This was an on-farm trial in conjunction with a series of experiments at the Musgrave Research Farm in Aurora, NY and the USDA Beltsville Agricultural Research Center in Beltsville, MD, which explored how different cultivars and termination timing of these three rolled-crimped winter cereal species affected weed suppression and soybean crop performance. Previous research suggested that optimal termination timing with a roller-crimper occurs when winter cereal cover crops have reached anthesis (flowering, Feekes growth stage 10.51), which is typically between late May and early June in the Northeast, depending on the winter cereal cover crop species. With anthesis signifying the transition from vegetative to reproductive growth, cover crop termination with a roller-crimper can be as effective as termination with synthetic herbicides (Ashford and Reeves, 2003; Davis, 2010; Mirsky et al., 2009).
Termination timing is particularly important for multiple reasons. If the cover crops are rolled prior to anthesis, termination can be incomplete and the cover crops will continue to grow, competing with soybean seedlings for light, water, and nutrients, and eventually producing seed that can become a weed later in the rotation. However, if termination timing occurs well past anthesis (i.e., too late), the winter cereal cover crops might similarly produce viable seed that can become a weed the following year, and late rolling will delay soybean planting, possibly reducing yield potential.
Winter cereals were planted with an Amazone Airstar Profi combination drill-power harrow on September 16, 2013, and terminated in 2014 on May 30 and June 5 with a 10-ft front-mounted roller-crimper (I & J Mfg., Gordonville, PA; Figure 1). The cover crops were drilled 1 inch deep in 5-inch wide rows with an Esch No-Till 5507 on the same day, and immediately after, rolling-crimping (Figure 2). Cereal grains can mature quickly in mid-May, which makes frequent growth stage scouting particularly important during that period of time. Feekes growth stages were 10.5, 10.54, and 11.1 for triticale, rye, and barley at the early termination date (May 30) and 10.54, 11.1, and 11.2 at the later date (June 5), respectively. These stages correspond to the onset of flowering (anthesis) through milky ripe for the early termination date, and the end of flowering through soft dough for the later date.
Cover crop biomass. Winter cereal biomass production at this site was relatively high, with over 8000 lb/acre for rye, 7000 lb/acre for triticale, and 5000 lb/acre for barley across both dates (Figure 3). After being rolled, the cover crops form a thick layer of mulch (Figure 4), which serves as the primary source of weed suppression in this system.
Based on work by Teasdale and Mohler (2000), achieving at least 7000 lb/acre of cover crop biomass at termination is likely to result in good weed suppression when rolled-crimped in this system (Mirsky et al., 2012; Mirsky et al., 2013). Thus on both planting dates, the rye and triticale cover crops produced enough biomass to exceed the recommended threshold, but barley did not. However, too much cover crop biomass can also be a problem. Lodging of up to 60% of the plants in a given plot was observed in rye terminated at the late termination date. As coulters on no-till planters and drills are not typically designed to cut through large amounts of residue, lodged plants that lay diagonally or perpendicular to the direction of rolling-crimping and no-till planting can impede adequate soybean seed placement, which can reduce germination and potentially decrease soybean yield. Also, if hair-pinning (i.e., residue forced into the furrow) is particularly problematic, poor seed-to-soil contact can result in gaps in the canopy, which can reduce late-season weed suppression.
Cover crop bounce-back was relatively low across all treatments with less than 20% of the barley plants “standing back up” after rolling-crimping, and less than 15% of the triticale and 10% of the rye plants doing the same. It is unlikely that the incompletely-terminated cover crops—most of which stood at a 45° angle and simply died at a slower rate than their flattened counterparts—impacted soybean yield. However, the resulting seed some cover crop plants produced might have resulted in volunteer cover crops in the following year.
It is worth noting that no-till drilling soybean seed into rolled cover crop mulch is not the recommended practice for most situations (Mirsky et al., 2013). Drilling can require adding a considerable amount of additional weight to the drill units to achieve acceptable, uniform planting depth if soil conditions are dry. Instead, a no-till planter set at 15- or 30-inch rows tends to perform better over a wider variety of soil conditions and biomass levels. We used a drill for the on-farm trial because it was the only no-till equipment available. Similarly, rolling-crimping and no-till drilling would ideally be completed in a single pass, but two operations were required in this experiment because the no-till drill width did not match the width of the roller-crimper.
Weed biomass. Across all treatments, weed biomass in early fall (September 15) tended to be lower in plots with greater cover crop biomass (measured before rolling-crimping). We observed lower weed biomass in late-terminated rye and triticale compared with early-terminated barley (P < 0.05), but weed biomass was not statistically different between the two termination dates within each species (Figure 5).
The perennial weed quackgrass (Elymus repens [L.] Gould) comprised 44% of the total weed biomass across all treatments. Across all species, mean quackgrass biomass was 512 lb/acre at the early termination date and 294 lb/acre at the late termination date (P = 0.08). This is an important consideration, since perennial weeds tend to proliferate in the absence of tillage. Common ragweed was the other dominant weed species in the experiment at 42% of the total weed biomass across all treatments. Similarly, mean common ragweed biomass was lower (P = 0.09) in the cover crop treatments terminated later (220 lb/acre) compared with the earlier termination date (541 lb/acre).
Soybean yield. Soybean yield was relatively high across all treatments, averaging 40 bu/acre (Figure 6). Even if weeds do not reduce crop yield, they can produce seeds and cause problems for future crops in the rotation. In this trial, late-terminated rye and triticale produced similar results, with high cover crop biomass, minimal cover crop bounce-back, low weed biomass, and relatively high soybean yields. Although soybean yield was not statistically different, early-terminated barley had the lowest cover crop biomass and greatest weed biomass (Figures 3 and 5). Thus, our results indicate that rye or triticale perform better than barley in this system, and terminating the cover crops at a slightly later date can be advantageous for reducing weeds (especially quackgrass and common ragweed) without sacrificing soybean yield.
Watching the weather. Soil moisture conditions are also very important to consider. In an extremely dry spring, such as in 2016, transpiration from a dense cover crop stand can reduce soil moisture, which can inhibit soybean seed germination and reduce yield potential. When the soil is this dry, the best option might be to forgo planting soybean entirely. Instead, it might be advisable to allow the cover crop to grow to maturity, harvest it, and plant a different crop afterwards. In most years in New York, however, limited spring rainfall is not a problem. Still, winter cereal cover crops can dry out the surface of the soil, making seed placement difficult. In this situation, we have found that adjusting planting dates based on rain events can be helpful to ensure the planter can penetrate the soil and achieve good seed-to-soil contact. In addition to no-till planting right after a rain, another trick that we have used is to add weight to the planter to increase the down pressure on the front coulters.
Conclusions. This on-farm trial augmented our research farm experiments in several ways. We had high cover crop biomass production at this site, and we were able to observe the results from different types of equipment than were used at the Musgrave Research Farm or Beltsville Agricultural Research Center. Perhaps most importantly, the good yields on this small field gave the farmer confidence in using this method on more soybean acres, and he has since advocated this approach at farmer meetings. However, our on-farm results were only from one year, so trials on more sites and over more seasons are needed to refine our management recommendations.
This work was supported by a joint research and extension program funded by the Cornell University Agricultural Experiment Station (Hatch funds) and Cornell Cooperative Extension (Smith Lever funds) received from the National Institutes for Food and Agriculture (NIFA) U.S. Department of Agriculture (Project: 2013-14-425). Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture.
Ashford DL, Reeves DW (2003) Use of a mechanical roller-crimper as an alternative kill method for cover crops. Am J Altern Agric 18:37–45
Davis AS (2010) Cover-crop roller–crimper contributes to weed management in no-till soybean. Weed Sci 58:300–309
Mirsky SB, Curran WS, Mortensen DA, Ryan MR, Shumway DL (2009) Control of cereal rye with a roller/crimper as influenced by cover crop phenology. Agron J 101:1589–1596
Mirsky SB, Ryan MR, Curran WS, Teasdale JR, Maul J, Spargo JT, Moyer J, Grantham AM, Weber D, Way TR, Camargo GG (2012) Conservation tillage issues: cover crop-based organic rotational no-till grain production in the mid-Atlantic region, USA. Renew Agric Food Syst 27:31–40
Mirsky SB, Ryan MR, Teasdale JR, Curran WS, Reberg-Horton CS, Spargo JT, Wells MS, Keene CL, Moyer JW (2013) Overcoming weed management challenges in cover crop- based organic rotational no-till soybean production in the Eastern United States. Weed Technol 27:193–203
Teasdale JR, Mohler CL (2000) The quantitative relationship between weed emergence and the physical properties of mulches. Weed Sci 48:385–392
Brian Caldwell1, Chris Pelzer1, and Matthew Ryan1
|1Soil and Crop Sciences Section – School of Integrated Plant Science, Cornell University
The InterSeeder is a new tool developed at Penn State University that allows for drilling of cover crops into standing cash crops (Figure 1). At the same time, liquid fertilizer and herbicides can also be applied to reduce the number of tractor passes. Three 7.5”-spaced rows of cover crops are drill interseeded in the space between 30” corn or soybean rows, allowing for excellent establishment of the cover crops. This takes place after the cash crop is established and is no longer susceptible to competition from weeds (i.e., after the critical period for weed control, which is roughly stage V5 for corn and V4 for soybeans (Hall et al. 1992). Compared to being planted after cash crops are harvested in late fall, interseeded cover crops have more time to grow before winter (Figure 2). As corn and soybean begin senescing in late summer, cover crop plants quickly add biomass before winter. In proportion to their growth in the fall and the next spring, cover crops provide a number of benefits such as recycling of nitrogen in the soil, protecting soil from erosion, and adding organic matter.
Previous research was done in New York State using other methods of interseeding into corn (Scott et al. 1987) and soybeans (Hively and Cox 2001). See also http://mysare.sare.org/wp-content/uploads/917698final.pdf. Results were promising, but problems remained with inconsistent cover crop establishment (Jane Mt. Pleasant, personal communication). Although drilling cover crops with the InterSeeder has potential to increase consistency of establishment so that cover crop benefits are achieved, there are a number of questions about the best way to implement this practice. Optimal seeding dates, cover crop species, varieties, mixtures, and soil nutrient levels have yet to be determined. Here we report on field experiments in NYS over the past two years.
On-farm cover crop interseeding trials
In 2013 and 2014, several trials were conducted in at four on-farm sites and at the Cornell Musgrave Research Farm. Five treatments consisting of two annual ryegrass varieties, tillage radish, a legume mix (hairy vetch, red clover, and crimson clover), and ryegrass + legume mix were interseeded into corn. Roundup Ready corn was used at all locations and glyphosate was applied to control weeds prior to interseeding.
Interseeded tillage radish was grown in two trials only. It produced 100-500 dry lb/acre of biomass in the fall and was killed over the winter. Performance of annual ryegrass and mixes was variable. In general, fall cover crop dry biomass was less than 700 lb/acre. In the following spring, legumes and legume mixes often produced the most biomass. Spring biomass of winter hardy species was influenced by cover crop termination date. Overwintered cover crops in New York typically grow rapidly after May 1 until they begin to reproduce in late May to mid-June. Thus early May termination can result in much lower biomass than that of cover crops terminated in late May or early June. Biomass in the fall reflects the ability of a cover crop to reduce erosion and protect soil over the winter, whereas its biomass in the spring affects soil nutrient levels. For example, depending on management practices and weather conditions, a legume cover crop biomass of 1,000 lb/a in the spring can typically provide 15 lbs/acre of nitrogen to the following crop.
In our trials, yield of the “host” crop (a cash grain crop into which the cover crops were interseeded) was not affected by the presence of an interseeded cover crop, except in one case when the interseeding was done too late and a soybean crop was damaged by equipment. However, the host crop strongly affected the interseeded cover crop. At the Cornell Musgrave Research Farm, legumes produced over 1,500 lb/acre of biomass by May 22, 2014. In contrast, at the Reed Farm in northern New York, all cover crops produced less than 250 lb/acre of biomass by May 13, 2014. Temperatures were cooler at the Reed Farm and cover crop termination was earlier, partially explaining the lower biomass levels. In addition to climate differences, the 2013 Musgrave Farm host corn crop produced less than 100 bu/acre (due to excessive spring rain and poor drainage), whereas the Reed Farm host corn crop yielded twice as much. Cover crop growth at Musgrave Farm in spring 2014 was likely more vigorous because it established under the weaker-growing 2013 host corn. Dense, tall corn such as in the Reed Farm trial, and closed-canopy soybean stands will shade and suppress cover crops interseeded into them, especially under dry conditions.
In 2013, cover crops also performed very well at the Evanick Farm, a dairy where corn was grown for silage instead of grain. Corn was planted on May 4, 2013 and cover crops were interseeded on July 2, 2013. At this site, ‘KB Royal’ annual ryegrass produced over 2,000 lb/acre of fall biomass, sampled on October 30, 2013, and the annual ryegrass + legume mix produced 1,850 lb/acre. The next spring KB Royal, legumes, and the ryegrass/legume mixture each produced about 750 lb/acre by May 1, 2014. On dairy farms such as the Evanick Farm, manure applications may result in relatively large amounts of nitrogen mineralization after silage harvest in mid-September. This, plus the early date of corn silage removal, can allow for high cover crop biomass levels in the fall, and impressive growth in spring before an early termination. Silage yield was moderate and was not affected by the interseeded cover crops.
Comparing interseeded cover crop species in soybean
In 2013, 11 cover crop species and mixes were drill interseeded into soybeans at the Cornell Musgrave Research Farm in Aurora, New York and their performance was compared. Again, Roundup Ready soybeans were planted and glyphosate was applied for weed control prior to cover crop interseeding. Cover crops were drill interseeded into soybeans on July 16, which resulted in good establishment. Soybean yields averaged 53 bu/acre across interseeded cover crop treatments. Fall 2013 cover crop biomass, sampled after soybean harvest on November 19, 2013, was high for crimson clover, the legume mix, perennial ryegrass, cereal rye, and annual ryegrass. Red clover and tillage radish produced intermediate amounts of biomass. Orchardgrass, yellow sweet clover, ladino clover, and Kentucky bluegrass produced a low amount of fall biomass (Figure 3).
The following spring, several species grew well before termination on May 22, 2014. Cereal rye produced 2,000 lb/acre and medium red clover produced over 1,200 lb/acre. Yellow blossom sweet clover, perennial ryegrass, and orchardgrass also produced around 1,000 lb/acre. Annual ryegrass, Kentucky bluegrass, and ladino clover performed poorly, and winter survival of crimson clover and tillage radish was very low (Figure 3).
In the 2014-15 soybean trial, results were quite different. Weather conditions during the 2014 growing season were more challenging and cover crops were not interseeded until August 11, almost a month later than in 2013. Soybean yields were lower at 38 bu/acre, and again no differences in soybean yield were observed between treatments. Fall 2014 cover crop biomass was visibly much lower than in 2013, but cover crops were not sampled. In spring 2015, annual ryegrass produced the greatest biomass, which was similar to the amount of annual ryegrass produced in the spring of 2014. However, the other cover crop treatments did not perform as well as in the previous year (Figure 4).
Interseeding cover crops into soybeans has potential, but this practice needs more research. We observed that earlier-seeded cover crops could establish well and produce more fall and spring biomass than later-seeded cover crops, without impacting soybean yield. In both years of the experiment, red clover, orchardgrass, and the ryegrass treatments were among the top producers of biomass.
Interseeding cover crops into corn and soybeans can be a successful strategy to improve cover crop performance without decreasing host cash crop yields. Despite variable results, our findings indicate that: 1) interseeding cover crops too late can reduce cover crop establishment and limit biomass production; and 2) delaying cover crop termination until the second half of May can increase biomass production substantially. Interseeding cover crops in silage corn (rather than grain corn) results in better cover crop growth because corn silage is harvested earlier than corn grain, thus allowing for unobstructed cover crop growth for about an extra month in the fall.
We suggest that a reasonable interseeding program may be to establish a mixed ryegrass and legume cover crop under soybeans before next year’s corn; or ryegrass alone under corn before next year’s soybeans. Cover crops should produce a fall biomass of 200 to 500 lb/acre and protect the soil over winter. The following spring, delaying cash crop planting until late May can allow production of 2000 lb/acre cover crop biomass. Increased duration of spring cover crop growth could increase nitrogen content of biomass to 60 lb N/acre, in addition to cycling other nutrients and adding organic matter to the soil. There would likely be a minor 2nd year corn yield loss with this approach due to late planting date, but this could be offset by a reduction in corn nitrogen fertilization costs. Research is needed to better understand tradeoffs with yield potential and fertilizer costs associated with delaying cover crop termination in the spring.
The InterSeeder was designed by Bill Curran, Corey Dillon, Chris Houser, and Greg Roth at Penn State and they have developed additional guidelines and herbicide recommendations for cover crop interseeding. For more information about this practice and the InterSeeder see:
This work was supported by a joint research and extension program funded by the Cornell University Agricultural Experiment Station (Hatch funds) and Cornell Cooperative Extension (Smith Lever funds) received from the National Institutes for Food and Agriculture (NIFA) U.S. Department of Agriculture (Project: 2013-14-425). Partial support was also provided by the Northern New York Agriculture Development Program (Project: The early interseeded cover crop gets the worm) and the USDA NRCS CIG program (Project: Maximizing conservation in the Chesapeake Bay Watershed with an innovative new 3-way interseeder for early establishment of cover crops in no-till corn and soybean). Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture.
Hall, M.R., C.J. Swanton, and G.W. Anderson. 1992. The Critical Period of Weed Control in Grain Corn. Weed Science. 40:441-447.
Hively, W. D. and W. J. Cox. 2001. Interseeding Cover Crops into Soybean and Subsequent Corn Yields. Agron. J. 93:308–313.
Scott, T. W., J. Mt. Pleasant, R. F. Burt, and D. J. Otis. 1987. Contributions of Ground Cover, Dry Matter, and Nitrogen from Intercrops and Cover Crops in a Corn Polyculture System. Agron. J. 79:792-798.
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