What’s Cropping Up? Volume 29 Number 3 – July/August 2019

Organic compared to Conventional Crop Rotations lost $ during the Transition but made more $ in the 2 years after the Transition and in the total 4 Years of the Study

Bill Cox, John Hanchar, Eric Sandsted, and Mark Sorrells

2016 July corn, soybeans, and wheat
The organic corn-soybean-wheat/red clover rotation was the most profitable rotation from 2015 to 2018.

We conducted a 4-year study at the Aurora Research Farm from 2015 to 2018 to compare different sequences of the corn, soybean, and wheat/red clover rotation in conventional and organic cropping systems under recommended and high input management. Unfortunately, we were unable to plant wheat after soybean in the fall of 2016 because green stem in soybean, compounded with very wet conditions in October and early November, delayed soybean harvest until November 9, too late for wheat planting. Consequently, corn followed soybean as well as wheat/red cover in 2017 so we compared two sequences of the corn-soybean-wheat/red clover rotation with a corn-soybean rotation (Table 1). Please refer to previous What’s Cropping Up? articles from 2015 to 2018 for the various inputs for each crop for each year within each cropping system (https://scs.cals.cornell.edu/extension-outreach/whats-cropping-up/). Also, you can refer to Table 2 for a general overview of the management inputs for each crop within cropping systems across years. This article will first discuss the economics of the three crops in Year 3 or 4 of the study. We will then discuss the economics of the three rotations during the 36-month transition period (Year 1 and 2 of the study), the 2-year period after the transition (when the organic premium is in place), and the total 4 years of the study.

Tables 3-6 show the revenue, selected costs, and returns above selected costs for corn in 2017, soybean in 2017, and wheat in 2018. The selected costs differed slightly for each crop across years because of changes in input prices (for example fertilizer and fuel prices change somewhat from year to year). The differences in selected costs between cropping systems for each crop, however, are consistent across years so Tables 3-6 are very representative of selected costs of each crop. On the other hand, revenue and returns for each crop differed significantly across years mostly because of different yields (for example, organic corn averaged ~115 bushels/acre in 2015 but ~185 bushels/acre in 2017), but also because commodity prices varied somewhat across years. So use Tables 3-6 as references in the discussion on selected costs for each crop but not for the revenue and returns for each crop in each year. We didn’t include the 2018 soybean economics data, however, because the differences in revenue and returns between organic and conventional systems were similar as were comparisons between rotations, and  the costs did not vary by more than $6/acre for each treatment.

Organic compared with conventional corn with recommended inputs had ~$15/acre lower selected costs following wheat/red clover (C3 vs. C1 comparison, Table 3) but ~$275/acre higher selected costs following soybean (C3 vs. C7 comparison, Table 3). With high inputs, organic compared with conventional corn had ~$120/acre higher selected costs following wheat/red clover (C4 vs. C2 comparison, Table 4) and ~$365/acre higher selected costs following soybean (C8 vs. C6 comparison, Table 4). As expected, organic compared with conventional corn had lower seed costs because the organic hybrid did not receive a seed treatment and did not have GM traits (Tables 3 and 4). Organic compared with conventional corn had higher fertilizer costs because of the much greater cost for composted poultry manure relative to conventional starter and N fertilizer. The fertilizer and selected costs were much greater for organic corn following soybean (C7 and C8, Tables 3 and 4) compared with following wheat/red clover (C3 and C4) because of the greater N requirement for corn when following soybean. Organic compared with conventional corn also had higher labor, repair and maintenance, and fuel and lubricant costs because of the 4-time use of labor and equipment for mechanical weed control in organic corn (rotary hoe 1x and cultivation 3x) compared with the 1-time use of labor and equipment in conventional corn (herbicide application). Organic compared with conventional corn also had greater fixed costs because of greater wear and tear with the 4-time use of tractors and equipment compared to 1-time use of tractors and equipment for weed control purposes.

Organic compared with conventional corn with recommended inputs had ~$70/acre greater revenue when following wheat/red clover in 2017 (C3 vs C1 comparison, Table 3) and similar revenue when following soybean (C7 vs. C5 comparison, Table 3) in the absence of an organic premium. All prohibited inputs (synthetic fertilizer, GM crops, pesticides, etc.), however, had been applied to the three fields in our study by June of 2014, more than 36 months prior to corn harvest in 2017, so organic corn would have been eligible for the organic premium. We will thus use organic prices for 2017 corn and soybean crops grown under organic management in this study. Organic compared with conventional corn with recommended inputs had ~$830/acre greater revenue following wheat/red clover and ~$685/acre greater revenue when following soybean in the presence of the organic premium (Table 3). Likewise, organic compared with conventional corn with high inputs had ~$990/acre greater revenue when following wheat/red clover (C4 vs. C2 comparison, Table 4) and ~$780/acre greater revenue following soybean (C8 vs. C6 comparison, Table 4). Please keep in mind that organic corn yields averaged ~185 bushels/acre; whereas conventional corn yields averaged ~175 bushels/acre in 2017.  In 2015, however, organic compared with conventional corn had much lower revenue because of ~35% lower yields and the organic premium was not in place (first year of the transition). Likewise, in 2016, organic corn had lower revenue because of 7% lower yields, similar or higher selected costs, and no organic premium (2nd year of the transition). So please use Tables 3 and 4 as representative of selected costs but not of revenue and returns above selected costs.

Organic compared with conventional soybean had ~$20/acre higher selected costs with recommended inputs (S3 vs. S1 comparison, Table 5) but ~$5/acre lower selected costs with high inputs (S4 vs. S2 comparison, Table 5). Organic compared with conventional soybean had lower variable costs because of lower seed and other crop input costs, despite higher labor, repair and maintenance, and fuel and lubricant costs (Table 5). As with organic corn, organic compared with conventional soybean had higher fixed costs because of more wear and tear on the machinery with 5 trips (1x rotary hoeing and 4x cultivations) compared to 1 trip over the field (herbicide application) with recommended inputs or 2 trips over the field (herbicide and fungicide applications) with high inputs .

Organic compared with conventional soybean had ~$55/acre lower revenue with recommended inputs (S3 vs. S1 comparison, Table 5) or with high inputs (S4 vs. S2 comparison, Table 5) in 2017 because of ~8% lower yield in the absence of an organic premium (Table 5). In the presence of an organic premium, organic compared with conventional soybean had ~$370/acre greater revenue with recommended or high inputs. Unlike corn that had inconsistent yield differences between organic and conventional corn across years, organic and conventional soybean yield differences did not vary much (similar yields in 2015 and 2016; ~8% lower in 2017; and ~11% lower in 2018).  Because of the small differences in yield and selected costs, organic and conventional soybean had similar returns above selected costs in 2015 and 2016 and higher returns in 2017 and 2018. Organic soybean with recommended and high inputs had similar returns in 2017 (S4 vs. S3 comparison) as well as in 2015 and 2016 but somewhat higher returns in 2018.

In 2018, organic compared with conventional wheat had ~$160/acre greater selected costs with recommended inputs (W3 vs. W1 comparison, Table 6) and ~$190/acre greater costs with high inputs (W4 vs. W2 comparison, Table 6). Organic compared with conventional wheat had lower seed costs (same variety but no seed-applied pesticide), but much higher fertilizer costs, associated with the use of composted chicken manure, which costs almost 13x the cost of the ammonium nitrate (33-0-0) used on conventional wheat. Organic compared with conventional wheat with recommended inputs in 2018 had ~$205/acre greater revenue because the yields were similar and organic wheat received the organic price premium. Also, organic compared with conventional wheat with high inputs had ~$255/acre greater revenue because of ~7% higher yields and the presence of an organic premium.

Organic compared with conventional wheat with recommended inputs (W3 vs. W1 comparison, Table 6) had ~$45/acre higher return in 2018, despite the ~$160/acre higher selected costs. Obviously the increased revenue, associated with the organic premium, offset the higher selected costs, associated with the use of composted chicken manure. Likewise, organic compared with conventional wheat with high inputs had ~$65/acre higher returns above selected costs (W4 vs. W2 comparison, Table 6). Despite the higher revenue of organic wheat with high vs. recommended inputs, organic wheat with recommended inputs had ~$75/acre higher returns (W3 vs. W4 comparison) because the added revenue from the ~7% yield increase did not offset the higher selected costs, associated mostly with the higher rates of composted manure. Organic compared with conventional wheat, however, had lower returns in 2016 because yields were ~7% lower, selected costs were higher, and the organic premium was not in place (2nd year of transition).

Table 7 shows the costs, revenue, and returns above selected costs of the red clover-corn, corn-soybean, and soybean-wheat/red clover rotations during the transition period, the first 2 years (2015 and 2016) of the study. (A value in Table 7 equals the sum of the 2015 and 2016 values for that treatment). As explained in previous news articles, we planted red clover alone in the early summer of 2015 and plowed it under in the spring of 2016 to see if a green manure crop would provide agronomic and economic benefits to subsequent organic crops in the rotation. The 2-year organic compared with conventional rotations generally had higher selected costs, especially with high input management, mostly because of the very high costs for the composted manure applied to corn and wheat. Revenue was similar as were returns between conventional ($152/acre) and organic ($179/acre) red clover-corn rotations with recommended inputs. Most conventional growers, however, would not plant a green manure crop so a comparison of the organic red clover-corn rotation vs. the conventional corn-soybean rotation with recommended inputs is more appropriate. In this comparison, the organic red clover-corn rotation had ~$455/acre lower returns, similar to the comparison between the conventional vs. organic corn-soybean rotation. The organic compared with the conventional soybean-wheat/red clover rotation with recommended inputs had ~$220/acre lower returns, which proved to be the most economical organic rotation in this study during the transition years. Many conventional growers, however, use high inputs on soybean (200,000 seeds/acre, fungicide/insecticide seed treatment, and foliar fungicide application) and even more so on wheat (high seeding rate, seed treatment, fall herbicide application, split-N application, and foliar fungicide application). A comparison of the organic soybean-wheat/red clover rotation with recommended inputs vs. the conventional soybean-wheat/red clover rotation with high inputs shows only ~$95/acre lower returns during the first 2 years of the transition. All rotations in conventional and organic cropping systems with recommended vs. high inputs had greater returns, except for the conventional corn-soybean rotation, which had similar returns.

During the first 2 years after the transition (2017 and 2018) in this study, selected costs were once again mostly higher in the organic compared with the conventional rotations, especially with high input management (Table 8, a value in the table equals the sum of the 2017 and 2018 values for that treatment). Again, the higher costs for composted manure on organic corn and wheat compared to synthetic fertilizer contributed to the higher costs. The organic compared with the conventional cropping system in all three rotations had much greater revenue because of similar to greater corn and wheat yields or slightly lower soybean yields, coupled with the organic premiums. So despite the mostly higher selected costs for organic compared with the conventional rotations, higher costs did not offset the higher revenue, resulting in much higher returns above selected costs for the organic rotations (Table 8). When averaged across input treatments, organic compared with the conventional cropping system had ~$410/acre higher returns in the red clover-corn-soybean-wheat/red clover rotation, ~$720/acre higher in the corn-soybean rotation, and ~$1200/acre higher in the soybean-wheat/red clover-corn-soybean rotation. When averaged across input treatments in the organic rotation, the organic soybean-wheat/red clover-corn-soybean rotation had ~$435/acre higher returns than the organic corn-soybean rotation and ~$930/acre higher returns than the organic red clover-corn-soybean-wheat/red clover rotation. Similar to the transition period, the soybean-wheat/red clover-corn-soybean rotation was the most economical organic rotation during the first 2 years after the transition.

The organic compared with the conventional cropping system had much higher total selected costs in all 4-year crop rotations, which was more than offset by the much greater revenue in all 4-year crop rotations (Table 9). When averaged across input treatments, the organic compared with the conventional cropping system had ~$270/acre higher returns above selected costs in the red clover-corn-soybean-wheat/red clover rotation, ~$200/acre higher returns in the corn-soybean rotation, and ~$955/acre higher returns in the soybean-wheat/red clover-corn-soybean rotation. When averaged across input treatments in the organic rotation, the organic soybean-wheat/red clover-corn-soybean had ~$470/acre higher returns than the organic corn-soybean rotation and ~$1030/acre higher returns than the organic red clover-corn-soybean-wheat/red clover rotation. Obviously, planting a green manure crop was the least profitable organic rotation to select. Despite the lower returns for organic wheat compared with organic soybean or organic corn, the inclusion of wheat/red clover in the organic rotation was far more profitable than just the corn-soybean rotation over the 4-year period. In contrast, the corn-soybean rotation was most profitable for the conventional cropping system.

In the organic cropping system, recommended input compared with high input management had $412/acre higher returns above selected costs in the red clover-corn-soybean-wheat/red clover rotation and $169/acre higher returns in the corn-soybean and soybean-wheat/red clover-corn-soybean rotation. Consequently, the results clearly suggest that organic cropping systems, regardless of rotation, did not respond to high input management in this study. Many organic growers have been advised to use higher than recommended seeding rates with the goal of improved weed control. In our study, we saw statistically fewer weeds with high input management in corn, soybean and wheat but differences were so small that it had no effect on crop yield in this environment. Based on the returns above selected costs in our study, the use of higher seeding and N rates is not justified in the first 4 years of organic soybean-wheat/red clover-corn-soybean rotation on silt loam soils in central New York.

Conclusions

Field crop producers who transition to organic corn, soybean, and wheat production can generate greater returns above selected costs than conventional field crop producers after 4 years under the environmental conditions of this study, if they can successfully manage the cash-flow challenges during the transition period. To help manage the cash-flow challenges, transitioning growers should not apply prohibited inputs in their last conventional crop after late spring/early summer so the 36-month transition period can be accomplished in two growing seasons. Given the growing conditions during this study and the economic analyses reported here, transitioning growers should not use a green manure crop in the first year of transition but rather plant soybean. Soybean does not require N fertilizer, a major constraint to organic corn and wheat production, so growers should begin their transition in a field where soybean is the intended crop. In addition, soybean with the use of aggressive cultivation is also competitive with weeds, the other major constraint to organic field crop production.

Based on the economic results of this study, field crop producers should include winter wheat as the second crop in the transition after soybean. Organic growers may be able to no-till wheat after soybean harvest, if few winter perennial weeds are observed in the soybean crop. Growers should also frost-seed red clover into standing wheat in early spring, a typical practice for many conventional wheat growers.

Economic analyses of this study suggests that field crop producers, who transition to an organic cropping system, should plant corn in the 3rd year, or the first year when crops are eligible for the organic premium. Organic corn typically has a higher premium when compared with premiums for organic soybean and organic wheat. Corn should follow wheat with interseeded red clover, which provides considerable slow-release N to the subsequent corn crop. In addition, the wheat/red clover crops can disrupt weed cycles, as evidenced by the much lower weed densities in organic corn in the soybean-wheat/red clover-corn-soybean rotation compared with the corn-soybean rotation in 2017. In the 4th year of the study, field crop producers should begin the soybean-wheat/red clover-corn-soybean rotation again by planting soybean.

Based on the economic results of this study, field crop producers should use current recommended inputs for conventional crops and not use elevated seeding rates to improve weed control or use higher N rates to provide more available soil N to corn and wheat. Although the organic compared to the conventional cropping system generated greater returns above selected costs in this study, we recognize that commodity prices, farm size, individual/personal beliefs, and other factors influence a grower’s decision on whether to transition to an organic cropping system. Furthermore, we recognize that the growing conditions and soils were unique to this study so results could differ for different years or locations in New York.

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What’s Cropping Up? Volume 28, Number 5 – November/December 2018

“Deja Vu all over again”: Organic soybeans in a soybean-wheat/red clover-corn rotation comes in at 55 bushels/acre but high input conventional beans come in at 62 bushels/acre

by Bill Cox, Eric Sandsted, Phil Atkins, and Wes Baum

Conventional soybean remained weed-free throughout the season.
Organic soybean was generally clean but the weeds were quite robust in locations of the field where weeds were not controlled.

We initiated a 4-year study at the Aurora Research Farm in 2015 to compare different sequences of the corn-soybean-wheat/red clover rotation in conventional and organic cropping systems under recommended and high input management during the transition period (and beyond) to an organic cropping system. Unfortunately, we were unable to plant wheat after soybean in the fall of 2016 because green stem in soybean, compounded with very wet conditions in October and early November, delayed soybean harvest until November 9, too late for wheat planting. Consequently, soybean followed corn as well as wheat/red cover in 2018 so we are now comparing different sequences of the corn-soybean-wheat/red clover rotation with a corn-soybean rotation (Table 1). This article will focus on soybean yields in 2018 in both rotations.

The fields were plowed on May 17 and then cultimulched on the morning of May 18, the day of planting. We used the White Air Seeder to plant the treated (insecticide/fungicide) GMO soybean variety, P22T41R2, and the non-treated non-GMO variety, P21A20, at two seeding rates, ~150,000 (recommended input) and ~200,000 seeds/acre (high input). P21A20 is a not an isoline of P22T41R2 so only the maturity of the two varieties and not the genetics are similar between the two cropping systems. We treated the non-GMO, P21A20, in the seed hopper with the organic seed treatment, Sabrex, in the high input treatment (high seeding rate). We used the typical 15” row spacing in conventional soybean and the typical 30” row spacing (for cultivation of weeds) in organic soybean. Consequently, the soybean comparison is not as robust as the corn or wheat comparisons in this study because of the different row spacing and genetics between the two cropping systems.

We applied Roundup on June 20 for weed control in conventional soybean (V4 stage) under both recommended and high input treatments. The high input soybean treatment in the conventional cropping system also received a fungicide, Priaxor, on August 2, the R3 stage. We used the rotary hoe to control weeds in the row in recommended and high input organic soybean at the V1 stage (May 29). We then cultivated close to the soybean row in both recommended and high input organic treatments at the V3 stage (June 14) with repeated cultivations between the rows at the V4-V5 stage (June 19), the V5-V6 stage (June 29), the R1 stage (July 10), and the R3 stage (July 26).

Weather conditions were exceedingly dry from planting until July 16 with only 3.12 inches of precipitation recorded at the Aurora Research Farm. In fact, the 3.12 inches of precipitation in 2018 was the driest 5/17-7/16 period ever in 59 years of record keeping at the Aurora site (http://climod.nrcc.cornell.edu/runClimod/1d121489c4dfec7b/3/). The Aurora Research Farm, however, received 10 inches of rain over the next 2-month period (7/16-9/15), the date when organic soybeans attained physiological maturity (R7 stage). The 10 inches of rain was the 8th wettest 7/16-9/15 period ever at Aurora (http://climod.nrcc.cornell.edu/runClimod/60f4a05670d22553/1/), which contributed to high soybean yields throughout the area.

We discussed early plant establishment of our 2018 soybeans in a previous article (http://blogs.cornell.edu/whatscroppingup/2018/06/05/more-rapid-emergence-but-lower-early-plant-densities-v1-stage-in-organic-compared-to-conventional-2018-soybean/). Briefly, organic soybeans emerged earlier but only had 67-76% early plant establishment compared with 78-91% in conventional soybeans (Table 2). We noted that the organic soybeans with recommended inputs had early plant stands mostly below 105,000 plants/acre, and wondered if stands would be too low for maximum yields. We do not have our final plant stand data for soybeans completely counted yet so we are not sure if final stands in recommended input organic soybeans dipped below 100,000 plants/acre. Regardless, organic soybeans with recommended inputs yielded the same as organic soybeans with high inputs (~54 bushels/acre and ~55 bushels/acre, respectively), despite having 40,000-50,000 fewer plants/acre established at the V1 stage (Table 2).

As in 2017, organic soybeans in the soybean-wheat/red clover-corn rotation yielded around 55 bushels/acre, a significant 7 bushel/acre lower yield than high input conventional management. Organic soybeans in the corn-soybean rotation yielded 53 bushels/acre, statistically similar to organic soybeans in the soybean-wheat/red clover-corn rotation. We thought that the extended rotation of the soybean-wheat/red clover-corn rotation in conjunction with its somewhat lower weed densities in 2018 (Table 2) would boost yields more, perhaps resulting in similar yields between organic and conventional soybeans. But that was not the case in 2018. What was the case, however, was the lack of yield response to higher seeding rates for organic soybeans in 2018, for the 4th consecutive year in this study.

When averaged across the three previous 2014 crops (or three different fields) and the two different rotations (corn-soybean and wheat-red clover-corn-soybean), conventional soybean with high inputs yielded about 62 bushels/acre compared to about 58 bushels/acre in recommended conventional soybeans. The 4 bushel/acre yield response for high input conventional soybean was probably associated with the fungicide application rather than the higher seeding rates (conventional soybeans had average early stands of greater than 125,000 plants/acre-too high for a seeding rate response). We sampled two 1.52 square meter areas of each plot for yield component analysis so once those samples have been processed, we can determine if plant number, pod number, seed number, or seed weight contributed the most to the 4 bushel/acre yield advantage for high input conventional soybeans. If seed weight contributed the most, then the 4 bushel/acre response was probably associated with the fungicide application.

In conclusion, conventional soybean yielded higher than organic soybean for the second consecutive year of this study. Organic soybean, however, would receive the organic price premium (typically more than 2x the conventional soybean price). Consequently, organic soybean, despite the ~10% overall lower yield, would be more profitable, especially at the recommended 150,000 seeds/acre seeding rate and no organic seed treatment. We will conduct a final economic analyses of soybeans and the entire study over the winter and write up the final results next spring or early summer.

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What’s Cropping Up? Volume 28, Number 4 – September/October 2018

Extremely Low Weed Densities in Conventional Soybean and Relatively Low Weed Densities in Organic Soybean (especially in the Corn-Soybean-Wheat/Red Clover Rotation) in 2018

Bill Cox and Eric Sandsted

We initiated a 4-year study at the Aurora Research Farm in 2015 to compare different sequences of the corn, soybean, and wheat/red clover rotation in conventional and organic cropping systems under recommended and high input management during the transition from conventional to an organic cropping system. We provided a detailed discussion of the various treatments and objectives of the study in a previous news article (http://blogs.cornell.edu/whatscroppingup/2015/07/23/emergence-early-v4-stage-and-final-plant-populations-v10-psnt-values-v4-and-weed-densities-v12-in-corn-under-conventional-and-organic-cropping-systems/). Unfortunately, we were unable to plant wheat after soybean in the fall of 2016 because green stem in soybean, compounded with very wet conditions in October and early November, delayed soybean harvest until November 9, too late for wheat planting. Consequently, corn followed soybean as well as wheat/red cover in 2017 so we are now comparing different sequences of the corn-soybean-wheat/red clover rotation with a corn-soybean rotation (Table 1). This article will focus on weed densities in soybean in 2018 (highlighted in red in Table 1) at the full pod stage (R4), the end of the critical weed-free period for soybean.

The fields were plowed on May 17 and then cultimulched on the morning of May 18, the day of planting. We used the White Air Seeder to plant the treated (insecticide/fungicide) GMO soybean variety, P22T41R2, and the non-treated, non-GMO variety, P21A20, at two seeding rates, ~150,000 (recommended input) and ~200,000 seeds/acre (high input). We also treated the non-GMO, P21A20, in the seed hopper with the organic seed treatment, Sabrex, in the high input treatment (high seeding rate). We used the typical 15” row spacing in conventional soybean and the typical 30” row spacing (for cultivation of weeds) in organic soybean. We rotary hoed the organic soybeans on May 29, followed by a close cultivation on June 14, and then three in-row cultivations (June 19, July 10, and July 26). We applied a single application of Roundup to conventional soybeans on June 20.

Conditions were very dry for the 2 months following planting (3.12 inches from May 17 until July 16). Consequently, weed densities were quite low through late July. Over the next 10-day period (July 17-27), however, 4.89 inches of precipitation were recorded at the Aurora Research Farm. Consequently, very robust weeds (velvet leaf, foxtail, and ragweed in particular) were visible in the organic plots when we took our weed counts on August 10 at the full pod stage (R4 stage), the end of the critical weed-free period in soybeans. Conditions remained relatively moist with 3.53 inches of rain in August and another 2.0 inches of rain during the first 2 weeks of September.

Photo 1: Weed free conventional soybeans (soybeans in the corn-soybean-wheat/red clover on the left and in the corn-soybean rotation on the right) at the R 8.0 stage.

Weeds were almost non-existent in the conventional plots that received only a single application of Roundup (Table 2). This is the 4th consecutive year in soybeans where we applied a single application of Roundup for weed control and had almost complete control. Rotation and management inputs did not affect weed densities in conventional soybean (Table 2). The use of the moldboard plow in conjunction with a Roundup application about 5 weeks after planting has certainly been an excellent weed control combination for conventional soybean in this study (Photo 1).

Photo 2: Organic soybean had fewer weeds in the corn-soybean-wheat/red clover rotation (on the left) compared with the corn-soybean rotation (on the right) at the R 8.0 stage.

Although weed densities were relatively low in organic soybeans (mostly less than 1.0 weed/m2, Table 2), the weeds were very robust (Photo 2). Undoubtedly, the very wet conditions from mid-July through mid-September provided excellent growing conditions for the late-emerging velvet leaf and ragweed. Unlike conventional soybean, rotation did affect weed densities in organic soybeans with higher weed densities in the corn-soybean rotation compared with the corn-soybean-wheat/red clover rotation in all three fields (spring grain, corn, and soybean fields in 2014). We also observed a rotation effect for weed densities in organic corn in 2017 (but not in conventional corn) with far fewer weeds in organic corn in the corn-soybean-wheat/red clover rotation compared to the corn-soybean rotation (http://blogs.cornell.edu/whatscroppingup/2017/08/10/wheatred-clover-provides-n-and-may-help-with-weed-control-in-the-organic-corn-soybean-wheatred-clover-rotation/). High seeding rates did not affect weed densities in organic soybean in 2018.

In conclusion, conventional soybean had virtually no weeds in 2018 for the 4th consecutive year when combing moldboard plowing with a single application of Roundup. In contrast, organic soybean had very robust weeds in 2018, which resulted in a somewhat trashy looking field, but weed densities were relatively low for the 4th consecutive year. The corn-soybean- wheat/red clover rotation had lower weed densities when compared to the corn-soybean rotation in organic soybean so the inclusion of wheat/red clover in the rotation appears essential to maintain weed densities at a manageable level in organic soybeans. The very wet conditions from about mid-July (R3 stage) through mid-September (R7 stage), however, may mitigate any potential yield losses in the corn-soybean compared to the corn-soybean-wheat/red clover rotation, despite ~ 2x higher weed density. High (~200,000 seeds/acre) compared to recommended seeding rates (~150,000 seeds/acre) did not reduce weed densities in organic soybean. Perhaps more emphasis should be placed on identifying the best crop rotations rather than high seeding rates for reducing weed densities in organic soybean in New York.

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