What's Cropping Up? Blog

Articles from the bi-monthly Cornell Field Crops newsletter

September 26, 2016
by Cornell Field Crops
Comments Off on Organic Wheat Looked Great but Yielded 7.5% Less Than Conventional Wheat in 2015/2016

Organic Wheat Looked Great but Yielded 7.5% Less Than Conventional Wheat in 2015/2016

By Bill Cox1, Eric Sandsted1, Jeff Stayton2, and Wes Baum2
1Soil and Crop Sciences Section – School of Integrated Plant Science, Cornell University; 2Cornell University Agricultural Experiment Station

The lower leaves of wheat were senescing in mid-June, despite more N being applied to high input conventional wheat (right), because of exceedingly dry conditions at Aurora and the droughty soil of the experimental area.

The lower leaves of wheat were senescing in mid-June, despite more N being applied to high input conventional wheat (right), because of exceedingly dry conditions at Aurora and the droughty soil of the experimental area.

We initiated a 3-year study at the Aurora Research Farm in 2015 to compare the corn, soybean, and wheat/red clover rotation with different crop sequences in conventional and organic cropping systems during the 3-year transition period (2015-2017) to an organic cropping system. Three of the many objectives of the study are to determine 1) the best entry or 1st year crop (2015) to plant during the transition, 2) the best crop sequence during the 3-year transition (soybean-wheat/red clover-corn, corn-soybean, wheat/red clover, or plowed in red clover-corn-soybean) and 3) do corn, soybean, and wheat respond similarly to management inputs (high and recommended) in conventional and organic cropping systems? This article will compare the agronomic performance of organic wheat with conventional wheat following soybean in a soybean-wheat/red clover-corn sequence during the second year of the transition from conventional to an organic cropping system.

We used a John Deere 1590 No-Till Grain Drill (7.5 inch spacing between drills) to plant the treated (insecticide/fungicide seed treatment) Pioneer soft red wheat variety, 25R46, in the conventional cropping system; and the untreated 25R46, in the organic cropping system at two seeding rates, ~1.2 million seeds/acre (recommended input) and ~1.6 million seeds/acre (high input treatment) on September 24, the day after soybean harvest. We applied about 200 lbs. /acre of 10-20-20 as a starter fertilizer to wheat in both conventional treatments. We also applied Harmony Extra (~0.75 oz. /acre) to the high input conventional treatment at the GS 2 stage (November 5) for control of winter perennials (dandelion in particular).

In both organic treatments, we applied the maximum amount of Kreher’s composted chicken manure (5-4-3 analysis), as a starter fertilizer, that would flow through the drill, or about 150 lbs. of material/acre. We also broadcast Kreher’s composted manure to provide ~60 lbs. of actual N /acre (assuming 50% available N from the composted manure) in the high input treatment in the organic cropping system immediately after planting. In addition, we also added Sabrex, an organic seed treatment with Tricoderma strains, to the seed hopper of 25R46 in the high input treatment in the organic cropping system.

We frost-seeded red clover into all the wheat treatments on March 9 to provide N to the subsequent corn crop in 2017. We applied ~60 lbs. of actual N/acre (33-0-0, ammonium nitrate) in the recommended input treatment in the conventional cropping system on March 21, about a week after green-up. In the high input conventional treatment, we applied ~45 lbs. of actual N/acre (33-0-0) on March 21 and then applied another 45 lbs. of actual N/acre on April 25 about a week before the jointing stage (GS 6). We also applied a fungicide (Prosaro) to the high input treatment on May 31.

We applied Kreher’s composted chicken manure to provide 75 lbs. of available N/acre in the recommended input treatment on March 21. Also, we applied an additional 55 lbs. of available N/acre to the high input treatment in the organic cropping system on March 21. All the plots were harvested with an Almaco plot combine on July 6. We collected a 500 gram from each plot to determine kernel moisture and test weight in the laboratory.

We presented data on wheat emergence as well as wheat densities and weed densities in the fall (http://blogs.cornell.edu/whatscroppingup/2015/11/23/wheat-emergence-early-plant-populations-and-weed-densities-following-soybeans-in-conventional-and-organic-cropping-systems/) and weed densities in the early spring (http://blogs.cornell.edu/whatscroppingup/2016/04/05/no-till-organic-wheat-continues-to-have-low-weed-densities-in-early-spring-march-31-at-the-tillering-stage-gs-2-3/) in previous news articles. Briefly, organic wheat emerged about 1 day earlier, had ~10% more plants/acre, and fewer weeds in the fall. In the spring, organic wheat also had lower weed densities when compared with the recommended input treatment in conventional wheat (no herbicide) and the same weed density as the high input conventional wheat (received an herbicide after fall weed counts) in the spring (Table 1). Consequently, organic compared with conventional wheat had a similar or higher yield potential in early April, the beginning the active spring tillering period, based on stand and weed densities.

cox-table-1

Nevertheless, the 10% greater plant density and lower weed density in organic compared with conventional wheat, especially in the recommended input treatment, did not translate into a yield advantage. In fact, organic wheat yielded ~7.5% lower than conventional wheat (Table 2) when averaged across input treatments (no response to high input treatments in either cropping system). We suspect that the use of an organic N source may have resulted in less available N to the organic wheat crop, although visual symptoms of N deficiency were not observed. We did sub-sample before harvest (two 1.52 m2 areas/plot) to determine yield components. Organic compared with conventional wheat did have higher spike densities (533 to 509/m2, respectively) probably because of its higher plant density. Organic wheat, however, had fewer kernels/spike (22.1 vs. 24.5, respectively) and lower kernel weight (311 vs.315 mg, respectively), which indicates that the organic wheat may have been short of N, similar to organic corn in 2015 (http://blogs.cornell.edu/whatscroppingup/2016/03/29/why-did-organic-compared-with-conventional-corn-yield-30-lower-during-the-first-transition-year/).

cox-table-2

On the other hand, the recommended input (~75 lbs. of N/acre applied in late March) treatment yielded the same as the high input (~60 lbs. of N/acre in the fall followed by another ~55 lbs. /acre of N in late March) treatment in the organic cropping system. If available N were the limiting factor in organic wheat yields, then we would expect the high input treatment to yield higher because it received more total N (albeit at different timings). We will submit our wheat samples for total kernel N analysis. If total kernel N in organic and conventional wheat is similar, then total N availability may not have resulted in the 7.5% lower yields. Then we would have to explore the idea that perhaps the use of Kreher’s composted chicken manure as a starter fertilizer may not have provided adequate P or K to organic wheat.

In conclusion, organic wheat, despite not receiving an insecticide/fungicide seed treatment, had better stands than conventional wheat and fewer weeds in both the fall and spring. Organic wheat, however, yielded 7.5% lower than conventional wheat in the second year of the transition from conventional to an organic cropping system. We expect that net returns will also be ~7.5% lower for organic compared with the recommended input conventional treatment because the lower seed costs, associated with no insecticide/fungicide seed treatment, will be offset by the higher costs for N, associated with the cost of Kreher’s composted chicken manure vs. ammonium nitrate. Many growers, however, practice high input wheat (high seeding rates, fall herbicide application, split N application, and a fungicide application), which provided no additional yield response to conventional wheat in the dry 2016 growing season. Consequently, organic wheat with recommended inputs will provide a greater return to conventional wheat with high inputs in this study in 2016.

September 12, 2016
by Cornell Field Crops
Comments Off on NYCSGA Precision Ag Project Update

NYCSGA Precision Ag Project Update

Authored by: Savanna Crossman, Research Coordinator, CCA
Statistical Analysis by: Margaret Krause, Cornell University PhD Student

 *This article is part of an ongoing series.  Previous articles can be found at www.nycornsoy.org/research*

crossman-fig-1New York State has always presented a unique challenge to grain growers due to the large amount of in field variability.  In recent years, growers have also added adverse weather conditions to that list.  From the project’s perspective, two of the past three growing seasons have fallen far outside the conditions of a normal year.  The 2015 season brought early precipitation amounts far above than the historical average while the 2016 season is setting up to be one of the driest in decades.  These conditions have resulted in significantly lower, less uniform yields than a typical year such as 2014 (Figure 1).  Variable rate seeding technology is one of the many tools that NYS growers can use to help overcome these challenging conditions.  However, mainstream companies have yet to design a prescription writing software that is developed to meet the unique conditions of New York State and the Northeast.  This project seeks to address this void by developing a software that will do just that.

The project has been collecting data on a large scale since 2014 in order to create a model that will select hybrids and population rates given certain soil properties and characteristics.  To do this, six major data types are being examined; seeding rate, hybrid, topographical information, NRCS soil survey maps, Veris soil sampling data, and grid soil sampling data.  Each data type consists of many variables which are analyzed individually and as interacting networks.

Figure 2. This example random forest regression analysis demonstrates that phosphorus is the variable with the largest effect on yield in this field.

Figure 2. This example random forest regression analysis demonstrates that phosphorus is the variable with the largest effect on yield in this field.

To examine the effect that each variable has on yield, a statistical approach called random forest regression is being used.  This method essentially ranks each variable based on its importance to yield.  The greater the importance number that is assigned to a variable, the larger effect that variable has on yield (Figure 2).

The project has seen that the variables can rank very differently given the field, crop type, or year.  Each field location is unique and thus has a unique combination of variables influencing yield.  Some fields exhibit a very strong yield response to seeding rate, while others exhibit a strong yield response to fertility factors or topography.

Figure 3. 2014 and 2015 resulted in similar population curves on this corn field in Clyde, NY.

Figure 3. 2014 and 2015 resulted in similar population curves on this corn field in Clyde, NY.

Though each field may be different, it is important to see stability within a field across years.  For example, this 80 acre corn field in Clyde, NY produced similar population curves in two drastically different seasons.  The first year, 2014, resulted in high and uniform yields across the field.  The second year, 2015, yielded dramatically lower with a large variance in yield uniformity.  Though the two seasons were very different, both demonstrated a negative yield response to increased seeding rate (Figure 3).  The lowest rate of 27,000 sds/ac yielded the highest across the two years and which was 5,000 sds/ac lower than the grower’s typical rate.  The random forest regression confirmed that seeding rate was the most important variable influencing yield across both years.

This year to year stability in yield response to seeding rate has been seen between crop types as well.  This 60 acre field in Pavilion, NY is managed as a conventional till field in a corn-soybean rotation.  In 2014, its soybean crop exhibited a strong positive yield response to increased seeding rate.  The random forest regression confirmed that seeding rate held a dramatically greater importance than any of the other variables.  The next year, 2015, the field was planted with corn and again exhibited a positive yield response to seeding rate.  This time, the analysis showed that while seeding rate was still the most important variable, many other factors were also important.  This difference could be due physiological preferences between the two crops or the different weather conditions between the two years. (Figure 4)

Figure 4. Random forest regression analysis of 2014 soybean and 2015 corn of a sixty acre field in Pavilion, NY.

Figure 4. Random forest regression analysis of 2014 soybean and 2015 corn of a sixty acre field in Pavilion, NY.

To explore the idea of physiological differences between corn and soybean, some further analysis was conducted.  In this same Pavilion field, soybean exhibited positive relationships with calcium and pH, while corn exhibited negative relationships with the same variables.  These observations are likely related to the differences in crop preference for pH.  Soybeans grow best in more neutral soils where the rhizobia bacteria that provide the soybean plant nitrogen are most active.  Whereas the corn plant is known to prefer a slightly acidic soil where some key micronutrients, such as zinc and manganese, are more available.  It is understanding relationships such as these from an agronomic and a statistical perspective that will result in a reliable model for NYS growers.

This year has marked the first infield testing of the model which will provide side by side comparison of grower practice to the model’s prescriptions.  Each year of additional data collected will serve to further the development of the model into a robust and reliable resource to growers of the State.

The project is currently looking to bring on additional participants for the 2017 season and encourages any interested growers to contact Savanna Crossman at (802) 393-0709 or savanna@nycornsoy.com .

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July 29, 2016
by Cornell Field Crops
Comments Off on What’s Cropping Up? Volume 26 No. 4 – July/August Edition

What’s Cropping Up? Volume 26 No. 4 – July/August Edition

The full version of What’s Cropping Up? Volume 26 No. 4 is available as a downloadable PDF and on issuu.  Individual articles are available below:

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July 28, 2016
by Cornell Field Crops
Comments Off on Recent results from the Cornell Organic Cropping Systems Experiment

Recent results from the Cornell Organic Cropping Systems Experiment

Brian Caldwell, Matthew Ryan, and Charles Mohler
Soil and Crop Sciences Section, School of Integrative Plant Science, Cornell University

In 2015, over 1000 certified organic farms were operating in New York State (NYS Dept. of Agriculture and Markets).   Nationwide, New York ranks third in number of organic farms and organic cropland harvested (USDA 2011).  Of the approximately 5000 dairy farmers in NYS, about 430 are currently certified organic.  This number is expected to rise to 500 within two years (Fay Benson, Cornell Cooperative Extension, personal communication).  Thus 10% of NYS dairy farms will then be organic.  However, organic grain production has not kept up with demand, and well over half of feed grains sold to New York livestock farmers are from out of state (Mary-Howell Martens, Lakeview Organic Grain, personal communication). Consequently, land-grant university research is needed to support more organic feed and forage production in NYS.

The Cornell Organic Cropping Systems Grain Experiment (OCS) was initiated in 2005 at the Musgrave Research Farm in Aurora, NY. The purpose of this long-term experiment is to compare four approaches to organic production. Results from 2005-2010, including the 3-year transition period, were documented previously (Caldwell et al. 2014).  This article discusses recent findings from the experiment and its future prospects.

Experimental Design

The OCS compares organic cropping systems: high fertility (HF), low fertility (LF), enhanced weed management (EWM) and reduced tillage (RT) organic cropping systems.  We consider them systems because they are different in multiple ways.  They have evolved over time to address production challenges with help from our organic farmer advisory board.  Currently, HF employs higher nutrient additions during each rotation than the others, and uses both belly-mounted and rear-mounted cultivators.  LF receives only corn starter fertilizer once during every 3-year rotation and only rear-mounted cultivators are used.  EWM has an intermediate nutrient regimen and employs both types of cultivators, short tilled fallows, and extra cultivation to reduce weeds.  In contrast to the moldboard plow-based tillage program of the other systems, RT uses a mixture of deep zone tillage, ridge tillage, and chisel plowing depending on the crop.  It has an intermediate soil nutrient regimen.

The experiment includes four replications and two rotation entry points of each system.  Plots are 30 x 100 feet and are managed with farm scale equipment. Soils are in the Lima series, relatively flat calcareous silt loams with fair internal drainage.  All systems started with a

Caldwell - Arrow 1

 

rotation for the first six years (RT used other legumes instead of red clover in the spelt year).  A group of local organic farmers and extension educators advise on the management of this experiment.

Weed biomass in HF and RT systems was much higher than in LF and EWM by 2010 (Figure 1), and was reducing yields significantly.  It was decided by the OCS researchers based on advisory group input to change the rotation for HF and RT to address this issue.  The rotation for HF and RT was lengthened to six years:

Caldwell - Arrow 2

 

In essence, a double crop of winter barley and buckwheat was substituted instead of corn at year 4 (2013 for EP A and 2014 for EP B).  This enabled extra mid-season tillage to reduce weeds, particularly perennials.  It also meant that no red clover was grown that year.  In the other years of the rotation, crops were similar to those in LF and EWM.

Figure 1. Weed biomass in soybeans before and after 2013-2014 crop years, average of entry points.

Results 2005-2010

Results from 2005 to 2010 were reported in Caldwell et al. (2014).  Briefly, applied organic chicken manure compost increased spelt yields but not corn yields.  The LF system had the best overall financial returns.  Corn was a poor choice during the transition period to certified organic production, but soybeans performed relatively well and spelt was intermediate.  After the transition period, corn yields increased and were similar to Cayuga County averages.  Organic crops with an arbitrary 30% price premium (chosen to reflect a conservative value) were more profitable than analogous conventional crops with County average yields.  In recent years, the organic premium for corn and soybeans has often been higher than 30%.  Currently (7/8/16) it is over 100% for corn and about 50% for soybeans (USDA, Chicago Board of Trade).

Results 2011-2016

Weather extremes

The current six-year cycle, starting in 2011, will finish at the end of this season for both entry points.  HF and RT will complete one 6-year rotation and LF and EWM will complete two, 3-year rotations.  The period 2011-15 was marked with a dry July (2011) and August (2012) and two very wet Junes (2013 and 2015).  OCS stands were poor and areas of crops were severely stunted in 2013 and 2015 due to insufficient drainage, but crops tolerated the dry spells.  Figure 2 shows yields of OCS crops over the period.  Yields were normalized as a percentage of Cayuga County (if available) or NYS average yields for each year and crop, then placed in two groups based on wet or “normal” years.  Buckwheat yields were not included due to lack of State or County averages.  In 2011, 2012, and 2014, yields were close to County averages for the conventionally tilled systems, whereas in 2013 and 2015 they were quite reduced.  The RT system had about 60% of County yields in all years, regardless of June precipitation.  In the wet years, the low fertility system was affected most severely.

Figure 2. OCS yields, 2011-2015. Buckwheat not included due to lack of published County or State yields. “Normal” years were 2011, 2012, and 2014. Wet June years were 2013 and 2015.

In 2015, 8 inches of rain fell in June, whereas in 2016, the June total was only 0.74 inch, the lowest growing season monthly precipitation during this experiment.  It appears likely that such extreme weather periods will be common in the future.   Our results indicate that under organic management on this soil type, higher nutrients can ameliorate some of the negative effects of excess rainfall.  The extremely dry June of 2016 was preceded by a dry May, and drought continued into July.  Whereas the winter spelt crop looks excellent in HF, EWM, and RT as of this writing, corn growth has been slowed dramatically.  Corn harvest this fall will give us insight into whether any of these systems are better able to withstand severe dry spells.

Caldwell - Fig 3

Figure 3. Spelt prior to harvest in the High Fertility (HF) system on July 5, 2016.

New crop rotation

Weed biomass was reduced in HF and RT after the barley/buckwheat year in their expanded rotations (Figure 1).  Whether weed biomass will remain lower in these systems is not yet clear.  However, this strategy under our constraints was likely unprofitable.  The introduction of new crops such as winter barley and buckwheat into the crop mix often requires new equipment and knowledge.  Our buckwheat yields in particular were low because of equipment limitations and unfamiliarity with harvesting this crop. Local organic buckwheat farmers often use a swather and combine pickup head to harvest buckwheat.  The swather mows and gently windrows the buckwheat, allowing it to remain in the field to fully mature and dry. The windrows are then gathered into the combine using the pickup head.  Instead, we direct-harvested the crop, a method that can result in field losses (Bjorkman 2010).  Similarly, our inexperience with barley also resulted in some harvest losses.  Although we have not yet put together financial budgets for these crops, net returns for the barley and buckwheat with our yields would likely have been much lower than those from corn achieved in LF and EWM in corresponding years.  Our experiences mirrored those of many farmers when starting out with new crops.

Future plans

The OCS grain experiment begins a new phase in 2017.The first twelve years have yielded valuable insights into nutrient regimens, crop yields, and weed dynamics, but farmers are now facing additional challenges and attractive opportunities.  For example, climate change seems to make “normal” seasons rarer and rarer.  Extremes of rainfall and drought are encountered more frequently.  On the plus side, markets for organic dairy feed including balage and other forages are strengthening.  Buyers for crops such as sunflowers (Bob Gelser, personal communication) are looking for local producers.  Over the next year, we will work with our organic farmer advisory group to plan out the next 12 years of the experiment.  It will start in 2017 with a uniformity trial in which the same crop (sorghum sudangrass) will be grown over all plots.  This will allow us to assess cumulative effects on soil nutrients and weeds from 12 years of management using four different organic management systems.  In addition to updating management practices and data collection protocols, we will also work to improve the research site by installing new tile drainage in the alleyways between plots

This new phase of the Organic Cropping Systems Grain Experiment will explore scenarios and issues that we and our advisors anticipate will impact farmers in our region in coming years.

References
Bjorkman, T. 2010. Buckwheat Production: Harvesting.  Agronomy Fact Sheet 51.  Cornell Cooperative Extension.  Ithaca, NY.

Caldwell, B., C. L. Mohler, Q. M. Ketterings, and A. DiTommaso. 2014. Yields and Profitability during and after Transition in Organic Grain Cropping Systems. Agron. J. 106:871-880.

Chicago Board of Trade (accessed 7/25/16).    http://quotes.ino.com/exchanges/exchange.html?e=CBOT

NASS. USDA National Agricultural Statistics Service (accessed 7/25/16).https://quickstats.nass.usda.gov/

Schipanski, M.E. & Drinkwater, L.E. 2011. Nitrogen fixation of red clover interseeded with winter cereals across a management-induced fertility gradient.NutrCyclAgroecosyst 90: 105-119.

USDA. National Organic Grain Feedstuffs online price list(accessed 7/25/16).https://www.ams.usda.gov/mnreports/lsbnof.pdf

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July 28, 2016
by Cornell Field Crops
Comments Off on Emergence, Plant Densities (V2 Stage) and Weed Densities (R3 Stage) of Soybean in Conventional and Organic Cropping Systems in 2016

Emergence, Plant Densities (V2 Stage) and Weed Densities (R3 Stage) of Soybean in Conventional and Organic Cropping Systems in 2016

 Bill Cox1, Eric Sandsted1,  Phil Atkins2 and Brian Caldwell1
1Soil and Crop Sciences Section – School of Integrated Plant Science, Cornell University; 2New York Seed Improvement Project – Cornell University

Organic soybean (July 27) during the dry 2016 growing season has not canopied or filled in completely, especially with the recommended seeding rate (6 rows on the right), which may allow for some late-season weed escapes to affect soybean yield.

Organic soybean (July 27) during the dry 2016 growing season has not canopied or filled in completely, especially with the recommended seeding rate (6 rows on the right), which may allow for some late-season weed escapes to affect soybean yield.

We initiated a 3-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 3-year transition period (2015-2017) from conventional to an organic cropping system. We provided a detailed discussion of the various treatments and objectives of the study in a previous soybean article (http://blogs.cornell.edu/whatscroppingup/2015/09/16/emergence-early-v2-stage-plant-populations-and-weed-densities-r4-in-soybeans-under-conventional-and-organic-cropping-systems/). This article will focus on soybean emergence (days and %), plant densities at the 2nd leaf (V2 stage), and weed densities at the early pod (R3 stage) in 2016.

Corn preceded soybean in the rotation in this study. Despite the dry spring conditions (1.9 inches in March, 1.87 in April, and 0.75 inches from May 1-19), ideal soil conditions prevailed for plowing on May 19 (full soil water profile in contrast to corn that followed red clover that had very little stored soil water in the top 8 inches). The fields were then cultimulched on the morning of May 20, 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, 92Y21, at two seeding rates, ~150,000 (recommended input) and ~200,000 seeds/acre (high input). Unlike the corn comparison, P96Y21 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. As with corn, we treated the non-GMO, 92Y21, in the seed hopper with the organic seed treatment, Sabrex, in the high input treatment (high seeding rate). Unlike corn, however, we used different row spacing in the two cropping systems with the typical 15” row spacing in the conventional cropping system and the typical 30” row spacing (for cultivation of weeds) in the organic cropping system. Consequently, the soybean comparison is not as robust as the corn comparison for emergence and early plant establishment because of the different row spacing and genetics between the two cropping systems.

We applied Roundup (Credit 41) at 32 oz. /acre for weed control to conventional soybean at the V4 stage (June 22) under both recommended and high input treatments. We used the tine weeder to control weeds in the row in both recommended and high input organic treatments at the V1-V2 stage (June 9). We then cultivated close to the soybean row in both recommended and high input organic treatments at the V3 stage (June 15) with repeated cultivations between the entire row at the V4 stage (June 22), beginning flowering (R1) stage (July 1), and full flowering (R2) stage (July 14). The high input soybean treatment in the conventional cropping system also received a fungicide application on July 27, the R3 stage, for potential disease problems and overall plant health.

Weather conditions were warm and dry for the first 10 days after planting. Soybean emergence required 7 to 8 days, which was more rapid than corn emergence, probably because the lack of a green manure crop (red clover preceded corn) resulted in more soil water in the seed depth zone. As in 2015, organic compared to conventional soybean emerged 0.50 to 0.75 days earlier (Table 1). As mentioned in a 2015 article (http://blogs.cornell.edu/whatscroppingup/2015/06/16/days-to-emergence-and-early-corn-and-soybean-plant-populations-under-conventional-and-organic-cropping-systems/), variety differences between the cropping systems probably influenced days to emergence. Pioneer rated P92Y21, the variety used in the organic system, with a higher field emergence score (8 out of 10 rating) compared with P22T41R2 (7 out of 10), which probably contributed to the more rapid emergence in the organic system. The organic cropping system also was planted in 30 inch rows so there were 8.5 or 11.5 seeds emerging through the soil in 1 foot of row in the organic system compared with 4.25 or 5.75 seeds emerging in 1 foot of row in the conventional system, which may have hastened emergence in the organic cropping system. Days to emergence did not differ between the recommended and high input treatments in the organic cropping system, indicating that Sabrex, the organic seed treatment, did not hasten soybean emergence in 2016, similar to results in 2015.

Cox Soybean Table 1

We estimated soybean plant densities at the V2-V3 stage (June 13), prior to the close cultivation to the soybean row on June 15, but unfortunately after tine weeding the organic soybeans. Conventional soybean consistently had higher plant establishment rates (83 to 92%) compared with organic soybean (71 to 82%, Table 1). This was inconsistent with the 2015 data in which soybean in the organic cropping system under recommended input management had greater stand establishment than its counterpart treatment in the conventional cropping system (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/).  In 2015, we were able to estimate plant populations before tine weeding. In 2016, we estimated plant densities after tine weeding, which probably reduced plant establishment rates because of crop damage. Nevertheless, plant densities exceeded 114,000 plants/acre in all organic treatments, the threshold density below which soybean yields decrease under typical growing conditions (http://scs.cals.cornell.edu/sites/scs.cals.cornell.edu/files/shared/documents/wcu/WCU21-2.pdf). We will estimate soybean densities again at harvest to determine the extent of crop damage during the subsequent four cultivations in the organic cropping system to determine if final stands fall below the 114,000 plant/acre threshold.

As with corn, weed densities were exceedingly low in soybean in 2016 (Table 1), but even more so in soybean. As with corn, the dry soil conditions and lack of significant rainfall events required to initiate weed emergence after cultivations in the organic cropping system and herbicide application in the conventional cropping system contributed to very low weed densities. Weed densities were essentially the same between the organic (0.21 to 0.53 weeds/m2) and conventional cropping systems (0.07 to 0.38 weeds/m2) under both management systems. Such low weed densities should not contribute to yield losses in soybean in either cropping system in 2016.

In conclusion, organic soybean compared with conventional soybean consistently emerged 0.5 to 0.75 days earlier in 2016 probably because of variety and row spacing differences between cropping systems. Surprisingly, organic soybean compared with conventional soybean consistently had lower plant establishment rates at the V2-V3 stage, resulting in lower plant densities. This contradicts findings in the wet 2015 spring when organic compared with conventional soybean emerged more rapidly and had higher plant densities (http://blogs.cornell.edu/whatscroppingup/2015/09/16/emergence-early-v2-stage-plant-populations-and-weed-densities-r4-in-soybeans-under-conventional-and-organic-cropping-systems/). Plant densities of ~115,000 plants/acre at the V2-V3 stage in organic soybean with recommended inputs are close to the ~ 114,000 plant/acre threshold below which soybean yields decrease under typical growing conditions. Consequently, organic soybean yield with recommended inputs could be compromised a bit, especially if close cultivation or cultivations between the rows further reduced plant densities. On the other hand, the lower plant densities may provide a yield benefit, if weather conditions remain dry during August. The dry conditions, however, have resulted in limited soybean growth in 2016. Consequently, organic soybean in 30-inch row spacing has not canopied or filled in as of July 28, which could result in some weed escapes putting on enough growth to perhaps reduce yields in a dry growing season. Nevertheless, despite uncertainty on final plant and weed densities in organic soybean, the yield potential between the organic and conventional cropping system appears to be similar, which would reinforce 2015 results when organic and conventional soybean yields were mostly similar   (http://blogs.cornell.edu/whatscroppingup/2015/11/09/soybean-yield-under-conventional-and-organic-cropping-systems-with-recommended-and-high-inputs-during-the-transition-year-to-organic/).

July 27, 2016
by Cornell Field Crops
Comments Off on Emergence, Plant Densities (V3 Stage) and Weed Densities (V14 Stage) of Corn in Conventional and Organic Cropping Systems in 2016

Emergence, Plant Densities (V3 Stage) and Weed Densities (V14 Stage) of Corn in Conventional and Organic Cropping Systems in 2016

Bill Cox1, Eric Sandsted1,  Phil Atkins2 and Brian Caldwell1
1Soil and Crop Sciences Section – School of Integrated Plant Science, Cornell University; 2New York Seed Improvement Project – Cornell University

Dry soil conditions because of limited rainfall and a red clover crop contributed to early season drought stress in corn, especially in organic corn (10 rows to the left) compared with conventional corn (10 rows to the right).

Dry soil conditions because of limited rainfall and a red clover crop contributed to early season drought stress in corn, especially in organic corn (10 rows to the left) compared with conventional corn (10 rows to the right).

We initiated a 3-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 3-year transition period (2015-2017) from conventional to an organic cropping system. We provided a detailed discussion of the various treatments and objectives of the study in a previous corn 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/). This article will focus on corn emergence (days and %), plant densities at the V3 stage, and weed densities at the V14 stage in 2016.

A red clover green manure crop (~3.75 dry matter tons/acre) was mowed down on May 18. Because of the dry spring conditions (1.9 inches in March, 1.87 in April, and 0.75 inches from May 1-19) as well as the robust red clover crop, soil conditions were exceedingly dry and plow penetration was difficult in some regions of the fields on May 19.  The fields were then cultimulched on the morning of May 20, the day of planting. We planted a treated (insecticide/fungicide seed treatment) GMO corn hybrid, P96AMXT, in the conventional system; and its isoline, the untreated non-GMO, P9675, in the organic cropping system at two seeding rates, ~29,600 kernels/acre (recommended input treatment) and 35,500 kernels/acre (high input). The high input organic treatment also received the organic seed treatment (in-hopper), Sabrex. We applied Roundup (Credit 41) at 32 oz. /acre for weed control in conventional corn at the V4-V5 stage (June 22) under both recommended and high input management. We used the rotary hoe to control weeds in the row in recommended and high input organic corn at the V1-2 stage (June 9). We then cultivated close to the corn row in both recommended and high input organic treatments at the V3 stage (June 15) with repeated cultivations between the rows at the V4-V5 stage (June 22) and again at the V7-V8 stage (July 1).

Weather conditions were warm and dry for the first 10 days after planting. Nevertheless, corn emergence required 8 to 9 days (Table 1), or 140 to 160 growing degree days, instead of the typical 110-120 growing degree days. Presumably, the dry soil conditions at the time of planting extended the emergence time beyond the typical thermal unit requirement. Surprisingly, the non-GMO P9675, with or without the organic seed treatment (only in high input), compared with its isoline, the GMO P9675AMXT with seed treatment (insecticide/fungicide), emerged at the same time or 0.25 to 0.50 days more rapidly. In 2015, the GMO hybrid emerged about 0.50 days more rapidly than the non-GMO hybrid (http://blogs.cornell.edu/whatscroppingup/2015/06/16/days-to-emergence-and-early-corn-and-soybean-plant-populations-under-conventional-and-organic-cropping-systems/). Perhaps, the treated seed coat of the GMO hybrid reduced permeability of the scarce soil water necessary to initiate the germination process. Days to emergence did not differ between the recommended and high input treatments in the organic cropping system, indicating that Sabrex, the organic seed treatment, did not hasten corn emergence in 2016, similar to results in 2015.

Cox Corn - Table 1

We estimated corn plant densities in all treatments at the V3 stage (June 14), just prior to the cultivation close to the corn row on June 15, but unfortunately after the rotary hoeing that probably reduced corn densities in the organic cropping system. Corn emergence was relatively low in 2016 (Table 1) undoubtedly because limited rainfall resulted in dry soil conditions that was exacerbated by the red clover green manure crop. Conventional corn had only 71 to 85% plant establishment, whereas organic corn had 75 to 82% plant establishment (conventional corn had 91-100% and organic corn had 84 to 97% in 2015). Consequently, conventional corn in the recommended management treatment had plant densities of only ~22,500 to 24,000 plants/acre and organic corn in the recommended input treatment had plant densities of ~23,500 plants/acre (Table 1). In a typical year, plant densities of less than ~27,000 plants/acre would result in yield reductions. In a dry year, however, plant densities of 22,500 to 24,000 plants/acre may contribute to higher yields in recommended compared with the high input treatment (plant densities of ~25,000 to 30,000 plants/acre) because low plant densities tolerate drought stress better. If soil water conditions improve after silking, the high input treatment with plant densities of ~25,000 to 30,000 plants/acre may result in higher yields.

Weed densities were also quite low in 2016 (Table 1) because of the dry soil conditions and lack of significant rainfall events required to initiate weed emergence after cultivations in the organic cropping system or herbicide application in the conventional cropping system. Although weed densities were mostly higher in the organic cropping system, weed densities ranged from only 0.38 to 1.26 weeds/m2 (compared with 1.61 to 3.10 weeds/m2 in 2015), which probably will not reduce yields greatly. Weed densities in the conventional cropping system ranged from 0.08 to 0.38 weeds/m2, which indicates excellent efficacy of a Roundup application with drought-stressed weeds that emerged after the May 20 planting date and before the June 22 Roundup application.

In conclusion, organic corn compared with conventional corn emerged at the same time or earlier in dry soil conditions in 2016. Likewise, organic corn compared with conventional corn generally had similar plant densities at the V3 stage, despite a previous rotary hoeing operation to organic corn, which probably resulted in some corn damage. This contradicts findings in the wet 2015 spring when conventional corn compared with organic corn emerged more rapidly and had higher plant densities (http://blogs.cornell.edu/whatscroppingup/2015/06/16/days-to-emergence-and-early-corn-and-soybean-plant-populations-under-conventional-and-organic-cropping-systems/). Similar to the 2015 growing season, organic compared with conventional corn had mostly higher weed densities but weed control in organic corn in 2016 was generally satisfactory. Consequently, based on plant and weed densities, the yield potential for organic compared with conventional corn is similar. Organic compared with conventional corn, however, had lower pre-sidedress nitrate (PSNT) concentrations (11 and 19 ppm, respectively), although both averaged less than the threshold 25 ppm that signifies adequate soil N for maximum yields. We expected much higher PSNT values because red clover dry matter production averaged almost 4 tons/acre with average N concentrations of 3.35%. Apparently, the exceedingly dry soil conditions minimized N mineralization of the N in red clover. Organic corn also had PSNT concentrations of ~11 ppm in the wet 2015 growing season, which underscores the difficulty of providing adequate N for organic corn, as indicated by the 20 to 40% yield reductions in 2015 because of inadequate N (http://blogs.cornell.edu/whatscroppingup/2015/11/09/corn-yield-under-conventional-and-organic-cropping-systems-with-recommended-and-high-inputs-during-the-transition-year-to-organic/).

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