Category: Research

Bill Cox, Eric Sandsted, and Phil Atkins

We initiated a 4-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 36-month transition and early certification period to an organic cropping system. One of the many objectives of the study was to determine if corn, soybean, and wheat respond similarly to management inputs (high and recommended) in conventional and organic cropping systems. This article will discuss the agronomic performance of organic wheat and conventional wheat with recommended and high inputs in the 4^th year of the study (red clover-corn-soybean-wheat/red clover).

We no-tilled a 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 ~1.7 million seeds/acre (high input treatment) with a John Deere 1590 No-Till Grain Drill (7.5 inch spacing between drills) on September 27, 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 early tillering or GS 2 stage in the fall (October 27) for control of winter perennials (dandelion in particular).

We applied the maximum amount of Kreher’s composted chicken manure (5-4-3 analysis) that would flow through the drill as a starter fertilizer (~150 lbs. of material/acre) in both organic treatments. We also broadcast Kreher’s composted manure the day after planting  to provide ~50 lbs. of actual N /acre (assuming 50% available N from the composted manure) in the high input treatment of the organic cropping system. 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 22. We applied ~70 lbs. of actual N/acre (33-0-0, ammonium nitrate) in the recommended input treatment of conventional wheat on March 23, about a week before green-up. In the high input conventional treatment, we applied ~50 lbs. of actual N/acre (33-0-0) on March 23 and then applied another 50 lbs. of actual N/acre on April 26 about 10 days before the jointing stage (GS 6). We also applied a fungicide (Prosaro at 4 oz. /acre) to the high input treatment on May 30.

We applied Kreher’s composted chicken manure to provide ~70 lbs. of available N/acre to organic wheat in the recommended input treatment on March 21. Also, we applied an additional ~50 lbs. of available N/acre to organic wheat in the high input treatment on March 21. All the plots were harvested with an Almaco plot combine on July 10. We collected a 1000 gram from each plot to determine kernel moisture and grain N% in the laboratory.

We presented data on wheat emergence as well as wheat densities and weed densities in the fall (https://blogs.cornell.edu/whatscroppingup/2017/12/01/organic-compared-with-conventional-wheat-once-again-has-more-rapid-emergence-greater-early-season-plant-densities-and-fewer-fall-weeds-when-following-soybean-in-no-till-conditions/) and weed densities in the early spring (https://blogs.cornell.edu/whatscroppingup/2018/05/25/no-till-organic-wheat-continues-to-have-low-weed-densities-in-early-spring-april-9-at-the-tillering-stage-gs-2-3/) in previous news articles. Briefly, organic wheat had more plants/acre, and similar weed densities in the fall and spring (Table 1). This is the second time that organic compared to conventional wheat no-tilled into soybean stubble had better stands and very low weed densities. Organic growers who harvest soybean fields with low winter weed pressure (dandelion, mallow, chickweed, henbit, mayweed, etc.) should consider no-tilling organic wheat, especially if the soybean field had been moldboard plowed. If soybeans were no-tilled into roller-crimped rye in early June, the rye residue could harbor significant slug/snail populations during the cool and damp fall mornings, which could impact wheat stands.

A cropping system x management input interaction was observed for wheat yield in 2018 (Table 2). Organic and conventional wheat yielded 80 bushels/acre with recommended inputs in 2018. Organic wheat showed a 6 bushel/acre response to high input management (500,000 more seeds/acre and an additional 30 lbs. of N/acre). In contrast, conventional wheat did not respond to high input management, despite 500,000 more seeds/acre, a fall herbicide application, 30 lbs. more N/acre, and a fungicide application. Once again, conventional wheat did not respond to the “new way” of managing wheat, high input wheat, which is similar to results that we have observed in all years with dry springs when we compared high and recommended input wheat in the 1980s and 2000s. Obviously, there is no need to apply additional N or apply a fungicide to wheat during dry springs because fertilizer N applied in late March or early April will not be lost to the environment via leaching or denitrification and disease pressure is low.

In 2016, a year with very similar precipitation patterns to 2018 (5.88 inches vs. 6.5 inches of precipitation, respectively, from April 1 through June 30), organic wheat yielded ~7.5% lower than conventional wheat when averaged across input treatments with no response to high input treatments in either cropping system(https://blogs.cornell.edu/whatscroppingup/2016/09/26/organic-wheat-looked-great-but-yielded-7-5-less-than-conventional-wheat-in-20152016/). Temperatures in May when N demand by wheat is the highest, averaged 62.0^o in 2018 but only 56.5^o in 2016. Cool temperatures limit N mineralization from organic sources so in 2016 we speculated that the use of an organic N source may have resulted in less available N to the organic wheat crop. Indeed, grain N% concentration in organic (1.66%) vs. conventional wheat (2.03%) was much lower in 2016 lending credence to the lack of available N as the major factor in the lower organic wheat yields. In 2018, conventional compared with organic wheat once again had greater grain N% concentration (1.99% vs. 1.77%, respectively, Table 2) but the difference was not as vast. Evidently, the warm May conditions allowed for release of adequate N from Kreher’s composted manure to maximize yields. May of 2018, however, was the second warmest on record in central and western NY. In years with cool late April and May conditions, organic wheat production may face N availability challenges because of low mineralization rates of organic N sources.

In conclusion, organic wheat yielded the same as conventional wheat with recommended inputs and yielded 9% greater than conventional wheat with high inputs. Kreher’s composted chicken manure, however, is very expensive (~$300/ton with only 5% N analysis of which we assumed only 50% N availability) so N costs approximated $6/lb. of N or ~12x higher than the ammonium nitrate source for conventional wheat. Consequently, organic compared with conventional wheat with recommended inputs probably had lower returns in 2018, despite being eligible for the organic price premium in the 4^th year of this study (we will conduct a complete economic analysis of this 4-year study in late fall or spring of next year). Organic wheat with high inputs probably had similar economic returns as conventional wheat with high inputs, a common practice among some NY wheat growers, because the 12x higher cost for N in organic wheat would be offset by the higher cost for treated seed, fall herbicide application, the second N application, and late spring fungicide application in high input conventional wheat. Most organic wheat growers, however, probably use a dry solid manure source that is far less expensive than Kreher’s composted chicken manure so the economic analyses in this study will be slanted against organic wheat. On the other hand, the use of dry solid manure is far more difficult to apply precisely and at the correct time to insure availability to the wheat crop in May during stem elongation so the yield data may be slanted towards wheat in this study.

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

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 1^st 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 (https://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 (https://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.

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 (https://blogs.cornell.edu/whatscroppingup/2016/03/29/why-did-organic-compared-with-conventional-corn-yield-30-lower-during-the-first-transition-year/).

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.