What's Cropping Up? Blog

Articles from the bi-monthly Cornell Field Crops newsletter

December 2, 2016
by Cornell Field Crops
Comments Off on Alfalfa-Grass Mixtures – 2016 Update

Alfalfa-Grass Mixtures – 2016 Update

J.H. Cherney, D.J.R. Cherney, and K.M. Paddock
Cornell University

The vast majority of alfalfa acreage in NY is sown with a perennial grass. Until recently, there has been very little research on grass species selection or management of mixtures. We do not know what the optimum percentage of grass should be in mixtures, and it is unclear how consistent grass percentage is across species, varieties and environments.

An informal survey of forage seed companies active in NY in 2014 found timothy to still be over 30% of all forage grass seed sales in NY, with tall fescue and orchardgrass each around 20% of grass seed sales. Eight other grass species make up the remaining 30%, with each of these less than 10% of total seed sales. Forage tall fescue seed sales went from essentially zero 10 years ago to 20% of grass seed sales, and most of it is seeded with alfalfa.

Alfalfa-Grass Ratio in Stands

The primary negative point with mixtures is not lower forage quality, but variable forage quality. The main cause of this variability is a variable alfalfa-grass ratio. Botanical composition of alfalfa-grass fresh and ensiled mixtures is a key parameter for assessing forage and diet quality, as well as for managing mixed stands. Previous attempts to validate near infrared reflectance spectroscopy (NIRS) equations for estimating botanical composition have not been very successful. We collected alfalfa-grass samples from across NY over several years, and Dairy One Forage Laboratory has successfully calibrated NIRS instruments to estimate grass percentage in alfalfa-grass samples.

We are also developing a cell phone app that will estimate grass percentage in the field, by evaluating a cell phone photograph of a mixed stand. Keeping track of grass percentage in alfalfa-grass fields is useful for field and forage management.

Meadow Fescue Potential for Mixtures

Meadow fescue is grown extensively in Canada and Europe, but dropped out of use in the USA decades ago primarily due to reduced yield and disease susceptibility, compared to other grasses. It can be grown in areas suitable for timothy, and is considerably more winter hardy than tall fescue in northern environments. Primarily grown for pasture use in recent decades, meadow fescue has considerable potential in mixture with alfalfa. Alfalfa-grass mixtures are as high or higher yielding than pure alfalfa, and have been shown to be an excellent forage for lactating dairy cattle.

Meadow fescue has higher fiber digestibility (NDFD) than most other grasses, consistently 2-4 percentage units higher than tall fescue. Feeding trials across the USA have shown that a one percentage unit increase in NDFD increases milk production by 0.5 to 1.0 lbs/cow/day, and more than 1.0 lb/cow/day for the highest producing cows. Meadow fescue in combination with new reduced-lignin alfalfa varieties has the potential to produce a very high quality forage for lactating dairy cows. A somewhat reduced yield potential for meadow fescue may actually be advantageous for alfalfa-grass mixtures, where a modest grass percentage is desirable.

2016 Trial Results

Ten grasses [meadow fescue (MF), tall fescue (TF), orchardgrass (OG) and festulolium (Fest.) varieties] were established in binary mixtures with 2 alfalfa varieties in spring 2015 in Oneida and Wyoming Counties. We thank Dave Curtin/Curtin Dairy and Dave Russell/Southview Farms for providing study sites. Optimum rainfall throughout the 2015 season resulted in abundant growth, and three seeding-year harvests were taken at both sites. Cold spring weather in 2016 resulted in immature, very low fiber alfalfa forage under 30% neutral detergent fiber (NDF) and a little over 30% crude protein (CP) when harvested the last week of May, while NDF of grasses was generally optimum in the low 50’s.

Meadow fescue headed out between May 26 and June 1, 2016, depending on variety and location. Tall fescue and festulolium had a similar heading date range, while orchardgrass varieties headed a few days earlier. About half of the grass varieties were at an early heading stage at spring harvest.

Both sites have fertile soils and, in spite of the weather conditions prior to the first two harvests of 2016, averaged a total of 4 tons dry matter/acre. The last three harvests in Oneida County produced good yields, totaling an average of 7.5 tons DM/acre (Fig. 1). Some combinations exceeded 8 tons DM/acre. Severe drought in Wyoming County prevented much regrowth the rest of the year after Cut 2, and reduced total yield to an average of 5.3 tons DM/acre.

Fig. 1. Dry matter yield of alfalfa-grass mixtures at two NY sites in 2016.

Fig. 1. Dry matter yield of alfalfa-grass mixtures at two NY sites in 2016.

With somewhat adequate rainfall at the Oneida County site, grass% was relatively stable or increasing (Fig. 2), tending to decline in late fall, except for MF. Less rainfall on a soil with less water-holding capacity resulted in a decrease in grass% from Cut 1 to Cut 2 in Wyoming County (Fig. 3). The relative ranking of grass% among varieties was generally consistent over locations, but environmental conditions significantly impacted all grasses. Festulolium dropped from 70% grass in Cut 1 to about 10% grass in Cut 3 (Fig. 3), possibly due to drought.

Meadow fescue was relatively inconsistent, with greatly increased grass% later in the year for two of the entries in Oneida County. In Wyoming County, grass% dropped sharply for all entries after cut 1, and then increased significantly for all entries in the late fall after some rainfall returned. Overall, grass% was too high in Oneida County, except for Bariane TF and meadow fescues. Grass% dropped for all entries in the fall in Oneida County, except for meadow fescues.

Fig. 2. Grass% in Oneida County over 5 harvests.

Fig. 2. Grass% in Oneida County over 5 harvests.

Fig. 3. Grass% in Wyoming County over 5 harvests.

Fig. 3. Grass% in Wyoming County over 5 harvests.

Quality Analysis

For Oneida County, averaged over 5 cuts, Hi-Gest360 alfalfa was 4% higher fiber digestibility (NDFD) and 4% lower lignin, compared to Pioneer 55H94. For Wyoming County (3 cuts analyzed to-date), Hi-Gest360 was 8% higher NDFD and 7% lower lignin, compared to Pioneer 55H94. In three seeding year cuts in 2015, Hi-Gest averaged 9% higher NDFD and 8% lower lignin (Oneida); and 5% higher NDFD and 3% lower lignin (Wyoming), compared to 55H94.

As the grass% increases in a mixed stand, there is less nitrogen available to grass from alfalfa, and also more grass requiring the limited available N. As the high-crude protein (CP) alfalfa% decreases, grass CP greatly decreases and total mixed forage CP drops correspondingly. However, CP should remain relatively high in the mixed forage up to at least 40% grass.

Alfalfa averaged 58, 38, 43, 43, and 61% NDFD for 5 cuts. Festulolium was highest in NDFD for all cuts except Cut 2, but was only significantly better than meadow fescue for Cut 1 (Fig. 4). Festulolium headed out after Cut 1, due to moisture stress, greatly reducing NDFD for Cut 2. Cuts 2 & 4 were made about one week too late, resulting in lower NDFD than desired.

Fig. 4. Grass 48h fiber digestibility, Oneida County, 2016.

Fig. 4. Grass 48h fiber digestibility, Oneida County, 2016.

 

Conclusions

Mixtures can increase both yield and quality of forage stands. Grass% in mixed stands is strongly influenced by environmental conditions. Environmental conditions during the establishment phase have a great impact on the alfalfa:grass ratio in succeeding years. Average grass percentage of stands over the 2016 season was double that of the previous fall for both sites.

Grass CP content is greatly impacted by the grass percentage of stands, as a limited supply of available soil N is diluted through increased grass production. As the amount of alfalfa in a stand declines, this also reduces the total supply of available N for grasses. Nevertheless, a mixed stand with up to 40% grass is still likely to have reasonably high CP content.

Results in 2016 indicate that the optimum grass percentage in alfalfa-grass stands at the end of the seeding year may be around 5-15% grass, with about 20-30% in the first production year. A grass percentage as low as 10% can still result in a significant increase in total forage fiber digestibility. Switching from a lower quality grass to a higher quality grass such as meadow fescue may impact forage quality as much as a switch to a higher quality reduced-lignin alfalfa.

Right now our best bet is to first select a site reasonably well drained with near neutral pH and maintain high soil K. In mixture with alfalfa at 12-15 lbs/acre, meadow fescue should be seeded at 4-5 lbs/acre in either the spring as early as possible, or late summer about 4-5 weeks prior to first freeze. Plan to manage it 4×4; 4 cuts/season with a 4” stubble height, with somewhat higher stubble height for the last cut of the season. Meadow fescue often contains a naturally occurring endophytic fungus, but unlike the tall fescue endophyte, no harmful anti-quality alkaloids are produced. Meadow fescue cannot be infected by the tall fescue endophytes, so there are no concerns of livestock disorders with meadow fescue.

Acknowledgment: Alfalfa-grass research was made possible by funding from the New York Farm Viability Institute and the Northern New York Agricultural Development Program.

November 28, 2016
by Cornell Field Crops
Comments Off on Organic Corn Only Yields 7% Lower than Conventional Corn during the Second Transition Year

Organic Corn Only Yields 7% Lower than Conventional Corn during the Second Transition Year

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

Extremely dry soil conditions in June (0.74 inches of precipitation), exacerbated by a robust red clover green manure crop, resulted in natural crop mortality in late-emerging corn, as well as crop mortality from cultivation in organic corn (photo taken on June 26).

Extremely dry soil conditions in June (0.74 inches of precipitation), exacerbated by a robust red clover green manure crop, resulted in natural crop mortality in late-emerging corn, as well as crop mortality from cultivation in organic corn (photo taken on June 26).

We initiated a 3-year study at the Aurora Research Farm in 2015 to compare different sequences of a corn, soybean, and wheat/red clover rotation in conventional and organic cropping systems with recommended and high input management during the 3-year transition period (2015-2017) from conventional to an organic cropping system. We provided detailed discussions of the experiment (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/) and the timing of management practices in 2016 and weather conditions through July of 2016 in previous soybean articles (http://blogs.cornell.edu/whatscroppingup/2016/07/27/emergence-plant-densities-v3-stage-and-weed-densities-v14-stage-of-corn-in-conventional-and-organic-cropping-systems-in-2016/).

Briefly, a preceding red clover green manure crop (~3.75 dry matter tons/acre) was mowed down on May 18. Dry weather conditions (1.9 inches in March, 1.87 in April, and 1.35 inches from May 1-19), exacerbated by the robust red clover crop, made soil conditions exceedingly dry so plow penetration was difficult in some regions of the fields on May 19. 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) on May 20. The high input organic treatment also received the organic seed treatment (in-hopper), Sabrex. We applied Roundup at 32 oz. /acre for weed control in conventional corn at the 4th-5th leaf stage (V4-V5 stage) on June 22 under both recommended and high input management. We also side-dressed the high input treatment with 60 lbs. N/acre. 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). We harvested the crop on November 3 when conventional corn averaged 20.3% and organic corn averaged significantly lower at 19.6% moisture.

Corn plant densities at the V3 stage (June 14), just prior to the close cultivation to the corn row on June 15 but after the rotary hoeing, were relatively low in 2016 (Table 1), undoubtedly because limited rainfall coupled with the robust green manure crop resulted in dry planting conditions. Conventional (70 to 85% plant establishment) and organic corn (75 to 82% plant establishment) had similar plant densities at the V3 stage, unlike 2015 when conventional corn had greater plant establishment. Conventional and organic corn in the high input treatment averaged ~28,000 plants/acre (Table 1), which usually results in close to optimum yield (http://scs.cals.cornell.edu/sites/scs.cals.cornell.edu/files/shared/documents/wcu/WCUvol23no1.pdf). Conventional and organic corn in the recommended input treatment averaged only ~23,500 plants/acre (Table 1), which typically results in yield reductions in most growing seasons. Unfortunately, dry conditions persisted (0.74 inches in June and 1.89 inches in July) so plant densities decreased further by the V14 stage probably because of crop mortality in conventional and a combination of crop mortality and crop damage by cultivation in organic corn. Consequently, conventional corn at the V14 stage (1300 fewer plants/acre or a ~5% decrease from V3 to V14) compared with organic corn (3150 fewer plants/acre or a ~12% decrease) now had greater plant densities (Table 1). Such low plant densities in the recommended input treatment in conventional (~23,000 plants/acre) and organic corn (~21,000 plants/acre) should reduce yields, even in a dry growing season, because of the limited capacity of corn to compensate at low plant densities.

cox-corn-table-1

Weed densities at the V14 stage were also quite low in 2016 (Table 1) because of the lack of significant rainfall events required to initiate weed emergence after cultivations in organic corn or herbicide application in conventional corn. 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 had limited impact on yield. Weed densities in the conventional cropping system ranged from 0.08 to 0.38 weeds/m2, which indicates excellent efficacy of a Roundup application on drought-stressed weeds that emerged after the May 20 planting date and before the June 22 Roundup application.

Conventional compared with organic corn yielded ~7% higher in 2016 (Table 1). Yields, however, were low because of exceedingly dry conditions, including during the critical 2 week period before and after silking (~July 25). Grain yield did not correlate with plant densities at the V3 stage, but had a highly significant correlation with plant densities at the V14 stage (r=0.46, Table 2). Grain yield, however, had virtually no relationship with weed densities in 2016 (Table 2). In 2015, the 20 to 40% lower yield in organic compared with conventional corn in the first transition year (no red clover green manure crop was in place) was associated with lack of soil N availability in organic corn (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/).The 3.5 ton/acre red clover green manure crop probably provided adequate soil N to both organic and conventional corn in 2016 (although the release of N was slow because of the dry conditions). On the other hand, the robust red clover crop probably also contributed in part to the low establishment rates and subsequent low corn yields.

screen-shot-2016-11-28-at-10-24-24-am

Likewise, high compared with the recommended input treatment in corn yielded significantly higher (Table 1). Although not a significant 2-way interaction (p=0.08), high compared with recommended input had a 9.2% yield advantage in conventional corn compared with a 3.2% yield advantage in organic corn. Again, the higher yield in high compared with recommended input, especially in conventional corn, was associated with the higher plant densities at the V14 stage. Despite yielding ~11 bushels/acre higher, the high input compared with the recommended input treatment in conventional corn would not provide greater partial returns at a ~ $4.00/bushel corn selling price because greater seed (6000 more seeds/acre) and N costs (60 lbs./acre of side-dressed N in the high input) offset the greater partial returns.

In conclusion, organic compared with conventional corn yielded ~7% lower in 2016, the second year of the transition from conventional to an organic cropping system. In contrast, organic compared with conventional corn yielded 20-40% lower during the first transition year in 2015 when a green manure crop was not in place. Based on the results of this study, planting a green manure crop to build-up the soil N supply during the first transition year, followed by corn in the second year, is probably a viable strategy instead of planting corn in the first year of the transition period. Corn will follow a wheat/red clover crop as well as soybean (unable to plant wheat after soybean harvest this year because of green stem in soybean and a record wet October) in 2017 so we will be comparing corn in a corn-soybean-corn rotation and in a soybean-wheat/red clover-corn rotation next year. Corn will be eligible for the organic premium in 2017 because 36 months would have elapsed from harvesting conventional spring barley (August), soybean (October) and corn (early November) in 2014, provided we delay corn harvest until the second week of November. Consequently, the inability to plant wheat after soybean harvest this year may be a blessing in disguise because of low current wheat prices and the eligibility of corn for the organic price premium in 2017.

November 28, 2016
by Cornell Field Crops
Comments Off on Organic Soybean Once Again Yields Similarly to Conventional Soybean during the Second Transition Year

Organic Soybean Once Again Yields Similarly to Conventional Soybean during the Second Transition Year

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

Organic compared with conventional soybean yielded similarly, despite not filling in between the rows until the first week of August, which contributed to in part to greater weed densities at harvest (photo taken on July 27).

Organic compared with conventional soybean yielded similarly, despite not filling in between the rows until the first week of August, which contributed to in part to greater weed densities at harvest (photo taken on July 27).

We initiated a 3-year study at the Aurora Research Farm in 2015 to compare different sequences of a 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 detailed discussions of the experiment (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/) and the timing of 2016 management practices and weather conditions through July of 2016 (http://blogs.cornell.edu/whatscroppingup/2016/07/28/emergence-plant-densities-v2-stage-and-weed-densities-r3-stage-of-soybean-in-conventional-and-organic-cropping-systems-in-2016/).

Briefly, corn was the preceding crop in 2015 and we moldboard plowed (May 19) and culti-mulched the experimental sites. We planted (May 20) the treated (insecticide/fungicide) GMO variety, P22T41R2 with the RR2Y and SCN traits, in 15-inch row spacing and the non-treated, non-GMO variety, 92Y21, in 30-inch row spacing at two seeding rates, ~150,000 (recommended input) and ~200,000 seeds/acre (high input). We treated the non-GMO, 92Y21, in the seed hopper with the organic seed treatment, Sabrex, in the high input treatment. We applied Roundup at 32 oz. /acre for weed control in conventional soybean at the V4 stage (June 22) in 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), followed by repeated cultivations between the entire row at the V4 (June 22), beginning flowering (R1) (July 1), and full flowering (R2) stages (July 14). The high input soybean treatment in the conventional cropping system also received a fungicide application on July 27, the R3 stage. We harvested all treatments on November 9 when conventional and organic soybean averaged ~12.0% moisture.

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). The lower plant establishment rates in organic soybean were probably associated in part with some crop damage during tine weeding. Nevertheless, plant densities exceeded 114,000 plants/acre in all organic treatments, the threshold density below which soybean yields decrease in NY under typical growing conditions (http://scs.cals.cornell.edu/sites/scs.cals.cornell.edu/files/shared/documents/wcu/WCU21-2.pdf). We are in the process of estimating soybean densities (and yield components) at harvest to determine the extent of crop damage during the subsequent four cultivations in the organic cropping system.

cox-soybean-table-1

Weed densities were exceedingly low in soybean through July or the R3 stage in 2016 (Table 1) probably because of the lack of significant precipitation events in June (0.74 inches) and July (1.89 inches). Weed densities were not significantly different between organic (~0.50 to 1.00 weeds/m2) and conventional cropping systems (~0.20 to 0.55 weeds/m2). In August, however, the experimental site received 4.56 inches of precipitation, which contributed to a significant increase in weed densities in both cropping systems, especially the organic cropping system. The exceedingly dry conditions (3.28 inches from the May 20 planting date through July 31) limited soybean vegetative growth, especially in organic soybean in 30-inch row spacing, which did not canopy in until early August. In contrast, the 15-inch conventional soybean canopied in by mid-July to provide some shade and perhaps reduce weed emergence after the Roundup application on June 22. Consequently, the later shading in between the rows in organic soybean probably contributed in part to greater weed emergence after the last cultivation on July 14 and subsequent greater weed densities at the R8 stage (~3.0 weeds/m2) compared with conventional soybean (~0.80 weeds/m2, Table 1). In addition, the preceding organic corn in 2015 averaged about 2.25 weeds/m2 compared with ~0.55 weeds/m2 in conventional corn at the V10 stage in 2015 (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/), which may have contributed to a greater weed seed bank in the organic soybean plots.

Despite lower plant densities and greater weed emergence from the R3 to R8 stage, organic soybean yielded similarly compared to conventional soybean (Table 1). Obviously, lower plant densities and greater weed emergence after the R3 stage did not affect organic soybean yields in a growing season when the least amount of rainfall was ever recorded at the experimental site from May 20-July 31 (3.28 inches), but adequate precipitation occurred from the R3 to R7 stage (physiological maturity). Likewise, in 2015, when the 2nd wettest June (8.00 inches of precipitation; only 1972 was wetter when Hurricane Agnes flooded NY and June totaled 11.57 inches), but the driest 8/1-9/9 period (R3 to R7 stage when only 1.36 inches was received) ever were observed at the experimental site, organic and conventional soybean also yielded similarly (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/). It will be interesting to see if organic and conventional soybean will yield similarly in a growing season with normal precipitation patterns, if indeed a normal precipitation pattern ever does occur again!

Organic soybean did not respond to high inputs (organic seed treatment and high plant populations), similar to results in 2015. The organic seed treatment did not improve soybean emergence, and plant densities were not significantly correlated with yield in 2016 (Table 2). Soybean has tremendous compensation ability, via development of numerous side branches with numerous pods, which allows yields to be maintained despite plant establishment rates of only ~70%. Consequently, conventional soybean usually does not respond to high plant populations (>150,000 seeds/acre) in NY as long as early plant establishment rates are ~114,000 plants/acre. Weed control, however is usually not an issue in conventional soybean (narrow rows and residual and/or post-emergence herbicides for weed control) when plant densities are low. In contrast, organic soybean relies in part on shading for weed control in the row so organic soybean has responded to high plant densities in some locations, especially in more southern latitudes than NY, because of improved weed control. Plant densities did have a negative correlation with weed densities at the R3 and R8 stages (r=-0.33 and -0.37, respectively, Table 2), indicating significant negative associations between weed and plant densities. Seed yield, however, was not correlated with weed densities at the R3 nor at the R8 stages (Table 2), which is noteworthy in a dry growing season, when weeds compete with the crop for scarce soil water. As the weed seed bank increases in the organic cropping system, it will be interesting to observe if weed densities (and plant densities) continue to have no association with soybean yield. Unlike 2015, conventional soybean did not respond to high inputs in 2016, probably because dry conditions limited disease development, resulting in no response to the fungicide application at high plant densities.

screen-shot-2016-11-28-at-10-00-43-am

In conclusion, organic compared with conventional soybean yielded essentially the same during the second year of the transition from conventional to an organic cropping system, similar to yield data in 2015. As in 2015, organic soybean yielded the same under recommended input management, despite early plant establishment rates of only ~115,000-120,000 plants/acre. Based on the results of this study, soybean under recommended management practices appears to be an excellent crop for either the first or second year of the transition. Green stem, however, in the non-GMO organic variety prevented the harvest of soybean in late September when the seeds and pods of both varieties were ready for harvest. The ensuing wettest October on record at the experimental site (7.92 inches of precipitation), followed by another 1.10 inches of rain during the first week of November, further delayed harvest until November 9. Because of the wet soil conditions, we would not have been able to plant wheat after soybean until mid-November, which we deemed as too late in New York. The downside of an organic corn-soybean-wheat rotation is that delayed soybean harvest associated with late planting and/or a cool year or green stem (no registered organic desiccant for soybean) may prevent winter wheat planting and subsequent frost seeding of red clover (N source for organic corn in this rotation) in some years.

October 5, 2016
by Cornell Field Crops
Comments Off on What’s Cropping Up? – Volume 26 No. 5 – September/October Edition

What’s Cropping Up? – Volume 26 No. 5 – September/October Edition

The full version of What’s Cropping Up? Volume 26 No. 5 is available as a downloadable PDF and on issuu.  Individual articles are available below:

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September 30, 2016
by Cornell Field Crops
Comments Off on Impact of manure and compost management on soil organic matter and nitrate dynamics

Impact of manure and compost management on soil organic matter and nitrate dynamics

Amir Sadeghpour1, Sarah Hetrick1, Karl Czymmek1,2, Gregory Godwin1, Quirine Ketterings1
1
Cornell University Nutrient Management Spear Program, 2PRODAIRY

Introduction
When manure is applied in the fall or in spring without incorporation at rates to meet the nitrogen (N) needs of corn, phosphorus (P) often ends up being applied at a rate that exceeds crop removal, leading to an increase in soil test P over time. When soil test P levels are low or medium, this is a desirable way to build P fertility. As soil test P increases, agronomic justification for application is reduced, and the soil may reach a level of P saturation where managing risk of P runoff becomes a priority. It is important for farms that land-apply manure to consider P build up and draw down over time. To reduce the rate of P buildup, manure rates will need to be reduced while meeting N requirements where possible. Immediate incorporation of manure in the spring conserves significant ammonia N and is one way to compensate for lower application of N and also keep P in line. Manure, either in liquid or in more solid form, contains organic material that can contribute to an increase in SOM over time. On the other hand, SOM can be negatively impacted by tillage. Here we show changes in SOM and soil nitrate after surface application of compost and manure at high rates versus lower rate of manure with chisel incorporation in a corn silage system.

Field trial
In 2001, an experiment was initiated in Aurora, NY, on a field that had no prior manure history. The study implemented five replications and six treatments: (1) low rate of composted dairy solids (P-based; 20 tons/acre), (2) high rate of composted dairy solids (N-based; 32 tons/acre), (3) low rate of liquid dairy manure with immediate (within one hour) tillage incorporation (P-based; 7,000 gals/acre), (4) high rate of liquid dairy manure application (N-based; 21,000 gals/acre), (5) zero N control (0 lbs N/acre) and (6) side-dress inorganic N (urea ammonium nitrate) at the recommended rate of 100 lbs N/acre. For field preparation, each plot was chisel-plowed, disked, and rolled using a cultimulcher. The low rate of manure received one extra pass of the chisel-plow (two passes in total) to incorporate the manure directly after application. Corn for silage was planted and harvested from 2001-2006.

What did we find?
Soil Organic Matter:
At the start of the experiment, the SOM was 3.5%. After five years of annual addition of high rates of compost, SOM had increased to 3.9% (Fig. 1). Addition of compost at the low rate did not increase SOM. Applying the high rate of manure did not impact SOM while the tillage-incorporation of the lower manure rate resulted in an 11% decrease in SOM (Fig. 1). The plots that did not receive any manure or compost showed an 18% decrease in SOM compared to the original levels (Fig. 1).

Fig. 1: Soil organic matter. Treatments were HC: high rate of compost; LC: low rate of compost; HM: high rate of manure; LM: low rate of manure; N0: zero N control; and N100: 100 lbs sidedressed N/acre. This figure is comparing soil organic matter in April 2006 with soil organic matter in April 2001 for each fertility treatment.

ig. 1: Soil organic matter. Treatments were HC: high rate of compost; LC: low rate of compost; HM: high rate of manure; LM: low rate of manure; N0: zero N control; and N100: 100 lbs sidedressed N/acre. This figure is comparing soil organic matter in April 2006 with soil organic matter in April 2001 for each fertility treatment.

Soil Nitrate: End-of-season soil nitrate was impacted by fertility management as reflected in the amount of nitrate present in 0-8 inch soil cores collected at three different time periods: immediately after harvest, December before snow, and the following April. We excluded the first two transition years and focused on the last three years of the study (2003-2005). Averaged over growing seasons 4, 5 and 6, once differences were observed, soil nitrate loss in the fall (from September to December) was highest where inorganic N had been used (38% loss). The large decrease in soil nitrate between September and snowfall (December) with inorganic N management of corn reflected N loss through leaching and/or denitrification. In compost amended plots, soil nitrate measured in December was 8% higher than what was measured in September (Fig. 2), suggesting that nitrate mineralization in that time period exceeded nitrate-loss. The same was seen for the plots that had received the lower rate of manure (Fig. 2).

Fig. 2. Soil nitrate (0-8 inches) levels as influenced by fertility treatments from September to April (averaged over 2003-2005). Treatments were HC: high rate of compost; LC: low rate of compost; HM: high rate of manure; LM: low rate of manure; N0: a zero N control; and N100: 100 lbs sidedressed N/acre.

Fig. 2. Soil nitrate (0-8 inches) levels as influenced by fertility treatments from September to April (averaged over 2003-2005). Treatments were HC: high rate of compost; LC: low rate of compost; HM: high rate of manure; LM: low rate of manure; N0: a zero N control; and N100: 100 lbs sidedressed N/acre.

These results suggest that when manure and compost are added, mineralization of organic N into nitrate continues between September and December. The following April, soil nitrate levels were similar among all treatments each year, showing a “reset” of nitrate levels reflecting weather in the fall, winter and spring. The nitrate dynamics for both the inorganic fertilizer plots and the manure and compost plots emphasize the importance of planting cover crop species with the ability to grow rapidly in the fall and to overwinter as some of the N lost between harvest and the planting the next spring could have been captured by winter hardy cover crops.

Conclusions
In this experiment, SOM levels decrease in a tilled corn silage/hay/corn grain rotation, with all but the highest level of carbon addition in the high compost treatments. This suggests that application of manure during the corn years is not enough to improve SOM when regular tillage is also part of the management system. The benefits to increasing SOM are well known. For farms that want to increase SOM, it may be necessary to minimize tillage and include cover crops. A shift from high to low rates of manure and compost decreased end-of-season nitrate in the soil but, when combined with tillage-incorporation of the manure, negatively impacted SOM. Manure injection rather than tillage-based incorporation may counteract the negative impacts of a tillage-based manure incorporation system while conserving N and reducing soil test P buildup over time. Inclusion of overwintering cover crops when manure and compost are applied, will aid in capturing of N mineralized in the fall. This could also help with N supply in the spring as earlier work has shown somewhat suppressed yields with P-based application of manure and compost due to an N limitation.

Relevant References

  • Sadeghpour, A., Q.M. Ketterings, G.S. Godwin, K.J. Czymmek. 2016a. Nitrogen vs. phosphorus-based manure and compost management of corn. Agronomy Journal 108: 185-195.
  • Sadeghpour, A., Q.M. Ketterings, F. Vermeylen, G.S. Godwin, K.J. Czymmek. 2016b. Soil properties under nitrogen- vs phosphorus-based manure and compost management of corn. Soil Science Society of America Journal doi: 10.2136/sssaj2016.03.0086.

Acknowledgments
This material is based upon work that is supported in part by Federal Formula Funds and the National Institute of Food and Agriculture, USDA, under Award no. 2013-68002-20525. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the USDA. We thank Aurora Ridge Dairy Farm for providing the liquid manure. Composted dairy solids were supplied by Willet Dairy (years 1 and 2) and Fessenden Dairy (years 3 through 5). For questions about these results contact Quirine M. Ketterings at 607-255-3061 or qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.
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September 30, 2016
by Cornell Field Crops
Comments Off on Managing soil test phosphorus in corn with manure and compost

Managing soil test phosphorus in corn with manure and compost

Amir Sadeghpour1, Sarah Hetrick1, Karl Czymmek1,2, Gregory Godwin1, Quirine Ketterings1
1Cornell University Nutrient Management Spear Program, 2PRODAIRY

Introduction
Surface application of manure (i.e. without incorporation) to meet corn nitrogen (N) needs adds more phosphorus (P) than what corn and subsequent sod crops together can remove. This leads to buildup of P over time. To reduce the risk of long term soil test P (STP) buildup to excessive levels, at some point, manure rates need to be curtailed. Spring injection or immediate incorporation of a lower rate of manure increases the N-value of the manure and can avoid N limitation by a lower manure rate. The question addressed here is how effectively can switching from high rate of manure (N-based) to low rate with immediate incorporation (P-removal based) reduce STP buildup during five corn silage years?

Field trial
An experiment was conducted from 2001 to 2006 in a field with no prior manure history in Aurora, NY. The study had six treatments each replicated five times totaling 30 plots. Treatments were: (1) low rate of composted dairy solids (P-based; 20 tons/acre), (2) high rate of composted dairy solids (N-based; 32 tons/acre), (3) low rate of liquid dairy manure with immediate (within one hour) tillage incorporation (P-based; 7,000 gals/acre), (4) high rate of liquid dairy manure application (N-based; 21,000 gals/acre), (5) a zero N control (0 lbs N/acre) and (6) side-dress inorganic N (urea ammonium nitrate) at the recommended rate of 100 lbs N/acre. Field preparation consisted of chisel-plowing, disking, and cultimulching prior to planting silage corn. The low rate of manure received an extra pass of chisel-plow (two passes in total) to conserve ammonia-N.

Results
Phosphorus balance:
Application of P with low rates of manure and compost (P-based) was designed to meet 90 lbs P2O5/acre removal a year. The actual yearly P removal was 63 lbs P2O5/acre with the low rate of compost and 35 lbs P2O5/acre for low rate of manure, reflecting lower than anticipated yields and a lower P2O5 content of the corn (Table 1). The high rate of manure had the highest 5-yr average annual P balance (151 lbs P2O5/acre per year) and shifting to a low rate of manure decreased the P2O5 balance by 77% (Table 1). Changing the high rate of compost to a low rate of compost reduced the P2O5 balance by 45%. Both low rates of manure and compost were showing balances above zero (lower corn silage yield than anticipated) so we would expect an increase in STP in all four treatments.

Soil test phosphorus: Compared to the initial levels (10 lbs P/acre), the high rate of manure led to a four-fold increase in STP as compared to a two-fold increase with a low rate of manure (Fig. 1). The highest STP increase occurred with the high rate of compost (6x), while the low rate of compost resulted in a three-fold increase in STP consistent with differences in P balances. Lower application rates resulted in slower buildup but because annual balances were positive for both application rates, an increase in STP took place for both the high and the low rates. Soil test P buildup with compost was faster (11 lbs P2O5/acre increased STP by 1 lbs/acre) than manure (25 lbs P2O5/acre increased STP by 1 lbs/acre) suggesting differences in nutrient sources in increasing STP over time (Fig. 2). Soil test P remained unchanged for inorganic N management. These data suggest that STP levels increase faster with compost application than with liquid manure application.

Fig. 1. Soil test P (0-8 inches) levels as influenced by fertility treatments from April 2001 to April 2006. Treatments were HC: high rate of compost; LC: low rate of compost; HM: high rate of manure; LM: low rate of manure; N0: a zero N control; and N100: 100 lbs sidedressed N/acre.

Fig. 2. Changes in STP (0-8 inches) as a function of P2O5 balances after five years of manure and compost addition to corn from April 2001 to April 2006. Treatments were HC: high rate of compost; LC: low rate of compost; HM: high rate of manure; LM: low rate of manure; N0: a zero N control; and N100: 100 lbs sidedressed N/acre.

Fig. 2. Changes in STP (0-8 inches) as a function of P2O5 balances after five years of manure and compost addition to corn from April 2001 to April 2006. Treatments were HC: high rate of compost; LC: low rate of compost; HM: high rate of manure; LM: low rate of manure; N0: a zero N control; and N100: 100 lbs sidedressed N/acre.

Conclusions
With water quality concerns, managing STP levels to reach, but not exceed, the agronomic optimum range will be increasingly important. This experiment shows that increases in STP levels can be better managed with appropriate conservation of manure N, allowing for lower overall rates. In addition, this research shows the importance of maintaining accurate yield records so actual P removal rates can be established and the importance of accurate manure records so management decisions can be made that focus on achieving P balance over crop rotations for soils in the agronomic optimum STP range.

Relevant References

  • Sadeghpour, A., Q.M. Ketterings, G.S. Godwin, K.J. Czymmek. 2016a. Nitrogen vs. phosphorus-based manure and compost management of corn. Agronomy Journal 108: 185-195.
  • Sadeghpour, A., Q.M. Ketterings, F. Vermeylen, G.S. Godwin, K.J. Czymmek. 2016b. Soil properties under nitrogen- vs phosphorus-based manure and compost management of corn. Soil Science Society of America Journal doi: 10.2136/sssaj2016.03.0086.

Acknowledgments
This material is based upon work that is supported in part by Federal Formula Funds and the National Institute of Food and Agriculture, USDA, under Award no. 2013-68002-20525. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the USDA. We thank Aurora Ridge Dairy Farm for providing the liquid manure. Composted dairy solids were supplied by Willet Dairy (years 1 and 2) and Fessenden Dairy (years 3 through 5). For questions about these results contact Quirine M. Ketterings at 607-255-3061 or qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.
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