Author: mmh262

Manure nutrient variability during land application in four New York dairies

Aidan Villanueva1, Carlos Irias1, Juan Carlos Ramos Tanchez1, Kirsten Workman1,2, Quirine Ketterings1

1 Department of Animal Science, Cornell University, Ithaca, NY, United States; 2PRO-DAIRY, Department of Animal Science, Cornell University, Ithaca, NY, United States

Introduction

               Dairy manure is a rich source of essential plant nutrients, making it an excellent natural fertilizer. When applied correctly, it can enhance soil health, boost crop yields, and reduce reliance on synthetic fertilizers, thereby increasing agriculture’s sustainability and contributing to a more circular economy. Unlike inorganic fertilizers that have a guaranteed analysis, manure dry matter and nutrient content can vary, influenced by numerous factors such as dairy rations, type and amount of bedding, rainfall and wash water, manure storage systems and handling. Manure sampling and analyses will be essential in determining the potential value of the manure as a nutrient source. Our objectives were to assess the variability in manure dry matter (DM), nitrogen (N), phosphorus (P), and potassium (K) content across farms, across different storage units within a farm, and across time (hourly versus daily sampling), and to document the impact of agitation on DM and manure nutrient content. 

How was the data collected?

               Four New York dairy farms participated in this study. Manure samples were collected during land application in the spring of 2023 for all four farms and repeated in the spring of 2024 for one of the farms. Manure management and storage practices (Table 1) varied from farm to farm. Storages were sampled in the spring across days (“daily sampling”), and for the 2023 sampling we also took samples every two hours on selected days (“intense sampling”) to compare variability across hours and across days.

Table indicating manure management of different farms.

A manure spreader moving in a field on the left and a bucket of liquid manure on the right.
Fig. 1. Manure collection from a spreader.

               Manure samples were collected by filling a five-gallon bucket directly at the pump or the manure spreader (Figure 1). For each sampling round, three subsamples were taken and submitted for nutrient analyses to ensure outliers could be captured. Samples were analyzed for DM, total N, inorganic N, organic N, P, and K. Means, standard deviation, and coefficient of variation (CV) were determined to assess variability in the results across farms, storages, spreading events, and sampling intensity.

What was found?

               Storages varied greatly from farm to farm (results not shown) and within a farm (Figure 2). This highlights the importance of sampling each storage unit individually and maintaining accurate storage-to-field application records. 

A bar graph indicating mean nutrient content.
Fig. 2. Mean nutrient content at farm D for dry matter, total nitrogen, inorganic nitrogen, organic nitrogen phosphorus (P2O5), and potassium (K2O) in manure samples collected from four manure storage units (S1, S2, S3, and S4) in 2023. Error bars are standard deviations.

               Composition varied as the manure storage was emptied (results not shown). In general, across storages and farms, K content showed lower variability compared to P and N. In general, variability in N (total, organic, and inorganic) and P among hours within a day was much smaller than the variability from day to day (Figure 3). Hourly sampling often resulted in CVs below 13% while daily sampling showed CVs up to 34%. Because of the much lower CVs for hourly sampling, sampling over multiple days is recommended instead of sampling within a day.

Bar graph showing manure variation.
Fig. 3. Coefficient of variation for daily versus hourly sampling at three dairy farms for total nitrogen, phosphorus (P2O5), and potassium (K2O) in manure samples collected in 2023. # = Agitation, + = solid-liquid separation.

               Manure agitation completed the day before and on the day of application resulted in higher nutrient content, specifically for total N and P (Figure 3), reflecting settling of manure solids without agitation. Dry matter content was correlated with total N and P with lower N and P content for the more liquid upper layers in the storage. Potassium did not show much variability reflecting that K is predominantly found in the liquid fraction of the manure. These results show the benefits of consistent agitation to ensure a greater homogeneity over time as manure is land applied.

Bar graph indicating the impact of agitation.
Fig. 4. Impact of agitation the day before land application, during land application, and no agitation on manure mean nutrient content at farm B24 for dry matter, total nitrogen, inorganic nitrogen, organic nitrogen, phosphorus (P2O5), and potassium (K2O).

Conclusions

               Manure nutrient composition and variability differed across farms and across storage units on the same farm. Variability was also present over time as storages were emptied, although there was little variability between samples taken just a few hours apart (same day sampling). Agitation helped reduce variability. We recommend sampling each storage unit separately, keeping storage-to-field application records, agitating storages where feasible prior to and during land application, sampling manure from pumps or spreaders during land application, and sampling every time a significant change in manure dry matter content is seen.

Additional Resources

Acknowledgements

               We thank Dairy Support Services as well as farmers and their certified crop advisors who worked with us to collect manure samples. This research was funded by a USDA-NIFA grant, funding from the Northern New York Agricultural Development Program (NNYADP), the New York Farm Viability Institute (NYFVI), New York State Department of Agriculture and Markets (NYSAGM) and Environmental Conservation (NYSDEC). For questions, contact Quirine M. Ketterings at qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.

Icons for the Nutrient Management Spear Program, Cornell University, Cornell CALS, and PRO-DAIRY

Enhancing nitrogen management in corn silage: insights from field-level nutrient use indicators

Agustin J. Olivo1, Kirsten Workman1,2, Quirine M. Ketterings1

1 Department of Animal Science, Cornell University, Ithaca, NY, United States; 2PRO-DAIRY, Department of Animal Science, Cornell University, Ithaca, NY, United States

Introduction

              Optimizing nitrogen (N) management in corn silage production can help improve farm profitability while reducing potential environmental impacts derived from N losses in dairy farms. One strategy to monitor and improve nutrient management at the field level is the calculation of end-of-season field balances, the difference between nutrients supplied to the crop, and what is removed with harvest. Ideal field-level N balances are positive, but not excessively large.

Fig. 1. Nitrogen pools considered for N supply and N uptake when calculating field-level N balances.

              To assess the use of field N balances as an evaluation tool, field-level N balances (N supply – N uptake) and associated N use indicators were derived for 994 field observations from eight NY dairy farms across NY. Available and total N balances per acre, which differed only in the fraction of manure N accounted for (plant-available N or total N), yield-scaled N balances, and N uptake/N supply were calculated (Fig. 1).

Key findings

Nitrogen use indicators varied widely

              The median balance across all fields was 99 lbs/acre for available N and 219 lbs/acre for total N. Excluding soil N contributions reduced these medians to 26 lbs/acre for available N and 145 lbs/acre for total N. Median N uptake/N supply were 0.60 (available N) and 0.41 (total N). Balances varied by farm, ranging from 41 to 145 lbs/acre for available N and from 126 to 338 lbs/acre for total N (Fig. 2).

Two bar graphs.
Fig. 2. Relative frequency distributions for available nitrogen (N) balances per ac (A), and total N balances per ac (B), for all observations across farms and years.

Nitrogen supply considerably affected N use indicators

              Nitrogen supply was a bigger driver for N use indicators than N uptake (Fig. 3), suggesting that decisions on N inputs influence N use indicators more than yield itself. Larger balances were associated with high N supply and low-yielding fields, indicating that for those fields factors other than N supply limited yield. These could be in-season factors that prevent a field from achieving its yield potential (such as extreme weather events and pest problems), or (semi) permanent limitations (such as shallow depth to bedrock, subsurface compaction, and drainage issues) not acknowledged in N application planning.

Manure-N availability impacted N use efficiency

              The database showed a wide range of manure and fertilizer N supply to fields. Available manure organic and inorganic N played the largest roles in explaining the variability of N use indicators, with available N balances increasing with an increase in manure N supply. The study showed a 0.2 unit decrease in fertilizer N application on average in corn fields, with a 1 unit increase in available N from manure. This suggests that manure is valued as an N source, but its N content is not credited to the full extent possible, resulting in larger N balances at the end of the season.

Scatter plot.
Fig. 3. Available nitrogen (N) balances per acre, as related to N uptake and available N supply. Each data point represents a field*year observation in the database.

Sod-N crediting impacted N use efficiency

              First year corn fields showed reduced fertilizer and manure N applications than 2nd through 4th year fields (Fig. 4). Average available N balances (black dots in Fig. 4) for 1st year corn were, however, slightly larger than for fields with no sod N credits, suggesting opportunities for further reductions in nutrient allocation to 1st year corn.

A bar graph.
Fig. 4. Area-weighted average available nitrogen (N) from fertilizer and manure applications (colored bars), across all farms and years and for different stages of the crop rotation. Blue numbers (line one) on top of the graph represent number of observations in each category, and green numbers (line two), the area-weighted average N credits from sod for observations in each rotation stage. Black bolded numbers on top of each bar represent the sum of the area-weighted average available N from fertilizer and manure. COS1, COS2, COS3 = first, second and third crop year of corn silage after sod.

Farm animal density was associated with N use indicators

              At the whole-farm level, N balances per acre were positively related to animal density (animal units per acre) and impacted by farm crop rotations and within-farm allocation of manure N (Fig. 5).

Fig. 5. Relationship between farm animal density and (A) area-weighted farm averages for available nitrogen (N) balance, and (B) total N balance. Dotted horizontal gray lines represent the area-weighted average for each dependent variable across farms and years. AU = animal unit = 1,000 lbs of live animal weight.

Conclusions

              Nitrogen supply impacted N balance indicators more than N uptake (yield) and N balances tended to increase with larger farm animal density. Adjusting N supply based on realistically attainable yield, fully crediting manure and sod N contributions, improving manure inorganic N utilization efficiency, optimizing animal density, and/or exporting manure can aid in improving field N use indicators over time.

Full citation

              This article is summarized from our peer-reviewed publication: Olivo A.J., K. Workman, and Q.M. Ketterings (2024). Enhancing nitrogen management in corn silage: insights from field-level nutrient use indicators. Frontiers in Sustainable Food Systems 8. https://doi.org/10.3389/fsufs.2024.1385745.

Acknowledgements

              We thank farmers and their certified crop advisors who shared farm data. This research was funded by a USDA-NIFA grant, funding from the Northern New York Agricultural Development Program (NNYADP), and contributions from the New York Corn Growers Association (NYCGA) managed by the New York Farm Viability Institute (NYFVI), and the Department of Animal Science, Cornell University. For questions about these results, contact Quirine M. Ketterings at qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.

Characterization of phosphorus balances in corn silage fields from eight New York dairies

Agustin J. Olivo1, Laura Klaiber2, Kirsten Workman1,3, Quirine M. Ketterings1

1 Department of Animal Science, Cornell University, Ithaca, NY, United States; 3William H Miner Agricultural Research Institute, Chazy, NY, United States; 3PRO-DAIRY, Department of Animal Science, Cornell University, Ithaca, NY, United States

Introduction

              Optimizing phosphorus (P) application in corn silage production systems to align with crop P requirements while sustaining soil test P (STP) levels can help mitigate environmental risks and enhance farm profitability. Nutrient balances (supply minus uptake) can be an effective strategy to monitor P management in fields (Fig. 1). Sustained negative P balances (uptake > supply) can lead to a reduction in STP and negative impacts on crop productivity over time. Conversely, regular nutrient applications beyond crop removal can lead to increases in STP, which may be desirable in the short term to raise low STP, but undesirable if continued once soils reach optimum levels.

A graph with two bars.
Fig. 1. Phosphorus (P) pools considered for P supply and P uptake when calculating field-level P balances.

              Data on P balances from 994 corn silage field observations across eight New York dairies were analyzed to characterize this metric and identify drivers that may point towards opportunities for improved management. Data on manure management practices that affect field P dynamics and nitrogen (N) availability for the crop were also evaluated, as well as the relationship between P balances and STP for four of the farms.

Key findings

Phosphorus balances were low, but with a wide range across farms and fields

              On average, P balances across all fields were low (median of 7 lbs/acre), partially reflecting reductions in P surpluses on NY dairy farms over the last two decades as farm nutrient management has improved. However, there was a wide range across farm averages (-10 to 27 lbs/acre) and individual fields (-48 to 122 lbs/acre) (Fig. 2).

Two bar graphs.
Fig. 2. Relative frequency distribution for phosphorus (P) balances per acre (A), and area-weighted average P balance per acre (B) for Farms 1-8 across all years analyzed in the study.

Manure P supply was the main driver of balances

              Phosphorus supply was a more relevant driver of balances than P removed with harvest. Manure was the main source of P for all farms (Fig. 3), and farm to farm differences explained the largest portion of the variability in P supply. Higher P supply across farms was associated with higher manure application rates (driven partially by farm animal density) and higher manure P content connected to higher P rations.

A bar graph.
Fig. 3. Area-weighted average P supply from fertilizer and manure in Farms 1-8 across all years analyzed in the present study.


Phosphorus was applied at higher rates to fields with adequate STP than to lower STP fields

A b
Fig. 4. Phosphorus (P) supply (A) and P balances per acre (B) for individual observations in the dataset across agronomic soil test P categories in Farms 1, 3, 4 and 5 for all years analyzed in the study. Numbers in the top row represent means for each category. Values with different letters are statistically different.

              Morgan-extracted STP levels varied across farms and fields, with averages of 9, 13, 22 and 22 lbs P/acre for Farms 1, 3, 4 and 5, respectively (the only ones analyzed in the study for Morgan-extracted STP). These values corresponded to sub-optimal (<9 lbs P/acre), optimal (9-19 lbs P/acre), and high (20-39 lbs P/acre) agronomic P levels, according to land-grant university guidelines. Across the entire database, P was applied at higher rates to fields with adequate STP levels, indicating potential opportunities to re-allocate P within farms (Fig. 4).

P-based manure applications could cover a large fraction of crop N requirements

              Under management practices currently implemented by the farms assessed in the study, application of manure at N-based rates to corn would lead to large P balances for all farms, if utilized, due to a mismatch between manure available N to P ratio and corn N to P ratio needs. Similarly, P-based applications would cover only 51% of corn N requirements, on average. Increasing the rate of spring manure injection/incorporation or in-season injection on these farms could cover an average of 66 to 85% of corn N requirements, respectively, illustrating the greater N value of manure when more is incorporated/injected.

Conclusions

Results across the dataset showed low P balances on average, reflecting continued efforts from farms to efficiently manage manure nutrients and limit use of fertilizer P. Farms with large P balances may improve their performance by optimizing diet formulation to lower P excretion, reducing animal density, and/or exporting manure to move excess P off-farm. The data also showed potential opportunities to better allocate P within farms, re-allocating P from high or very high testing fields to P deficient fields. Combining appropriate rates of manure and N fertilizer or implementing manure treatment technologies that conserve N during storage and/or remove P, could help reduce P overapplication with N-based manure use. Similarly, spring or in-season manure incorporation or injection at P-based rates could recover a larger fraction of manure N, enough to cover almost all corn N requirements in some cases.

Full citation

This article is summarized from our peer-reviewed publication: Olivo A.J., L. Klaiber, K. Workman, and Q.M. Ketterings (2024). Characterization of phosphorus balances in corn silage fields from eight New York dairies. Agronomy Journal. https://doi.org/10.1002/agj2.21710.

Acknowledgements

We thank farmers and their certified crop advisors who shared farm data. This research was funded by a USDA-NIFA grant, funding from the Northern New York Agricultural Development Program (NNYADP), and contributions from the New York Corn Growers Association (NYCGA) managed by the New York Farm Viability Institute (NYFVI), and the Department of Animal Science, Cornell University. For questions about these results, contact Quirine M. Ketterings at qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.

New York state, regional and county level nitrogen and phosphorus balances for harvested cropland

Olivia Godber1, Kirsten Workman1,2, Kristan Reed3, and Quirine Ketterings1

1Nutrient Management Spear Program, 2PRODAIRY, 3Department of Animal Science, Cornell University, Ithaca, NY 14853

Introduction

              New York (NY) state is one of five states that collectively produce more than 50% of the annual milk supply within the United States. The local environment allows farmers to integrate crop and livestock systems, facilitating cycling of manure nutrients back to cropland. Thus, dairy farming provides NY with benefits, opportunities, and challenges in terms of environmental sustainability and climate resiliency. Improved balancing of crop needs for nitrogen (N) and phosphorus (P) with supply from manure is key for a circular agricultural economy. The objectives of this study were to calculate and evaluate (1) regional and county level N and P balances of harvested cropland; and (2) the contribution of manure to a circular agricultural economy for NY. 

              Nutrient balances were calculated for 2017 (most recent USDA Census of Agriculture year at the time) as the difference in nutrient inputs through purchased fertilizer and recoverable manure, and nutrients removed in harvested crops. Atmospheric N deposition, legume N fixation, and manure nutrient losses during collection, transfer, storage, and treatment were also estimated.

Key Findings!

              The 2017 NY State P balance was 9 lbs P/acre. The N balance was between 35 and 85 lbs N/acre, depending on the proportion of legume cropland assumed to have received manure (Figure 1). 

2 bar graphs with a key.
Figure 1: Breakdown of the inputs and crop removal of (A) phosphorus (P), and (B) nitrogen (N) at the New York state level in 2017. Estimated N losses of manure N during storage through volatilization and denitrification are identified.

              For P balances at the regional level, a small range of 5 to 10 lbs P/acre was seen (Figure 2). Chemung County was the only county with a negative balance (-3 lbs P/acre).

Image of New York State sectioned off by region. Each region has a corresponding small bar graph indicating phosphorus input and crop phosphorus uptake. A few counties in gray are excluded.
Figure 2: Breakdown of phosphorus (P) inputs and crop P uptake at the regional level, and P balance at county and regional level for New York in 2017; counties in gray were excluded.

              For N balances at the regional level, a small range of N balances from 17 to 41 lbs N/acre was seen (Figure 3A) when balances were calculated assuming that manure and purchased fertilizer N were applied to all cropland, and no N fixation occurred. Under the assumption that no manure or purchased N fertilizer was applied to legume cropland, and additional N inputs were included as a result of N fixation on legume cropland, a higher but still small range in N balances from 60 to 94 lbs N/acre was seen (Figure 3B). Under both assumptions the balances were calculated before storage and application losses of N.

              Redistribution and application of manure to meet P-removal on only the non-legume cropland left a surplus of 3 lbs P/acre at the NY state level. Applying surplus manure to legume and non-legume cropland resulted in a slight, state-level, P deficit. In both scenarios, the large N deficit that cannot be met through legume N fixation alone indicates N fertilizer is required to meet crop needs under the reported yield and manure supply conditions. These results show NY’s ability to capitalize on the value of manure.

Two maps of the state of New York, sectioned off by region, with excluded counties colored in gray. Each map has small bar graphs corresponding with each region indicating the nitrogen input and crop uptake of nitrogen of the region. The map on top includes manure and purchased nitrogen being applied to all cropland, whereas the one on the bottom refers to non-legume cropland only. The maps are each purple.
Figure 3: Breakdown of nitrogen (N) inputs and crop N uptake at the regional level, and N balance at county and regional level for New York in 2017, assuming manure and purchased N was applied to (A) all cropland (assumes no legume N fixation) versus (B) non-legume cropland only (assumes legumes received N through fixation). Counties in gray were excluded.

              Manure has value to cropland beyond N and P and consideration of these factors at the field level, in combination with field management history and soil test results, could help to prioritize where manure should be applied, and where purchased N and P inputs are required. Development and adoption of advanced manure treatment, storage, and application practices, with consideration of how livestock feeding practices can influence manure characteristics, could all help to further improve the value of manure, improve balances, and increase circularity and sustainability of the agricultural sector in NY.

Next Steps?

              As updated manure excretion rates and the amount of nutrients lost during storage and application of manure become available, combined with an expected continuation in the upward trend of both cow numbers and milk production for NY, it will be important to continue assessments of nutrient balances and animal densities, and explore manure treatment options to allow for transport of manure nutrient throughout NY to avoid creating nutrient “hotspots” within the state. With the recent release of the 2022 USDA Census of Agriculture data, we aim to evaluate these scenarios in more detail for the 2022 state balances.

Full Citation

              This article is summarized from our peer-reviewed publication: Godber O.F., Workman K., Reed K., and Ketterings Q.M. (2024) New York state, regional and county level nitrogen and phosphorus balances for harvested cropland. Frontiers in Sustainability 5:1352296. https://www.frontiersin.org/journals/sustainability/articles/10.3389/frsus.2024.1352296/full.

Acknowledgements

              This research is funded primarily by a gift from Chobani, in addition to Federal Formula Funds and grants from the New York State Department of Agriculture and Markets (NYSAGM) and New York State Department of Environmental Conservation (NYDEC). For questions about these results, contact Quirine M. Ketterings at qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.

Manure Can Offset Nitrogen Fertilizer Needs and Increase Corn Silage Yield – Value of Manure Project 2023 Update

Juan Carlos Ramos Tanchez1, Kirsten Workman1,2, Allen Wilder3, Janice Degni4, Paul Cerosaletti4, Dale Dewing4, and Quirine M. Ketterings1

Cornell University Nutrient Management Spear Program1, PRO-DAIRY2, Miner Agricultural Research Institute3, and Cornell Cooperative Extension4

Introduction

              Manure contains all seventeen nutrients a plant needs, making it a tremendously valuable nutrient source for crop production. Applying manure to fields can also build soil organic matter, enhance nutrient cycling, reduce reliance on commercial fertilizer, and improve overall soil health and climate resilience. The Value of Manure Project of the New York On-Farm Research Partnership is funded by the New York Farm Viability Institute (NYFVI) and the Northern New York Agricultural Development Program (NNYADP). This statewide project evaluates nitrogen (N) and yield benefits of various manure sources and application methods to corn silage and corn grain crops. Eight trials were conducted in 2023, adding to three trials established in 2022. Here we summarize the findings of the trials conducted in 2023.

What we did in 2023

              Trials were implemented within commercially farmed corn fields in western (2 trials), northern (2 trials), central (3 trials), and southeastern (1 trial) New York. Each trial had three strips that received manure and three that did not, for a total of six strips per trial (Figure 1a). One trial (Trial B) received manure in spring of 2022. For this trial we tested carryover benefits into the 2nd year (2023). For all other trials, manure was applied in spring 2023 before planting corn. Manure source and application method varied across sites (Table 1).

Images of the manure plots for the study. Entire study area 1,200 ft by 120 ft, each study plot 200 ft by 120 ft.
Figure 1. Layout of a 2023 Value of Manure study plot. Three strips received manure before planting corn (1a). At the V4-V6 stage each of the six strips received six different inorganic N sidedress rates (1b).

              Strips were 1200-1800 ft long and 35-120 ft wide for all but one site, where strips were 300 ft long 35 ft wide. When corn was at the V4-V6 stage, each strip was divided into six sub-strips (Figure 1b) and subplots were sidedressed at a rate ranging from 0 up to 300 pounds N/acre. Sidedress rates were trial-specific, based on the expected N requirement of each field. For each trial, we measured manure nutrient composition, general soil fertility, Pre-Sidedress Nitrate Test (PSNT), Corn Stalk Nitrate Test (CSNT), yield, and forage quality.

Table describing the soil type, manure type, and manure application rate of the different trials in spring of 2023.
*Note: manure was applied in spring of 2022 in farm B, and we tested its carryover value for 2023.

              Soil test phosphorus (P) of the trials was classified as optimum (between 9 and 19 pounds P/acre), high, or very high (Table 2). Soil potassium (K) was optimum or very high for six of the trials while trials A and G tested medium in K. Magnesium soil test values were high (> 101 pounds Mg/acre) or very high. Soil test zinc (Zn) was medium for trials A and G (between 0.5 and 1.0 pounds Zn/acre) and high for all other trials. Manganese and iron were in the normal category (< 49 pounds Fe/acre, < 99 pounds Mn/acre).

Table describing the results of the Cornell Morgan test.
SOM = soil organic matter, P = phosphorus, K = potassium, Ca = calcium, Mg = magnesium, Zn = zinc, Mn = manganese, Fe = iron, Al = aluminum.

What we have found so far

              Similar to what we found in 2022, trials differed in their responses to manure and inorganic N (Figure 2). Trials D and E did not respond to manure or N sidedress application likely due to past N credits providing enough N to the crop. In trials A, B, C, G, and H, yield increased due to both manure and sidedress N application. Yields increased in manured plots beyond what could be obtained with fertilizer N by 0.3 to 4.6 tons/acre, and 5 to 21 bushels/acre (Table 3). In trials A and G, the ones with medium K and Zn classification, manure applications increased yield to such elevated levels (4.6 tons/acre for trial A and 21 bushels/acre for trial G), that it also increased the crop’s need for fertilizer N (in other words, the required sidedress N rate also increased). In both trials, manure application shifted soil K levels from medium to optimum and increased K content in silage, suggesting K was yield limiting at these locations.

Figure describing the MERN of different trials.
Figure 2. Most Economic Rate of Nitrogen (MERN) in eight trials. Orange text boxes are the MERN and yield at MERN for manured plots; gray text boxes are MERN and yield at the MERN for no manure plots. Corn silage yields are in tons/acre at 35% dry matter (DM), and corn grain yields are in bushels/acre at 84.5% DM.

Table describing the MERN for manure and no-manure plots.

              The PSNT levels of the manured plots were higher than their no-manure counterparts for all trials where liquid or digested manure was applied, showing that manure supplied crop available N to the soil (Table 4). In contrast, for farm A the PSNT-N was 15 ppm where compost had been applied versus 20 ppm without compost application, likely due to the high carbon content compared to N content of the compost used in that site. (Table 4). The impact of manure applications was also reflected in CSNT levels (Table 4). For trials D and E, CSNT levels of the plots that did not receive manure or sidedress fertilizer N were optimal or excessive, consistent with the lack of a yield response to N for those two sites. Similarly, for site F, the marginal classification suggested that limited (very little) to no N was needed, consistent with the lack of a manure-induced yield response and minimal fertilizer N response at that site. For the five trials where a crop response to N was determined (trials A, B, C, G, H), the CSNT’s of the zero N plots were low, accurately reflecting the need for additional N. For four trials, the CSNTs where manure but no N fertilizer was applied, were low (trials A, B, and G) or marginal (trial H), consistent with the response to sidedress N in the manured strips. For trials C, D, and E, the CSNTs were excessive in the manure strips without N fertilizer addition, consistent with the lack of a response to sidedress N (MERN = 0 pounds N/acre, Table 3). For trial F, the CSNT of the manured plots without sidedress N application was optimal. This trial showed a small response in yield to the addition of just over 30 pounds N/acre (Table 3).

Table describing the results of the Pre-Sidedress Nitrate Test.
*Note: Farm A applied compost that impacted PSNTs and had a very wet growing season (15 inches of rainfall higher than the 10-year average).

Conclusions and Implications (and Invitation)

              In 2023 we documented “yield bumps” resulting from manure application beyond what could be obtained with fertilizer only in five of the eight trial, consistent with observations for two of the three trials in 2022. For the sites with optimal or high fertility status, this yield increase shows that manure is not just supplying nutrients, but also benefits yield beyond nutrient contributions. The PSNT and CSNT results consistently reflected where N was needed and allowed for documentation of the N contributions of the various manure sources.
              The Value of Manure Project will continue in 2024. We will be testing additional manure types and manure application methods in various soil types and weather conditions. Join us in the Value of Manure Project in 2024 and obtain valuable insights about the use of manure in your farm! If you are interested in joining the project, contact Juan Carlos Ramos at jr2343@cornell.edu.

Additional resources

            The NMSP Value of Manure Project website and on-farm field trial protocols are accessible at: http://nmsp.cals.cornell.edu/NYOnFarmResearchPartnership/Value_of_Manure.html (project website),  http://nmsp.cals.cornell.edu/NYOnFarmResearchPartnership/Protocols/NMSP_Value_of_Manure_Protocol2024.pdf (protocol). Value of Manure phone app: https://valueofmanure-nmsp.glideapp.io/. For the 2022 project results: https://blogs-dev.cornell.edu/whatscroppingup/2023/02/15/manure-can-offset-nitrogen-fertilizer-needs-and-increase-corn-silage-yield-value-of-manure-project-2022-update/.

Acknowledgments

              We thank the farms participating in the project for their help in establishing and maintaining each trial location, and for providing valuable feedback on the findings. For questions about this project, 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/.

Common Misconceptions about Concentrated Animal Feeding Operation (CAFO) Regulations and Comprehensive Nutrient Management Planning in New York State

Carly Bass1,7, Kirsten Workman2,3,7, Greg Albrecht4, Ron Bush4, Brendan Jordan4, Dale Gates5, Josh Hornesky5, Sara Latessa6, Kristan Reed7, Quirine M. Ketterings3,7

1Masters of Professional Studies in Animal Science, 2PRO-DAIRY, 3Nutrient Management Spear Program (NMSP), 4New York State Department of Agriculture and Markets (NYSAGM), 5United States Department of Agriculture Natural Resources Conservation Service (USDA-NRCS), 6New York State Department of Environmental Conservation (NYSDEC), and 7Department of Animal Science, Cornell University

Introduction

Farms that have more than 300 mature dairy cows (or an equivalent in other livestock animals) are required to operate under the New York State Pollutant Discharge Elimination System (SPDES) General Permit for Concentrated Animal Feeding Operations (CAFOs). The permit dictates that the farms follow environmental conservation practices and meet state standards designed to maintain the highest quality of water possible by mitigating the risk of pollution to New York waters. As only a small portion of our population is involved in agricultural production, it is not always understood what farms in New York State are required to do to stay in compliance. This article highlights and addresses some of the most common misconceptions surrounding New York CAFO farms and the CAFO permit.

Misconception 1:

“New York’s permit is less strict than the federal permit” 

New York works closely with federal agencies such as NRCS and the EPA to ensure their standards and permit satisfy or exceeds the federal requirements. New York takes the minimum guidelines set forth in the federal Clean Water Act (CWA) CAFO Rule and makes additional requirements for farms to follow within their Comprehensive Nutrient Management Plan (CNMP) to meet water quality and sustainability goals of the state. The following are examples where the New York CAFO permit is more environmentally protective, and thereby restrictive, than the federal CAFO rule.

  • New York CAFOs must maintain no discharge from their production areas (farmsteads) through a 100-year, 24-hour storm compared to the federal no discharge standard which is for a 25-year, 24-hour storm.
  • New York CAFOs must utilize an AEM Certified Planner, whereas no professional certification is required by the CWA CAFO Rule.
  • New York CAFO permitted farms must follow an integrated system of NRCS Conservation Practice Standards for management of nutrients throughout their farmsteads and fields; such engineering and management standards are not required by the CWA CAFO Rule.
  • Farms must sample soil for nutrient values every three years versus every five years.
  • Farmer fields need to be planned and managed to conserve soil and reduce erosion, whereas this is not a CWA CAFO Rule.
  • New York CAFO’s must develop and maintain facility specific winter and wet weather application procedures and identify low-risk fields to be used for winter application in the case of an emergency.
  • New structural practices need to be designed considering future flood risk due to climate change.
  • Farm staff must be present and monitor active waste transfers from the production area (farmstead) while material is being transferred.
  • The NRCS-NY 590 Nutrient Management Standard and associated Land Grant University Guidelines require New York CAFOs to account for nitrogen already present on the farm (soil, manure, crop rotation credits, etc.) when developing spreading recommendations.

Misconception 2:

“Manure storages are not safe and impact drinking water”

Manure storages located and operated on New York CAFOs are required to be designed and constructed by a trained, State of New York licensed professional engineer to meet national standards (Natural Resources Conservation Practice Standard – NY 313). The NRCS-NY 313 Standard requires that manure storages are designed, built, and operated to fully contain manure nutrients and any direct precipitation for future application to crops as fertilizer while remaining isolated and protected from ground- and surface waters. These standards require geological investigations, prior to the design, to properly site these structures and ensure an appropriate liner is selected to minimize any risk of leaking. To date, there has been no evidence of a certified manure storage contributing to an impact to groundwater in New York. In addition to the groundwater protections outlined in the standards, there are measures to ensure and protect against these structures overtopping. The standards themselves require maximum fill markers to help ensure that safety volume requirements are maintained. The New York CAFO permit also requires the final as-built plans, certified by a professional engineer, be maintained on site; fill levels be monitored and recorded; and operation and maintenance measures outlined by the professional engineer be followed. Finally, no farm in New York is allowed to impact the water resources of the state, no matter the size of the farm. Any impact to Waters of the State is considered a significant violation of the Environmental Conservation Law and is subject to substantial penalties and/or fines.

Misconception 3:

“Farmers can spread manure under any weather conditions”

All CAFO farmers are required to have a current Comprehensive Nutrient Management Plan (CNMP) developed by an AEM Certified Planner in accordance with the permit, NRCS standards, and guidelines. The CNMP must be updated annually and prescribes how much manure and fertilizer can be spread on each field, as well as the anticipated application method and timing. In addition to their individualized plans, the New York CAFO permit sets maximum single-application spreading rates. New York’s CAFO permit also contains specific requirements pertaining to winter and wet weather spreading, including a prohibition against spreading if the field is saturated or frozen-saturated.

New York does not have a calendar-based ban on winter spreading because calendar-based regulations do not take current weather and specific field conditions into account. Drivers of nutrient losses are based on specific field, soil, and weather conditions/forecasts. New York’s CAFOs must assess field conditions every time they spread and follow the specific guidance outlined in the “Revised winter and wet weather manure spreading guidelines to reduce water contamination risk”.

Misconception 4:

“New York regulations allow phosphorus to be applied to fields even when the crop does not need it”

Manure contains all 17 essential nutrients for plant growth and is a key to building soil health by providing organic matter and enhancing the soil ecosystem. Properly managed, use of manure can offset the need for purchased fertilizer, reducing the amount of imported nutrients onto farms and into a watershed. However, nutrients in manure aren’t necessarily present in the balance required by a specific crop grown on a specific field. Within a farm’s CNMP, the New York P-Index governs how much phosphorus can be applied to fields each year to ensure proper recycling of on-farm nutrients through crops and long-term, sustainable soil test levels for the benefit of water quality. In accordance with the New York P-Index, a farmer and AEM Certified Planner must assess the risk of phosphorus leaving the field. This needs to be done for all fields on the farm. Those assessments will determine how and how much manure may be applied and must be documented in the farms’ CNMP. Farmers implement beneficial management practices to further reduce P runoff risk to lower the New York P-Index rating for fields. Making the most of manure nutrients is critical for water quality, air quality, and crop production, and to reduce N and P imports into watersheds. Most soils in New York are currently deficient in phosphorus so proper phosphorus management is needed to maintain productive and healthy soils for food production.

Misconception 5:

“Farmers pay AEM Certified Planners, therefore plans are biased”

New York has strict rules for who can develop and update CNMPs. A farm’s CNMP needs to be written by a state-certified planner who has gone through extensive training, is required to keep certifications current through training sessions, and has signed a code of ethics. Such a certification is akin to other state certified professionals used across sectors, such as professional engineers, architects, accountants, etc. To become an AEM planner, an individual must first become a Certified Crop Adviser (CCA), which involves passing two exams (an international and a regional exam) and meeting further educational and experience requirements to demonstrate their knowledge in agronomy and environmental conservation in agriculture. The next step is satisfying participation in the state led CNMP Training. After completing these two steps, the individual’s first three CNMPs must be submitted to CNMP specialists at the New York State Department of Agriculture and Markets (NYSAGM) for review, revision, and acceptance. Once the three plans satisfy the CNMP requirements, the individual becomes an AEM Certified Planner. Certified planners must sustain their CCA status, maintain compliant work through ongoing quality assessments by NYSAGM staff, and satisfy 40 credit hours of continuing education every two years to maintain their certification. In addition to this rigorous certification and assessment process, the NYSDEC reviews CNMPs during regular CAFO inspections and pursues enforcement if deficiencies are identified.

Misconception 6:

“Only large dairy farms are regulated”

New York State laws and regulations require all animal feeding operations (AFOs) that meet certain animal thresholds, to obtain coverage under a State Pollutant Discharge Elimination System (SPDES) permit prior to operation. However, per Environmental Conservation Law Article 17, Title 5, Section 17-0501, no farm, regardless of size or permit coverage, is allowed to contribute to a water quality violation and impact New York’s water resources. New York also funds several programs that are available to all farms, including smaller AFOs. The AEM program, Dairy Advancement Program (DAP), and NRCS’s program help farms with conservation plan development (including CNMPs) and implementation of best management practices. To date, 13,500 practices on over 2,500 farms have been implemented through the AEM programs, the DAP has helped more than 300 non-CAFO farms develop CNMPs, and those NYS program accomplishments can be doubled when considering projects completed through USDA NRCS and the Farm Service Agency. These programs augment the substantial investment by farmers and ensure that farms of all types and scales have the resources to implement nutrient management practices on their farms to aid with environmental management. Roughly 1,000,000 acres of cropland are impacted annually in New York by nutrient management guidelines due to the various programs in place.

Additional Resources 

Acknowledgements

The information shared in this article comes from a larger extension document that outlines regulations and comprehensive nutrient management planning in New York State (see additional resources above). We thank the members of the Nutrient Management Spear Program advisory committees for their feedback on the larger document. For questions, contact Quirine M. Ketterings (qmk2@cornell.edu) or Kirsten Workman (kw566@cornell.edu).

 

Icons for the Nutrient Management Spear Program, Cornell University, Cornell CALS, and PRO-DAIRY