HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Figures Only Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Sanford, G. R. Articles by Baldock, J. O. Search for Related Content PubMed Articles by Sanford, G. R. Articles by Baldock, J. O. Agricola Articles by Sanford, G. R. Articles by Baldock, J. O. Related Collections Sustainable Agriculture Crop Rotation Systems Best Management Practices Maize Agricultural Systems Crop Systems Nutrient Management Animal Waste

Linking Wisconsin Dairy and Grain Farms via Manure Transfer for Corn Production

^a Dep. of Agronomy, Univ. of Wisconsin, 1575 Linden Dr., Madison, WI 53706
^b Massachusetts Association of Conservation Districts, 52 Boyden Rd., Holden, MA 01520
^c Michael Fields Agricultural Institute, W2493 County Rd. ES, East Troy, WI 53120
^d Agstat, 6394 Grandview Rd., Verona, WI 53593

^* Corresponding author (gsanford{at}wisc.edu).

	ABSTRACT

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
One relatively under-used manure management strategy employed by dairy farmers is to transport and apply manure onto the fields of nearby grain farmers. While this system offers advantages to both parties, little of the existing research on manure management has been conducted on grain farms. As part of an effort to link grain and livestock farms in southern Wisconsin, 20 on-farm trials were conducted to study the agronomic and environmental effects of including manure in cash-grain rotations. Manure was applied at a rate of approximately 107 m³ ha^–1 as slurry (11,000 gal acre^–1) or 54 Mg ha^–1 (24 ton acre^–1) as a solid. Across-site analysis indicated that the manured treatment increased corn (Zea mays L.) yields significantly (alpha = 0.05), by 0.5 Mg ha^–1 (11.5 vs. 11.0 Mg ha^–1), with 67 kg ha^–1 less purchased fertilizer N during the 3 yr of this study. However, there were environmental concerns: (i) Early fall manure spreading significantly increased fall nitrate (NO₃) levels in the manured plots (175 vs. 87 kg NO₃–N ha^–1); (ii) Following corn harvest, fall NO₃ levels were fairly low and equivalent between treatments with the exception of three sites where manuring resulted in significantly higher NO₃–N; and (iii) Soil tests following corn harvest indicated a significant increase in soil test phosphorus (STP) on the manured plots. These results indicate that dairy manure can reduce fertilizer inputs although there is a risk of NO₃–N leaching and P accumulation. Informal interviews were conducted with farmer-participants following this study to asses current manure use.

Abbreviations: BLUP, best linear unbiased predictors • FC, farmers' check • GDD, growing degree days • M, manure + supplemental fertilizer • PSNT, presidedress soil nitrate test • RCBD, randomized complete block design • RHA, rolling herd average • SFAL, Soil and Forage Analysis Laboratory • SPAL, Soil and Plant Analysis Laboratory • STK, soil test potassium • STP, soil test phosphorus

Received for publication April 21, 2008.

	INTRODUCTION

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
CURRENT TRENDS in the Wisconsin dairy sector indicate that average herd size is increasing, with a growing proportion of the milk produced on farms of 200 cows or more (Barham et al., 2005). By 2005, farms with more than 200 cows housed 32% of the state herd and accounted for 34% of the milk production (USDA-NASS, 2006a). These larger farms tend to have an uncovered, lined slurry pit for long-term manure storage (Turnquist et al., 2006), and higher stocking rates than smaller dairy farms according to a study by Saam et al. (2005). This situation can result in dairy farmers having large quantities of manure to manage on an insufficient land base. In addition, stricter nutrient management regulations are now in place, requiring phosphorus-based spreading standards in some cases, which limit the rates, timing, and availability of cropland for manure applications (USDA-Natural Resources Conservation Service, 2005).

At the same time that the state's dairy industry is expanding, cash grain farmers are facing increasing costs for commercial fertilizer. Prices in Wisconsin per kilogram for N increased by 123%, phosphate (P₂O₅) by 89%, and potash (K₂O) by 41% between 1999 and 2007 (USDA-NASS, 2000–2007). This largely explains why the cost of fertilizer for corn production in Wisconsin nearly doubled from $86 to $164 ha^–1 during approximately the same period (USDA-NASS, 2000, 2006b). As prices for commercial fertilizer increase there is a growing incentive for grain farmers to use alternative nutrient sources such as livestock manure. Manure provides N, P, K, S, and many trace minerals, as well as serving as a soil conditioner by increasing organic matter and improving soil porosity and water-holding capacity (Safley et al., 1986; Eghball and Power, 1994; Eghball et al., 2002).

Comparisons of corn yields in some studies have shown little statistical difference between treatments receiving livestock manure and commercial fertilizer (Motavalli et al., 1989; Jokela, 1992; Eghball and Power, 1999), and in others, the manured corn has outyielded fertilized corn (Ginting et al., 1998). Studies have also shown that grain protein does not differ in a predictable manner between treatments receiving either manure or commercial fertilizer (Evans et al., 1977; Jokela, 1992; Eghball and Power, 1999).

While the potential of manure to produce good corn yields is generally known, many grain farmers are concerned about manure heterogeneity and the difficulties in accurately estimating the amount of nutrients being applied. Estimation of manure nutrient content is generally done in one of three ways: (i) using default "book" values, (ii) conducting manure nutrient analysis and using nutrient availability ratios, or (iii) using the presidedress soil nitrate test (PSNT); alone, each has its drawbacks. Nutrient crediting, using "book" values for plant-available N, P, and K can be risky as these standardized values may not accurately represent the nutrient content of a particular manure; especially in cases of concentrated or dilute material. Manure sampling and analysis can provide a clear picture of nutrients applied, but sampling is an onerous task and due to its heterogeneity, frequent sampling may be required (Dou et al., 2001; Davis et al., 2002). The PSNT taken in the late spring has proven useful in predicting when available NO₃–N from manure and legume sources will be adequate for optimum yields (Magdoff et al., 1984; Klausner et al., 1993; Andraski and Bundy, 2002). The test however, is less precise when cold wet springs inhibit N mineralization (Andraski and Bundy, 2002) or when measured NO₃–N is below the critical value of 21 mg kg^–1. At these lower values, where yields have been shown to decline without supplemental N fertilizer, the PSNT is less precise in predicting the economically optimal fertilizer recommendation (Klausner et al., 1993; Miller, 1996). In addition, the general practicality of this test is somewhat compromised by the narrow window between the time of sampling (V4–V6 corn growth stage) and canopy closure, constraining a farmer's opportunity to sidedress N.

Despite its production potential, the use of manure can also have adverse environmental impacts. In addition to the release of gasses implicated in global climate change and air pollution (Sommer and Olesen, 1991; Lessard et al., 1996), the overapplication of manure can lead to increased nutrient runoff and/or leaching. Bundy et al. (1994a) has shown surface water contamination and eutrophication via runoff of manure. Phosphorus accumulation in the topsoil from repeated manure applications increases the potential for P loss through soil erosion, subsequently increasing the likelihood of eutrophication in freshwater ecosystems (Powell et al., 2001; Bundy and Sturgul, 2001).

Also of concern is the increased risk of mineralized manure N leaching at a time of year when available NO₃–N is not in synchrony with corn growth. Measuring residual soil NO₃–N in the soil profile following manure applications has been used as an indicator of potential NO₃ leaching in several studies. There seems to be no clear trend regarding the effects of manure vs. N fertilizer on soil NO₃ levels. Many authors have found equivalent levels between the two N sources (Beauchamp, 1986; Jokela, 1992; Zebarth et al., 1996), while some studies have shown either higher residual levels of NO₃–N under manure (Evans et al., 1977; Roth and Fox, 1990) or fertilizer treatments (Kimble et al., 1972; Xie and MacKenzie, 1986; Comfort et al., 1987).

In addition to the problems of NO₃–N leaching, studies on STP levels have shown significant P accumulation where fields receive frequent manure applications (Proost, 1999; Randall et al., 2000; Ritter, 2000). For example, Proost (1999) surveyed 96 Wisconsin dairy farmers, and found that 77% of the fields had STP levels over the optimal range, as defined by the UW Extension (Kelling et al., 1998). During a 5-yr study in Minnesota, Randall et al. (2000) found that manure applications substantially increased both STP and STK levels when compared to a fertilizer-only treatment. While STP does not take into account landscape information such as field slope, proximity to water, soil erosion potential, or information on the soil's capacity for P sorption: it is a frequently used measure in nutrient management plans for determining where, when, and how much manure will be spread each year (USDA-NRCS 590).

While it is clear that there are a growing number of dairy operations that need to move manure off their farms, and a growing logic for grain farms to use dairy manure in their rotations, little research on manure management in cash grain systems has been conducted. As part of a larger effort to link grain and livestock farms in southern Wisconsin, six dairy farms and nine grain farm collaborators were invited to participate in a series of on-farm trials (n = 20) conducted to address the following questions: (i) What are the effects of manure on corn yield and grain protein? (ii) Do manure applications result in potentially problematic accumulations of NO₃–N or P in the soil? (iii) Would these growers, at the end of the research phase be interested in continuing to include manure in their production system? Companion studies to the current work have reported on manure spreading impacts on soil compaction (Sanford et al., 2008), manure's impact on weed populations (Cook et al., 2007), and manure hauling economics (Sanford, G.R., J.L. Posner, and G.L. Hadley. 2008. Economics of hauling dairy slurry and its value in Wisconsin corn (Zea mays L.) grain systems. J. Agric. Food Environ. Sci.. in review).

	MATERIALS AND METHODS

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Initial Layout
Between 2004 and 2006 20 corn trials were conducted on cash-grain farms in south-central and southeastern Wisconsin. Each trial was located near one of six cooperating dairy farms in the study. Five of the six cooperating dairies were confinement operations housing their cattle in free-stall barns and using a liquid slurry storage system for their manure. These farms had between 250 and 900 milking cows with a rolling herd average (RHA) of 12,250 kg milk. On one of the six farms, 90 milking cows (RHA of 7260 kg milk) were rotationally grazed, and manure collected from their stanchion barn was spread as a solid. Each year, fields going into corn on the cooperating grain farms were selected. These were large grain farms (490 production hectares on average) and the selected fields were between 0.2 and 12.2 km from the source of manure. The trials were established using a randomized complete block design (RCBD), with three replications. Two treatments were compared: a nonmanured treatment representing the farmers' current corn production practices ("farmers' check" or FC), and a system where the majority of nutrient inputs were applied as manure (M). Plot sizes were determined to accommodate manure spreading, corn planting, and corn harvesting equipment. Plots ranged from 9.1 to 18.3 m wide, and approximately 91 to 152 m long (0.08–0.28 ha plot^–1). The five cooperating dairy farms using slurry manure systems either owned a tractor-pulled manure tank or hired custom manure haulers with truck-mounted manure tanks. Manure tank capacity ranged in volume from 15 to 27 m³. Solid manure was applied with a box spreader. Calibration of manure spreading equipment at each site involved measuring several pilot areas, determining the manure spreader's capacity and spreading width, and then manipulating the tractor drive speed to meet the target application rate on the experimental plots.

Baseline soil fertility samples (0–15 cm depth) were taken from each site before manure applications and analyzed for pH (1:1 soil to water), organic matter (loss on ignition), and STP and STK levels (using Bray P1 extract) at the UW Soil and Plant Analysis Laboratory (SPAL) in Madison, WI. These laboratory methods are cited in Kelling et al. (1998). As a result of the two different manure storage systems used in this study (slurry and solid), slurry was applied at 17 of the on-farm environments while solid manure was applied at the other three. Based on discussions with professional manure applicators and UW Extension personnel, the target application rate for slurry was between 94 and 112 m³ ha^–1 (10,000 to 12,000 gal acre^–1) and for solid manure between 45 and 56 Mg ha^–1 (20–25 ton acre^–1). At 19 of the 20 sites manure was either directly injected or incorporated into the soil via tillage. Manure samples were taken directly from the application equipment before spreading. Samples were analyzed for dry matter content and total N, P₂O₅, and K₂O, at the UW Soil and Forage Analysis Laboratory (SFAL) in Marshfield, using total Kjeldahl N for N and dry ash methods for P and K (Association of Official Analytical Chemists, 2008a, 2008b).

To estimate the potential for NO₃ leaching within a soil profile, soil cores were collected in the late fall with a truck-mounted hydraulic probe. Each core was comprised of a homogenized sample taken from 0 to 91 cm. Three paired cores (in-row and between-row) were take per plot and bulked in this analysis. Samples were analyzed for NO₃–N at the SPAL using automated colorimetric methods at 0 to 30, 31 to 60, and 61 to 90 cm. The sum of these three horizons was termed "profile fall nitrate."

On-Farm Site Characterization
Corn was planted following either wheat (Triticum aestivum L.) (n = 10 environments) or soybean [Glycine max (L.) Merr.] (n = 10 environments) depending on the cooperating grain farmers' rotation. All of the environments were located on prairie-derived loam or silt loam soils typical of south-central Wisconsin with relatively high organic matter concentrations (NO₃ = 30 g kg^–1) and modest slopes ranging from 0 to 6%. Both STP and STK in these environments were in the optimum to high range for a typical cash grain rotation with the exception of one environment that had recently come out of the USDA's Conservation Reserve Program. Details regarding soil characteristics and tillage used for manure incorporation at the 20 on-farm environments can be found in Table 1 . Application date, rate, method, and nutrient content of applied manures are specified for each on-farm environment in Table 2 .

Spring Procedures
The farmer participants were responsible for all corn production decisions including hybrid selection, date of planting, seeding rates, starter fertilizer additions, and weed control program. Standard PSNT protocol was followed, in which soil cores (0–30 cm deep) were taken when corn was between 15 and 30 cm tall, or between the V4 and V6 stages (Magdoff et al., 1984; Bundy et al., 1994b). Like the profile fall NO₃ samples, these samples were analyzed at SPAL using automated colorimetric methods. These results were then discussed with growers before their making final decisions on N-sidedressing rate.

Harvest and Postharvest Procedures
Depending on the farmers' combine size, the central four to six rows in each plot were harvested and weighed, and a sample was assessed for grain quality at the SFAL, using wet chemistry for P, K, Ca, and Mg assays, and near infra-red reflectance spectrophotometry for crude protein. Another series of soil samples was taken for routine fertility (0–15 cm) and postharvest fall NO₃ (0–91 cm) analysis.

Statistical Analyses
Production variables (yield and grain quality) as well as the environmental variable of fall soil NO₃ levels were analyzed as a RCBD, on a combined-environment basis. That is, the effect of sites (soil, drainage, management, etc.) and years (weather, technology, etc.) were combined into one variable referred to as "environment." The resulting mixed model was

In this model, µ = the population mean, = environment, β = block, = treatment, and e = experimental error. Environment and block were treated as random effects to consider the results as valid for an inference zone of all south-central Wisconsin. Treatment () was considered as a fixed effect and tested using the environment by treatment term (). The analysis was made using PROC MIXED of SAS Software Version 9.1.3 (SAS Institute, 2004). Best linear unbiased predictors (BLUP's) were used to evaluate the effect of M vs. FC treatments in individual environments (Littell et al., 2006).

Changes in STP and STK were analyzed using a repeated measures design, with PROC MIXED of SAS Software Version 9.1.3 (SAS Institute, 2004). The compound symmetric covariance structure (TYPE = CS), which assumes equal variance and a correlation between sampling times, was used in this analysis to account for natural temporal correlation.

Farmer–Researcher Interaction
Participating farmers were visited or contacted by phone several times during each cropping season and received written annual update reports from the research team. During the winter of 2007 group meetings were organized at three of the cooperating dairy farms where an overview of the results was presented to the farmer-participants, extension personnel, and agriculture consultants. One year after those meetings, a follow-up telephone interview was conducted. Of the nine grain farmers who participated in this study, six agreed to participate in a follow-up survey. The survey was conducted to assess their continuing cultural practices regarding the use of manure.

	RESULTS AND DISCUSSION

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
Manure Analyses
Results from the manure analyses confirm farmers' concerns about the variability of dairy manure as a nutrient source. In the case of dairy slurry, while the average N content from across all environments was relatively close to its "book value," the standard deviation for the 17 environments was 0.57, 0.25, and 0.41 kg m^–3 for N, P₂O₅, and K₂O, respectively. Solid manure, used at three sites, was particularly variable in K₂O, for which the standard deviation was 4.09 kg Mg^–1. This heterogeneity among dairies is typical for manure analyses (Davis et al., 2002; Peters et al., 2003) and is most likely due to differences in animal feeding and manure management. Despite this overall variability, when manure samples were compared within a given dairy, nutrient variability markedly decreased. For example the overall, or across-dairy coefficients of variation (CV), for total manure N, P₂O₅, and K₂O were 27, 26, and 22%, respectively, while the average within dairy CV's were only 9% for N, and somewhat higher for P₂O₅, and K₂O (16 and 19%). This trend lends support to the idea that as long as major dairy management changes do not occur, a grain farmer doing regular business with a single dairy farm could estimate with some accuracy the nutrient content of applied manure based on historical manure analyses.

Nitrogen Sidedressing
The results from the PSNT are presented in Fig. 1 . The most striking observation is that the test did not always distinguish between the M and FC treatments, even though total N additions from the manure averaged 336 kg ha^–1. And, although fall N-additions each year were approximately the same, PSNT results were generally highest in 2005. Nearly 90% of M and more than 50% of FC plots tested above the 21 mg kg^–1 threshold- indicating no need for additional N fertilizer. In both 2004 and 2006 however, many sites were below the minimum threshold (10 mg kg^–1) indicating that full rates of N were required. These analyses and the resulting N-fertilization recommendations were discussed with each cooperating farmer. In general, growers felt it was necessary to modify "extreme" PSNT results. On their FC plots, even if PSNT levels indicated no additional N was necessary beyond the already added starter fertilizer (n = 7), an average of 65 kg N ha^–1 was sidedressed. On the M plots, when PSNT readings indicated that no manure N was available and full N rates were required (n = 6), they cut N sidedressing from 180 to about 80 kg ha^–1. As a result, if PSNT recommendations had been followed to the letter in this set of trials, M plots would have received 90 kg N ha^–1 on average and FC plots 100 kg N ha^–1 for a savings of only 10 kg N ha^–1. With the modifications that farmers made, actual fertilizer savings on the M plots averaged 67 kg N ha^–1 over the 20 environments. Not surprisingly, growers had the most confidence in basing their N-sidedressing plan on the nutrient content of the added manure, recent weather, and the crop history of the field. They were less confident of the PSNT recommendations if they deviated markedly from their expectations.

View larger version (33K): [in this window] [in a new window]   Fig. 1. Presidedress soil nitrate test results (mg kg–1). Solid black line designates the level (10 mg kg–1) below which full rates of N fertilizer are recommended by UW Extension for corn. Dotted black line designates the level (21 mg kg–1) above which no further N fertilizer is recommended by UW Extension for corn (Bundy et al. 1994b). Bars represent standard error for comparison between treatments within a field-site. Asterisks indicate significance within a field-site (alpha = 0.05). FC = farmers' check (fertilizer-only), M = manure + supplemental fertilizer.

View larger version (45K): [in this window] [in a new window]   Fig. 2. Corn grain yield at 20 on-farm environments. Bars represent standard error for comparison between treatments within a field-site. Asterisks indicate significance within a field-site (alpha = 0.05). FC = farmers' check (fertilizer-only), M = manure + supplemental fertilizer.

Profile Fall Nitrate
Results from the combined-environment analysis showed that where manure was applied early in the fall, significantly higher NO₃–N levels (P = 0.0232) were present under the M treatment than under the FC treatment in the late fall, the year before corn planting. In addition to being statistically different from the FC treatment, mean profile NO₃–N levels in the M treatment were also notably high (175 vs. 87 kg ha^–1 in the FC treatment).

These results indicate that late summer applications of manure are likely to raise soil NO₃–N levels in the late fall before planting corn. One strategy to prevent this occurrence is the planting of cover crops, especially grass crops such as rye (Secale cereale L.) that can use NO₃ late into the fall (Staver and Brinsfield, 1998; Strock et al., 2004). In a meta-analysis comparing conventional cash crop systems (no-cover crop, with N) to systems using nonleguminous (with N) and leguminous cover crops (no N), Tonitto et al. (2006) showed that while yields did not differ among systems, NO₃–N leaching was reduced 70% by the presence of a winter cover. Winter cover crops can also provide the ancillary benefits of decreasing soil erosion, and thus reducing nutrient movement off-site in sediments.

Post harvest fall NO₃ levels are shown in Fig. 3 . The combined-environment analysis for postharvest soil NO₃ levels resulted in a nonsignificant effect of treatment overall (P = 0.2380), and generally modest levels of profile NO₃. The mean profile NO₃ load in the M treatment was 75 kg NO₃ ha^–1, and 65 kg NO₃ ha^–1 in the FC treatment. However, NO₃ levels were statistically greater under the M treatment in three of the environments.

View larger version (27K): [in this window] [in a new window]   Fig. 3. Postharvest nitrate levels at 19 on-farm environments: total from 0 to 91 cm. Bars represent standard error for comparison between treatments within a field-site. Asterisks indicate significance within a field-site (alpha = 0.05). FC = farmers' check (fertilizer-only), M = manure + supplemental fertilizer.

Follow-Up Interviews with Grain Farmer Cooperators
All the participants found that the manured strips produced good to excellent corn yields, and four of the six producers were continuing to use manure as a major part of their fertility program for corn. The two respondents who were not using manure cited sourcing issues as their primary hindrance and commented that they would like to use manure but are not able to get it with any regularity. All the growers saw spreading on wet soils as a potential problem limiting the use of dairy slurry. They all felt however, that they were able to work with their neighboring dairy producer to minimize this problem. The one predominately no-till farmer in the sample remained reluctant to expand his use of manure due to his remaining concerns about compaction and slurry run-off. He did think however, that using a tanker set up with no-till type injection tines that mimicked a strip-till system would work well. He would then consider planting directly into the injection strips the following spring.

Of the farmers that have continued to use manure, all determine their supplementary fertilizer additions after crediting the applied manure. Manure credits in all of these cases are based on lab test results provided by the dairy farm supplying the manure. None of the farmers were continuing to use the PSNT test.

There were a range of opinions on how to value the manure but all producers did agree that they would be willing to "pay" for the manure. In the three cases where farmers were experimenting with manure spreading contracts, two felt that paying for the trucking costs to haul the manure could possibly work. Another participant is paying his neighbor the cost equivalent of 25 kg (1 bushel) of corn per acre. Two of the producers, who have standing spreading contracts, do not pay for the manure but custom grow corn silage on ground that will receive manure from the nearby dairy farm. The dairy farmer selects a corn variety and planting date and in return the grain farmers sell the silage to the dairy farmer based on any market value (bushels of grain equivalence) between 1 January and 1 September.

	CONCLUSIONS

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
On-farm trials and producers' evaluations indicate that manure is a viable source of crop nutrients in highly productive cash-grain corn systems. Using the PSNT and nutrient crediting to estimate sidedressed fertilizer needs, farmers applied approximately 67 fewer kg N ha^–1 on the manured plots. Still, corn yield and crude protein content in the manured treatment showed modest increases over the nonmanured plots. In addition, fall NO₃ levels following the corn phase were nearly equal in the fertilized and manured plots. Manure applied following small grains however, did result in an accumulation of NO₃ N in the soil by the late fall. We found only mediocre agreement between the N recommendations resulting from nutrient crediting and the PSNT, particularly during the wetter springs of 2004 and 2006. Based on our farmer interviews, producers preferred estimating nutrient availability via manure analysis rather than PSNT, and research results suggest that the variability in nutrients, especially N, from the same dairy is relatively low. Interviews with participating grain farmers indicated that they were positive about the prospect of using dairy slurry, particularly given the current (2008) price of fertilizer. The major factor barring the continued use of manure for two of the six producers interviewed was finding a reliable and nearby manure source.

	ACKNOWLEDGMENTS

 
This research was funded by USDA-ARS Dairy Forage Specific Cooperative Agreement 3655-21630-003-01S. The authors gratefully acknowledge the many technical contributions made by our summer helpers Herika Kummel, Devrah Arndt, and Brandon Helm. We would also like to acknowledge the dairy and grain farmers that collaborated in making this research possible, their insights and suggestions were invaluable.

	NOTES

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher.

	REFERENCES

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSIONS REFERENCES

 

• Andraski, T.W., and L.G. Bundy. 2002. Using the presidedress soil nitrate test and organic nitrogen crediting to improve corn nitrogen recommendations. Agron. J. 94:1411–1418.[Abstract/Free Full Text]
• Association of Official Analytical Chemists. 2008a. Method 978.02. Nitrogen (total) in fertilizers. Available at http://eoma.aoac.org/(accessed 28 Mar. 2008; verified 21 Nov. 2008). AOAC, Gaithersburg, MD.
• Association of Official Analytical Chemists. 2008b. Method 985.01. Metals and other elements in plants. Available at http://eoma.aoac.org/(accessed 28 Mar. 2008; verified 21 Nov. 2008). AOAC, Gaithersburg, MD.
• Barham, B.L., J. Foltz, and U. Aldana. 2005. Expansion, modernization and specialization in the Wisconsin dairy industry. Program on Agricultural Technology Studies. Research Summary, No. 7, March 2005. Available at http://www.pats.wisc.edu (accessed 13 July 2007; verified 21 Nov. 2008). The Univ. of Wisconsin, Madison.
• Beauchamp, E.G. 1986. Availability of nitrogen from three manures to corn in the field. Can. J. Soil Sci. 66:713–720.
• Bundy, L.G., K.A. Kelling, and E.E. Schulte. 1994b. Nutrient management: Practices for Wisconsin corn production and water quality protection. Univ. of Wisconsin Coop. Ext. Rep. A3557. Univ. of Wisconsin, Madison.
• Bundy, L.G., L. Knobeloch, B. Webendorfer, G.W. Jackson, and B.H. Shaw. 1994a. Nitrate in Wisconsin groundwater: Sources and concerns. Univ. of Wisconsin Coop. Ext. Rep. G3054. Univ. of Wisconsin, Madison.
• Bundy, L.G., and S.J. Sturgul. 2001. A phosphorus budget for Wisconsin cropland. J. Soil Water Conserv. 56:243–249.
• Comfort, S.D., P.P. Motavalli, K.A. Kelling, and J.C. Converse. 1987. Soil profile N, P, and K changes from injected liquid dairy manure or broadcast fertilizer. Trans. ASAE 30:1364–1369.[Web of Science]
• Cook, A.R., J.L. Posner, and J.O. Baldock. 2007. Effects of dairy manure and weed management on weed communities in corn on Wisconsin cash-grain farms. Weed Technol. 21:389–395.
• Davis, J.G., K.V. Iversen, and M.F. Vigil. 2002. Nutrient variability in manures: Implications for sampling and regional database creation. J. Soil Water Conserv. 57:473–478.
• Dou, Z., D.T. Galligan, F.D. Allshouse, J.D. Toth, C.F. Ramberg, Jr., and J.D. Ferguson. 2001. Manure sampling for nutrient Analysis: Variability and sampling efficacy. J. Environ. Qual. 30:1432–1437.[Medline]
• Eghball, B., and J.F. Power. 1994. Beef cattle feedlot manure management. J. Soil Water Conserv. 49:113–122.
• Eghball, B., and J.F. Power. 1999. Composted and noncomposted manure application to conventional and no-tillage systems. Corn yield and nitrogen uptake. Agron. J. 91:819–825.
• Eghball, B., B.J. Wienhold, J.E. Gilley, and R.A. Eigenberg. 2002. Mineralization of manure nutrients. J. Soil Water Conserv. 57:470–473.
• Evans, S.D., P.R. Goodrich, R.C. Munter, and R.E. Smith. 1977. Effects of solid and liquid beef manure and liquid hog manure on soil characteristics and on growth, yield, and composition of corn. J. Environ. Qual. 6:361–368.[Abstract/Free Full Text]
• Ginting, D., J.F. Moncrief, S.C. Gupta, and S.D. Evans. 1998. Corn yield, runoff, and sediment losses from manure and tillage systems. J. Environ. Qual. 27:1396–1402.[Abstract/Free Full Text]
• Jokela, W.E. 1992. Nitrogen fertilizer and dairy manure effects on corn yield and soil nitrate. Soil Sci. Soc. Am. J. 56:148–154.[Abstract/Free Full Text]
• Kelling, K.A., L.G. Bundy, S.M. Combs, and J.B. Peters. 1998. Soil test recommendations for field, vegetable, and fruit crops. Univ. of Wisconsin Coop. Ext. Rep. A2809. Univ. of Wisconsin, Madison.
• Kimble, J.M., R.J. Bartlett, J.L. McIntosh, and K.E. Varney. 1972. Fate of nitrate from manure and inorganic nitrogen in a clay soil cropped to continuous corn. J. Environ. Qual. 1:413–415.[Abstract/Free Full Text]
• Klausner, S.D., W.S. Reid, and D.R. Bouldin. 1993. Relationship between late spring soil nitrate concentrations and corn yields in New York. J. Prod. Agric. 6:350–354.
• Lessard, R., P. Rochette, E.G. Gregorich, E. Pattey, and R.L. Desjardins. 1996. Nitrous oxide fluxes from manure-amended soil under maize. J. Environ. Qual. 25:1371–1377.[Abstract/Free Full Text]
• Littell, R.C., G.A. Milliken, W.W. Stroup, R.D. Wolfinger, and O. Schabenberger. 2006. SAS for mixed models, 2nd ed. SAS Inst., Cary, NC.
• Magdoff, F.R., D. Ross, and J. Amadon. 1984. A soil test for nitrogen availability to corn. Soil Sci. Soc. Am. J. 48:1301–1304.[Abstract/Free Full Text]
• Miller, G. 1996. Animal manure utilization in crop nutrient planning. Leopold Center for Sustainable Agriculture, Competitive Grant Progress Rep. 93–10. Vol. 5:30–34. Available at http://www.leopold.iastate.edu/research/grants/1996/1993-10_On-Farm_Mngt_Demo_[_Manure_Nutrient_&_Compost_Mngt_].pdf (accessed 5 Nov. 2005; verified 25 Nov. 2008). Iowa State Univ., Ames.
• Motavalli, P.P., K.A. Kelling, and J.C. Converse. 1989. First-year nutrient availability from injected dairy manure. J. Environ. Qual. 18:180–185.[Abstract/Free Full Text]
• Peters, J., S. Combs, B. Hoskins, J. Jarman, J. Kovar, M. Watson, A. Wolf, and N. Wolf. 2003. Recommended methods of manure analysis. Univ. of Wisconsin Coop. Ext. Publ. A3769, Univ. of Wisconsin, Madison.
• Powell, J.M., Z. Wu, and L.D. Satter. 2001. Dairy diet effects on phosphorus cycles of cropland. J. Soil Water Conserv. 56:22–26.
• Proost, R.T. 1999. Variability of P and K soil test levels on Wisconsin farms. p. 278–282. In K.A. Kelling and J.L. Wedberg (ed.) Proc. of the 1999 Wisconsin Fertilizer, Aglime and Pest Management Conf., Madison, WI. 19–21 Jan. 1999. Univ. of Wisconsin Ext., Madison.
• Randall, G.W., T.K. Iragavarapu, and M.A. Schmitt. 2000. Nutrient losses in subsurface drainage water from dairy manure and urea applied for corn. J. Environ. Qual. 29:1244–1252.[Abstract/Free Full Text]
• Ritter, W.F. 2000. Implications with a phosphorus based land application management strategy. p. 408–416. In J.A. Moore (ed.) Proc. of the Eighth Int. Symp. on Animal, Agricultural and Food Processing Wastes, Des Moines, IA. 9–11 Oct. 2000. ASAE, St. Joseph, MI.
• Roth, G.W., and R.H. Fox. 1990. Soil nitrate accumulations following nitrogen-fertilized corn in Pennsylvania. J. Environ. Qual. 19:243–248.[Abstract/Free Full Text]
• Saam, H., J.M. Powell, D.B. Jackson-Smith, W.L. Bland, and J.L. Posner. 2005. Use of animal density to estimate manure nutrient recycling ability of Wisconsin dairy farms. Agric. Syst. 84:343–357.[CrossRef][Web of Science]
• Safley, L.M., Jr., P.W. Westerman, J.C. Barker, L.D. King, and D.T. Bowman. 1986. Slurry dairy manure as a corn nutrient source. Agric. Wastes 18:123–136.
• Sanford, G.R., J.L. Posner, R.T. Schuler, and J.O. Baldock. 2008. Effect of dairy slurry application on soil compaction and corn (Zea mays L.) yield in southern Wisconsin. Soil Tillage Res. 100:42–53.
• SAS Institute. 2004. SAS 9.1.3 Help and Documentation, 2000–2004. SAS Inst., Cary, NC.
• Sommer, S.G., and J.E. Olesen. 1991. Effects of dry matter content and temperature on ammonia loss from surface-applied cattle slurry. J. Environ. Qual. 20:679–683.[Abstract/Free Full Text]
• Staver, K.W., and R.B. Brinsfield. 1998. Using cereal grain winter cover crops to reduce groundwater nitrate contamination in the mid-Atlantic coastal plain. J. Soil Water Conserv. 53:230–240.
• Strock, J.S., P.M. Porter, and M.P. Russelle. 2004. Cover cropping to reduce nitrate loss through subsurface drainage in the northern U.S. corn belt. J. Environ. Qual. 33:1010–1016.
• Tonitto, C., M.B. David, and L.E. Drinkwater. 2006. Replacing bare fallows with cover crops in fertilizer-intensive cropping systems: A meta-analysis of crop yield and N dynamics. Agric. Ecosyst. Environ. 112:58–72.[CrossRef]
• Turnquist, A., J. Foltz, and C. Roth. 2006. Manure management on Wisconsin farms. Program on Agricultural Technology Studies. Research Summary, No. 15. Univ. of Wisconsin-Madison, Madison.
• USDA-National Agricultural Statistics Service. 2000. Agricultural chemical usage 1999 field crops summary. Available at http://usda.mannlib.cornell.edu/reports/nassr/other/pcu-bb/agch0500.pdf (accessed 15 June 2007; verified 25 Nov. 2008). USDA– NASS, Washington, DC.
• USDA-National Agricultural Statistics Service. 2006a. 2006 Wisconsin agricultural statistics bulletin. Available at http://www.nass.usda.gov/Statistics_by_State/Wisconsin/Publications/Annual_Statistical_Bulletin/index.asp (accessed 17 June 2007; verified 21 Nov. 2008). USDA– NASS, Washington, DC.
• USDA-National Agricultural Statistics Service. 2006b. Agricultural chemical usage 2005 field crops summary. Available at http://usda.mannlib.cornell.edu/usda/nass/AgriChemUsFC//2000s/2006/AgriChemUsFC-05-17-2006.pdf (accessed 17 June 2007; verified 25 Nov. 2008). USDA– NASS, Washington, DC.
• USDA-National Agricultural Statistics Service. 2007. Quick Stats, Wisconsin county level data. Available at http://www.nass.usda.gov/Statistics_by_State/Wisconsin/index.asp (accessed 2 Jan. 2008; verified 21 Nov. 2008). USDA– NASS, Washington, DC.
• USDA-National Agricultural Statistics Service. 2000–2007. Wisconsin annual statistics bulletin. Available at http://www.nass.usda.gov/Statistics_by_State/Wisconsin/Publications/Annual_Statistical_Bulletin/annbull_2007.pdf (verified 21 Nov. 2008). USDA-NASS, Washington, DC.
• USDA-Natural Resources Conservation Service. 2005. Nutrient management atandard 590. Available at http://datcp.state.wi.us/arm/agriculture/land-water/conservation/nutrient-mngmt/planning.jsp (accessed 10 Dec 2007; verified 21 Nov. 2008).
• Xie, R., and A.F. MacKenzie. 1986. Urea and manure effects on soil nitrogen and corn dry matter yields. Soil Sci. Soc. Am. J. 50:1504–1509.[Abstract/Free Full Text]
• Zebarth, B.J., J.W. Paul, O. Schmidt, and R. McDougall. 1996. Influence of the time and rate of liquid-manure application on yield and nitrogen utilization of silage corn in south coastal British Columbia. Can. J. Soil Sci. 76:153–164.

This Article Abstract Figures Only Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Sanford, G. R. Articles by Baldock, J. O. Search for Related Content PubMed Articles by Sanford, G. R. Articles by Baldock, J. O. Agricola Articles by Sanford, G. R. Articles by Baldock, J. O. Related Collections Sustainable Agriculture Crop Rotation Systems Best Management Practices Maize Agricultural Systems Crop Systems Nutrient Management Animal Waste