Manure slurry-enriched seeding is a new manure land application process that combines low-disturbance aeration tillage, manure use and the seeding of forage grasses, legumes and cover crops in one efficient operation. This new seeding method was used to improve dry matter yield and increase botanical diversity in pastures and grass hay fields, and to extend the grazing season by seeding late season grazing crops such as forage turnips and forage rape in wheat stubble. The manure slurry seeding process involved mixing seed in the slurry tank and passing the seed-laden slurry through drop tubes to the fractured and loosened soil behind each set of rolling tines. Red clover and orchard grass were inter-seeded in a mature brome grass stand using swine slurry at a rate to supply about 70 lb nitrogen per acre. The slurry seedings were compared to no-till drilling and frost seeding, with and without a chemical burn-down to suppress competition from the following crop.
Manure slurry seeding of orchardgrass and red clover was an effective way to expand the land base for manure application, recycle manure nutrients for crop growth, and increase the botanical diversity of pasture and hay ground. No-till drilling and slurry seeding resulted in more uniform stands of red clover and orchardgrass than frost seeding. Compared to the no aeration, no manure control, the no-till, slurry and frost seeded red clover plots increased yields by 105%, 87% and 43%, respectively. Inter-seeding orchard grass in an existing brome grass stand increased the botanical diversity but did not increase dry matter yield. Slurry seeding pastures lead to a yield increase from the added nitrogen but we did not see a clear increase in botanical diversity, presumably because we did not restrict cattle access after seeding to allow an establishment period. Introducing red clover to the brome grass hay improved forage quality by increasing crude protein (CP) and reducing neutral detergent fiber (NDF). The pre-plant burn-down improved the establishment of orchard grass but did not improve the establishment of red clover.
Forage turnip, forage rape, oats and sorghum-sudan were drilled with 50 lb/ac commercial nitrogen and slurry seeded with swine slurry at a rate to supply 50 lb/ac of readily available N. The dry matter yield of the slurry seeded crops was equal to the drilled crop with 50 lb/ac of commercial N.
Cattle grazing preference following sub-surface deposition of manure slurry was variable. Where the stocking density was low and they had access to excessive forage they avoided the area where slurry had been applied for three grazing cycles, even after significant rainfall. Where the stocking density was greater the cattle preferentially graze desirable species in the area where slurry had been applied and avoid undesirable species, such as tall fescue, in areas where no manure had been applied.
In recent years, interest has grown in the use of managed intensive grazing for beef and dairy cattle. Managed intensive grazing can reduce feed and manure handling costs, increase farm profitability, improve animal health, and help reduce manure nutrient loss to the environment. In the Great Lakes region cattle are often on pasture during the growing season and housed during the winter months. Pasture land is often nutrient deficient because crop nutrients are removed in harvested hay early in the growing season when forage supply exceeds grazing demand. Manure nutrients collected throughout the winter can be used to meet the nutrient needs of hay and pasture crops. Manure nutrients are often not well used because the best time for applying manure conflicts with other farming operations such as harvest or planting. A more complete integration of cropping and nutrient management systems on grass-based dairies offers an opportunity to expand the on-farm land base available for manure spreading, minimize manure transport costs, improve on-farm manure nutrient recycling, and improve forage quality and farm profitability.
Thinning stands are often a problem on a grazing farm, particularly after a dry summer when over grazing occurs. The objective of this project was to develop and evaluate a process whereby forage grass and legume seed was sown in established pasture and hay ground in nutrient rich manure slurry for stand improvement. The seed was mixed with manure slurry in a commercially available tank spreader with by-pass flow from the tank pto-driven pump providing in-tank agitation for seed distribution and uniformity. An AerWay aeration tillage tool with the species-sensitivity distribution (SSD) manure distributor and drop tubes were used to deliver the seed-laden manure slurry to the fractured and loosened ground behind the aeration tines. The overall goal was to develop a process that integrates manure use and nutrient recycling, aeration tillage to alleviate shallow soil compaction, and the seeding of forages and cover crops in one efficient operation.
Grass-based dairy and livestock producers in the Great Lakes region are the intended audience, but the process will benefit producers throughout the North Central states.
Specific objective of this project are to:
•Evaluate changes in the species richness and yield of pasture and hay ground from low-disturbance, slurry-enriched seeding of forages and cover crops,
•Evaluate the effect of slurry seeding on the grazing preference of cattle,
•Develop guidelines for on-farm pasture and grassland enrichment with slurry seeding,
Portions of this work were conducted at cooperating grazing dairies in central Michigan and in the pastures and crop land at Michigan State University (MSU). At MSU, the inter-seeding of red clover or orchard grass in an existing smooth brome grass sod and the subsequent effect on forage yield and botanical diversity was evaluated in large replicated plots (13 ft X 35 ft).
The ten treatments were:
1) slurry seeded orchard grass,
2) no-till orchard grass,
3) frost seeded orchard grass,
4) slurry seeded red clover,
5) no-till red clover,
6) frost seeded red clover,
7) no aeration tillage, no manure slurry (control),
8) aeration tillage,
9) aeration tillage with manure slurry, and
10) surface banded manure.
Because competition from the existing brome grass was likely to limit germination and growth of the seeded orchard grass and red clover, a pre-plant, burn-down split (Paraquat dichloride as Gramoxone Extra; 0.47 lb a.i./gal in 10 gal/acre) was applied to one-half of each block of treatments to suppress competition between the existing vegetation and the new seedlings. The frost seedings were done in early March and the no-till and slurry seeded treatments were done later that year on March 15.
The no-till treatments were sown with a Great Plains no-till drill with coulter openers and trailing semi-pneumatic press wheels. The manure slurry seeding was done with a commercially available slurry tanker (3,000 gal.) equipped with a rear-mounted rolling-tine aerator (12 ft; Aer-Way, Holland Equipment Ltd. Norwich, Ontario, Canada) and a SSD (sub-surface deposition) slurry distribution system. The rolling-tine aerator was ground-driven with sets of four 8-inch tines mounted on a rotating shaft with 7.5 inch spacing between each set of tines. The tines were angled slightly on the shaft to provide lateral movement and loosening of the soil. The angle of the rotating shaft was adjustable in 2.5 increments from 0 to 10 degrees from perpendicular relative to the direction of travel. The 0 gang angle provided little soil disturbance while the 10 gang angle provided the most soil loosening. A 2.5 gang angle was used for slurry seeding. No additional seedbed tillage or soil firming was used.
Dry matter yield was measured with a rotary flail harvester with a cutting height of 3.5 inches. Dried subsamples were ground to pass through a 1mm screen and a portion was used for forage quality analysis. Stand composition prior to harvest was determined by 1) visual rating and 2) hand separation of red clover, orchardgrass, other legume, other grass, and weed components from two pre-harvest subsamples per plot. Visual ratings of introduced species were rated by two trained observers on a scale of 1 to 10 with a rating of 1 being 0-10 % of the treatment area being covered by the introduced species, and a rating of 10 being 91-100% of the stand being introduced species. Separated components were dried and weighed and the fraction of each component was calculated as a percentage of the total weight of each sample collected.
Forage quality was evaluated as crude protein (CP %), acid detergent fiber (ADF %) and neutral detergent fiber (NDF %) and net energy (NE milk Mcal/lb) were determined for samples from harvest one and two each year of the study using near infrared reflectance spectroscopy (NIRS).
At a separate location, forage rape (Barkant var., 6 lb/ac), forage turnip (Pasja var., 6 lb/ac), brown mid-rib sorghum-sudan (Sudex var., 30 lb/ac) and common oats (64 lb/ac) were sown in untilled wheat stubble on a Capac sandy loam soil on 8 August 2005. Two seeding methods were used: 1) conservation tillage with two passes of a combination tillage tool (12 ft Kongskilde Triple-K, 3-inch tillage depth), and 2) slurry seeding with aeration tillage and seed-laden swine slurry (10 gang angle, 6,000 gal/ac). Fifty lb/ac N as urea was applied to the tilled-and-drilled plots before tillage and planting. No commercial N was applied to the slurry-seeded plots. The sudex and oats were harvested on 21 October and the rape and turnip on 27 October 2005.
At the MSU dairy, the impact of low-disturbance slurry injection on the grazing preference of cattle was evaluated in large (12 ft x 100 ft) plots with a manure slurry application rate of 6,000 gallons per acre over two grazing cycles. Two-12 ft strips of swine slurry were applied through the center of the paddock two days before a group of 20 to 30 dairy heifers and dry cows entered the paddock. Cattle grazing preferences were observed for 24 hours (daylight hours). Cattle grazing preferences were also observed at the on-farm locations by the farmer-cooperators, and at the MSU beef pastures by observing where the cattle had grazed after the next grazing cycle.
Inter-seeding Orchard Grass and Red Clover: Visual Rating of Plant Composition
Visual ratings of orchard grass and red clover inter-seeded in the existing brome grass sod were evaluated by two trained observers and rated on a scale of 1 to 10 with a 1 being 0-10 % of the treatment area covered by the introduced species, and a rating of 10 being 91-100% of the stand being introduced species. The most uniform red clover stands were with the no-till (8.5) and slurry seeding (7.2) methods. The orchardgrass ratings ranged from 6.6 with slurry seeding to 8.0 with no-till drilling. No-till drilling and slurry seeding were more effective than frost seeding.
Visual ratings of the percentage of the introduced crop in 2007. Treatments with the same superscript letter within cuttings are not significantly different.
Hand Separation of Forage Components
The red clover, orchardgrass, legumes other than red clover, grass other than orchardgrass and weed components were separated by hand and each component was determined as a percentage of the total dry matter collected. Forage samples were taken in both the chemical burn-down and no burn-down subplots.
Grasses contributed the greatest portion of forage dry matter in the first cutting and red clover contributed the greatest portion in later cuttings when the grasses were not growing as vigorously. Red clover established more quickly than orchard grass. There was little difference in species diversity in the red clover plots due to the pre-plant burn-down. In the first cutting the grass content of the no burn-down plots was significantly greater with frost seeding (81%) than with the no-till (56%) or slurry seeding (53%). In the first cutting of the burn-down plots the grasses ranged from 51% with the no-till seeding to 68% with the frost seeding and there was no significant difference between treatments. The red clover content was significantly greater in the no-till (37%) and slurry seeded (30%) plots than in the frost seeded plots (14%).
The pre-plant burn-down improved the rate of orchardgrass establishment and the quantity of orchardgrass established in the brome grass sod. In the first cutting in the spring after the pre-plant burn-down the orchardgrass content was about 19% of forage dry matter with the frost seeding, 37% with slurry seeding and 62% with no-till seeding. The orchardgrass content in the no-till seeding was significantly greater than the frost seeding, but the no-till seeding and slurry seeding were not significantly different. In the second cutting the no-till orchard grass contributed more forage dry matter (74%) than the slurry seeding (49%), and slurry seeding contributed significantly more than the frost seeding (10.5%).
The pre-plant burn-down improved the establishment of orchard grass but also led to a noticeable increase in weed content. In the first cutting the increase was most noticeable in the plots that were not seeded with red clover or orchardgrass. In the no burn-down plots the weed component ranged from less than one percent to three percent and there was no significant difference between treatments. The same treatments with pre-plant burn-down ranged from about 3% to 13%. The weed component was a greater fraction of forage dry matter in the second cutting when the grasses were not growing as vigorously.
Dry Matter Yield 2006-2007
Total forage dry matter over two growing seasons was significantly greater for no-till (11.23 ton/acre) and slurry seeded (10.27 ton/acre) red clover than the frost seeded red clover (7.87 ton/acre). All red clover treatments yielded significantly greater forage dry matter than the non-red clover treatments. Among the non-red clover treatments, only the slurry seeded orchardgrass (6.63 ton/acre) and the surface applied slurry (6.99 ton/acre) yielded significantly greater forage dry matter than the no aeration, no slurry control (5.49 ton/acre). Compared to the no aeration, no manure control, yields for the no-till, slurry and frost seeded red clover plots increased 105%, 87% and 43%, respectively.
Dry matter yield of brome grass inter-seeded with red clover or orchard grass. Treatments with the same superscript letter within each time increment are not significantly different.
Forage quality was measured at each harvest and analyzed for crude protein (CP, %), acid detergent fiber (ADF, %), neutral detergent fiber (NDF, %) and net energy lactation (NE milk; Mcal/lb DM). Over the 2 year harvest period the CP of the no-till red clover was significantly greater than the other treatments and averaged 3.7 percentage units greater than the untreated control. The CP of the slurry seeded red clover was significantly greater than all treatments other than the slurry seeded orchardgrass and averaged 1.9 percentage units greater than the untreated control. The NDF of the no-till red clover was significantly less than the other treatments and averaged 5.1 percentage treatments less than the untreated control. The no-till red clover tended to have greater NE milk but was generally not significantly different from the control.
Key Observations, Inter-seeding Orchard Grass and Red Clover
• After a late summer slurry seeding of red clover in a brome grass sod, grasses were predominating in the first cutting the following spring, red clover was predominant in later cuttings.
• Slurry seeding and no-till drilling were effective methods for inter-seeding red clover and created a more uniform stand than frost seeding.
• The brome grass with inter-seeded red clover increased dry matter yield about 50% to 100% compared to the no aeration, no slurry control.
• Inter-seeding orchard grass in a brome grass sod increased the botanical diversity but did not increase dry matter yield.
• A pre-plant burn-down treatment improved the establishment of orchard grass but did not improve the establishment of red clover.
• The pre-plant burn-down tended to increase weeds in the forage dry matter.
Late Season Graze: Dry Matter Yield
Forage rape, forage turnip, oats and sudex sorghum-sudan were sown in wheat stubble in early August as a late season crop to extend the grazing season. The crops were sown by slurry seeding with swine manure or by drilling after incorporating 50 lb/ac actual N with two passes of a combination tillage tool to prepare a seedbed. The plant population of the slurry seeded crop was generally 75% to 85% of the drilled crop, but dry matter yields were not significantly different. The sudex sorghum-sudan did not establish well with either seeding method.
Dry matter yield of forages sown in early August to extend the grazing season. Crop species with the same superscript letter are not significantly different by Tukey’s HSD test with p ≤ 0.05.
Late Season Graze: Forage Quality
The CP of the slurry seeded crops tended to be higher and the NDF lower than the drilled crops with 50 lb/ac N, but those differences were not statistically significant. A second sample and quality measurement was analyzed in mid-December. Crude protein content generally decreased about 2% and NDF increased 3 to 4% compared to the earlier harvest.
Forage quality of four forages seeded in early August and harvested in late October. Individual quality parameter superscripts with the same letter are not significantly different by Tukey’s HSD procedure with p ≤ 0.05.
On-farm pasture trials
A goal of the on-farm slurry seeding trials was to evaluate the potential of slurry seeding under a range of soil and management conditions and a range of manure types and consistencies. We had excellent success establishing orchard grass and red clover in a brome grass hay crop, and we had vigorous stands of festulolium, ladino clover, annual rye and cereal rye seeded with swine and dairy slurry in wheat stubble. Pasture ground is a greater challenge because manure nitrogen causes rapid growth of the existing forage that can suppress seed germination and emergence.
At the Anderson farm we seeded alternating strips of festulolium, ladino clover, oil seed radish and a manure/no crop control in a 17 acre pasture, and in a separate location the following year in the same field. We also slurry seeded strips in a nearby field under a center pivot irrigation system. The manure slurry ranged from 9% to 10.8% dry matter and was not highly flowable. At the Straub farm we slurry seeded oil seed radish in a winter sacrifice lot, and alternating strips of festulolium, ladino clover and oil seed radish in a portion of a grazing paddock used by the dairy herd. The liquid manure used at the Straub farm was from a nearby swine farm and was less than 2% dry matter.
The slurry seedings were made in late August after the cattle had grazed and rotated to a new pasture. At the Anderson farm the slurry was viscous and did not infiltrate well. The cattle were allowed to graze the pasture in the next grazing cycle, about 30 days later. There was a clear yield increase in the treated area. We did not see significant increases in the introduced species either year. Irrigation caused vigorous growth of the existing vegetation and greatly limited the emergence of the introduced species.
At the Straub farm, the manure N increased the weed growth in the sacrifice lot and the seeded forage was not able to compete with the existing vegetation for available light. Consequently, the introduced forages did not establish well. In the grazing paddock area the conditions were dry after seeding and slow to establish. Cattle grazed the paddock in the next grazing cycle and the following spring. We did not see a significant increase in botanical diversity in the pasture in the following year.
Cattle Grazing Preference
In slurry seeding the liquid manure is placed through drop tubes in narrow bands near the soil surface, over tilled aeration slots. In general, about 40% of the surface is in contact with the banded manure slurry. At the MSU dairy, dilute (1% DM) swine slurry was applied in early July in a 24 ft swath across the center of two paddocks grazed by heifers and young stock. The stocking density was low and the cattle were able to freely choose between grazing in the manured and non-manured areas. The cattle were observed during daylight hours during the next two grazing cycles (approx. 30 and 60 days after slurry application). In each grazing cycle the cattle neither grazed nor rested in the manured treated area, a clear indication that they preferred to not graze in that area.
At the Anderson and Straub farms the stocking density was higher and the cattle were less able to graze preferentially. After the slurry application we noted that the cattle grazed desirable species such as orchard grass in manured areas and avoided less desirable species such as tall fescue in areas where no manure had been applied. So in general, cattle preferred to avoid areas were manure had been applied but often favored high quality forage in manured ground to poor quality forage in areas where no manure had been applied.
Our most consistent results with slurry seeding have been in hay ground and in wheat stubble or other areas where there is little competition from an existing crop for available light and moisture. Adding nitrogen to an existing crop causes vigorous growth that can limit seed germination and emergence. Based on the results of our work we have developed the following recommendation for slurry seeding pasture ground:
• Thinning and nutrient deficient stands are most suitable for slurry seeding. Minimize competition from the existing forage by grazing the pasture aggressively in mid-summer and slurry seeding in mid-August when cool season grasses are not growing vigorously.
• Limit the manure slurry application to apply no more than 100 lb/acre N to avoid aggressive re-growth and competition for available light between the existing forage and new seedlings.
• Do not traffic or graze the slurry seeded area in the fall. Allow time in the fall for seedling establishment. Cattle will not try to avoid the slurry seeded area in the spring.
• If possible, take the first cutting as hay the next spring. This will limit damage to the new seedlings from foot traffic.
• Dilute liquid slurry that is highly flowable is most suitable for slurry seeding because it quickly infiltrates and carries the seed to protected micro-sites. Slurries with high dry matter may be less suitable.
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Manure slurry seeding is a new land application process and a feasible alternative for seeding cover crops in untilled crop land, establishing late season grazing crops such as forage rape, forage turnips and annual ryegrass in small grain stubble, and for improving the yield and botanical diversity of hay and pasture ground. This new process combines low-disturbance aeration tillage, manure application and the seeding of cover crops in one efficient operation. Low- disturbance aeration tillage creates an absorptive surface in untilled ground that inhibits overland flow by fracturing the soil, increasing surface roughness, improving infiltration, and conserving crop residues. The nutrient-rich, seed-laden slurry quickly infiltrates the soil matrix, thereby minimizing volatile nitrogen losses. The loose, absorptive soil surface prevents soil erosion and phosphorus runoff. This resource efficient process provides a practical option to enrich nutrient deficient pasture and hay ground, and a way to sustain a dense vegetative cover without the need to plow and reseed. It will also protect soil and water quality by reducing sediment and nutrient runoff. The process will increase the species richness, yield and quality of hay and grassland and provide a more complete, balanced feed.
Because this new process requires commercially available but specific manure application equipment and the process is new, the on-the-ground impact has been limited. However, it has:
• Increased farmer awareness of the options for recycling manure nutrients and their options for renovation pasture and hay ground.
• Increased interest in the use of cover crops on corn silage ground by providing a slurry application method that effectively incorporates seeding and manure application in one efficient pass across the field. Combining the seeding and manure application process will provide a vegetative cover to stabilize the soil and reduce runoff of nutrients and contaminants.
• Provided a new and efficient process for establishing mid-summer and late-season forages in untilled ground. Such a management practice can provide a more steady forage supply, reduce the “mid-summer slump” associated with grazing systems and improve the efficiency of manure nutrient cycling.
• Offered an option for the start-up or enhancement of new rural enterprises dedicated to sustainable and environmentally sensitive custom manure application. Not every producer needs to own the equipment needed for slurry seeding. The proposed slurry seeding process adds value to manure in a way that is environmentally sensitive, provides real labor efficiency, and encourages the use of manure nutrients on non-traditional crop land and land that is underutilized for manure use.
The economic benefits of slurry seeding are linked to nutrient cycling, labor efficiency and increased crop production. A grazing farm in the Great Lakes Region requires six months of feed and manure storage. When the animals are housed in the winter months they will produce about 440,000 gallons of manure with a likely nutrient analysis of 24 lb N, 12 lb P205 and 24 lbK20 per 1000 gal. with a nutrient value of $17.85/1000 gal based on current prices (0.65 N, 0.90 P, and 0.75 K). The nutrient value of the stored manure is $78,540. Equipment ownership and operating costs for a 150 pto-hp tractor and 3000 gal slurry tank with low-disturbance injectors is and hauling to fields within 1 mile of the farm is 1.8 cents per gallon, and pumping and agitation costs are about 1 cent per gallon. Fifty hours of hauling time will be needed to haul and apply with an hourly cost of $256/hour, about $65/acre. The nutrient needs of grass-legume mixture are with typical yields are about 80 lb/ac N (with 80 lb credit from a good legume stand), 60 lb/ac P and 240 lb/ac K). If the nutrients are applied to meet the N, P and K needs of the hay and pasture land, plus 50 acres of corn and corn silage ground, slurry seeding and efficient nutrient management with cover the manure hauling, pumping and land application and provide a $7,500 reduction in the purchase of commercial fertilizer. Additionally, if the slurry seeding increases the yield of good quality grass/legume hay by an average of 1 ton per acre on 75 acres of hay ground the potential income from hay sales at $150 per ton is $10,500. The potential benefit above machinery and operating costs for a 75-cow herd in reduction of commercial fertilizer purchase and hay sales is about $240/cow-yr.
There has been considerable interest in slurry seeding for cover crop and pasture improvement but the adoption has been slow because the process requires commercially available but specialized equipment for low-disturbance application of the slurry-laden seed. In addition, the process is new and farmers are often cautious in adopting new technology. Because tank spreaders and related equipment are major equipment purchases and farm mangers typically replace such equipment on a 5 to 10 year cycle, the adoption process is somewhat slow. In presentations in Indiana and Ohio livestock producers with the equipment have expressed interest and indicated an intention to try this new process. Our intention is to demonstrate the new process to custom manure applicators as a way to add value to their custom hauling operations and provide environmentally sensitive manure land application.
Educational & Outreach Activities
Several publications and outreach activities have resulted from this work.
Harrigan, T.M., R. Leep and T. Dietz. (In review). Pasture and Grassland Restoration with Manure Slurry-Enriched Micro-Site Seeding of Orchardgrass and Red Clover (Crop Management).
Harrigan, T.M. 2009. One Pass Operation: Slurry Seeding of Forages and Cover Crops. Presentation at: Extension Professional Development: Water Quality for Small- and Medium-sized Livestock Farms. In cooperation with the 2009 Upper Midwest Manure Handling Expo, July 22, Clive IA
Harrigan, T.M., R. Leep and T. Dietz. 2009. Improving Pasture and Hay Ground with Manure Slurry-Enriched Seeding. ASABE Paper No. 096719. St. Joseph, MI: ASABE June 21-24, Reno, NV
Harrigan, T.M. 2009. Slurry Seeding Forages and Cover Crops for Soil and Water Quality. Northern Indiana Soil Management Seminar. March 5, Goshen, IN
Harrigan, T.M. 2009. Slurry Seeding of Forage and Cover Crops for Soil and Water Quality. Annual meeting of the Midwest Cover Crops Council. February 9, Windsor, Ontario, Canada.
Harrigan, T.M. 2009. Trends in Liquid Manure Land Application. Southwest Ontario Ag. Conference, January 5-6, Ridgetown College, Ontario, Canada.
Harrigan, T.M, R. Leep and T. Dietz. 2008. Seeding Pastures and Cover Crops using Liquid Manure. Ohio Conservation Tillage Conference, Ada, OH. Feb 21-22, Ohio Northern University.
Harrigan, T.M., R. Leep and T. Dietz. 2008. Seeding Pastures with Manure Slurry. Forage Technology Conference, Kellogg Center, Michigan State University. March 6.
Harrigan, T.M. and D.R. Mutch. 2008. Slurry Seeding of Cover Crops for Soil and Water Quality Protection. Inservice training, NRCS. June 4, Kellogg Biological Station, Gull Lake, MI
Harrigan, T.M. 2008. Slurry Seeding. Field demonstration in collaboration with the Ohio Great Lakes Manure Handling Expo. July 9, London, OH.
Harrigan, T.M. and R. Leep. 2007. Linking Manure Land Application and Pasture Productivity. Meeting of the Michigan Hay and Forage Council. St. Johns, MI January 9.
Harrigan, T.M. 2007. Improving Pasture and Hay-Ground with Low-Disturbance, Manure Slurry-Enriched Seeding. Field day in collaboration with Michigan Ag Expo farm show. July 18, Michigan State University.
Harrigan, T.M. 2006. Slurry Seeding. Field demonstration in collaboration with the Michigan Manure Handling Expo. July 28.
Areas needing additional study
Because manure slurry seeding is a novel and new process there are many questions about the on-farm benefits and practical applications. There is a need to better understand:
• The effects of slurry seeding on nutrient cycling, specifically nutrient uptake and release in the following cropping program.
• The range of manure types and consistencies that is compatible with manure slurry seeding. Our experience is that dilute, flowable slurries provide the best results. There is a need for a broader spectrum of producer guidelines.
• Seeds vary in their tolerance to manure induced salinity. We know that crimson clover does not establish well with slurry seeding although most other cover crops and forages have established well with the dairy and swine slurries we have used. There is a need to gain a wider understanding of high EC manure on seed germination and emergence in this new system.
• There is a need to evaluate the long-term benefits of slurry seeding soil and water quality.