Evaluation of Quality at Pioneer Farm and Suitability for End-Use By: Steve, Advisor Dr. Chris Baxter As livestock operations continue to grow farms are generating more manure. This excess manure is becoming problematic in Wisconsin and the Midwest as nutrient levels in the soil are rising. Excess nutrients, particularly Nitrogen and Phosphorus, result in elevated levels in surface and ground water supplies, resulting in algal growth in fresh water ecosystems and/or contamination of drinking water supplies. Furthermore, manure contains weed seeds that can remain viable in the soil for up to 20 years, and considerable amounts of herbicides are required to control their growth. One way to curb this dilemma is to compost. In this study a thorough evaluation of the feedstocks and compost of dairy, swine, and cattle pack manure was performed at Pioneer Farm. Each was subjected to and analyzed on the following parameters: moisture content, bulk density, viable weed seed content, germination rates, total Carbon, Ammonium Nitrogen, Nitrogen, Potassium, and Phosphorus content. The results showed that composting reduces the mass of the manure, generates significant heat which destroys weed seeds and potentially reduces the need for herbicides, provides the soil with a more stable source of organic matter, which leads to greater stability of soil aggregates, greater water infiltration and potentially lower runoff volumes. Introduction As livestock operations continue to grow and get larger, farms are generating more manure. This excess amount of manure often results in high nutrient levels in the soil, and this is beginning to be a chronic problem in many agricultural areas in Wisconsin and throughout the Midwest. Excess nutrients, particularly nitrogen (N) and phosphorus (P) can result in elevated levels in surface and ground water supplies, resulting in excess algal growth in fresh water ecosystems and/or contamination of drinking water supplies. Furthermore, fresh manure can transfer viable weed seeds. These weed seeds can remain viable in the soil for up to 20 years, and can be very expensive for farmers to suppress and kill. Each year the U.S. uses nearly 220 million Kilograms of herbicides, over half of which are used in Midwestern States. ing has been shown to be an effective method for reducing or eliminating the amount of viable weed seeds in manure, thereby potentially reducing the need for herbicides. The Big M, Vol III, 2007 62
Europe is a world leader in compost and they place ample attention on the viability of weed seeds in their compost. In fact, four countries: Holland, Germany, Austria, and the United Kingdom all regulate the amount of viable weed seeds in certified compost. Holland and Germany has a limit of 2 weeds/ liter, and the United Kingdom allows no more than 5 weeds per liter of compost. Currently there are no U.S. standards for viable weed seeds in certified organic compost. However, because composted manure provides the possibility of reducing the amount of herbicide usage, characterization of viable weed seed content remains an important parameter, and could potentially make composting more attractive to farmers. If high-quality compost can be produced, the farmer stands to benefit in the following ways. ing in and of itself will reduce the mass of the manure, making it easier and more efficient to spread on a field. The composting process also generates significant heat which destroys weed seeds. ed manure provides the soil with a more stable source of organic matter, leading to greater stability of soil aggregates, greater water infiltration and potentially lower runoff volumes. ing also gives farmers more flexibility in manure management. Farmers will have the option of converting the manure to a high quality and pure compost that can either be land applied or marketed and sold off-farm. quality is defined by multiple parameters according to its end-use. For example, compost that is to be used for greenhouse potting mixes must meet more stringent standards for salt content and maturity than compost that is used as a natural fertilizer in field crop production systems. Currently in the U.S., compost quality standards are defined by both public and private organizations. The U.S. ing Council s Seal of Testing Assurance (STA) program, and Woods-End Research Laboratory (WERL) compost quality standards are the most commonly used in the U.S. Both of these standards evaluate multiple parameters to determine if compost The Big M, Vol III, 2007 63
meets quality criteria for a specific end use. Among the parameters evaluated are: ph, soluble salts, nutrient content (Nitrogen, Phosphorus, Potassium, Calcium, and Magnesium), moisture content, organic matter content, particle size, maturity (bioassay), stability, and finally trace metals. certification requires that analysis of the above parameters be conducted by certified testing laboratories; however this is an expensive process and should only be conducted after compost production methods are standardized within a given composting operation. Additionally, current composting standards do not require that a specific evaluation of weed seed germination is performed. This potentially useful parameter would be of great interest to organic farmers that are limited in the amounts and types of herbicides that can be used. Pioneer Farm has been using compost as a manure management practice for several years. Currently all of the swine manure and the majority of cattle manure is composted before spreading back onto the fields or transferring it off-farm (Table 1). However, little work has been completed thus far to evaluate compost quality parameters, other than nutrient content. The UW-Platteville Pioneer Farm has not yet standardized its compost production methods and therefore it is unclear whether or not the compost currently being produced will qualify for certification or if further adjustments to compost management are required. This research will also help farm production and research personnel determine if current composting methods are producing compost of high enough quality to be marketed for a specific end-use such as organic crop production. UW-Platteville stands to benefit greatly form this research. A thorough evaluation of compost quality will determine if current composting methods are adequate or if adjustments are necessary. Producing high-quality compost is essential for the making of a marketable compost The Big M, Vol III, 2007 64
product for various end-uses. If this can be accomplished, the farm will have generated yet another source of income, and will have greatly reduced the problem of excess manure. Therefore, this research project is important for two reasons. First, it has the potential to effect how farmers deal with excess manure by demonstrating the effectiveness of an on-farm composting program. Secondly, it has potential to provide valuable information for farmers interested in starting composting operations on their own farms. Research Objective: The objective of this project was to evaluate the effect of manure feedstocks on compost quality and nutrient value at the UW-Platteville Pioneer Farm. Research Goals: In doing this research we had the goals of answering the following questions. 1.) How do differences in manure feedstocks affect compost quality? 2.) How long does it take raw manure to become a finished compost? 3.) How do nutrient values of finished composts compare to raw feedstocks? Approach: Description of Feedstocks Three types of manure feedstocks were used in this research. The first type of feedstock used was separated dairy solids. The solids were collected from a mechanical liquid: solid separator. Bedding material manure includes oat straw and sawdust. The second type of feedstock was swine pack manure. The swine manure was composed semi-solid swine waist mixed with wood chips and/or oat straw in a 1:1 ratio. The final type of feedstock used was cattle pack manure. This manure was taken from the dairy heifers and was composed of a mixture of corn fodder and oat straw bedding. The Big M, Vol III, 2007 65
Approach: Materials Needed This research required relatively few resources. At Pioneer Farm I had access to the cement composting pad, a bucket loader, and instruments used for measuring bulk density and pile temperature. Most of the analysis was completed by sending samples to the University of Wisconsin Soil and Forage Analysis Lab in Marshfield, WI or using equipment and facilities available on the UWP campus. The University of Wisconsin Soil and Forage Analysis Lab analyzed the feedstocks and compost for Ammonium Nitrogen, total Phosphorus and total Potassium. Total Carbon and total Nitrogen levels were analyzed using the Universities C:N Analyzer. Because there is currently not a testing lab available that evaluates viable weed seed in compost, I conducted this analysis myself. This required the purchase of a three and five gallon plastic pail, 300-µm plastic mesh that was placed in the bottom of the three gallon pail, and plastic trays four inches high, with a cumulative surface area of 4500 cm 2. This test was carried out in the Soil and Crop Science and Reclamation portion of the greenhouse. Approach: ing Monitoring and Management Approximately 5 m 3 (6.5 yd 3 ) of the dairy, swine, and cattle pack manure feedstocks was collected at the Pioneer Farm. All of the collected feedstocks were placed on an uncovered cement pad, and daily temperatures taken. The piles were turned with a bucket loader weekly while temperatures were in the thermophilic stage, between 130-160 F, and more often when temperatures increased above160 F. Pile height was maintained at approximately 1.5-2.0 m (5-6 ft) after each turning. Water was added to the compost piles when necessary to maintain a minimum moisture content of 40%. The compost was considered a finished compost when it reached a Carbon to Nitrogen (C:N) Ratio of 15:1 or lower. During the composting process, weekly samples were collected and analyzed for total Carbon and Nitrogen, moisture content, The Big M, Vol III, 2007 66
and bulk densities using the methods listed in Table 2. At the conclusion of the compost process, the initial feedstocks and final (composted) feedstocks were analyzed using the methods listed in Table 2. All analysis were performed in duplicate. Results: Monitoring Monitoring of compost C:N ratio indicated that there are differences between initial manure C:N ratio and the time needed to reach a C:N ratio below 15:1. Much of the time differences can be attributed to the initial feedstocks of the compost. Figure 1 shows that dairy solids possessed the highest initial C:N ratio (35:1) and took the longest time to reach a finished compost (13 weeks). With an initial C:N ratio of 23:1, the swine pack manure reached a finished compost in 9 weeks. The cattle pack manure had the lowest initial C:N ratio (17:1) and took the least amount of time to reach a finished compost (5 weeks). The low initial C:N ratio of the cattle pack is likely due to the cattle pack having undergone significant decomposition prior to active composting. Results: Total and Ammonium Nitrogen in Raw and ed Manure Using the information in Figures 3 and 4 we were able to determine that total nitrogen concentration in the composts were higher than raw manures for all three types of manure feedstocks. Total nitrogen concentrations of composted dairy solids and swine pack were higher then cattle pack. This most likely occurred because of the higher initial C:N ratios of the raw manure feedstocks and greater conservation of nitrogen during the composting process. Ammonium-N concentration decreased in all composed manures compared to raw manure feedstocks, indicating a conversion of Ammonium-N to organic-n or Nitrate-N during aerobic decomposition. The Big M, Vol III, 2007 67
Results: Total P 2 O 5 and K 2 O in Raw and ed Manure Total P 2 O 5 concentrations increased in all composts compared to raw manure feedstocks due to the immobile nature of phosphorus and dry matter losses during decomposition. Total P 2 O 5 concentration increased by 60, 363, and 141% for the cattle pack, dairy solids, and swine pack respectively. Total K 2 O concentrations also were greater in composts compared to manure feedstocks, but the percentage increases were not as large as those observed in the P 2 O 5 concentration. Total K 2 O concentrations increased 39, 162, and 49% for the cattle pack, dairy solids, and swine pack, respectively. The lesser K 2 O concentration may be attributed to leaching of Potassium from piles during precipitation events. Results: Viable Weed Seeds and Radish Seed Germination in Raw and ed Manure Viable weed seeds in raw manure feedstocks were highest in swine pack and lowest in the cattle pack. The differences in viable weed seeds may have been due to the fact that the swine pack contained newly harvested straw that likely contained a relatively high amount of viable weed seeds. Viable weed seeds decreased in all composted manure compared to raw manure feedstocks, with the greatest decrease (76%) observed in the dairy solids (Figure 5). The percentage of radish seed germination increased in all composts compared to the raw manure feedstocks, with the greatest increase (100%) observed in dairy solids (Figure 6). Results: Value of Raw Manure and ed Manure We were able to determine monetary values for the raw feedstocks and compost. Figure 6 shows the value of compost versus its raw feedstocks. In each case, the compost has a higher value then the manure feedstock. Diary solid manure portrayed the largest value gain (approximately $15/ ton) from feedstock to compost, while the cattle pack manure displayed the least value added (approximately $5/ton). The values are based on total N, P 2 O 5, and K 2 O The Big M, Vol III, 2007 68
concentrations, and nutrient values were based on the current price per pound of N (Urea), P 2 O 5 (Diammonium Phosphate), and K 2 O (Potassium Chloride). Summary and Conclusion Differences in the initial C:N ratio, bulk density, and nutrient concentrations of manure feedstocks were observed from the three types used in this study. The initial C:N ratio of manure feedstocks was highest in dairy solids (35:1) and lowest in cattle pack manure (17:1) The initial nutrient concentrations of manure feedstocks ranged from 10-17 lbs/t for total N, 4-11 lbs/t for P 2 O 5, and 11-25 lbs/t for K 2 0. The time needed to reach a C:N ratio of <15:1 increased with initial C:N ratio, and ranged from 5-13 weeks. While all composts evaluated met compost quality criteria of a low C:N ratio, differences in other quality parameters were evident. Nutrient (total N, P 2 O 5 and K 2 0) concentration increased in all composts compared to raw manure feedstocks, which resulted in a 194% increase in value of dairy solids based on nutrients (Figure 6). Viable weed seed concentration decreased and seed gerninability increased in compost compared to manure feedstocks. Our results support the concept that composting can improve the quality and value of manure as a soil amendment. Of the manure feedstocks evaluated, dairy solids were the most favorable feedstock based on the increase in nutrient value and germinability, and the decrease in weed seedling survival. Further research is needed to determine the effects of manure feedstocks and composting on nutrient availability and soil quality. The Big M, Vol III, 2007 69
References Brinton, William F. COMPOSTING QUALITY STANDARDS & GUIDELINES. December 2000: 1-42p. Online. Internet. 27 January 2006. Available http://compost.css.cornell.edu/brinton.pdf Cooperband, Leslie. The Art and Science of ing: A resource for farmers and compost producers. 29 March 2002: 1-14 p. Online. Internet. 27 January 2006. Available http://www.wastenotorganics.wisc.edu/05composting/publications/index.php Peters, John B. (ed.) Recommended Methods of Manure Analysis. University of Wisconsin Extension Publication A2809 USDA, 2002. Test Methods for the Examination of ing and. ing Council Research and Education Foundation. Raw Manure Type Manure Treatment Treated Manure Type Liquid Dairy Manure Mechanical Solids Separation Liquid Fraction Liquid Effluent Solid Cattle Manure (Dairy and Beef) Solid fraction Windrowing and Turning (Uncovered Soil Pad) Cattle Manure Swine Manure Windrowing and Turning (Covered Cement Pad) Swine Manure Table 1: Current manure / compost management at Pioneer Farm. The Big M, Vol III, 2007 70
Parameter Method Name TMECC Method Number* Moisture Content Total solids and moisture at 70±5ºC 03.09-A Bulk Density Test for bulk density 03.01-A Viable Weed Seed Shield Rinse Method 05.09-A Germination Test Shield Rinse Method 05.09-A Total Carbon Total Nitrogen Ammonium-N Dry Combustion (Elementar variomax CN) Dry Combustion (Elementar variomax CN) Standard Methods of Manure Analysis, UW Extension Publication A3769 J.B. Peters (ed.) Total Phosphorus Standard Methods of Manure Analysis, UW Extension Publication A3769 J.B. Peters (ed.) Total Potassium Standard Methods of Manure Analysis, UW Extension Publication A3769 J.B. Peters (ed.) *Procedures described in Test Methods for the Examination of ing and (2002). Table 2: List of Methods Used In Determining Quality C:N Ratio 40 35 30 25 20 15 10 5 0 Dairy Solids Swine Manure Cattle Pack 0 2 4 6 8 10 12 14 Time (weeks) Figure 1: Total Carbon: Total Nitrogen (C:N) ratio for manure feedstocks during active composting The Big M, Vol III, 2007 71
Total N (lbs/ton) 30 25 20 15 10 5 Manure Feedstock 0 Cattle Pack Dairy Solids Swine Pack Figure 2: Total Nitrogen in raw and composted (C:N Ratio <15:1) manure. NH4-N (lbs/ton) 5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 Manure Feedstock Cattle Pack Dairy Solids Swine Pack Figure 3: Ammonium- Nitrogen in raw and composted (C:N Ratio <15:1) manure. Viable weed seeds/kg 18 16 14 12 10 8 6 4 2 0 Manure Feedstock Cattle Pack Dairy Solids Swine Manure Figure 4: Viable weed seeds in raw and composted (C:N Ratio <15:1) manure. The Big M, Vol III, 2007 72
Seed germination, % 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Manure feedstock Cattle Pack Dairy Solids Swine Manure Figure 5: Radish seed germination (% of potting mix control) in raw and composted (C:N Ratio <15:1) manure. Value $/ton 18 16 14 12 10 8 6 4 2 0 Manure Cattle Pack Dairy Solids Swine Manure Figure 6: Value of raw and composted manure based on total N, P 2 O 5, and K 2 O concentrations The Big M, Vol III, 2007 73