BioCycle September 2007, Vol. 48, No. 9, p. 27
Cornell University study on manure-based compost shows its effect on turf quality, organic matter content, nitrogen, phosphorus, water infiltration and nutrient availability over three-year period.
Mary Schwarz, Jean Bonhotal, Ellen Harrison, Joann Gruttadaurio and A. Martin Petrovic

WEB EXTRA
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A THREE-YEAR project conducted by the Cornell Waste Management Institute and the Department of Horticulture at Cornell University examined effects on soil and grass of topdressing manure-based composts on established turf fields. Funded by the New York State Energy Research and Development Authority and the Cornell Agricultural Experiment Station, this research explored markets for manure-based compost.
Turfgrass conditions on athletic fields are not only an aesthetic concern, but can have an effect on playability. Athletic fields are prone to compaction due to heavy traffic, use of fields when wet, and weight of vehicles used on the fields. Wet and/or hard surfaces can cause injury to the turf and the players. Compaction restricts rooting depth, reducing the uptake of water and nutrients by plants, which can lead to poor growth and loss of turf cover. Addition of organic matter to soil promotes aggregation of soil particles, increasing porosity and reducing bulk density to make a less compact soil.
An article in the July 2007 issue of BioCycle (p. 55) reported on our research findings regarding use of manure-based compost in landscaping on highly compacted soils. This article focuses on our research findings related to turfgrass.
Field research was conducted at four sites in New York State (NYS) from September 2003 through July 2006. At each site, there were six treatments in a randomized complete block design. Composts were applied five times. The composts used were analyzed prior to application for both pathogen levels (fecal coliforms and Salmonella) and compost quality parameters. Soil samples were taken for analysis of chemical and physical properties at the beginning and four times throughout the study. Turf quality was rated monthly during the growing season by trained professionals. Water infiltration rates were determined at the beginning and end of the study.
Two sites used in this study were located in western New York, and two in southeastern New York. The sites were very different in their use and management. At Site 1 in western New York, experimental plots were on the far edge of a baseball field in a park. The site was more like a lawn than a sports field in traffic intensity and use. It was mowed weekly at two-inches and did not receive supplemental irrigation, nor was there any weed control. The soil texture is a loam (43 percent sand, 17 percent clay). At Site 2, the experimental plots were on a soccer field used by both schools and the community for about two games per week. The site started out with about 60 percent grass, 30 percent weeds and 10 percent bare spots. It had moderate traffic during the study. The field was mowed at 2 1/2 inches every 10 days and weed control was not used. Soil texture is a very fine sandy loam (61 percent sand, 10 percent clay).
At Site 3 in southeastern New York, experimental plots were on a community recreation field that hosts 25 to 30 baseball games per season and a summer recreation program in July and August. It was mowed weekly at three inches. The soil here is a coarse sandy loam (66 percent sand, 11 percent clay) that was established on rubble and had no more than 2 to 2 1/2 inches of actual soil. At Site 4, experimental plots were on a high school sports field with excessive use and highly compacted soils. It was used for high school football practice and games. It also served as the daily physical education site. The field was mowed twice a week at 2 to 2 1/4 inches. Weed control was used. Soil texture is a sandy loam (68 percent sand, 8 percent clay).
MANURE-BASED COMPOST FROM FOUR SUPPLIERS
Two types of manure-based compost (dairy and poultry) from four different suppliers were used in this project. Table 1 shows the average range of properties of composted dairy and poultry manures used at the four sites for the three years of the study. Data on the quality of 25 manure-based composts in NYS (a previous study conducted by Cornell Waste Management Institute) can be found on the web at http://compost.css.cornell.edu/mlreporthome.htm.
Each field had a 34 by 70 foot area designated for the experiment. There were eighteen 10 by 10 foot plots with a two foot buffer around each for three replicates of six treatments. Each site received five applications of compost. Because composts varied in moisture content and were applied on a volume basis, the dry weight (Table 2) and thus the quantity of nutrients, organic matter and other constituents added varied. Treatments started in September of 2003 and continued in June and September of 2004 and 2005. The treatments were: 1/4 inch layer of poultry manure compost; 1/2 inch layer of poultry manure compost; 1/4 inch layer of dairy manure compost; 1/2 inch layer of dairy manure compost; Fertilized control (no compost); Unfertilized control (no compost).
All plots, except the unfertilized control, received nitrogen fertilizer (no phosphorus) at the rate of 1 lb/1,000 sq. ft. At Site 4, however, after September 2003, all plots, including the “unfertilized” control, received fertilizer.
Prior to application of compost, soil samples were taken for chemical and physical analysis. The plots were then core aerated. Compost was weighed and applied on a volume basis (two bushel baskets per plot for the 1/4 inch rate and four for the 1/2 inch rate) and raked into an even layer on the plots. The plots were then core aerated a second time to allow the compost to mix with the soil. Unfertilized control plots were then covered with tarps and fertilizer was applied to the remaining plots. Water infiltration rates were determined at the beginning of the study in September 2003 and at the end in June 2006. Individual plots at all sites were rated monthly during the growing season for percent grass, weeds and bare spots and overall turfgrass quality rating using the National Turfgrass Evaluation Program (NTEP) method.
One very important lesson learned from this project was that the properties of the composts can have an effect on the suitability of that compost for use on turf. For ease of application and transportation, moisture content is important. If it is too wet it will clump, and if it is too dry it may be dusty. Particle size is also important. Large pieces such as wood chips present a challenge to application and can also remain on the lawn surface and smother the turf. A maximum particle size of 3/8 inch is recommended. High conductivity (or soluble salts) can indicate that the compost is not fully mature and may “burn” the grass leaving voids that allow weed encroachment. Immature composts may also have an ammonia odor causing problems with players and neighbors.
ORGANIC MATTER, SOIL pH
In this study, use of manure-based composts on turfgrass improved soil organic matter content, increased the pH of acidic soils closer to neutral, and decreased bulk density thus reducing compaction. For turf, soil organic matter values between 7 and 10 percent are considered acceptable. Soil organic matter levels increased significantly over time with all compost types and application rates at all sites, except Site 1, where 1/4 inch dairy compost did not cause a significant increase in organic matter over the course of the study. Compost application at Sites 2 and 3, especially poultry compost, brought the soil organic matter up from approximately five percent to between eight and 16 percent, greatly improving the organic matter content at these sites.
An improvement in the physical characteristics of the soils would be expected due to the increase in organic matter that resulted from the addition of compost; however, results were not uniform. Bulk density of the soils at all sites decreased over the course of the study on all plots due to the core aeration performed as part of the experiment. In addition, bulk density at the end of the study was significantly lower in one or more compost treated plots in comparison to the controls at two of the sites. At Site 1, the 1/2 inch dairy treated plots had significantly lower bulk density than no fertilizer, no compost plots. At Site 2, all of the compost treated plots except 1/4 inch dairy had significantly lower bulk density than the no compost plots. At Sites 3 and 4, no significant differences were noted after three years of compost application in the bulk density of any of the plots.
Soil pH has an effect on the availability of soil nutrients. Most minerals and nutrients are more soluble or available in acid soils than in neutral or slightly alkaline soils. A pH range of approximately six to seven promotes the most readily available plant nutrients. Compost application did not have an effect at the western New York sites (1 and 2) where the pH averaged over all plots started at 7.4 and ended at about 7.6. At Site 3 where initial soil was acid, application of poultry compost over three years did significantly increase the pH from 6.1 to 7.2 for the 1/4 inch treatment plots and from 5.0 to 7.3 for the 1/2 inch treatment plots. The addition of 1/2 inch dairy compost at Site 3 increased the pH from 5.9 to 7.0. At Site 4, all of the plots, including the control plots, showed an increase in pH over the course of the study from just above six to around seven.
Application of manure-based composts increased available soil phosphorus (P) to levels that may cause concern about runoff or leaching losses of P. Levels of 4.5 mg/kg P are considered to be high and levels approaching 50 mg/kg may become an environmental issue as they are more prone to discharge P to the environment in water runoff. Soil phosphorus, which started high at Sites 3 and 4 and was optimum at Sites 1 and 2, increased significantly over time at all four sites on plots receiving compost. There was an immediate effect on soil P levels from the poultry compost, but it took longer to see an effect from the dairy compost. By the end of three years, all compost treated plots had significantly greater soil P levels than non-compost treated plots at Sites 1, 2 and 3. At Site 4 though, as P levels increased in the non-compost treated plots as well, only the 1/2 inch compost levels (both poultry and dairy) had greater soil P.
INFILTRATION RATES AND TURFGRASS QUALITY
The infiltration rate of a soil is the rate at which water soaks into it, measured as cm of water soaking in per hour. If the infiltration rate is very low, say less than 0.5 cm per hour, even very gentle rain falling on moist medium will cause surface ponding or runoff of water. Under such conditions, surfaces of playing fields will remain mushy for days after rain, allowing play to cause much damage to the turf. Infiltration rate is a useful indicator of aeration in the soil. Good aeration is probable if the infiltration rate is greater than 2 cm/h. Poor turf growth can be traced to poor aeration of the root zone. The approximate infiltration rate of loam soils is between 0.5 and 2.0 cm/hour depending on type of loam. Initial infiltration rates at all sites were within this range. At Site 1, both poultry treated plots and at Site 2, the 1/2 inch poultry plots had significantly higher infiltration rates than the control plots at the end of the study. There were no differences between plots at the end of three years at Sites 3 and 4.
Over the three years, at Site 2, compost additions improved turfgrass quality. At all sites, compost additions improved grass cover and reduced weeds in the short term, but these changes did not persist into the next season. In addition, many of the managers at the sites reported earlier spring green-up on the compost-treated plots, possibly related to the addition of iron. However, at some sites high salt levels and immature composts had detrimental effects such as burning of the grass that resulted in leaving voids that resulted in exacerbation of weed problems. On sites where fields were poorly constructed and where field-use was very high, compost additions could not overcome these limitations and did not result in significant improvements in turf quality.
The authors are members of the Cornell Waste Management Institute and Department of Horticulture at Cornell University in Ithaca, New York. For a complete report go to http://cwmi.css.cornell.edu/turf.htm.

WEB EXTRA
Tables prepared by the authors with additional research findings,including: Beginning and ending soil organic matter levels; Average soil bulk density, by plot treatment; and Beginning and ending soil P levels. Click here to view the pdf of the tables.