Concerns about sustainability of crop production systems have led to the idea that agronomists and soil scientists need devote attention to the effects of crop cultural practices on soil quality or, as some prefer to call it, soil health. The purpose of this project is to observe how fertilizers of differing compositions influence select measures of soil quality and how these measures relate to turf quality.

METHODS

The study is being conducted on a stand of "Providence" creeping bentgrass established on Batavia silt loam, soil at the O.J. Noer Turfgrass Research and Education Facility near Verona, Wisconsin. Each entity electing to participate in the study pays $500/year/fertilizer tested to help defray the project costs.

The bentgrass on the experimental site is being maintained under fairway conditions. Mowing is at ½-inch height three times per week with clippings removed. The turf is irrigated to prevent moisture stress. Snow mold fungicides are applied on a preventive basis. Other fungicides are used on a curative basis. Two Daconil applications for dollar spot were required in 1996.

Twelve fertilizer treatments are included in the trial. These range from purely synthetic Country Club 18-4-10 to purely organic N products (Table 1). The standardized N rate is 3.0 lb/M split into monthly applications of 0.5 lb N/M. Due to delays in obtaining some of the fertilizers, the first application in 1996 was made on June 15 and the N total for the year was 2.5 lb/M.

Soil quality parameters currently scheduled for measurement are density, porosity, infiltration rate, routine tests for pH, organic matter, P and K, and biological activity. Measures of soil density, porosity infiltration rate and earthworm populations were not completed in 1996 due to the disruptive influences of core aeration of the entire fairway research area. Samples were taken for measurement of microbe respirtory activity prior to treatment application and again on August 8 and Septembers 17. Enzyme analyses are being contemplated for 1997.

The bentgrass quality parameters measured included weekly color/quality ratings, clipping weights on two dates, clipping analyses, root weights and thatch levels. Measure ment of turf density will be added to this list in 1997.

RESULTS

Bentgrass color ratings averaged by month and for the entire season are presented in Table 2. For July, Country Club 18-4-10 provided lowest color ratings, although not significantly less than nine of the other 11 fertilizers. The Carbo-Aid treatment gave the best color and out-performed eight of the other fertilizers.

In August, the Spring Valley 21-3-12 also performed somewhat poorly in September, even though this was the month of highest color ratings. In contrast, Spring Valley 12-2-12 gave excellent color, though not significantly better than 10 of the other fertilizers. In October, the monthly average color ratings ranged from 7.18 to 7.36, but none of the treatment differences were significant.

For the season as a whole, the Carbo-Aid gave better bentgrass color than eight other fertilizers in the trial (Table 2). Fertilizer treatments with season average color rating above 7.8 included EXP 6200, Spring Valley 12-1-12, Carbo-Aid, and Natural Science 12-0-0. Those with average color ratings of less than 7.7 were Spring Valley 21-3-12 and Country Club 18-4-10.

Standard deviations of the color ratings for the season (Table 2) provide a convenient rating of the treatments for uniformity of the bentgrass color over time. The fertilizers providing the most color uniformity were EXP 6200, EXP 1011, Spring Valley 12-1-12 and Natural Products Research 12-3-10. The greatest variations in bentgrass color arose from application of EXP 7170, Creekwood 4-5-3, Natural Science 12-0-0, and Country Club 18-4-10.

Clippings collected on July 11 and-October 14 were analyzed for their N concentrations. Not enough tissue remained from each date for total nutrient analysis. Therefore, clippings from both dates were combined. To be consistent, tissue N concentrations were averaged over the two dates.

Tissue N concentrations ranged from a low of 3.53% for the Spring Valley 21-3-12 and Creekwood 4-5-3 treatments to a high of 3.90% for the Carbo-Aid (Table 3). Not surprisingly these contrasts correspond well with the color ratings discussed earlier. Clipping N for the Carbo-Aid treatment was significantly higher than for all but the EXP 1628 treatment.

All clipping P concentrations (Table 3) were well in excess of the satisfactory level ;0f 0.35%. Even though the amounts of P being applied range from 0 to 1.6 lb/M (Table 1), the only significant clipping P differences were in the contrasts of the Country Club 18-4-10 with Carbo-Aid, NPR 12-3-10, and Creekwood 4-5-3. These observations are consistent with the fact that the soil on the experimental site is high in phosphorus.

| Results Continued | Summary |

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