LOrganic-8, a liquid turf fertilizer derived from leather scraps, was applied to creeping bentgrass and Kentucky bluegrass. The purposes were to document bentgrass color response to the Lorganic-8 when applied at different N rates and frequencies and to determine the longevity of Kentucky bluegrass color response to different rates of the fertilizer.

EXPERIMENTAL METHODS

Lorganic-8 was applied to a 4-year-old stand of "Pencross" creeping bentgrass established on silt loam soil and mowed at ½-inch and irrigated to prevent moisture stress. Nitrogen rates/frequencies of application were 0.1 lb/wk, 0.2 1b/2 wk, 0.3 1b13 wk, and 0.4 lb/4 wk. The bentgrass color was rated weekly from May 30 to September 29.

LOrganic-8 was applied at four N rates to a stand of a four-cultivar blend of Kentucky bluegrass mowed at 2.5 inches and irrigated only to prevent severe moisture stress. The N rates were 0, 0.5, 1.0, and 1.5 lb/M. When weekly color ratings dropped to the unsatisfactory value of 7.0, repeat applications were made on July 27.

In both experiments, the treatments were replicated four times in a randomized complete block design.

RESULTS

All of the N treatments maintained satisfactory color in the bentgrass throughout the duration of the study. Although the total amount of N applied at the different rates and frequencies was the same, application of 0.1 lb N/week resulted in the highest mean bentgrass color ratings (Table 1). Extending the application interval to 2 weeks or more led to significantly lower mean color ratings and there were no differences among the means for the 2-, 3-, and 4-week application intervals.

Maximum bentgrass color ratings increased with increases in the rate of N per application (Table 1). This is indicative of the fact that color was more uniform over time when N was applied at the 1-week rather than 2-, 3-, or 4-week intervals. Extending the application interval beyond 1 week had virtually no effect on maximum color development.

When Lorganic-8 was applied in May to strongly N-deficient Kentucky bluegrass, 0.5 lb N/M was barely enough to achieve satisfactory color, the time required was 19 days, and the color remained satisfactory for only about 3 weeks (Table 2). In contrast, application of 1.5 lb N/M resulted in green-up in 8 days and satisfactory color was maintained for more than 7 weeks.

Repeat application of the LOrganic-8 in July, when color ratings at all N rates had dropped below 7.0, resulted in restoration of satisfactory color in as little as 2 days. The duration of satisfactory color ranged from about 6 weeks for the 0.5 lb N rate to greater than 13 weeks for the 1.5 lb N rate.

Mean color ratings revealed that for the first N application, 1.0 lb N/M was the minimum amount required for a satisfactory mean color rating (Table 2). For the second N application, 0.5 lb N was sufficient to result in mean color rating above 7.0.

CONCLUSIONS

The bentgrass study confirms that LOrganic-8 is suitable for use in the low rate-high frequency N programs often employed on golf courses. While the study was conducted under fairway conditions, there is no reason for assuming that similar results cannot be achieved on bentgrass putting greens and tees.

The fact that a single application of LOrganic-8 in May at the 1.0 or 1.5 lb N rate resulted in maintenance of satisfactory color for 4 to 7 weeks, attests to the fact that the product contains a substantial amount of slow-release nitrogen. Even longer response times for the second N application suggest that there was carryover and release of additional N from the first application. Thus, the conclusion here is that LOrganic-8 performs much like other slow-release N fertilizers.

Excellent Kentucky bluegrass quality was achieved throughout the season with two 1.5 lb N applications. This corroborates 1994 observations, which also indicated that 3.0 lb N/M/season are reasonable for LOrganic-8 when applied to home lawns, institutional grounds, and athletic fields. The only limitation one encounters with two applications is that multiple sprayer passes are likely needed to achieve even 1.0 lb N rates unless something like flood-jet nozzles are used.

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