Bermudagrass Fertilized with Slow‐Release Nitrogen Sources. I. Nitrogen Uptake and Potential Leaching Losses

Abstract

With the objectives of analyzing N recovery and potential N losses in the warm-season hybrid bermudagrass 'Tifgreen' [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy], two greenhouse studies were conducted. Plugs were planted in PVC cylinders filled with a modified sandy growing medium. Urea (URE), sulfur-coated urea (SCU), and Hydroform (HYD) (Hydro Agri San Francisco, Redwood City, CA) were broadcast at rates of 100 and 200 kg N ha-1 every 20 and 40 d. The grass was clipped three times every 10 d and analyzed for N concentration and N yield. In addition, leachates were analyzed for NO3-N. Use of the least soluble source, HYD, resulted in the lowest average clipping N concentration and N yield, as compared with SCU and URE. Clipping N concentration and N yield showed a cyclic pattern through time, particularly under long-day (> 12 h) conditions. When the photoperiod decreased below 12 h, leachate NO3-N concentration exceeded the standard limit for drinking water (10 mg L-1) by 10 to 19 times with the high SCU and URE application rate and frequency. However, leaching N losses represented a minimal fraction (< 1%) of the total applied N. More applied N was recovered in plant tissues using SCU and URE (89.5%) than using HYD (64.1%), with more than 52% of applied N accumulating in clipping. Highly insoluble N sources such as HYD decrease N leaching losses but may limit bermudagrass growth and quality. Risks of NO3-N losses in bermudagrass can be avoided by proper fertilization and irrigation programs, even when a highly soluble N source is used.

Normal and Flush Irrigation Effects on Nitrogen Leaching from Simulated Golf Greens in the Greenhouse

“…A similar result was found by comparing urea to controlled-release nitrogen sources where as much as 10% of the urea-N leached compared with less than 1.7% for controlled-release fertilizers (Paramasivam and Alva 1997). Small differences between urea and sulfur-coated urea were reported for greenhouse column studies where total leaching was less than 1% of that added (Quiroga-Garza et al 2001). Other studies have also shown that controlledrelease fertilizer sources will decrease the amounts of nitrogen leached compared with soluble sources (Snyder and Cisar 2000;Shuman 2001Shuman , 2003.…”

Bermuda grass sod production as related to nitrogen rates

“…Rates exceeding 355 kg ha -1 N can result in a reduced rhizome and root production and increased leaf and stem production, which is not desirable due to the increased requirement for cuts of leaves (mowing), raising the production costs (Quiroga-Garza et al, 2001). The cuts also deplete the carbohydrate pool in lawns which is a reserve for stress periods (Qian & Fry, 1996).…”

“…However, the amount of available soil N is insufficient to meet the high demands of the lawn, so regular applications of nitrogen fertilizers are needed to increase grass growth (Bowman et al, 2002;Easton & Petrovic, 2004). Therefore, an ideal lawn quality (color, density and texture) requires an intensive fertilization program with high N rates and irrigation (Exner et al, 1991;Quiroga-Garza et al, 2001).…”

Quantidade de nutrientes extraídos pela grama bermuda e função de doses de nitrogênio

“…A qualidade ótima de um gramado requer um programa intensivo de adubação nitrogenada com altas doses (EXNER et al 1991;QUIROGA-GARZA et al 2001). …”