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This article in AJ

  1. Vol. 77 No. 1, p. 33-36
    Received: Mar 8, 1984

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Effect of Acidity and N Source on the Growth and Thatch Accumulation of Tifgreen Bermudagrass and on Soil Nutrient Retention1

  1. J. B. Sartain2



Turfgrasses are commonly grown on a soil with a near neutral pH using synthetic organic slow-release N sources which are more costly than soluble inorganic N materials. Acidic soil conditions slows nitrification and may decrease the long-term leaching loss of inorganic NH+4 source fertilizers, thereby increasing the N efficiency of the fertilizer source. Specific studies evaluating the effects of soil acidity on N fertilizer efficiency and turfgrass growth and thatch accumulation have not been conducted; therefore this study was initiated with the following objectives: (a) to assess the influence of acidity and N source on the quality, growth rate, N uptake, and thatch accumulation of Tifgreen bermudagrass [Cynodon transvaalensis Burtt-Davis ✕ C. dactylon (L.) Pers.1 and (b) to evaluate the effects of acidity on the retention of selected nutrients by the soil. Treatments were applied in a randomized complete block design with four replications to a 5-year-old Tifgreen bermudagrass turf growing on a loamy fine sand (Typic Quartzipsamment). Three N sources (Ammonium sulfate [AS], Isobutylidene diurea [IBDU], and activated sewage sludge [SS)) were applied at two frequencies (5 g and 10 g N m−2) every 14 and 28 days, respectively. The bermudagrass was rated every 14 days, clippings were collected every 45 days for growth rate and N uptake estimates and cores for thatch accumulation estimates were collected after each of three growing seasons. Maximum growth rates occurred at pH less than 4.0. Overall turfgrass quality was not significantly influenced by N source or frequency of application. Acidity promoted thatch accumulation, except in the presence of applied Ca. Significantly lower levels of thatch accumulated on plots receiving IBDU. Application of 5 g N m−2 as AS every 14 days promoted the accumulation of more thatch than 10 g N m−2 applied every 28 days. Frequency of application had no effect on the thatch accumulation of plots receiving IBDU and SS. Mehlich I extractable nutrients (P, K, Ca, and Mg) in the top 5 cm of soil declined with increasing levels of acidity. Turfgrass growth rate was not reduced in the presence of a 100 to 1 soil extractable Ca to Mg ratio.

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