Relationship of Turfgrass Growth and Quality to Soil Nitrate Desorbed from Anion Exchange Membranes

do not completely contact the soil. Furthermore, it is possible that the adsorption of ions by resins is governed by Anion exchange membranes (AEMs) are a potential method for two distinct diffusion coefficients, an internal and an exdetermining the plant available N status of soils; however, their capacity for use with turfgrass has not been researched extensively. The ternal coefficient (Cooperband and Logan, 1994). Theremain objective of this experiment was to determine the relationship fore, there is uncertainty in the calculation of exchangebetween soil nitrate desorbed from AEMs and growth response and able nutrients on a per weight basis from data collected quality of turfgrass managed as a residential lawn. Two field experiusing exchange resins. This is of particular concern when ments were conducted with a bluegrass–ryegrass–fescue mixture reexchange resins are not in contact with soil long enough ceiving four rates of N fertilizer (0, 98, 196, and 392 kg N ha 1 yr 1 ) to negate diffusion limitations (Bhadoria et al., 1991). with clippings returned or removed. The soils at the two sites were a Ion exchange membranes (IEMs), by virtue of their Paxton fine sandy loam (coarse-loamy, mixed, active, mesic Oxyaquic two-dimensional nature and dynamic exchange properDystrudepts) and a variant of a Hinckley gravelly sandy loam (sandyties, provide an alternative to traditional measurements skeletal, mixed, mesic Typic Udorthents). Anion exchange memof available soil N and exchange resin techniques (Abbranes were inserted into plots and exchanged weekly during the growing seasons of 1998 and 1999. Nitrate-N was desorbed from AEMs rams and Jarrell, 1992). The nascent study using IEMs and quantified. As N fertilization rates increased, desorbed NO3-N for measuring in situ soil N availability was performed increased. The relationship of desorbed NO3-N from AEMs to clipping by Subler et al. (1995) and involved the use of AEMs yield and turfgrass quality was characterized using quadratic response buried in a silt-loam soil with various amendments. Suplateau (QRP) and Cate-Nelson models (C-Ns). Critical levels of bler et al. (1995) found that AEMs successfully meadesorbed NO3-N ranged from 0.86 to 8.0 g cm 2 d 1 for relative dry sured soil N processes and availability during a 4-wk matter yield (DMY) and from 2.3 to 12 g cm 2 d 1 for turfgrass period in soils with widely variable mineralization– quality depending upon experimental treatment. Anion exchange immobilization rates. Other important findings of Sumembranes show promise of indicating the critical levels of soil NO3bler et al. (1995) were that NO 3 uptake by AEMs was N desorbed from AEMs necessary to achieve maximum turfgrass nonlinear with time and that the membranes had the quality and yield without overapplication of N. potential to influence some soil processes. However, they acknowledged the potential influence of the small amounts of soil used in the study (20 g) and suggested T are many existing methods for monitoring that in the field, the AEM techniques’ influence on soil available N in soils. Traditional chemical extractions processes might be relatively small. are the most common methods; however, these meaSubsequent studies using AEMs to measure available surements provide only a snapshot measurement of soil N have been performed. Pare et al. (1995) compared available N. They are unable to measure fluxes that soil NO 3 extracted by KCl to that adsorbed by AEMs occur with changing environmental conditions. Exand found that the quantity of NO3-N adsorbed on change resins, in the form of capsules or spheres, provide AEMs was correlated (R2 0.78) to the amount exanother technique for measuring available soil N (Binktracted using the traditional KCl method. Qian and ley and Hart, 1989). Exchange resins are superior to tradiSchoenau (1995) assessed the contribution of N mineraltional methods because they are able to measure N availization from soil organic matter to plant-available N ability with time. Even so, the three-dimensional nature using AEMs and correlated the results to a 0.001 M of exchange resins necessitates a great deal of soil disturCaCl2 extraction. They found that 2-wk AEM incubabance when they are deployed. Consequently, in situ tions were more closely correlated with plant N uptake conditions, as well as the measure of available soil N, than were CaCl2 extractions. Wander et al. (1995) comare compromised. In addition to concerns regarding soil pared AEM extractions to traditional KCl extractions disturbance, the prevailing view of exchange resins as for measuring changes in NO 3 concentration in a field infinite sinks to which ions may be adsorbed but never during winter and found that NO 3 availability declined desorbed limits their use as an index of bioavailability with both methods. However, only the AEM method (Cooperband and Logan, 1994). A further limitation of produced statistically significant results. exchange resins involves their three-dimensional nature. Anion exchange membranes have been used in the Because of their three-dimensional shape, exchange resins field to measure NO 3 fluxes in soils of grass hay crops. In a field study of grasslands, Ziadi et al. (1999) found Kelly L. Kopp, Dep. of Plants, Soils, and Biometeorology, Utah State that NO 3 fluxes from AEMs were significantly correUniv., 4820 Old Main Hill, Logan, UT 84322-4820; Karl Guillard, Dep. of Plant Science, Univ. of Connecticut, 1376 Storrs Road, UAbbreviations: AEM, anion exchange membrane; CRM, clippings 4067, Storrs, CT 06269-4067. Contribution no. 1971 of the Storrs Agric. removed; CRT, clippings returned; C-N, Cate-Nelson model; DMY, Exp. Stn. Received 2 May 2001. *Corresponding author (kellyk@ext. dry matter yield; HDPE, high density polyethylene; IEM, ion exusu.edu). change membrane; QRP, quadratic response plateau model; RF, Plant Science Research and Teaching Farm; SM, Spring Manor Farm. Published in Crop Sci. 42:1232–1240 (2002).