70 Compost Science & Utilization Spring 2007

Introduction

In the past decade, the use of biowaste compost asa substrate for soil melioration has been strongly pro-moted by German policy in order to establish the com-plete cycling of organic matter from household andgarden waste via compost back to food production inthe field. Winegrowers favor biowaste compost main-ly because of its nature to increase the water holdingcapacity (Aggelides and Londra 2000; Jamroz andDrozd 1999; McConnell et al. 1993) and to enhancestructure and elasticity (Aggelides and Londra 2000;Bresson et al. 2001) when incorporated into the soil. Forthis reason, compost is now frequently applied in Ger-man vineyards. The fact that compost contains varyingamounts of nutrients which are released soon after thecompost is applied to the soil is often ignored. Howev-er, the nutritional value of the compost is of particularimportance when it comes to calculating fertilizer rec-ommendations (Pinamonti 1998). In order to enlightenthe process of nutrient release from biowaste compostunder the conditions of German viticulture, field mon-itoring was established. Focussing on nitrogen (N) asthe most important nutrient for crops, a compost trialwas conducted at several vineyards in southern Ger-many. The soil mineral N dynamics were observed forthree years after the application of mature biowastecompost, with the aim of understanding the general ef-

fect of the compost addition, and for the developmentof a simulation model to consider the contribution ofthe compost to the N mineralization of the soil organicmatter. The soil mineral N dynamics of four differentvineyards will be presented in the following work.

Materials and Methods

The Vineyards

Between April 1999 and February 2002 composttrials were performed at four vineyards in wine-grow-

Compost Science & Utilization, (2007), Vol. 15, No. 2, 70-77

Soil Biology and Nitrogen Dynamics Of Vineyard Soils As Affected by a Mature Biowaste Compost Application

Claas Nendel1 and Stephan Reuter2

1. Department of Modelling and Knowledge Transfer, Institute of Vegetable and Ornamental Crops, Großbeeren, Germany 2. Institute of AgroEcology, RLP AgroScience GmbH, Neustadt an der Weinstraße, Germany

Biowaste compost is frequently used in German viticulture to improve soil physical characteristics andto replace soil organic matter losses. A monitoring program was carried out to investigate the effect of amature biowaste compost application on soil biology and soil mineral N dynamics. At four vineyard sitesin southern Germany, compost was applied at two different rates in a random block design with fourreplicates. Soil mineral N, soil microbial biomass and soil respiration were observed over a period ofthree years. At three of the four investigated sites, the compost application induced a priming effect, lead-ing to mineral N contents of between 87 and 440 kg N ha-1 shortly after the amendment. During the in-vestigation period, the pattern of N mineralization and translocation in all soils otherwise followed com-mon rules which are governed by environmental conditions. Due to the priming effect, the N release fromthe compost was sufficient to cover the vine’s N demand for the first and second year after application atthree of the four vineyard sites. In the third year, a mineral N fertilizer application would have been re-quired. High soil mineral N contents as a consequence of the priming effect may be exposed to leachingand denitrification.

TABLE 1. Site properties of the investigated vineyards.

Rupperts- Bad berg Nierstein Wolf Kreuznach

Sand (%) 62.8 22.4 45.4 27.4

Silt (%) 29.9 64.3 37.6 48.2

Clay (%) 7.3 13.3 17.0 24.4

C (%) 0.8 1.5 1.4 1.7

N (%) 0.07 0.16 0.19 0.17

Soil pH 6.8 7.7 5.7 7.3

Riesling clone N90 Weiß 21 Gm 110 Tr 356

Rootstock SO4 Binova 5C 5BB

Planting year 1998 1987 1997 1988

Planting space (m2) 2.09 2.20 2.60 2.60

Slope 0° 2°-5° 5°-22° 10°-25°

Soil Biology and Nitrogen Dynamics Of Vineyard Soils as Affected by a Mature Biowaste Compost Application

Compost Science & Utilization Spring 2007 71

ing regions of major importance in Germany: thePalatinate (“Ruppertsberger Linsenbusch”), Rhine-hessen (“Niersteiner Kranzberg”), Nahe (“Kreuznach-er Kronenberg”) and Moselle-Saar-Ruwer (“WolferKlosterberg”). The sites, which had an area of about0.5 ha each, were planted with Vitis vinifera cv. Ries-ling. The soil types were Aric Anthrosols (FAO 1998)(Table 1).

Biowaste Compost

Biowaste compost produced from organic house-hold and garden waste (Würzburger Kompostwerke,Germany) was used for the trials. It was sieved to aparticle size of between 6 and 12 mm. This type ofsieving contains a low amount of fine particles andthus of nutrients. Compost with poor nutritional val-ue can be applied in higher quantities in order to im-prove soil physical characteristics. The compost wasclassified as class 5 (completely matured) and appliedin approx. 1.5 m bands between the rows (Table 2).

Experimental Design

The compost was applied in April 1999 at levels of30 Mg ha-1 and 50 Mg ha-1 to the vineyard soils. At theNierstein site, 25 Mg ha-1 compost was applied for thelower level. A treatment with zero compost applica-tion was included in order to allow calculations of ap-parent N mineralization from the compost. At Wolf,the zero compost treatment was fertilized with 60 kgN ha-1 annually, according to common regional prac-tice. All other zero treatments remained unfertilized.There were four randomized replicates in each trial.

Soil Sampling

During the monitoring program, the vineyardsoils were sampled every second month with a core

sampler down to a depth of 0.9 m. At sites where al-ternate rows were undersown with grass or legumes,only the rows with bare soil were chosen for sampling.Each replicate block was divided into two subplots,from each of which three soil samples were taken ran-domly. The three samples were divided into 10 cmlayers and merged to one representative sample foreach layer. At each date, 216 samples were obtained (3treatments � 4 replicates � 2 subplots � 9 layers).These were stored in a cold box during transport andsubsequently sieved to 2 mm aggregate size. Thesieved samples were then stored at -18°C prior to fur-ther processing. Deep-freezing of the fresh soil sam-ples leads to a partial destruction of the microorgan-ism’s cell walls, causing a release of additional N. Aslight overestimation of the soil mineral N can thusnot be ruled out. The effect of deep-freezing and sub-sequent drying at 105°C causes a rise of soil mineral Nof approximately 0.3 kg N ha-1 as it was found in a pre-liminary experiment.

For the analysis of soil microbiological parame-ters, the soil samples were taken in the second andthird year after the compost application: in April, Au-gust and December in 2000 and 2001. The samplingwas only performed in one of the 4 replicates. Thesamples were taken from the top soil down to a depthof 10 cm. Several sampling points were mixed toachieve one representative sample for each treatment.After sieving (< 2 mm) the soil samples were adjustedto a water content of 60% of maximum water holdingcapacity, equilibrated at room temperature for at leastone week and stored at 4°C prior to further analysis.

Soil Analysis

50.0 g oven dry soil was homogenized and subse-quently shaken with 0.01 M CaCl

2for one hour. The

suspension was filtered using nitrogen-free fluted fil-ters. 20 ml aliquots of the filtrate were stored in plasticvials at -18°C for later analysis.

NO3-N and NH

4-N concentration in the filtrate

was determined photometrically with a Skalar contin-uous-flow analyzer (Skalar Analytical B.V., Breda,Netherlands).

The soil respiration was analyzed with an Ultra-gas-analyzer U4S-CO

2(Wösthoff Messtechnik GmbH,

Bochum, Germany) according to Anderson and Dom-sch (1978) and Alef (1995) on three replicates of 50 gsoil for each soil sample. The incubation was carriedout in the dark for between 16 and 24 h at room tem-perature. For the calculation of the respiration rate,only the data of constant CO

2-production at the end of

the incubation period were considered.Soil microbial biomass was analyzed by the Fumi-

TABLE 2. Chemical properties of the compost

(based on fresh matter).

Property Compost

pH (1:2 CaCl2) 8.1

Dry matter (%) 42.7

Organic matter (%) 19.3

Ptotal

(mg g-1) 0.78

Ktotal

(mg g-1) 2.44

Mgtotal

(mg g-1) 2.29

CaO (mg g-1) 33.40

Ntotal

(mg g-1) 7.0

NH4-N (mg g-1) 0.4

gation-Extraction-Method following Vance et al.(1987), modified according to Joergensen (1995), ontwo replicates of 25 g soil (fumigated and non-fumi-gated soil) for each soil sample. After fumigation for 16h with methanol-free chloroform the fumigated andnon-fumigated replicates were extracted with 100 mlof a 0.01 M CaCl

2solution. The soluble carbon was

measured by dry oxidation with a high TOC II+N-an-alyzer (Elementar Analysensysteme GmbH, Hanau,Germany). The coefficient used to convert extractableorganic carbon into microbial carbon (C

mic) was K

ec=

0.45. For technical reasons, no analysis was conductedin summer 2000.

Results

Soil Mineral Nitrogen

Regarding the mineral nitrogen con-tents of the soils, a significant seasonalcourse could be observed. In all soils, astrong accumulation of mineral N wasfound in the top soil in summer 1999.Throughout the year, it was translocat-ed down the profile, accompanied by adecrease in concentration. Consequent-ly, the soil profiles were depleted inmineral N in February (Ruppertsbergand Wolf) or April (Nierstein). A con-siderable amount of mineral N was onlystill measured in the profile of the BadKreuznach soil, especially in the com-post treatments. As early as June a re-in-crease of mineral N was measured in thetopsoil. The dynamics observed in 1999can also be applied for the following years, but withdeviating contents and translocation velocities.

Between the compost treatments, distinct differ-ences in soil mineral N contents were found in allsoils except for the Ruppertsberg soil. Althoughslightly higher mineral N contents were measured inthe Ruppertsberg compost treatments than in thecontrol treatment, these differences were never sta-tistically significant. At the Nierstein site, the differ-ences between the high-level compost treatment andthe control treatment could be confirmed statistical-ly for almost the complete investigation period.Thus, the effect of a 50 Mg ha-1 compost applicationon the soil mineral N content was observable forthree years.

For the Wolf, soil it can be stated that a 30 Mg ha-

1 compost application resulted in an effect compara-ble to a 60 kg N ha-1 mineral fertilizer (Calcium Am-monium Nitrate, CAN) application (control

treatment). Furthermore, in all Wolf treatments, avery strong increase of the soil mineral N contentwas observed during summer 1999. This increase ex-ceeded the amount that could have been explainedby the mineral fertilizer application or compost de-composition at common rates. This was also foundfor the Nierstein and Bad Kreuznach compost treat-ments. Here, the effect of the high-level compost ratecan be significantly separated from the control treat-ment. However, by the end of the second year, the ef-fect disappeared. The rapid mineral N depletion ofthe soil profile during autumn 2000 in comparisonwith the rather moderate decrease in the year beforewas particularly remarkable (Figures 1-3).

Soil Biological Parameters

No clear trend of the effects from the compost ap-plication could be observed in the second year afterthe compost was applied for the biological parame-ters soil respiration and soil microbial biomass. In thethird year, the Bad Kreuznach soil showed slightlyincreasing microbial biomass and activity in the com-post treatments in spring, whereas the effect was nolonger observed in the following sample. The soilstaken from Wolf and Nierstein indicated an increas-ing microbe population and activity with increasingcompost application in the summer. No compost ef-fect on both parameters could be observed in theRuppertsberg soil. Apart from different effectscaused by the compost application, the Nierstein soilalways showed the highest values for microbial bio-mass and respiration throughout the observation pe-riod compared to the other soils (Figures 4-5).

Claas Nendel and Stephan Reuter

72 Compost Science & Utilization Spring 2007

FIGURE 1. Weather conditions (daily precipitation and evapotranspiration over cutgrass) at the investigation sites.

Soil Biology and Nitrogen Dynamics Of Vineyard Soils as Affected by a Mature Biowaste Compost Application

Compost Science & Utilization Spring 2007 73

Discussion

Soil Mineral Nitrogen Dynamics in the Field

In all soils, typical seasonal N dynamics were ob-served. Most of the effects can be assigned to localweather conditions. Wet conditions in the soil and ris-ing temperatures during spring enhanced the miner-alization of the soil organic matter, which led to in-creasing mineral N contents. Precipitation eventsprovided water to gradually translocate mineral Ndown the profile. High evapotranspiration rates insummer extenuated the translocation velocity, whichthen increased during winter. Depending on the soiltexture, the profile was sooner or later depleted ofmineral N. In the sandy Ruppertsberg soil or the skele-tal Wolf soil, mineral N of the first investigated seasonwas washed out by February 2000. In the more reten-tive loess soil of Nierstein, the translocation processwas slowed down until depletion was complete inApril 2000. In the clayey Bad Kreuznach soil, the min-

eral N concentration peak was only translocateddown to approximately 60 cm below the surface.

In the following year, an unusually wet summerconserved relatively high soil moisture during the sea-son, so that autumn rainfall led to a far more rapiddownward movement of soil mineral nitrogen. Eventhe Bad Kreuznach soil was mainly drained within twomonths for mineral N. Denitrification is assumed tohave contributed significantly to the N loss here, too.

In 2001, the summer was again warm and dry, sothat newly released N in the topsoil was translocateddownwards at rates comparable to those in the first in-vestigated season.

In three of the investigated soils, at Nierstein, Wolfand Bad Kreuznach, the mineral N content in the pro-file of the compost treatments was already very high atthe first sampling date two months after compost ap-plication, or increased strongly up until the secondsampling date (Figures 2 and 3). Assuming that themineral N content in the preceding months was com-parable to the values observed later for the control

FIGURE 2. Soil mineral N dynamics at the Ruppertsberg and Nierstein sites. The greyscale code describes the mean mineral N concentra-tion in a 0.1 m layer over soil depth and time (n = 8). The area between the nodes was linearly interpolated. A = Ruppertsberg 0 t ha-1 com-post, B = Ruppertsberg 30 t ha-1 compost, C = Ruppertsberg 50 t ha-1 compost, D = Nierstein 0 t ha-1 compost, E = Nierstein 25 t ha-1 com-post, F = Nierstein 50 t ha-1 compost. The compost was applied in April 1999. Numbers on top of each chart denote the sum over therespective soil profile in [kg N ha-1].

treatment in April 2001, the strong increase can not beexplained by common mineralization rates known forthese three soils and for the compost (Nendel et al.2005). The high mineral N contents indicate a primingeffect set off by the incorporation of the compost. Theterm “priming effect” refers to an amplified N mineral-ization that follows the addition of easily decompos-able organic matter (Kuzyakov et al. 2000). However,common interpretations of the definition still differ inthe source of the additional N release, as it may be soilorganic matter, added organic matter or both. The lat-est attempt to give a conceptual model of the mecha-nisms leading to a priming effect was presented byFontaine et al (2003). In the Nierstein and Wolf soils, apriming effect following compost application was al-ready observed both in laboratory (Nendel et al. 2004)and in micro-lysimeter experiments (Nendel et al. 2005).

Soil Biology

The application of compost provides organic mat-ter to the soil, which is important to ameliorate physi-

cal and biological soil properties. Since in viticulturecrop rotation is not possible, because the main crop isperennial, the amendment of viticultural soils with or-ganic matter is of particular interest to provide carbonsources to the soil organisms (Reuter and Kubiak2001). In our investigation, four vineyard sites receivedcompost at two different application rates. However,the microbial parameters only showed a long-termpositive effect after compost application at two sites,Nierstein and Wolf. This is particularly remarkablesince a noticeable priming effect in terms of a stronglyincreasing and soon thereafter decreasing mineral Ncontent was also observed in the Bad Kreuznach soil.Here, the microbial parameters showed no distinctlong-term response to the organic matter application.

Following the concept of Fontaine et al. (2003), theoccurrence of a priming effect is a result of a competi-tion between soil microbial populations of differentfeeding strategies. Rapidly growing r-strategists con-sume energy-rich and simple-structured carbonsources while slowly growing K-strategists utilizemore complex ones. Assuming a clear and instanta-

Claas Nendel and Stephan Reuter

74 Compost Science & Utilization Spring 2007

FIGURE 3. Soil mineral N dynamics at the Wolf and Bad Kreuznach sites. The greyscale code describes the mean mineral N concentrationin a 0.1 m layer over soil depth and time (n = 8). The area between the nodes was linearly interpolated. A = Wolf 0 t ha-1 compost (60 kg Nas Calcium Ammonium Nitrate each April), B = Wolf 30 t ha-1 compost, C = Wolf 50 t ha-1 compost, D = Bad Kreuznach 0 t ha-1 compost, E= Bad Kreuznach 30 t ha-1 compost, F = Bad Kreuznach 50 t ha-1 compost. The compost was applied in April 1999. Numbers on top of eachchart denote the sum over the respective soil profile in [kg N ha-1].

neous response of both microbial biomass and respi-ration connected to an observed priming effect (Pas-cual et al. 1998; Fontaine et al. 2004), the long-term ef-fect should first ebb away with the exhaustion of thefreshly added organic matter. The easily available car-bon sources are expected to have been consumedwithin weeks after the compost amendment, whichwill have caused the r-strategists to die away or fallinto dormancy (Mary et al. 1992; Wu et al. 1993). Theobserved long-term effect at the Nierstein and Wolfsite is thus in all likelihood a trace of the K-strategistpopulation that has grown slowly but steadily on themore recalcitrant compounds of the compost. The rea-son why no microbial long-term effect can be readfrom the observations at the Bad Kreuznach site mightbe due to an inadequate ability of the Kstrategists tocompete with the r-strategists in the first weeks afterthe compost amendment in this particular soil. Whilethe r-strategists’ activity leads to the observed heavypriming effect, the K-strategists were not triggered by

the offered nutrient sources (Fontaine et al. 2003; DeNobili et al. 2001). Consequently, at the Ruppertsbergsite the over-all conditions do not seem to be favorablefor the occurrence of a priming effect.

Conclusions

The monitoring of both soil mineral N dynamicsand the response of the soil microbial biomass revealedstrongly deviating effects of the compost application.While at one site apparently no effect could be inducedat all, the response went to the extreme at another site.Although the observed effects of the compost applica-tion were highly variable, a rapid and strong nitrogenrelease as a consequence of the compost addition wasobserved in three of the four investigated vineyards.The observed magnitude of N release in a very shorttime suggests that the N release rates exceeded thecommon rates that could have been expected from thegiven environmental conditions. For this reason, we

Soil Biology and Nitrogen Dynamics Of Vineyard Soils as Affected by a Mature Biowaste Compost Application

Compost Science & Utilization Spring 2007 75

FIGURE 4. Microbial biomass measured in the investigated soilsat five dates in the second and third year after a compost applica-tion in April 1999.

FIGURE 5. Microbial respiration measured in the investigatedsoils at six dates in the second and third year after a compost ap-plication in April 1999.

have to assume that a priming effect was induced bythe compost application in three of four soils.

The above-mentioned priming effect leads to con-siderably high soil mineral N contents in the vineyardsoils. The observed soil mineral N patterns in some ofthe investigated soils as a result of the compost applica-tion lead to the assumption that even at a rate of 30 t ha-

1 nitrate leaching to below the root zone occurs. Alsodentrification is a likely pathway for N being lost fromthe system at the given conditions. Thus, from the envi-ronmental point of view an accumulative application ofcompost for three years would be disadvantageous ascompared to an annual application of 10 t ha-1 compost.However, economic considerations such as the laborand fuel costs for a single compost application are stillstrong arguments in favor of the current approach.

Considering an N demand of the vine under envi-ronmental conditions in Germany of between 60 and90 kg N ha-1 (Löhnertz 1991), an application of 30 t ha-

1 mature biowaste compost released sufficient N to al-low abstention from an additional mineral fertilizerapplication in the first year if a priming effect oc-curred. If this is the case, the N status of the soil in thesecond year after the compost application would alsonot necessarily require an extra addition of mineralfertilizer, although in single cases an N status mea-surement should preferably be carried out to confirmthis assumption. An additional dose of mineral fertil-izer only becomes indispensable in the third year.However, the effect of a mineral N fertilizer applica-tion of the N dynamics in compost-amended vineyardsoils has not yet been investigated.

Acknowledgements

The authors wish to thank R. Kubiak and R.Nieder for their scientific support. The assistance ofM. Schreieck, U. Bäsel, N. Mischke, A. Neuschaefer, D.Scherthan, H. Walter and M. Wörner in the field andlaboratory is gratefully acknowledged. The projectwas financed by the German Viticulture ResearchGroup (Forschungsring Deutscher Weinbau).

References

Aggelides, S.M. and P.A. Londra. 2000. Effects of compostproduced from town wastes and sewage sludge on thephysical properties of a loamy and a clay soil. Biores.Technol., 71: 253-259.

Alef, K. 1995. Soil respiration. In: Alef K and Nannipieri P(eds.). Methods in Applied Soil Microbiology and Biochem-istry. Academic Press: London, pp. 214-220.

Anderson, J.P.E. and K.H. Domsch. 1978. A physiologicalmethod for the quantitative measurement of microbialbiomass in soils. Soil. Biol. Biochem., 10: 215-221.

Bresson, L.M., C. Koch, Y. Le Bissonnais, E. Barriuso and V.

Lecomte. 2001. Soil surface structure stabilization by mu-nicipal waste compost application. Soil Sci. Soc. Am. J., 65:1804-1811.

De Nobili, M., M. Contin, C. Mondini and P.C. Brookes.2001. Soil microbial biomass is triggered into activity bytrace amounts of substrate. Soil. Biol. Biochem., 33: 1163-1170.

FAO. 1998. World Reference Base for Soil Ressources. WorldSoil Ressources Report No. 84, ISSS-ISRIC-FAO, Rome,Italy, 88 pp.

Fontaine, S., G. Bardoux, D. Benest, B. Verdier, A. Mariottiand L. Abbadie. 2004. Mechanisms of the priming effectin a savannah soil amended with cellulose. Soil Sci. Soc.Am. J., 68: 125-131.

Fontaine, S., A. Mariotti and L. Abbadie. 2003. The primingeffect of organic matter: a question of microbial competi-tion? Soil. Biol. Biochem., 35: 837-843.

Jamroz, E. and J. Drozd. 1999. Influence of applying compostfrom municipal wastes on some physical properties ofthe soil. International Agrophysics, 13: 167-170.

Joergensen, R.G. 1995. The Fumigation-Extraction methodto estimate soil microbial biomass: Extraction with 0.01 MCaCl2. Agrobiol. Res., 48: 319-324.

Kuzyakov, Y., J.K. Friedel and K. Stahr. 2000. Review ofmechanisms and quantification of priming effects. Soil.Biol. Biochem., 32: 1485-1498.

Löhnertz, O. 1991. Soil Nitrogen and the uptake of nitrogenin grapevines. In: Rantz, J. M. (ed.) Proceedings Interna-tional Symposium on Nitrogen in Grapes and Wine, 18-19June, Seattle, 1-11.

Mary, B., A. Mariotti and J.L. Morel. 1992. Use of C-13 Vari-ations at Natural Abundance for Studying the Biodegra-dation of Root Mucilage, Roots and Glucose in Soil. Soil.Biol. Biochem., 24: 1065-1072.

McConnell, D.B., A. Shiralipour and W.H. Smith. 1993.Compost application improves soil properties. Biocycle,34: 61-63.

Nendel, C., S. Reuter, K.C. Kersebaum, R. Kubiak and R.Nieder. 2005. Nitrogen mineralization from maturebiowaste compost in vineyard soils. II. Test of N mineral-ization parameters in a long-term in-situ incubation ex-periment. J. Plant Nutr. Soil Sci., 168: 219-227.

Nendel, C., S. Reuter, R. Kubiak and R. Nieder. 2004. Nitro-gen mineralization from mature biowaste compost invineyard soils. I. Long-term laboratory incubation exper-iments. J. Plant Nutr. Soil Sci., 167: 397-407.

Pascual, J., R. Hernandez and C. Garcia. 1998. Changes in theorganic matter mineralization rates of an arid soil afteramendement with organic wastes. Arid Soil Res. Rehab.,12: 63-72.

Pinamonti, F. 1998. Compost mulch effects on soil fertility,nutritional status and performance of grapevine. Nutr.Cycl. Agroecosys., 51: 239-248.

Reuter, S. and R. Kubiak. 2001. Soil management systems tosupport soil microbial biomass in vineyards. In: Vaneph,S. and J. Benites (eds.) Proceedings of 1st World Congress onConservation Agriculture, 1-5 October, Madrid, 497-501.

Vance, E.D., P.C. Brookes and D.S. Jenkinson. 1987. An Ex-traction Method for Measuring Soil Microbial Biomass-C.Soil. Biol. Biochem., 19: 703-707.

Wu, J., P.C. Brookes and D.S. Jenkinson. 1993. Formationand Destruction of Microbial Biomass During the De-composition of Glucose and Ryegrass in Soil. Soil. Biol.Biochem., 25: 1435-1441.

Claas Nendel and Stephan Reuter

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