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Small Ruminant Research 94 (2010) 17–24

Contents lists available at ScienceDirect

Small Ruminant Research

journa l homepage: www.e lsev ier .com/ locate /smal l rumres

oil nutrient accumulation in alpaca latrine sites

.A. McGregora,∗, A.J. Brownb

Livestock Production Sciences, Future Farming Systems Research Division, Department of Primary Industries, Attwood, Vic., 3049, AustraliaSoil Sciences, Future Farming Systems Research Division, Department of Primary Industries, Werribee, Vic., 3030, Australia

r t i c l e i n f o

rticle history:eceived 15 October 2009eceived in revised form 7 June 2010ccepted 8 June 2010vailable online 21 July 2010

eywords:oil nutrientshosphorusitrogenotassium

a b s t r a c t

Alpacas establish long-lasting communal latrine sites or dunghills. To quantify the extentof nutrient transfer and accumulation associated with alpaca latrine sites and to pro-vide a three-dimensional assessment of a pasture paddock with 11-year-old latrine sites,three comparisons were made: (a) centres of latrines were compared with non-latrinecontrol sites 20 m away; (b) surface soils (0–10 cm) were compared with subsurface soils(10–30 cm); and (c) across cardinal compass directions and regular distances from latrinecentres were compared. Accumulation of nutrients was clearly detected, with a significantsurface build-up, relative to controls, observed in phosphorus (3 times), nitrate-nitrogen(3.8 times), potassium (3.2 times), sulfur (1.9 times), organic carbon (1.3 times) and elec-trical conductivity (2.4 times). Soil pH was also significantly decreased in the centre of the

atrinesung hillcidityoil carbonrazing management

latrine sites (pHw 0.6–0.7 units). Across the main axes of the latrines there was a clear trendof decreasing electrical conductivity, organic carbon and nutrients (NO3, P, K, Ca, Mg, Na,and S) away from a peak concentration at or near the centre. Soil pH demonstrated theinverse with a decrease towards the centre. Under set stocking conditions large transfers innutrients towards latrines could have long-term effects on pasture growth and composition.Some management options are discussed.

Crown

. Introduction

A large percentage of total plant nutrients consumed byrazing ruminants are returned in excreta to the soil, e.g.5% in dairy cattle, 96% for fattening sheep (Sears et al.,948) and thereby become available for plant use. Studiesith grazing sheep have demonstrated that plant nutri-

nts are redistributed by sheep and concentrated in campites on higher ground (Hilder, 1966a; Davidson, 1985;iu et al., 2009), and where nutrients had not been sup-

lemented via fertilizer, a gradual nutrient decline acrosshe rest of the paddock (Hilder, 1966b). The movement ofutrients within and out of a farming system can affecthe efficiency and patterns of pasture growth (Gillingham

∗ Corresponding author. Current address: Deakin University, Geelong,ic., 3217, Australia. Tel.: +61 3 52 273 358; fax: +61 3 52 272 539.

E-mail address: bruce.mcgregor@deakin.edu.au (B.A. McGregor).

921-4488/$ – see front matter. Crown Copyright © 2010 Published by Elsevier Boi:10.1016/j.smallrumres.2010.06.004

Copyright © 2010 Published by Elsevier B.V. All rights reserved.

and During, 1973; Sheath and Boom, 1985; Hosking, 1986;Williams and Haynes, 1995; Haynes and Williams, 1999;Aarons et al., 2004), environmental aspects of the landscape(particularly in waterways) and biodiversity conservation(Dorrough et al., 2004).

Alpacas (Lama vicugna) are becoming increasinglyprominent in rural areas within Australia, Europe andNorth America, particularly on farms with smaller land-holdings in areas of environmental sensitivity. They are alsoappearing in extensive farming systems as guard animalswithin sheep flocks. In traditional alpaca management sys-tems in the Altiplano region of Peru and Bolivia, alpacasare usually corralled at night and the accumulation of nutri-ents in the corrals is used for fertilizing gardens and plots of

improved pasture species. However, under Australian tem-perate farming systems, where pastures are continuouslygrazed and livestock unhoused, alpaca have been observedto establish communal sites for defecation and urination(latrine sites or dunghills) (McGregor, 2002; Fig. 1). Such

.V. All rights reserved.

18 B.A. McGregor, A.J. Brown / Small Rumin

Fig. 1. Alpacas adjacent a latrine site during late spring, when herbage wasat its greatest abundance and highest nutrient quality. Alpacas normallyavoid grazing herbage growing on the latrine site.

latrine sites show greater herbage growth but unlike sheepand their camps, there is general avoidance by alpacasof their latrines for camping and grazing during the pas-ture growing season. The present research was designedto quantify the extent of nutrient transfer and accumula-tion associated with alpaca latrine sites and thereby informoverall pasture nutrition, potential environmental con-cerns and subsequently, effective grazing management.

2. Methods

2.1. Design

To determine the extent that alpacas move nutrients in pasture, threecomparisons were made.

1. To determine if the latrine site had different nutrients compared witha non-latrine site (Site): soils from the centres of 9 latrine sites werecompared (paired) with soils from 9 non-latrine control sites, 20 maway.

2. To determine if nutrients in latrine sites had leached into the soil profile(Depth): surface soils (0–10 cm depth) were compared to subsurfacesoils (10–30 cm depth).

3. To determine the size and shape of latrine sites and the extent of nutri-ent distribution around latrine site centres (Distribution): soils on 4sites were compared in north, east, south and west directions and at2.5, 5, 7.5 and 10 m distances from the latrine centres.

These measurements provide a three-dimensional assessment of thelatrine sites, i.e. distance from centre provides one dimension, multipledirections provide two dimensions, depth provides three dimensions.

2.2. Environment

Alpacas were grazed in a 3.2 ha paddock at Attwood, located 18 kmnorth–northwest of Melbourne (37◦40′S, 144◦53′E, altitude 135 m a.s.l.)under conditions typical for farmed alpacas in southern Australia. Thepaddock had a southerly aspect with a slope of 4◦ (7%). The soil was ayellow Sododol, derived from weathered granite with a moderately acid(pHw 5.7), very dark brownish grey (Munsell 10YR 2/2), strong, granu-lar, medium structured, sandy clay loam surface (0–10 cm) over a slightlyacid (pHw 6.0–6.4), darkish brownish grey (Munsell 10YR 4/2), massiveor weakly structured, heavy sandy loam or coarse sandy loam to sandy

clay loam subsurface (10–45 cm) and a slightly to moderately alkaline(pHw 7.0–8.0), somewhat mottled, darkish brownish grey, strong, poly-hedral, coarse breaking down to finely structured, medium clay uppersubsoil (45–60 cm), becoming strongly alkaline (pHw 8.6) and distinctlymottled, and yellowish brown (10YR 5/6) to brown (2.5YR 4/4) with depth.Weather records were obtained from the Australian Bureau of Meteorol-

ant Research 94 (2010) 17–24

ogy weather station at Melbourne International Airport located 2.5 km tothe west (Anon, 2009).

2.3. Animals and management

Non-breeding Huacaya alpacas grazed the site continuously at a stock-ing rate of ≈8 dry sheep equivalents (DSE)/ha from early 1994 until thepresent study was conducted in July 2005. Limited sheep grazing alsooccurred for 3 years during this period, with an increase in grazing pres-sure up to 17.5 DSE/ha for one 6-month period (McGregor, 2002). Alpacashave a similar grazing requirement compared with sheep (San Martinand Bryant, 1989) and stocking rate in DSEs were determined followingadjustment for differences in live weight0.75 and using a 45 kg sheep as = 1DSE. Fresh water was provided from a trough in the north-west cornerof the paddock. During the period 1994–2005, no supplementary feed-ing or artificial fertilizer was provided. The annual pasture germinatednaturally each autumn and consisted of Subterranean Clover (Trifoliumsubterraneum), Annual Rye Grass (Lolium rigidum) and other volunteerspecies (McGregor, 2002). Given the relatively poor autumn rainfall dur-ing 1994–2005, clover germination was generally poor and few cloverplants were present in the pasture.

2.4. Sampling and testing

Sampling zones across the paddock were determined from aerialphotos available for spring 1995 and 2005 (Fig. 2) combined with ground-based visual inspection. A comparison of the two aerial photos indicatedthat the latrine sites had not moved over that time period. Soil samplingtechniques were based on the guidelines of Brown (1993). On 11 July 2005,the latrine centre points and control site centre points were marked withsteel pegs and sampling zones marked with pegs and lines. The zonesaround the centres were defined by a 2 m × 2–5 m rectangle, which, forthe latrine centres, ensured coverage of the area where dung accumulationwas most prominent. From the centre rectangle of the latrines, four ovalsat distances of 2.5, 5, 7.5 and 10 m from the centre points were marked.Diagonal lines radiating from the centre point and intersecting the ovalswere used to mark the boundaries of the north, east, south and west zonesfor each distance from the centre (Fig. 3). The north-south axis coincidedwith the direction of down-slope at the latrine sites. Prior to samplingthe centres, all visible faeces were carefully removed without disturbingthe soil surface. In each sampling zone, 30 cores were taken with a tube-sampler (Vimpany and Bradley, 1980) and bulked for chemical analysis.For the 10–30 cm depth, samples were taken from the centres of both thelatrines and controls and from the north-south axis of the latrine distri-bution layout. Samples were kept in a cool dark storeroom and analysedwithin 1 month of collection.

Samples were prepared and analysed at the Chemistry Laboratoryof the Department of Primary Industries, Werribee Centre for pH (1:5soil:water and 1:5 soil:CaCl2), electrical conductivity (EC 1:5 soil:water),nitrate-nitrogen (1 M KCl), extractable phosphorus (Olsen), exchangeablecations (Ca, Mg, Na and K) (NH4OAC), extractable sulfur (CPC by ICP)and organic carbon (Leco) following standard methods (Rayment andHigginson, 1992). Prior to analysis, samples were dried to constant weightin a fan-forced oven at 40 ◦C and ground to pass a 2 or 0.5 mm sieve,depending on test.

Analysis of variance was conducted using GenStat 8.1 (Payne, 2005)to detect the significance of site (centre vs control, d.f. = 8), depth andinteractions (d.f. = 16). Because variance increased with the sample meanfor phosphorus, EC, carbon and sulfur, the data were transformed (log10).To assess the distribution of nutrients around the latrine sites, graphswere prepared showing the variation in relative terms, with the centresite given the index value of 1.0, and for pH, the divergence in pH from thecentre. This approach negates the effect of variation between sites. Datafrom one sample, that was a statistical outlier arising from a samplingerror, were omitted.

The area of the paddock used as latrine sites was determined by twomethods: (a) when the extent of latrine sites during spring was easiest toidentify (Fig. 1) their dimensions were measured; (b) from the area of thegrids used in sampling applied to all latrine sites in the paddock.

3. Results

The mean rainfall during the period 1994–2008 was478 mm (range 310–680 mm) and the long-term mean

B.A. McGregor, A.J. Brown / Small Ruminant Research 94 (2010) 17–24 19

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Fig. 2. Aerial photos of the experimental site showing latrine sit

1970–2008) was 536 mm. The latrine sites occupied 15% ofhe area of the paddock based on the area of excessive pas-ure growth in spring (Fig. 1) and 12.5% based on the area ofhe sampling grids (Fig. 3). However, based on visible dungccumulation, the core area of the latrines occupied <0.2%f the paddock.

.1. pH and electrical conductivity

There were significant differences between sites in

oil pH (centre vs control, P < 0.005) and between depthsP < 0.001) irrespective of measurement method (Table 1).n average, pH values at the centre of latrine sites were

ower than for the control at 0–10 and 10–30 cm depthsTable 1). There was no site × depth interaction in pH.

ig. 3. The layout of sampling zones around the centre of a latrine site.

rk areas (a) 1995 and (b) 2005. North is to the top of the photos.

There was a significant site × depth interaction in EC(P = 0.001) with the centre 0–10 cm samples having at least2.5× EC levels than all other samples. There were signif-icant differences between sites in electrical conductivity(EC) (centre vs control, P < 0.001) and between depths(P < 0.001) (Table 1). On average, EC values at the centresites were about 2.8× higher than for the control at 0–10 cmdepth and 2× higher at 10–30 cm depth (Table 1).

3.2. Nitrogen and phosphorus

There was a significant site × depth interaction in nitro-gen as nitrate (NO3-N) (P < 0.001) with the centre 0–10 cmdepth having at least 3× higher nitrate levels than all othersamples. There were significant differences between sitesin NO3-N (centre vs control, P < 0.005) and between depths(P < 0.001). On average, NO3-N values at the centre were3.8× higher than for the control at both depths (Table 1).

There were significant differences between sites inextractable phosphorus (Olsen P) (centre vs control,P < 0.001) and between depths (P < 0.001). On average,Olsen P-values at the centre were 4.1× higher than for thecontrol at both depths (Table 1). There was no site × depthinteraction in Olsen P.

3.3. Exchangeable cations

For the sum of exchangeable cations there were sig-nificant site × depth interactions (P < 0.001), no overalldifferences between sites (centre vs control), but signifi-cant differences between depths (P < 0.001) (Table 1). Thecentre at 0–10 cm depth had higher cations than the control0–10 cm depth but there were no differences between thesites at 10–30 cm depth. Most of the change in exchange-able cations was due to changes in potassium (K) with

significant site, depth and site × depth interaction differ-ences (P < 0.001). Mean exchangeable K at the centre was onaverage 3.2× higher than at the control. For exchangeableMg and Na, there was a significant site × depth interactionwith the centre at 0–10 cm depth values being significantly

20 B.A. McGregor, A.J. Brown / Small Ruminant Research 94 (2010) 17–24

Table 1Mean soil acidity, electrical conductivity and soil nutrient concentrations at the centre of alpaca latrine sites and at control sites for two soil depths (n = 9).The standard error of differences between means determined by ANOVA and P-value determined by GenStat analyses are provided, values in bold P < 0.05.

Depth Latrine centre Non-latrine control Standard error of differencea and P-value

0–10 cm 10–30 cm 0–10 cm 10–30 cm Site Depth Site × depth

pH H2O 4.97 5.44 5.28 5.87 0.082; 0.002 0.046; 3.1 × 10−9 0.094; 0.21pH CaCl2 4.54 4.77 4.72 5.11 0.065; 0.004 0.048; 9.4 × 10−6 0.081; 0.10EC (dS/m)a 0.381 0.143 0.137 0.070 0.055; 0.0002 0.016; 1.8 × 10−13 0.058; 0.001NO3-N (mg/kg) 142 34 43 8 13.4; 0.002 6.8; 1.4 × 10−8 15.1; 5.7 × 10−5

Extractable P (Olsen) (mg/kg)a 59 19 15 4.5 0.060; 1.3 × 10−5 0.020; 1.1 × 10−14 0.064; 0.29Sum of cations (meq/100 g) 8.5 4.6 7.0 5.0 0.448; 0.25 0.222; 3.8 × 10−10 0.500; 6.0 × 10−4

Exchangeable K (meq/100 g) 1.52 0.63 0.44 0.26 0.078; 1.5 × 10−5 0.056; 7.8 × 10−8 0.096; 1.9 × 10−5

Exchangeable Ca (meq/100 g) 4.8 2.6 4.8 3.3 0.364; 0.39 0.178; 1.7 × 10−8 0.406; 0.053Exchangeable Mg (meq/100 g) 1.8 1.0 1.4 1.1 0.113; 0.28 0.066; 2.9 × 10−7 0.131; 0.011

0.246.61.1

sforme

Exchangeable Na (meq/100 g) 0.33 0.22 0.26Extractable S (CPC) (mg/kg)a 20.2 11.6 10.0Organic carbon (%w/w)a 4.0 1.3 3.2

a Backtransformed means but standard error of difference not backtran

higher than all other values (P < 0.05). Exchangeable Ca, Mgand Na were all significantly higher at 0–10 cm depth thanat 10–30 cm depths.

3.4. Sulfur and carbon

There were significant differences for both sulfur andcarbon between sites (P < 0.005) and between depths(P < 0.001) (Table 1). Mean sulfur and carbon values at thecentre were on average 1.9× and 1.3× higher, respectively,than at the control (Table 1). There were no site × depthinteractions.

3.5. Uniformity of nutrient distribution

Across both the north-south and the east-west axis ofthe latrines there was a clear trend of decreasing EC andnutrients (NO3, P, K, Ca, Mg, Na and S) away from a peakconcentration at or near the centre. Organic carbon showedless variation than other nutrients and higher levels to thesouth of the centre. Soil pH demonstrated the inverse to thegeneral trend, with a decrease towards the centre. Trendsare shown for most soil attributes in Fig. 4. For nutrients,where the peak was not found in the exact centre of alatrine site, it was usually found within the first samplingzone from the centre, i.e. within 2.5 m. The peak concen-tration, relative to values further from the centre, variedbetween nutrients and trends across the axes were notalways smooth.

4. Discussion

The accumulation of nutrients in the latrine sites wasclearly detected, with a significant surface soil build-upcompared with the controls, seen in phosphorus (3×),nitrate-nitrogen (3.8×), potassium (3.2×) and sulfur (1.9×).The levels of these nutrients found on the latrine siteswere high and would be able to sustain a high level of

growth, other factors not limiting. Increases in EC (2.4×)and decreases in pH H2O (0.6–0.7 units) and pH CaCl2(0.2–0.3) were also significant and may have longer termimplications for pasture growth and composition. Organiccarbon only displayed increases on latrines compared to

0.025; 0.35 0.017; 0.003 0.030; 0.0170.062; 0.002 0.022; 3.1 × 10−8 0.066; 0.230.019; 0.003 0.027; 5.4 × 10−12 0.033; 0.37

d.

controls of 1.3×, despite the high accumulation of faecalmatter. The absolute amount of nutrients moved into thelatrine sites in this study can be determined, if required, byusing the values in Table 1 and Fig. 3 combined with thearea under the curves of Fig. 4.

4.1. Latrine dynamics

Variation in nutrient accumulation varied widelybetween latrines (Fig. 4). For example, phosphorus concen-tration for 0–10 cm across the nine latrines centres variedfrom 30 to 84 mg/kg and nitrate-nitrogen concentrationvaried from 34 to 299 mg/kg. These differences are likelyto reflect differences in latrine frequency of use. Whilethere is some evidence from this study, that latrines havegrown or their centres have shifted up to 5 m over time (e.g.exchangeable potassium for the E–W axis for one latrine,Fig. 4) the aerial photo evidence (Fig. 2) and the nutrient dis-tribution (Fig. 4) indicate that by and large the latrine siteshad not moved within the paddock over a period of 11 yearsof grazing. Timescale is important because, at one extreme,if sites are more or less permanent, then the cumulativeconcentration of nutrients in one place could be a seriousproblem; but, at the other extreme, if latrine sites changefrequently then, over the long term, there will be continu-ous redistribution of nutrients, with only temporary localbuild-ups.

The factors affecting alpaca behaviour in respect to newlatrine establishment and abandonment of old latrines areunknown. Discussions with farmers in Australia suggestedlatrine establishment is related to gender and breedingcycles of alpacas. Observations at other locations by theauthors suggest stocking rate, pasture availability, com-petition from other livestock and land slope should beinvestigated as factors that may impinge on latrine estab-lishment.

4.2. Nutrient transfer

For most of the period, alpaca rarely grazed the latrinesites. Alpaca did graze herbage on latrine sites duringseasons when pasture was dry and limiting (Fig. 5) andsheep have been observed eating urine stained dead grass

B.A. McGregor, A.J. Brown / Small Ruminant Research 94 (2010) 17–24 21

Fig. 4. The relative change in pH H2O, Olsen P, exchangeable K, EC, organic C, NO3-N and S (CPC), in four alpaca latrine sites at Attwood, Victoria. Values arerelative to the value at the centre of each latrine. The values are shown for various distances along the north-south (N–S) and east-west (E–W) axis fromthe centre of each latrine. Values are for the 0–10 cm depth unless indicated otherwise. Symbols: (©) Site 1 ; (�) Site 2; (�) Site 3; (�) Site 4; (×) 10–30 cmdepth. North–south: (a) pH – H2O, (c) Olsen P, (e) exchangeable K, (g) EC, (i) organic C, (k) NO3-N, and (m) S (CPC). East–west: (b) pH – H2O, (d) Olsen P, (f)exchangeable K, (h) EC, (j) organic C, (l) NO3-N, and (n) S (CPC).

22 B.A. McGregor, A.J. Brown / Small Ruminant Research 94 (2010) 17–24

(Contin

Fig. 4.

from latrine sites during periods of low pasture availabil-ity (McGregor, 2002). During those periods when bothspecies grazed together, alpaca may have learnt sheep graz-ing behaviour for behavioural transfer has been recordedwith other species (Provenza et al., 2003). Grazing latrinesites would result in redistribution of nutrients from themto non-latrine sites. In addition to grazing redistribution,potential re-transfer of nutrients via surface runoff mayoccur. However, and particularly as there were no othernutrient inputs to the pasture, the over-whelming directionof movement would appear to be towards the latrines.

For a low input annual pasture, such as that found in

the research site, the critical Olsen P concentration is closeto 11 mg/kg (Gourley, 1987). The levels found in the con-trol sites (mean of 15 mg/kg) were above this critically lowvalue. However, continued translocation of phosphorus tolatrine sites, or, as is practiced by some alpaca farmers, the

ued ).

removal of dung from the pasture thereby exporting thephosphorus, without replacement via fertilizer, could leadto depressed pasture production in the longer term.

Australian soils in general, have insufficient nitrogento optimise pasture production. Critical levels of availablenitrogen have been found to vary greatly, from as low as21 mg/kg up to 70 mg/kg (Peverill et al., 1999). The aver-age nitrate level of 43 mg/kg found in the control sites iswell above the critical levels for this pasture and typicalof soils under improved pasture conditions. However, themovement of nitrates into the latrine area may reduce pas-ture production during the peak of the growing season in

the remainder of the paddock. As latrine sites are a featureof farms where alpacas are grazed in southern Australia, itis expected that pasture production is already being com-promised on farms which have soils near or below criticalnitrogen levels and that this impact will increase with time

B.A. McGregor, A.J. Brown / Small Rumin

Fig. 5. Centre area of an alpaca latrine site with accumulation of dungflh

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ollowing a period of drought. Herbage is at its lowest abundance andowest nutrient quality. Due to shortage of feed, alpacas have grazed theerbage growing on the latrine site.

nless there are changes to animal and pasture manage-ent.In the control sites, sulfur and potassium were well

bove their critical levels for pasture growth of 4 mg/kg and.3 meq/100 g, respectively. As nitrate levels increased to areater degree than sulfur, ruminant animals could poten-ially suffer from a dietary imbalance in N:S with a resultantulfur deficiency but only if animals are eating high N:Sasture. The 4:1 ratio of N:S in the soil of the latrine sites

s likely to have little bearing on the total pasture intake oflpacas as the latrine sites are only a small proportion of theasture area and are being avoided by the alpacas duringhe pasture growing period when nitrogen concentrationn plants are at their greatest.

High concentrations of potassium in the diet can inter-ere with magnesium metabolism. There is currently novidence from this study that soil potassium has increasedo concentrations that may induce excessive K uptakend cause dietary imbalance on the grazed areas (con-rols). Soil potassium on the latrine centres is high, relativeo soil magnesium and may be of concern when pas-ure is restricted in the rest of the paddock and latrineite pasture is consumed (Fig. 5). Grass tetany may be

problem when K/(Ca + Mg) is greater than 0.07–0.08Lewis and Sparrow, 1991). Mean values well above thisritical level was found at both depths in the latrineentres. However, even if a soil K:Mg imbalance was toranslate through to imbalance in the diet, its effect onlpacas susceptibility to hypomagnesia (grass tetany) isnknown.

.3. Nutrient loss

Excessive nitrate leaching beyond the root zone can leado soil acidification over time (Ridley et al., 1990). How-

ver, the current data does not show that such is occurringere, with soil pH higher in the 10–30 cm depth than inhe surface soils, overlying an alkaline subsoil. The depres-ion of pH in the surface soils of the latrines compared tohe controls is likely the result of increased total soluble

ant Research 94 (2010) 17–24 23

salts, giving higher EC values and is as much an artefactof testing, as a real field effect (Slattery et al., 1999). Nev-ertheless, decreased pH as well as increased nitrogen maysee a reduced clover component in the pasture sward with asubsequent dominance of grasses and dicotyledonous flat-weeds (Davidson, 1985).

It would be expected that the accumulated, high con-centrations of nutrients found on the latrine sites wouldlead to substantial leaching due to the surface and subsur-face soils low inherent buffering capacity and coarse sandy,freely drained character. In fact, comparisons in nutrientconcentration between 0–10 and 10–30 cm depths werenot very different between the latrine centres and the con-trols. For example, ratios between surface and subsurfacesoils were 4.2 and 5.4 for phosphorus between centres andcontrols, 3.1 and 3.3 for nitrate-nitrogen, 2.4 and 1.7 forpotassium and 1.7 and 1.5 for sulfur. When tested, otherthan for K, there were no statistically significant differencesbetween centres and controls for these ratios. These resultsmay reflect the relatively dry period during which thisstudy was conducted. On the other hand, nutrient leach-ing may have occurred through and beyond the subsurface,with accumulation being manifest in the medium clay sub-soil. Testing for such an effect would be worthwhile in thefuture.

Rainfall runoff from the study site was not expectedto be high, given that the soil profile is reasonably per-meable to 45 cm but rather impermeable or only slowlypermeable thereafter. However, during storm events andparticularly when the soil profile is already wet, runoffcould well occur, as happened in February 2005 when201 mm of rain fell in <24 h. Movement of nutrients duringa storm event could be either by soluble nutrients mov-ing into the profile or down-slope with water or by massmovement of dung down-slope. Any nutrient loss via thisroute will depend more on the pattern of rainfall than fer-tilizer practice and location of livestock camps (Mellandet al., 2008), or in this study, alpaca latrine sites. Someevidence of nutrient movement down-slope appears forphosphorus and sulfur at 2 out of 4 latrines, for potas-sium at 3 latrines and for nitrate at one latrine but we didnot make sequential measurements over time to determineif increases in concentration down-slope are the result ofmovement via runoff or changes in defecation patterns overtime (Fig. 4). Further investigation of leaching and nutri-ent runoff from alpaca latrine sites should investigate ifand how nutrients move below the rooting zone into thegroundwater.

4.4. Management implications and recommendations

Although observation has not shown substantial detri-mental effects to the pasture under study, it is clear that theuse of latrine sites by alpacas with its consequent and sig-nificant nutrient transfer could be of longer term concernon both the overall growth rate and botanical composition

of any pasture.

There are numerous management and soil nutrientissues that need to be clarified. Management practices needto be identified that target: (1) excessive build up of nutri-ents at latrine sites; (2) potential nutrient loses from the

ll Rumin

24 B.A. McGregor, A.J. Brown / Sma

pasture system; (3) environmental impacts of any nutrientloss; (4) reduced quality of soil properties e.g. acidity; (5)economic loss due to pasture degradation or resulting fromweed invasion of latrine sites; and (6) effects on animalhealth of concentrating internal parasite eggs and larvae atlatrine sites.

While getting the animals to establish new latrine sitesmight be relatively easy, for example, by the use of stripgrazing, stopping them from using long established latrinesis highly unlikely. Some alpaca producers have observedthat male alpacas establish their own latrine site, a differ-ent behaviour to that of females and castrated males. Sucha difference in behaviour may enable producers to manip-ulate sex ratios to achieve a desirable nutrient distributionacross pastures. Latrine sites can be induced by placingalpaca dung in preferred locations and this approach hasbeen successfully undertaken by one of the authors (BAM)in recent work. Induced latrine locations should be wellclear of environmentally sensitive areas such as waterwaysand wetlands.

It is likely that the most cost-effective solution wouldbe to redistribute the build-up of nutrients by grazingwith sheep and cattle. Sheep will graze latrine sites inboth the growing and non-growing seasons (McGregor,2002). Under higher stocking rates used in rotational graz-ing systems, sheep and cattle are expected to distributeexcreta more uniformly over level paddocks. Howeversheep do form camps, particularly near vegetation or athigher elevations (Hilder, 1966a; Davidson, 1985; Niu etal., 2009). In contrast, cattle show little pattern to theirdistribution of excreta (Petersen et al., 1956; Haynes andWilliams, 1999). Alpaca grazed at high stocking rateswill graze latrine sites and this is particularly evidentduring dry summers and periods of drought (Fig. 5).Redistribution of the faecal matter building up on latrinesites could be done mechanically, requiring machinery,labour and greater cost, and would need to be undertakenregularly to achieve any significant impact on nutrientaccumulation.

5. Conclusions

Alpacas formed long-lasting latrine sites where there isa build-up of nutrient levels. Under set stocking conditionsthe large transfers in nutrients could be of longer term con-cern for pasture growth and composition. It is likely that themost cost-effective solution to redistribute the build-up ofnutrients is by grazing with sheep or cattle.

Acknowledgments

Will English is thanked for his assistance during his

work placement from the University of Melbourne. Themembers of the Australian Alpaca Association who donatedthe alpacas are gratefully thanked. The following colleaguesare thanked for their assistance: Kym Butler, Ron Walsh andDr. Tony Whetherley.

ant Research 94 (2010) 17–24

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