Soil phosphorus in a managed Mediterranean woodland ecosystem: herbage response and cattle grazing effects

Agriculture, Ecosystems and Environment, 47 ( 1 9 9 4 ) 299-311

299

Elsevier Science Publishers B.V., A m s t e r d a m

Soil phosphorus in a managed Mediterranean woodland ecosystem: herbage response and cattle grazing effects Z. Henkin a, I.Noy-Meirb, U. Katkafi ¢, N. Seligman d, M. Gutman d aGalilee Technological Center (MIGAL), Kiryat-Shmona, Israel bBotany Department, Hebrew University, Jerusalem, Israel CField Crops Department, Faculty of Agriculture, Hebrew University, Rehovot, Israel dNatural Resources Department, Agricultural Research Organization, Bet Dagan, Israel (Accepted 21 June 1993)

Abstract

A study of soil-plant relations in scrub woodlands on terra rossa soil in Israel, examined the following hypotheses: (a) that herbaceous plant growth on terra rossa is limited by phosphorus deficiency; (b) that shrub control and tree thinning can release available P for use by herbaceous vegetation; (c) that cattle fed P-rich poultry litter as a nitrogen supplement, can increase the available P level in the soil by recycling excess P through their excrements. Soil available P (bicarbonate-soluble) content was 4-9 mg kg - ~ soil in the surface 15 cm soil layer and 2-3 mg kg- 1 soil in the deeper 1530 cm layer. A bioassay showed that plant growth was restricted when P concentration was less than 11 mg P per kg soil. Addition of nitrogen did not increase herbaceous yield, Neither thinning of trees nor shrub control using herbicide had any significant effects on available soil P. There was a significant increase in available soil P concentration in the surface 3 cm layer of soils on sites that had been partially cleared and grazed for 3 years by cattle supplemented with poultry litter. Only near centers of cattle activity was there a significant increase of P in the 3-15 cm layer, and only there was the enrichment sufficient to remove phosphorus limitation to herbage growth.

Introduction Large areas of uncultivated hill rangeland in the Mediterranean region are dominated by sclerophyllous scrub forest and spiny shrubland with little herbaceous vegetation. In Israel, the traditional utilization of these areas by goats has decreased in recent years. Beef cattle are now raised on a large scale but their performance on scrub range is poor. It has been suggested that relatively heavy grazing following scrub thinning could change the existing vegetation to open woodland with a high cover of herbaceous vegetation and make beef raising successful (Gutman et al., 1985). However, in a pilot study of this management system, cover and yield of herbaceous vegetation remained poor even after drastic reduction of scrub cover (Gutman et al., 1985 ). © 1994 Elsevier Science Publishers B.V. All rights reserved 0 1 6 7 - 8 8 0 9 / 9 4 / $ 0 7 . 0 0

300

z. Henkin et al. /Agriculture Ecosystems and Environment 47 (1994) 299-31l

Previous studies suggested that growth of the herbaceous vegetation is limited by phosphorus deficiency in the soil (Ofer and Seligman, 1969; Rabinovitch-Vin, 1979; Henkin, 1986). Terra rossa soils in the region, derived from C e n o m a n i a n - T u r o n i a n limestone and dolomite rocks, have a low level of 'available' bicarbonate-soluble phosphorus (Koyumdjisky and Dan, 1969). The primary purpose of this study was to investigate the extent to which available phosphorus limits the growth of herbaceous vegetation, and whether various management treatments particularly cattle grazing, scrub thinning and herbicide spraying, have significant effects on the amount of available phosphorus in the soil. The authors' working hypothesis was that the dispersal of cattle dung on the rangeland and the massive addition of leaves to the upper soil layer as a result of scrub thinning or herbicide spraying, would cause an increase in soil available phosphorus and hence in herbaceous vegetation growth response. Murphy (1986) has stated that most of the nutrients in plants consumed are excreted and returned to the soil. Abbott and Tucker ( 1973 ) have shown animal manure to be an effective P source in calcareous soils. In general, cow grazing leads to greater turnover of nutrients (Petersen et al., 1956; Gillingham et al., 1980). In contrast, Center et al. (1989) and Marrs et al. (1989) found little effect of sheep grazing on soil chemistry. In the study area, the effect of cow grazing on soil phosphorus was expected to be enhanced especially during the months of supplementary feeding when the herd was fed large a m o u n t of phosphorus-rich poultry litter (Holzer and Levy, 1976 ). Materials and methods

Study site The study was conducted on an experimental range ('Hatal') in Western Galilee set up in 1981 to investigate utilization of scrub range by beef cattle ( G u t m a n et al., 1984). Hatal is located in the hilly part of western Galilee, 10 km east of Nahariya (35 ° 14' E, 33 ° 0 0 ' N ) , altitude 300-500 m. The average yearly precipitation is 780 m m . Hard limestone and dolomite rocks of the C e n o m a n i a n - T u r o n i a n age cover 15-40% of the surface. The soil is a red to brown-red terra rossa, that corresponds to Haploxerolls, Xerochrepts or Rhodoxeralfs in the American classification (Soil Survey Staff, 1975; Dan et al., 1976). In a preliminary survey of the area two main soil and vegetation units were distinguished as follows: ( 1 ) Red-brown terra rossa soil on dolomitic rock with a dense cover (90%100% before thinning) of tall shrubs (or multi-stem trees), mainly Quercus calliprinos Webb. The slope is about 20-30% facing north. (2) Red terra rossa soil on limestone rock with a relatively dense cover of low spiny bushes of Calycotome villosa (Poir). Link and Sarcopoterium spi-

301

Z Henkin et al./Agriculture Ecosystems and Environment 47 (1994) 299-311

nosum (L.) Spach (30-70% cover) with sparse tall shrubs. The slope is less than 10%. The following treatments were applied in the area: ( 1 ) Where the scrub was tall and dense, stems were thinned and pruned into tree form, leaving one to three stems per shrub, in two treatment levels: (i) Strong thinning + litter burning, leaving 34% of brush aerial cover (Henkin et al., 1988) (ii) moderate thinning leaving 45% of brush aerial cover. This took place during 1981-1984. (2) Where the vegetation was mainly composed of low spiny bushes, a herbicide spraying treatment with 50 1 ha-1 'Albar Super' - ( 10% 2, 4, 5-T) was given in April 1983. ( 3 ) Beef cattle were introduced at stocking rates heavy enough to suppress basal shrub regrowth and were given supplements during the summer and autumn (mainly poultry litter) according to animal needs. Before the experiment, the range had not been grazed for 20 years. The area was divided into four fields with different stocking rates (3.4-6.5 cow days ha-1 per 3 years) in three grazing fields, and a much higher stocking rate (48.3 cow days h a per 3 years) in the feeding paddock. Soil sampling and analysis Seven sites in each habitat were chosen to represent various combinations of vegetation and treatments (Tables 1 and 2). At these sites soil samples Table 1 Available phosphorus in terra rossa soil below the litter layer, in sites on dolomitic rock where the original stand of bushes was tall and dense Site no.

1 2 3 4 5 6 7

Vegetation treatment

Strong thinning+litter burning ( 1981 ) Moderate thinning (1981) Moderate thinning ( 1981 ) None Moderate thinning (1984) None None

Grazing pressure in plot

High

Average available soil phosphorus (mg P kg- ' soil) 0-15 cm

15-30 cm

11.2(2.3)A

3.9

High

7.3 (0.3) AB

3.9

No grazing No grazing Low

7.8 ( 1.0 )AB

3.0

8.7 ( 1.5 )AB

3.0

5.8 ( 0.3 ) B

2.6

Low Low (cattle camp )

8.8 ( 1.3)AB 9.1 ( 1.5)AB

2.6 -

Values are mean and standard error at 0-15 cm (in brackets). Different letters show statistically significant differences at 0-15 cm depth between sites tested by Duncan's multiple range test at P = 0.05.

302

z. Henkin et al. /Agriculture Ecosystems and Environment 47 (1994) 299-311

Table 2 Available phosphorus in terra rossa soil in sites on limestone rock where shrub vegetation was low Site no.

Vegetation

8

Noshrubs

9

Few shrubs

102 11 12 13 14

Dense Calycotome villosa Dense Calycotome villosa Dense Sarcopoterium spinosum Sparse Sarcopoterium spinosum Sparse Sarcopoterium spinosum

Grazing pressure Average available soil phosphorus in plot (mg P kg -1 soil) 0-3 cm

3-15 cm

15-30 cm

825

(48)A

348

42

103

(7.6)B

14.5(1.9)A

5.6

21.7(7.6)CDE

5.7(1.3)B

3.0

High

56(12.2)CD

8.1(1.1)B

3.9

High

65(15.4)BC

6.0(0.6)B

-

High

19.8(2.3)DE

Veryhigh (feeding plot ) High ( 100 m from feeding plot) High

No grazing

8.6(0.7)E

(177) 1

5.2(0.3)B 5.0(0.2)B

3.0 2.6

tDuncan's multiple range test at soil depth of 3-15 cm did not include Site 8. 2Site l0 was sprayed with herbicide (2, 4, 5-T). Values are mean and standard error at 0-3 and 3-15 cm (in brackets). Different letters show statistically significant differences at 0-3 and 3-15 cm depth between sites tested by Duncan's multiple range test at P = 0.05.

were taken in November 1984. From Sites 1-7, where the soil was covered by a litter layer 3-12 cm thick, eight soil samples from each site were taken from the 0-15 cm soil layer below the litter. From Sites 8-14, eight soil samples from each site were taken from the 0-3 cm and 3-15 cm layers. At all sites one sample was taken from the 15-30 cm layer.

Bioassay of phosphorus availability Soil samples for a bioassay of P availability were collected from the 14 sites mentioned above. The samples were taken from the upper 10 cm layer after removing 1-2 cm of top soil. The samples were air dried, crushed and sieved and samples were taken for analysis of N, P, and K in the soils (Table 3 ). The soil was well mixed and used to fill 750 ml plots that were sown with Setaria italica (L.) P. Beauv. Two levels of P were attained, 16.7 (P1) and 50.1 (P2) mg P kg -1 soil, as KH2PO4 to the pots. One level of N addition (N1) was applied (as NHaNO3) to bring the concentration to a level of 64 mg N kgsoil, which was the highest nitrogen concentration found in the sampled soil sites. The following combinations were used: PON0 (control), P 1NO, P2N0, P1N1, P2N1.

303

z. Henkin et aL /Agriculture Ecosystems and Environment 47 (1994) 299-311

Table 3 Concentration of available phosphorus, nitrogen and potassium in soil (0-10 cm layer) from different sampling sites that were used in the bioassay (in order of increasing phosphorus concentration) Site no.

Treatment (vegetation)

Grazing pressure

Concentration (rag kg -1 soil) Available P

14 2 5 6 10 12 3 4 7 9 13 1 I1 8

None (sparse bushes) Moderate thinning (1981) Moderate thinning (1984) None Sprayed (dense bushes) None (dense bushes) Moderate thinning None None (cattle camp) None None (opening in scrub) Strong thinning+litter burning None (dense bushes) None (feeding plot)

Nitrogen (N-NH4) + (N-NO3)

Potassium

None High

4.7 5.2

19.6 20.2

164 72

Low

5.6

18.5

135

Low High High None None Low High High High

6.0 6.5 6.9 6.9 9.1 13.4 13.9 14.2 15.1

24.6 15.4 24.1 19.3 20.2 28.8 19.6 63.4 20.2

167 242 287 67 135 466 204 480 75

High Very

19.5 194

22.4 50.7

312 1780

high Treatments were randomized in each block and replicated five times. Height of plants was measured after 13, 19 and 23 days of growth, then plant total topgrowth was harvested and oven dried at 65 °C. P and N concentrations in plants and soil were measured.

Soil and plant analysis Available phosphorus in the soil was measured by extraction with 0.5 M bicarbonate (Olsen et al., 1954); nitrogen by extraction with KC1 and determination of N-NH4 by distillation with MgO, and N-NO3 by distillation with Deverda reagent and titration with H 2 S O 4 (Black et al., 1965 ); and potassium by extraction with bicarbonate (Bar-Yosef and Akiri, 1978 ). Total P and N plant content in the plant was determined after wet ashing with H 2 S O 4 and H 2 0 2.

Statistical methods The statistical significance of differences between treatments in the bioassay, and differences between soil sampling sites was tested by the general lin-

304

z, Henkin et al. / Agriculture Ecosystems and Environment 47 (1994) 299-311

ear model procedure and Duncan's multiple range test at P = 0.05 with the SAS package (SAS Institute, 1985 ). Results

Available phosphorus concentrations in the field There was a general decrease of soil available phosphorus concentration with depth (Tables 1 and 2). This is a well-known phenomenon (Larsen, 1967 ). This decrease between soil layers was greater in heavily grazed sites. In the dense scrub (Table 1 ), the top layer was mostly organic, so that available P could not be measured, in the sparse scrub, where there was no cover of tree leaf-litter on the ground (Table 2 ), phosphorus concentration in the 0-3 cm layer increased from 8.6 mg P kg-1 soil in the ungrazed site (Site 14 ), to 20-65 mg P kg-1 soil in grazed sites that were relatively far from the supplementary feeding site (Sites 10-13 ), and to 100 mg P kg- 1 soil close to the feeding area (Site 9 ). It reached more than 800 mg P kg-~ soil inside the 1 ha feeding plot (Site 8 ). The influence of cattle grazing on the level of available phosphorus in the 3-15 cm soil layer (or 0-15 cm under litter), was relatively slight (Tables 1 and 2). In most of the sites in the grazed area, concentration of available phosphorus in this layer was between 5.7-8.8 mg P kg -~ soil and was not significantly different from the levels in ungrazed sites. A significant increase of phosphorus concentration occurred only in those sites where the local cattle pressure was high (Sites 8 and 9 ). In the 15-30 cm soil layer the concentration of available soil phosphorus in most sites was 2.6-3.9 mg P kg-1 soil regardless of treatment (Tables 1 and 2 ). The only site where the concentration in that layer increased substantialy was in the feeding plot (Site 8 ). A small increase was found also at a distance of 100 m outside the feeding paddock (Site 9 ). There were no significant differences in available soil P concentrations between sites with and without thinning of tree and shrub stems (Table 1 ). P concentration in the 0-15 cm layer was higher on the site which had the most drastic treatment (strong thinning, litter burning and heavy grazing) ( 11 mg P kg- 1 soil) than in other sites, but because of high variance among samples in this site, this was not significantly different from the other similar sites. Comparison of sites with and without herbicide spraying of bushes showed no significant effect on soil available P concentration (Table 2).

Bioassay of phosphorus availability The height growth of plants grown on soils from the field without nutrient addition was related to the concentration of available P (Fig. 1 ). On soils

305

Z. Henkin et al. / Agriculture Ecosysterns and Environment 47(1994) 299-311

•

1 3

• ........ o ......

4 14

o..~.o a.

0

J 10

30

20

DAYS

Fig. 1. Change in height of plants grown on soils from Sites 1, 3, 4 and 14.

Table 4 Average dry matter yield in bioassay, and significance of adding phosphorus, in relation to available soil phosphorus concentration Site no. 14 2 5 6 10 12 3 4 7 9 13 1 11 8

Available soil P (mg kg- ~ soil ) 4.7 5.2 5.6 6.0 6.5 6.9 6.9 9.1 13.4 13.9 14.2 15.1 19.5 194.0

Dry matter yield (g per pot) PON0

P1N0

P2N0

P1N1

P2N1

Significance of difference between treatments (probability)

0.88 1.38 1.17 1.15 1.10 2.11 1.25 2.01 2.32 2.65 2.90 2.98 3.18 4.48

1.73 3.93 2.16 2.27 2.07 2.68 2.30 2.58 2.63 2.35 3.55 3.09 4.06 5.53

2.38 3.49 3.16 3.66 2.96 2.50 3.69 3.11 4.09 2.61 3.82 3.22 3.50 5.18

1.86 2.77 2.48 2.08 2.41 2.76 2.21 2.56 3.57 3.18 2.73 3.68 3.06 5.22

3.84 3.04 2.88 4.63 3.47 3.47 3.55 3.40 4.51

0.0001 0.001 0.0017 0.0017 0.0001 0.044 0.018 0.064 0.011 0.670 0.017 0.899 0.185 0.145

from Site 14, where the available soil phosphorus was lowest (4.7 mg P kg-1 soil), vegetative growth stopped after 19 days (Fig. 1 ). The response of plant dry material topgrowth yield to added P was always significant when available soil P was less than 9 mg P kg- 1 soil. There was no response when available soil P was greater than 15 mg P kg-~ soil. At intermediate P concentrations the response was variable (Table 4). The addition of N after P had been added did not increase yield. The relation between plant dry-matter yield and concentration of available soil phosphorus (Fig. 2 ) shows a diminishing positive slope. The non-linear

306

z. Henkin et aL / Agriculture Ecosystems and Environment 47 (1994) 299-311

= a) ~

Y=-16.871X+4.14

4

R2

=0.74

v

q

3 flu

uJ >-

ta m

[]

b)

X<11

b)

X>11

R2

Y=-O.35÷O.20X =0.73

2

.~2

I

I

t

10

20

30

A V A I L A B L E SOIL P ( r a g

Plkg

Y.2.10+O.O6X =0.24

soil)

Fig. 2. Relationship between plant yield and available P concentration in soil. D o t t e d line, nonlinear regression, eq. a. Solid line, two partial linear regressions, eqs. b. Table 5 Concentration of phosphorus in plants of different treatments in the bioassay, in relation to available

soil phosphorus concentration Site Available soil P no. (nag kg-1 soil) 14 2 5 6 10 12 3 4 7 9 13 1 11 8

4.7 5.2 5.6 6.0 6.5 6.9 6.9 9.1 13.4 13.9 14.2 15.1 19.5 194.0

P concentrations in plants (mg P g-~ dry matter)

Significance of difference between treatments

PON0

P1N0

P2N0

P1N1

P2N1

(probability)

0.67 1.50 1.12 1.07 0.97 1.17 1.40 1.60 1.70 1.70 1.27 1.50 1.70 2.72

1.05 1.65 1.72 1.62 1.35 1.62 1.52 1.67 1.70 1.80 1.40 1.60 1.72 2.82

1.55 1.65 1.90 1.70 1.70 1.65 1.87 1.80 1.65 2.07 1.55 1.72 1.80 2.80

1.15 1.55 1.55 1.72 1.35 1.32 1.72 1.82 1.65 1.62 1.37 1.40 1.50 2.90

1.55 1.37 1.30 1.70 1.75 1.57 1.60 1.70 2.57

0.0001 0.6407 0.0026 0.0007 0.0001 0.1776 0.0455 0.5888 0.9290 0.3830 0.0209 0.2052 0.6116 0.2493

regression Y= - 1 6 . 8 7 / X + 4.14 gave a reasonably good fit (R 2 0.74). This relation can be also be expressed by fitting two linear regressions with different slopes that cross at 11 mg P kg- 1 soil (Fig. 2). No significant relation was found between herbage yield and the concentration of soil nitrogen or soil potassium. The phosphorus concentration in plants increased significantly in response to addition of P in most soils with low levels of available P (Table 5; Fig. 3 ). With increasing available soil P, P concentration in plants increased asymptotically towards a maximum of about 1.9 mg g - ~ (Fig. 3 ). The amount of phosphorus absorbed by the plants (P yield) was calculated =

Z. Henkin et al. / Agriculture Ecosystems and Environment 47 (1994) 299-311

307

2.5

D

2.0

= [] u=D ~n

,=,,

c3=D

w

E []

ore[]

1.5

1.0

=0,43

R 2

5D.

¢g 0.5 0

i

i

10

20

AVAILABLE SOIL P

(mg

30 soil)

P/kg

Fig. 3. Relationship between P concentration in plant and available P concentration in soil, and non-linear regression line. 12. e

10-

•

ee

6" .E I~.

~ 0-

4"

0. -2

10

20

AVAILABLE SOIL P

30 (rng

P/kg

soil)

Fig. 4. Relationship between P yield in plant in bio-assay and available P concentration in soil, and non-linear regression line.

as the amount of P in harvested plants minus the P in seeds. When the absorbed P was plotted against available soil P (Fig. 4), it appeared that there was virtually no P absorption by plants when the level of available soil P was less than 5 mg P kg- 1 soil, especially in the soil from the ungrazed plot (14). Phosphorus absorption by plants increased significantly and almost linearly between soil P concentrations of 5 and 11 mg P kg- 1 soil (linear regression, R 2 = 0 . 7 1 ). When the concentration of soil P was greater than 11 mg P kg -1 soil, the relation was weaker (R 2= 0.27 ) and the slope much lower. A reasonable overall fit was achieved by non-linear regression (Fig. 4 ). The amount of soil available P in each pot was calculated from the bicarbonate extractable P. The degree of utilization of this available phase by plants increased from 0 at a soil concentration of 5 mg P kg- ~ soil to a maximum of 40-60% in the 9-11 mg kg-~ range of soil available P concentration (Fig. 5 ). In soils with a higher P concentration there was a moderate decrease in the proportion of soil P utilized by the plants.

30 8

z. Henkin et al. / Agriculture Ecosystems and Environment 47 (1994) 299-311

70"

t

6O-

~ ~

6

5o4o.

A

A

i t .* A

Am

A

A

, A

A

AA

a

A~

~ w

g

a.,~

2oA

oA

qo

J

,

,

10

20

30

AVAILABLE SOIL P (mg p/kg soiL)

Fig. 5. Relationship between P utilization by plant (ratio of P in above-ground yield in plants to available P in soil) and P concentration in soil.

Discussion Black et al. ( 1965 ) suggested the following relationship between soluble P in the soil extract and the expected yield response to applied fertilizer P < 5 p.p.m., a positive response; between 5-10 p.p.m., probable response and P > 10 p.p.m., response unlikely. Sillanpaa ( 1982 ) showed a logarithmic relation between bicarbonate extractable P content of soil and P content of wheat and maize. In this study, all plant variables examined in the bioassay showed a similar response to available soil P (Figs. 1-4). As soil P increased from 5 to 11 mg P k g - 1 soil, there was a strong increase in dry matter yield, plant P concentration, P yield and height of the plants. In this range, soil available P was clearly the limiting factor for herbaceous plant growth. Between 11 and 15 mg P kgsoil increase in soil phosphorus had a moderate influence. Above concentration of 15 mg P kg- 1 soil the reaction of plants to an increase in soil P concentration was very slight, as other factors became limiting. No clear relation between plant yield and either soil potassium or nitrogen was found. It may be concluded, that in Mediterranean terra rossa soils where available P in the root zone is usually below 11 mg P kg- t soil, phosphorus is indeed the principal factor limiting growth of herbaceous plants. The cumulative influence of cattle grazing over 3 years increased the concentration of available phosphorus in the top soil layer (0-3 cm) in some grazed areas, compared with ungrazed control areas. The effect decreased with soil depth. In the 3-15 cm layer the effect was significant only in sites with locally high cattle activity. There was no change in phosphorus concentration in the soil at depths greater than 15 cm, except in the supplementary feeding site. Neither thinning of trees nor herbicide application to shrubs affected soil available phosphorus. The cattle in the natural scrubland browsed and grazed heavily on the woody and herbaceous vegetation. This did not, however, supply their full feed re-

Z. Henkin et al. /Agriculture Ecosystems and Environment 47 (1994) 299-311

309

quirements during most of the year. The requirements were met by ad lib feeding of supplementary feed mixes, 75% of which was poultry litter. The phosphorus concentration in poultry litter is between 1.5 and 2.5% (Katznelson, 1977; Holzer et al., 1986) of which about 75% is returned to the soil in animal excreta (Petersen et al., 1956a,b). The rest is digested and retained in the bodies of cattle. During the 3 years of grazing each cow received about 1500 kg of supplements a year and the grazing pressure was about 2 ha per cow in the heavily grazed plot. Thus, the cows excreted about 10 kg of phosphorus ha -1 year -1 on average, equivalent to 90 kg enriched (22% PaOs) superphosphate fertilizer h a - ~ year- 1. The cattle ranged over the whole area of the fields except for areas where the scrub was particularly dense. Evidence of cattle m o v e m e n t (signs of browsing, tracks and dung) were found even in areas with difficult access. However, the cows did not spend time uniformly over the area. Cattle movements and grazing habits were influenced by local topography and vegetation conditions and by the location of the feeding and watering points (Gillingham and Hamilton, 1980). Cattle have preferences for particular sites for camping (Barrow, 1967; Wilkinson and Lowrey, 1973 ) and for areas rich in palatable feed. These were more frequently visited and the cattle established a network of regularly used paths. The time spent in these sites and the amount of excreta deposited there are much greater than in the rest of the area (Petersen et al., 1956a; West et al., 1989 ). This uneven distribution of cattle activity was reflected in this study by the variation in the concentration of available phosphorus in the upper layer of the soil at the different sites. A consistent decrease of soil phosphorus concentration with distance away from the trough was found only up to a distance of 100 m. Beyond that distance, differences in concentrations were the result of local variation in grazing pressures from cattle site preference or because of factors not monitored in this study. Cattle grazing could be more effective in enriching the range in phosphorus and raising production of herbaceous plants if excreta were distributed more uniformly throughout the entire area. This could be achieved by changing the location of the feeding and watering points in the area from time to time. Over the years, continuous intensive grazing, together with high levels of poultry litter supplementation, is likely to increase the phosphorus availability gradually in larger parts of the area. Possibly, in time, P will also move down to deeper soil layers. As P is not easily leached from the soil, P concentration can build up over time. U n d e r the conditions of the present study, the time needed to obtain a satisfactory soil P level over the whole area grazed by cattle, could be more than 5 years. In order to improve herbaceous pasture production of scrub range lands on Mediterranean terra rossa soils suffering from phosphorus deficiency (4-9 mg P kg- 1 soil), soil available P concentration must be increased to at least 11 mg P kg- 1 soil in the upper layer. If this level is to be achieved rapidly,

310

z. Henkin et al. / Agriculture Ecosystems and Environment 47 (1994) 299-311

massive application of P fertilizer appears to be necessary (Henkin et al., 1990). Acknowledgements The authors thank the Jewish National Fund and the Water Authority, Ministry of Agriculture for financial support.

References Abbott, J.L. and Tucker, T.C., 1973. Persistence of manure phosphorus availability in calcareous soil. Soil Sci. Soc. Am. Proc., 37: 60-63. Barrow, N.J., 1967. Some aspects of the effect of grazing on the nutrition of pastures. J. Aust. I. Agric. Sci., 33: 254-262. Bar-Yosef, B. and Akiri, B., 1978. Sodium bicarbonate extraction to estimate nitrogen, phosphorus and potassium availability in soils. Soil Sci. Soc. Am. J., 42:319-323. Black, C.A., Evans, D.D., White, J.L., Ensminger, L.E. and Clark, F.E., 1965. Methods of soil analysis. Part 2. Am. Soc. Agron. Monograph 9. Center, M.D., Charles, E.V. and Jones, M.B., 1989. Effects of management on plant production and nutrient cycling on two annual grassland sites. Hilgardia, 57: 1-40. Dan, J., Yaalon, D.H., Koyumdjisky, H. and Raz, Z., 1976. The soils of Israel. Division of Scientific Publications, Bet Dagan, Israel, Pamphlet No. 159. Gillingham, A.G. and Hamilton, P.B., 1980. Phosphorus uptake and return in grazed, steep hill pastures: a. Pasture production and dung and litter accumulation. N.Z.J. Agric. Res., 23: 313-321. Gillingham, A.G., Hamilton, P.B., Syers, J.K. and Gregg, P.E.H., 1980. Phosphorus uptake and return in grazed, steep hill pastures: b. Above-ground components of the phosphorus cycle. N.Z.J. Agric. Res., 23: 323-330. Gutman, M., Noy-Meir, I., Seligman, N. and Holzer, Z., 1984. Research Report for 1981-1984 to Hatal Steering Committee (in Hebrew). Gutman, M., Noy-Meir, I., Seligman, N. and Holzer, Z., 1985. Beef cattle grazing in mediterranean oak (Quercus calliprinos) maquia. FAO - European cooperative network on pasture and foodder crop production, Bulletin No. 4, pp. 103-108. Henkin, Z., 1986. The relation between soil phosphorus, pasture yield and grazing in thinned out shrub land. M.Sc. Thesis, Hebrew University of Jerusalem, (in Hebrew). Henkin, Z., Gutman, M., Edelstein, G. and Noy-Meir, I., 1988. Changes in natural vegetative cover induced by thinning spraying and grazing. Hassadeh, 68:2016-2018 (in Hebrew). Henkin, Z., Noy-Meir, I., Kafkafi, U. and Gutman, M., 1990. The influence of phosphate fertilizer application on natural pasture in Galilee, Israel: triannual summary. Hassadeh, 71: 283-287 (in Hebrew). Holzer, Z. and Levy, D., 1976. Poultry litter as a protein supplement for beef cattle fed fibrous diets. World Review of Animal Production, 12:91-96. Holzer, Z., Morris, O.J., Gutman, M., Benjamin, R., Seligman, N. and Bogin, E., 1986. Physiological criteria for improvement of production efficiency in beef cows subjected to nutritional and environmental stress due to fluctuating grazing conditions. Final Report, BARD project No. 1 132-80, ARO, Bet-Dagan, Israel, 298 pp. Katznelson, J., 1977. Phosphorus in the soil-plant ecosystem. An introduction to a model. Oecologia, 26: 325-334.

z. Henkin et al. / Agriculture Ecosystems and Environment 47 (1994) 299-311

311

Koyumdjisky, H. and Dan, J., 1969. Forms and availability of soil phosphorus as related to genetic characteristics of Israel soils. Pamp. No. 13 I. Volcani Inst. Agric. Res., Bet-Dagan, Israel. Larsen, S., 1967. Soil phosphorus. Adv. Agron., 19:151-210. Marrs, R.H., Rizard, A. and Harrison, A.F., 1989. The effect of removing sheep grazing on soil chemistry, above-ground nutrient distribution, and selected aspects of soil fertility in longterm experiments at Moor house National Nature Reserve. J. Appl. Ecol., 26: 647-661. Murphy, W.E., 1986. Nutrient cycling in different pasture systems. 13th congress of the International Potash Institute. 25-28 August 1986, Reims, France, Int. Potash Institute, Bern, Switzerland. Ofer, Y. and Seligman, N.G., 1969. Fertilization of annual range in northern Israel. J. Range manage., 22: (5) 337-341. Olsen, S.R., Cole, C.M., Watanabe, F.S. and Dean, L.A., 1954. Estimation of available phosphorus in soils by extraction with sodium bicarbonate. U.S. Dept. Agric. Circ. No. 939. Petersen, R.G., Lucas, H.L. and Woodhouse, Jr., W.W., 1956a. The distribution of excreta by freely grazing cattle and its effect on pasture fertility: a. Excretal distribution. Agron. J., 48: 440-444. Petersen, R.G., Lucas, H.L. and Woodhouse, Jr., W.W., 1956b. The distribution of excreta by freely grazing cattle and its effect on pasture fertility: b. Effect of returned excreta on the residual concentration of some fertilizer elements. Agron. J., 48: 444-448. Rabinovich-Vin, A., 1979. Influence of parent rock on soil properties and composition of vegetation in the Galilee. Ph.D. Thesis, Hebrew University of Jerusalem (in Hebrew). SAS Institute, 1985. SAS user's guide: Statistics. Version 5 ed. SAS Inst. Cary, NC. Sillanpaa, M., 1982. Micronutrients and nutrient status of soils: A global study. F.A.O. Soil Bulletin, 48, FAO, Rome. Soil Survey Staff, 1975. Soil Taxonomy. Basic system of soil classification for making and interprinting soil surveys. Handbook U.S. Dep. Agric., 436. West, C.P., Mallarino, W.F., Wedin, W.F. and Marx, D.B., 1989. Spatial variability of soil chemical properties in grazed pastures. Soil Sci. Soc. Am. J., 53: 784-789. Wilkinson, S.R. and Lowrey, R.W., 1973. Cycling of mineral nutrients in pasture ecosystems. In: G.W. Butler and R.W. Bailey (Editors), Chemistry and Biochemistry of Herbage. Vol. 2. Academic Press, London, pp. 247-315.