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TECHNICAL REPORT
Waste Management

Irrigation with Effluents

Effects of Prewetting Rate and Clay Content on Runoff and Soil Loss

Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization (ARO), The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel

* Corresponding author (vwguy{at}volcani.agri.gov.il)

Received for publication August 21, 2000.

	ABSTRACT

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSOIN SUMMARY AND CONCLUSIONS REFERENCES

 
Stability of soil surface aggregates and irrigation water quality significantly affect runoff and soil erosion. Slow wetting of aggregates prevents slaking. We hypothesized that wetting rate will affect a soil's susceptibility to seal formation and soil erosion, and that this susceptibility will differ between effluent- and fresh water (FW)–irrigated soils. Effects of prewetting rate (2, 4, 8, and 64 mm h^-1) on runoff and interrill erosion from five Israeli soils exposed to 60 mm of simulated rain were studied in the laboratory. Soils were taken from fields irrigated with FW or effluents for >15 yr. In general, for effluent- and FW-irrigated samples, runoff and soil loss were greatest for the soil with 22.5% clay; at lower or higher clay contents, less runoff and soil losses were noted. Runoff and soil loss decreased with decreasing prewetting rate (PWR) mainly in soils with clay content 38%. Total runoff and soil loss were higher in effluent-irrigated soils than in FW-irrigated ones in the loamy sand (8% clay) only. Greater soil losses occurred from effluent-irrigated soils exposed to fast PWR (64 m h^-1) compared with FW-irrigated soils. In general, PWR had similar effects on total runoff and soil loss for effluent- and FW-irrigated soils. Use of wetting rates 8 mm h^-1 to prevent aggregate slaking decreased runoff and soil loss from loam and clayey soils exposed to simulated rainfall of high kinetic energy (15.9 kJ m^-3). Long term irrigation with effluents in soils containing >20% clay did not seem to adversely affect soil susceptibility to runoff and soil loss in soils exposed to simulated rainfall, beyond that observed in FW-irrigated soils.

Abbreviations: ESP, exchangeable sodium percentage • FW, fresh water • IR, infiltration rate • PWR, prewetting rate • SAR, sodium adsorption ratio • WG, Western Galilee • ZV, Zevulun Valley

	INTRODUCTION

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSOIN SUMMARY AND CONCLUSIONS REFERENCES

 
USE of secondary-treated sewage water (effluents) for irrigation of arable lands has become a common practice in regions suffering from a shortage of fresh water. In Israel, salt concentration and sodium adsorption ratio (SAR) of effluents may reach levels of 17 to 20 mmol_c L^-1 and 5 to 8, respectively, compared with salt concentration and SAR of 8 to 10 mmol_c L^-1 and 2, respectively, in FW (Feigin et al., 1991). Irrigation with water of such SAR leads to soils with exchangeable sodium percentage (ESP) of a similar value (U.S. Salinity Laboratory Staff, 1954), and to a subsequent deterioration in soil hydraulic properties when exposed to rain (Shainberg and Levy, 1992). Effluents also contain dissolved organic matter. The level of dissolved organic matter depends on the quality of the raw sewage water and the degree of its treatment. Dissolved organic matter may enhance clay dispersivity (Durgin and Chaney, 1984; Frenkel et al., 1992), although its effect on soil hydraulic conductivity appears to be inconclusive, having negative (Tarchitzky et al., 1999), or no effect (Levy et al., 1999).

Surface seal formation due to raindrop impact and low infiltration rate are the main reasons for runoff initiation and subsequent sediment transport. Seal formation is caused by two mechanisms: (i) physical disintegration of soil aggregates and their compaction and (ii) a physico–chemical dispersion and movement of clay particles into a region of 0.1 to 0.5 mm in depth, where they lodge and clog conducting pores (McIntyre, 1958; Agassi et al., 1981). The latter mechanism is controlled mainly by concentration and composition of cations in the soil and applied water (Agassi et al., 1981; Kazman et al., 1983) as well as clay content (Ben-Hur et al., 1985). Thus, it is expected that soils irrigated with effluents will have ESP levels of approximately 6, and will exhibit higher susceptibility to seal formation and soil erosion than soils irrigated with FW.

Physical disintegration of soil surface aggregates is a consequence of wetting (Kemper and Koch, 1966; Kay and Angers, 1999) and raindrop impact (Betzalel et al., 1995). Degree of aggregate disintegration by wetting depends on PWR (Quirk and Panabokke, 1962; Kay and Angers, 1999). Explosion by entrapped air and differential swelling were suggested as mechanisms for aggregate disintegration by wetting (Panabokke and Quirk, 1957; Quirk and Panabokke, 1962). The extent of aggregate disintegration by wetting, termed slaking, depends also on aggregate stability, which is related to organic matter and sesquioxides content, clay percentage, and soil sodicity (Kemper and Koch, 1966; Kay and Angers, 1999). For soils from semiarid regions, a good correlation was found between clay content (in the range between 5 and 90%) and wet sieve aggregate stability. This was attributed to clay particles acting as a bonding agent holding particles together in aggregates (Kemper and Koch, 1966). Recent studies showed that when aggregates were wetted slowly, by a matric potential of -1.0 kPa for 24 h (Le Bissonnais and Singer, 1992) or at a rate of 1 mm h^-1 (Levy et al., 1997), soil susceptibility to seal formation and runoff was reduced.

Aggregate disintegration by raindrops depends on drop impact energy (e.g., Betzalel et al., 1995; Mamedov et al., 2000). Mamedov et al. (2000), who studied the effects of rain kinetic energy on soil infiltration, reported that under moderate rain kinetic energy (8 kJ m^-3), final infiltration rate (IR) of effluent-irrigated soils was significantly lower than that of FW-irrigated soils; when rain kinetic energy was >12 kJ m^-3 or <4 kJ m^-3, final IR values for effluent- and FW-irrigated soils were similar. Mamedov et al. (2000) suggested that at rain kinetic energy >12.4 kJ m^-3, raindrop energy determined seal permeability; hence effects of higher ESP in the effluent-irrigated soils on seal permeability were overshadowed by the rain properties. It should be noted that Mamedov et al. (2000) prewetted the soils by a matric potential of 0.2 kPa, which has been considered as fast prewetting (Levy et al., 1997). The results of Mamedov et al. (2000) suggest that under conditions of fast PWR (where aggregate slaking is enhanced), and rain of high kinetic energy, the latter determines soil susceptibility to seal formation. It is hypothesized that when slow PWR is used (thereby preventing aggregate slaking), the effect of high kinetic energy rain on seal formation will be less pronounced, and the susceptibility of soils irrigated with effluents to seal formation and interrill erosion will be higher than that of soils irrigated with FW.

The objective of this study was to test our hypothesis on a range of soils varying in clay content, by studying four PWRs (2, 4, 8, and 64 mm h^-1) on runoff and soil loss from soils irrigated for >15 yr with FW and effluents, and subjected to simulated rainfall having a kinetic energy of 15.9 kJ m^-3.

	MATERIALS AND METHODS

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSOIN SUMMARY AND CONCLUSIONS REFERENCES

 
Soils
Five Israeli smectitic soils, varying in clay content, were chosen for this study: a loamy sand (Typic Haploxeralf) from the Coastal Plain; a loam (Calcic Haploxeralf) from the Be'er Sheva Valley; a sandy clay (Chromic Haploxerert) from the Pleshet Plains; and two clayey soils (Typic Haploxerert) from the Zevulun Valley (clay, ZV) and Western Galilee (clay, WG). Samples from the cultivated layer (0–250 mm) of each soil were taken from adjacent fields irrigated for >15 yr, one with FW and the other with effluents. Selected soil physical and chemical properties, determined by standard analytical methods (Klute, 1986; Page et al., 1986) are presented in Table 1. Effluent properties are presented in Table 2. Ion values given in Table 2 are actual effluent values used for irrigation. Organic load (biological oxygen demand [BOD], chemical oxygen demand [COD], total suspended solids) of the effluents changed over the years. Values presented were obtained in 1998. Fresh water samples used were taken from fields that were irrigated from the same FW source (the national water carrier of Israel). Coefficient of variation among replicates for soil properties and water properties determined was low (<6%).

Similar to common practice in many former seal formation studies (e.g., Shainberg and Levy, 1992, and references cited therein), the soil samples were air-dried and crushed to pass through a 4.0-mm sieve. Furthermore, Shainberg et al. (1997), who studied the effects of aggregate size in the range of <12 mm, concluded that although there is a possible risk of altering the structure of the soils when sieves with small opening are used to sieve the soil, differences in final infiltration rate (and hence seal properties) among the various aggregate sizes studied were meaningless. The sieved soil samples were packed in 200- x 400-mm trays, 40 mm deep, over a 10-mm-thick layer of coarse sand. The trays were placed in a horizontal position and wetted with tap water (electrical conductivity = 0.9 dS m^-1 and SAR = 2.5) from the bottom by a peristaltic pump at a rate of 2 (slow), 4 (intermediate), 8 (medium), or 64 (fast) mm h^-1. Tap water was used for wetting in order to avoid soil swelling and dispersion during the wetting procedure, especially in the more sodic effluent-irrigated soils. After wetting, soil trays were aged for 15 min, then placed in the rainfall simulator at a slope of 15%. This slope does not resemble natural slopes of agricultural fields. However, in order to obtain soil erosion and be able to detect differences in erosion among treatments, it was necessary to use this level of slope. Soil trays were exposed to 60 mm of distilled water (rain). During each storm, water infiltrating through the soil was collected intermittently (every 4 min) in graduated cylinders placed underneath a special outlet at the bottom of the tray, and its volume was recorded. Thus, for a 60-mm simulated rainfall event, infiltration water was collected 25 times. Runoff was collected continuously throughout the simulated rainfall event. At the end of the event, runoff and suspended sediments collected in buckets were thoroughly mixed and a 0.25-L subsample taken. The subsample was dried, weight of eroded material determined, and total soil loss from the entire storm calculated. Splash from the trays was not measured. The sediments collected were mainly due to wash erosion and to a smaller degree to splash sediments that landed on the soil tray. Three replicates were used for each treatment.

Data Analysis
Infiltration data obtained from rainfall simulator runs were analyzed using the nonlinear equation proposed by Morin and Benyamini (1977):

[1]

where I_t is the instantaneous infiltration rate (mm h^-1); I_i is the initial infiltration rate (mm h^-1); I_f is the final infiltration rate (mm h^-1); is the soil coefficient related to surface aggregate stability (mm^-1); t is the time from the beginning of the storm (h), and p is the rain intensity (mm h^-1).

A nonlinear regression program was used with measured I_t, I_f, and P values as input parameters to calculate I_i and to give the best coefficient of determination (R² > 0.9) between paired calculated and measured I_t values.

Runoff volume (R_off) for any given depth of rain (N) from each rainfall event was calculated as follows:

[2]

where I_t is the calculated instantaneous infiltration rate for interval j, p is the rain intensity, and d_j is depth of rain applied during interval j (d was taken as 1 mm for all intervals). For cases where (I_t)_j > p, (I_t)_j was taken as equal to p. We preferred to use calculated runoff values rather than measured runoff data because of water splash from the soil boxes, which could amount to 15% of the applied rain (Agassi and Levy, 1991).

Calculated runoff values and measured soil loss data were subjected to a multifactor analysis of variance (SAS Institute, 1995). In cases where interactions were noted among main treatments, differences among total runoff or soil loss of individual treatments was determined using a single confidence interval value.

	RESULTS AND DISCUSSOIN

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSOIN SUMMARY AND CONCLUSIONS REFERENCES

 
Irrigation of the soils with effluents increased their ESP from 0.9 to 2.1 (in FW) to 2.4 to 6.4 (Table 1). The SAR of effluents in Western Galilee (clay, WG) was relatively low, 3.2 (Table 2). The ESP of this soil, therefore, remained low even after long periods of irrigation with effluents. In addition, irrigation for >15 yr with effluents had no effect on soil organic matter content (Table 1). Intense cultivation under the Mediterranean climate generally prevented organic matter accumulation in fields irrigated with effluents.

Infiltration and Runoff
Measured IR values into the five soils irrigated with effluent or FW for the two extreme PWR are presented in Figure 1 . Prewetting rate, irrigation water quality (FW vs. effluents), and clay content influenced the IR curves. The IR decreased with an increase in rain depth, which was mainly due to seal formation (Fig. 1). Increasing PWR decreased IR and increased seal formation rate. Decrease in IR was sharper in effluent-irrigated soils than in FW-irrigated ones; however, the specific effect of the quality of the irrigation water depended on clay content and PWR. Effects of clay content on IR curves showed that soils with the lowest and highest clay content were less sensitive to seal formation. Because IR curves are only, in part, a quantitative comparison between treatments, two parameters have often been used to quantify changes in IR curves: (i) measured IR at the end of the storm (final IR), and (ii) total volume of runoff obtained from the storm. We preferred to use total runoff rather than the final IR, because the former is an integrated value that reflects the changes in IR during the entire infiltration curve, in contrast to final IR, which represents only one point of the infiltration curve. It should be borne in mind that in our study computed total runoff values (based on Eq. [1] and [2]) were used.

View larger version (36K): [in this window] [in a new window]   Fig. 1. Effect of prewetting rate on measured infiltration rates of five soils irrigated with (a) fresh water or (b) effluents.

View larger version (24K): [in this window] [in a new window]   Fig. 2. Computed total runoff as a function of clay content and prewetting rate for soils irrigated with (a) fresh water or (b) effluents. Bar indicates a single confidence interval value at = 0.05.

Effects of PWR on runoff differed among soils. In the sandy clay and the two clay soils, decreasing PWR decreased runoff significantly (Fig. 2a). The favorable effect of decreasing PWR on decreasing runoff in a clay soil was already noted by Levy et al. (1997). Clayey soils (>35% clay) are well structured and aggregated. Aggregate stability has been found to increase with an increase in clay content in the range of up to 90% clay (Kemper and Koch, 1966). Prewetting rate affects aggregate slaking (Panabokke and Quirk, 1957; Loch, 1994). By increasing PWR, degree of aggregate slaking in clayey soils increased, and the soil surface became more susceptible to compaction, particle rearrangement, clay dispersion, and seal formation. Thus, runoff increased with increased PWR (Fig. 2a). In addition, for any given PWR, total runoff was in the following decreasing order: sandy clay > clay (ZV) > clay (WG) (i.e., total runoff decreased as clay content increased) (Fig. 2a). This can be explained by the fact that aggregate breakdown by slaking decreases as clay content increases (Panabokke and Quirk, 1957), and/or fragments resulting from slaking are mainly microaggregates whose size increases with increasing clay content (Le Bissonnais, 1996). Larger fragments remaining at the soil surface after wetting result in a more permeable seal and less runoff (Shainberg et al., 1997). Hence, for any given PWR, total runoff in the clay (WG) was lower than that from the sandy clay and clay (ZV) whose clay content was lower than that of the clay (WG).

Unlike the clayey soils, PWR in the range of 2 to 8 mm h^-1 did not affect runoff in the loamy sand and loam; only with the fast PWR (64 mm h^-1) did a small but significant increase in runoff occur (Fig. 2a). Clay content of the loamy sand and the loam (8 and 22.5%, respectively) was markedly lower than that of the clayey soils (Table 1). These two soils are structureless and poorly aggregated. In structureless soils, slaking of aggregates by fast prewetting is limited. Thus no increase in runoff was observed for the PWR of the 2 to 8 mm h^-1 treatment. However, when these poorly structured soils where exposed to a high PWR (64 mm h^-1), soil particles at the soil surface became more susceptible to raindrop impact, seal formation, and runoff (Fig 2a).

Runoff for soils irrigated with effluents is presented in Fig. 2b. Changes in runoff with clay content followed the same patterns as those for FW-irrigated soils. With the exception of the loam (22.5% clay), effects of PWR were similar for effluent- and FW-irrigated soils (Fig. 2b). For the effluent-irrigated loam, changing PWRs in the range of 2 to 8 mm h^-1 increased runoff, a result not observed in the FW-irrigated loam (Fig. 2a). Long-term irrigation with effluents may have contributed to aggregate stabilization of the loess, making it sensitive to small changes in the prewetting rate, as was observed in the clayey soils. Note that the effluent used to irrigate the loam contained relatively high organic matter (Table 2). The favorable effect of high concentration of organic matter in the effluent on aggregate stability was also noted in the clay (ZV).

Higher loads of organic matter in effluents originating from municipal sewage water (as was the case in our study) could result from an incomplete purification treatment (e.g., short stay in oxidation ponds), and may suggest that the organic matter in the water could be more aliphatic, less oxidized, and of lower aromaticity than effluents exposed to a complete treatment. It has been reported that a soil containing organic matter whose humic acids are more aliphatic and have a lower aromaticity was less susceptible to sealing and/or crusting than a soil containing humic acids rich in aromaticity (Arshad and Schnitzer, 1987). This hypothesis that links the characteristics of the organic matter in the effluents to its effects on aggregate stabilization requires further in-depth investigation.

The soils can be divided into three groups based on comparisons of runoff from FW- and effluent-irrigated soils. Group 1 contained the loamy sands. Runoff was higher in effluent-irrigated soils than in FW-irrigated ones (Fig. 2a,b). Of the two mechanisms leading to seal formation (aggregate breakdown and clay dispersion), clay dispersion was dominant in this soil (Agassi et al., 1981; Ben-Hur et al., 1985). Thus, in the loamy sand, the difference in ESP between effluent- and FW-irrigated soils (Table 1) affected seal properties, resulting in higher runoff from effluent-irrigated soils. Furthermore, runoff for different PWRs hardly differed, especially when a PWR of 2, 4, or 8 mm h^-1 was used. Hence in the loamy sand, rain kinetic energy and ESP, rather than PWR, determined the susceptibility of effluent-irrigated soils to sealing and runoff relative to that of FW-irrigated ones.

The second soil group contained the loam, sandy clay, and clay (WG) soils. Runoff from effluent-irrigated soils was similar to or higher than those from FW-irrigated soils (Fig. 2a,b). In treatments where runoff from effluent-irrigated soils was significantly greater than that from FW-irrigated ones, differences in runoff were <10%. Hence for practical purposes, such differences were not considered meaningful. For Group 2 soils, PWRs had a similar effect on the susceptibility of effluent- and FW-irrigated soils to sealing and runoff production. Apparently, in this soil group, rain properties (i.e., high kinetic energy) dictated soil sensitivity to seal formation and runoff initiation irrespective of PWR. Thus, reducing aggregate slaking by using relatively slow PWRs was not effective in separating differences in the susceptibility to sealing and runoff of soils with ESP = 2 (FW-irrigated soils) and those with ESP = 6 (effluent-irrigated soils).

The third soil group contained the clay (ZV) soils. Although the ESP of effluent-irrigated soils was high (6.4), runoff was similar to or less from effluent-irrigated soils than from FW-irrigated ones (Fig. 2a,b). Irrigation with effluents seemed to decrease the susceptibility of the clay (ZV) to sealing compared with that of FW-irrigated soils. Observations are ascribed to characteristics of the organic matter in effluents used for irrigation (as discussed previously), and higher clay content of effluent-irrigated soil (54.6%) compared with the FW-irrigated one (51.3%).

Soil Loss
Soil loss as a function of PWR and clay content is presented in Fig. 3 . Results of a multifactor analysis of variance showed that each main treatment (soil type, irrigation water quality, and PWR) significantly affected soil loss (Table 3). Moreover, a significant interaction (p = 0.05) was observed among the main treatments in their effect on soil loss. (Table 3). A single confidence interval (Fig. 3) has been used to identify significant differences among individual treatments.

View larger version (24K): [in this window] [in a new window]   Fig. 3. Soil loss as a function of clay content and prewetting rate for soils irrigated with (a) fresh water or (b) effluents. Bar indicates a single confidence interval value at = 0.05.

View larger version (17K): [in this window] [in a new window]   Fig. 4. Soil loss versus computed total runoff for all soils studied.

Three trends emerged from the comparison of soil losses from effluent-irrigated vs. FW-irrigated soils. First, in the loamy sand, the soil with the lowest clay content (Table 1), soil losses from effluent-irrigated soils were significantly greater than those in the FW-irrigated ones at all the PWRs (Fig. 3a,b). Soil loss depended on water quality and PWR in a similar way to total runoff, as could be expected from the linear relation between the two parameters (Fig. 4). Second, in the loam, sandy clay, and the two clay soils, soil loss from effluent-irrigated soils was significantly greater than that from FW-irrigated ones when fast wetting rate (64 mm h^-1) was used (Fig. 3a,b). Third, in the loam, sandy clay, and the two clay soils, soil losses from effluent- and FW-irrigated soil were, generally, similar for the other PWR treatments (2, 4, and 8 mm h^-1), (Fig. 3a,b). Soil loss from effluent- and FW-irrigated soils at these PWRs resembled trends observed for runoff (Fig. 2a,b).

	SUMMARY AND CONCLUSIONS

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSOIN SUMMARY AND CONCLUSIONS REFERENCES

 
Effects of PWR and clay content on runoff and soil loss from five Israeli smectitic soils irrigated with FW or effluents were studied. Total runoff and soil loss depended on clay content. The soil with 22.5% clay was the most susceptible to runoff and soil loss compared with soils with lower or higher clay contents. Prewetting rate affected runoff and soil loss mainly in soils whose clay content was >38%. Prewetting rate had, in general, comparable effects on total runoff and soil loss for effluent- and FW-irrigated soils. Only for the loamy sand (8% clay) was total runoff and soil loss greater in effluent-irrigated soils than in FW-irrigated ones. Greater soil losses occurred from effluent-irrigated soils exposed to fast PWR (64 m h^-1) compared with losses from FW-irrigated soils. Conversely, in the loam and clay (ZV), there were indications that irrigation with effluents may have decreased the susceptibility of the soil to sealing. This could be due to variations in organic matter characteristics in effluents and their effects on soil structural stability.

Excluding the loamy sand, we conclude that slow wetting (8 mm h^-1) to limit aggregate slaking was not effective in soils exposed to high kinetic energy rain (15.9 kJ m^-3) in isolating susceptibility to runoff and soil loss from effluent- vs. FW-irrigated soils. Such a separation was noted when rain of medium kinetic energy (8 kJ m^-3) and fast wetting (64 mm h^-1) were used (Mamedov et al., 2000). Evidently, when high energy rain is used, its kinetic energy is high enough to override the favorable effects of slow prewetting on aggregate stability. Hence, for Mediterranean-type rainstorms it is expected for soils with medium and fine texture (>20% clay) that long term irrigation with effluents will not cause adverse effects on soil sensitivity to runoff and soil erosion beyond those observed with irrigation with FW.

	ACKNOWLEDGMENTS

 
A.I. Mamedov is grateful to MASHAV, Israel Ministry of Foreign Affairs, and the Agricultural Research Organization, Bet Dagan, Israel, for providing him with the funds that enabled him to contribute to this work. This study was supported by Grant no. 302-0240-98 from the Chief Scientist, Ministry of Agriculture and Rural Development, Israel. The support of the Chief Scientist is gratefully acknowledged.

	NOTES

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSOIN SUMMARY AND CONCLUSIONS REFERENCES

 
Contribution from the Agricultural Research Organization (ARO), The Volcani Center, Bet Dagan, Israel. No. 605/2000 series.

	REFERENCES

TOP NOTES ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSOIN SUMMARY AND CONCLUSIONS REFERENCES

 

• Agassi, M., and G.J. Levy. 1991. Stone-cover and rain intensity: Effects on infiltration, erosion and water splash. Aust. J. Soil Res. 29:565–575.
• Agassi, M., I. Shainberg, and J. Morin. 1981. Effect of electrolyte concentration and soil sodicity on infiltration rate and crust formation. Soil Sci. Soc. Am. J. 45:848–851.[Abstract/Free Full Text]
• Arshad, M.A., and M. Schnitzer. 1987. Characteristics of the organic matter in a slightly and in a severely crusted soil. Z. Pflanzenernaehr. Bodenkd. 150:412–416.
• Ben-Hur, M., I. Shainberg, D. Bakker, and R. Keren. 1985. Effect of soil texture and CaCO₃ content on water infiltration in crusted soils as related to water salinity. Irrig. Sci. 6:281–294.
• Betzalel, I., J. Morin, Y. Benyamini, M. Agassi, and I. Shainberg. 1995. The effect of water drop energy on seal formation. Soil Sci. 159:13–22.
• Durgin, P.B., and J.G. Chaney. 1984. Dispersion of kaolinite by dissolved organic matter from Douglas-fir roots. Can J. Soil Sci. 64: 445–455.
• Epema, G.F., and H.Th. Riezebos. 1983. Fall velocity of water drops at different heights as a factor influencing erosivity of simulated rain. Catena Suppl. 4:1–17.
• Feigin, A., I. Ravina, and J. Shalhevet. 1991. Irrigation with treated sewage effluent. Management for environmental protection. Adv. Ser. in Agric. Sci. Vol. 17. Springer–Verlag, Berlin.
• Frenkel, H., M.V. Fey, and G.J. Levy. 1992. Organic and inorganic anion effects on reference and soil clay critical flocculation concentration. Soil Sci. Soc. Am. J. 56:1762–1766.[Abstract/Free Full Text]
• Kay, B.D., and D.A. Angers. 1999. Soil structure. p. A229–A276. In M.E. Sumner (ed.) Handbook of soil science. CRC Press, Boca Raton, FL.
• Kazman, Z., I. Shainberg, and M. Gal. 1983. Effect of low levels of exchangeable Na and applied phosphogypsum on the infiltration rate of various soils. Soil Sci. 35:184–192.
• Kemper, W.D., and E.J. Koch. 1966. Aggregate stability of soils from western United States and Canada. Tech. Bull. 1355. USDA Agric. Res. Serv., Washington, DC.
• Klute, A. (ed.) 1986. Methods of soil analysis. Part 1. Physical and mineralogical methods. 2nd ed. Agron. Monogr. 9. ASA and SSSA, Madison, WI.
• Le Bissonnais, Y. 1996. Aggregate stability and assessment of soil crustability and erodibility. I. Theory and methodology. Eur. J. Soil Sci. 47:425–437.
• Le Bissonnais, Y., and M.J. Singer. 1992. Crusting, runoff, and erosion response to soil water content and successive rainfalls. Soil Sci. Soc. Am. J. 56:1898–1903.[Abstract/Free Full Text]
• Levy, G.J., J. Levin, and I. Shainberg. 1994. Seal formation and interrill soil erosion. Soil Sci. Soc. Am. J. 58:203–209.[Abstract/Free Full Text]
• Levy, G.J., J. Levin, and I. Shainberg. 1997. Prewetting rate and aging effect on seal formation and interrill soil erosion. Soil Sci. 162: 131–139.
• Levy, G.J., A. Rosenthal, J. Tarchitzky, I. Shainberg, and Y. Chen. 1999. Soil hydraulic conductivity changes caused by irrigation with reclaimed waste water. J. Environ. Qual. 28:1658–1664.[Abstract/Free Full Text]
• Loch, R.J. 1994. A method for measuring aggregate water stability with relevance to surface seal development. Aust. J. Soil Sci. 32:687–700.
• Mamedov, A.I., I. Shainberg, and G.J. Levy. 2000. Irrigation with effluent water: Effect of rainfall energy on soil infiltration. Soil Sci. Soc. Am. J. 64:732–737.[Abstract/Free Full Text]
• McIntyre, D.S. 1958. Permeability measurement of soil crusts formed by raindrop impact. Soil Sci. 85:185–189.
• Morin, J., and Y. Benyamini. 1977. Rainfall infiltration into bare soils. Water Resour. Res. 13:813–817.
• Page, A.L, R.H. Miller, and D.R. Keeney (ed.) 1986. Methods of soil analysis. Part 2. Chemical and microbiological properties. 2nd ed. Agron. Monogr. 9. ASA and SSSA, Madison, WI.
• Panabokke, C.R., and J.P. Quirk. 1957. Effect of initial water content on stability of soil aggregates in water. Soil Sci. 83:185–195.
• Quirk, J.P., and C.R. Panabokke. 1962. Incipient failure of soil aggregates. J. Soil Sci. 13:60–69.
• SAS Institute. 1995. SAS guide for personal computers. Version 6.07 ed. SAS Inst., Cary, NC.
• Shainberg, I., and G.J. Levy. 1992. Physico–chemical effects of salts upon infiltration and water movement in soils. p. 37–94. In R.J. Wagenet et al. (ed.) Interacting processes in soil science. Adv. in Soil Sci. Lewis Publ., Boca Raton, FL.
• Shainberg, I., G.J. Levy, J. Levin, and D. Goldstein. 1997. Aggregate size and seal properties. Soil Sci. 162:470–478.
• Tarchitzky, J., Y. Golobati, R. Keren, and Y. Chen. 1999. Wastewater effects on montmorillonite suspensions and hydraulic properties of sandy soil. Soil Sci. Soc. Am. J. 63:554–560.[Abstract/Free Full Text]
• U.S. Salinity Laboratory Staff. 1954. Diagnosis and improvement of saline and alkali soils. Handbook 60. USDA, Washington, DC.

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