120:
of ethanol with lower surface tension is then placed on a different area of the sample. The results of the MED test depend on the molarity of the ethanol solution whose droplets were absorbed in the allotted 10 seconds. Classifying soil water repellency from this test can be done by using a MED index where a non-water repellent soil has an index of less than or equal to 1 and a severely water repellent soil has an index of greater than or equal to 2.2. The MED index, 90º surface tension, ethanol molarity, and volume percentage correlate and can be converted into one another. In this test, the liquid-air surface tension value of the ethanol solution that is absorbed within this timeframe is used as the ninety-degree surface tension of the soil. The water entry pressure associated with the tested soil is another indicator of infiltration rates as it is associated with the degree of water repellency along with soil pore size.
155:
increased the yield by 1 t/ha within a time frame of 2 years. Liming is another method to reduce soil water repellency. The process of liming consists of adding calcium carbonate to increase the pH of soil. Humic acid is only water-soluble at a pH of greater than 6.5 while fulvic acid is soluble at all pH ranges. Both resident acids have a property that enables them to reduce the surface tension of water when in solution. By increasing the pH of soil, the ability of naturally occurring fulvic acid and humic acid to increase infiltration in hydrophobic soils increases. In contrast, it has been reported that soils with a deficiency of fluvic acid in solution would have more severe water repellency.
54:
plays a large role in predicting whether a soil could be water repelling as larger grained particles in the soil such as sand have smaller surface areas, making them more prone to being fully coated by hydrophobic compounds. It is much more difficult to entirely coat a silt or clay particle with more surface area, but when it does happen, the resulting water repellency of the soil is severe. As soil organic matter in the form of plant or microbial biomass decomposes, physiochemical changes can release these hydrophobic compounds into the soil as well. This, however, depends on the type of microbial activity present in the soil as it can also hinder the development of hydrophobic compounds.
42:
1327:
63:
infiltration is expressed as water entering the soil in a spontaneous fashion and correlates with the angle of the water-soil contact. If the water-soil contact angle is greater than 90º, then the soil is determined to be hydrophobic. It has also been observed that if the test droplet is placed on hydrophobic soil, it will rapidly develop a particulate skin before disappearing.
133:
If irrigation or precipitation events are large, the water could potentially flow below the root zone, making it unavailable to any plant life and oftentimes taking fertilizers and nutrients with it. This additionally leads to an uneven distribution of nutrients and applied chemicals resulting in patchy vegetation.
146:
coarse-textured soils such as sand-dominated soils, it affects soils of all different soil types and has been reported in forests, pastures, agricultural plots, and shrublands. Generally, the degree of hydrophobicity is more severe in the soils of legume-grass pastures compared to cultivated agricultural fields.
162:
Naturally forming holes and cracks in hydrophobic soil patches allow for water to infiltrate the surface. These can form from burrowing animals, root channels, or macropores from decayed roots. These macropores have been identified as important pathways in forest ecosystems for water to penetrate the
158:
The agricultural practice of tilling decreases the degree of soil water repellency. Tilling crop fields reduces the carbon content of the soil through mixing and mineralization, thus decreasing the likelihood of decomposition by microorganisms that can lead to the dispersal of the hydrophobic coating
132:
Drainage of nutrients occurs in weaker areas of repellency in hydrophobic soil where water preferentially drains into the soil. Because the water cannot drain into the stronger areas of hydrophobicity, the water finds pathways of preferential flow where it can infiltrate deeper into the soil profile.
37:
It was found that in a particular New
Zealand sand, this waxy lipid coating consisted of primarily hydrocarbons and triglycerides that were basic in pH along with a lesser value of acidic long-chain fatty acids. Capillary penetration amongst soil particles is limited by the hydrophobic coating on the
119:
Another method for determining soil water repellency is the molarity of ethanol droplet (MED) test. The MED test uses solutions of ethanol of varying surface tensions to observe soil wetting within a time frame of 10 seconds. If there is no wetting within the specified timeframe, an aqueous solution
53:
Other important soil water averting factors have been found to include soil texture, microbiology, soil surface roughness, soil organic matter content, soil chemical composition, acidity, soil water content, soil type, mineralogy of clay particles, and seasonal variations of the region. Soil texture
154:
One method of managing water repellent soils is claying. This is done by adding clay materials to the soil, making the overall soil texture have less surface area. It has been found that adding clay to a hydrophobic field of barley increased crop yield from 1.7 to 3.4 t/ha, and in a field of lupins
33:
Hydrophobic soil is most familiarly formed when a fire or hot air disperses waxy compounds found in the uppermost litter layer consisting of organic matter. After the compounds disperse, they mainly coat sandy soil particles near the surface in the upper layers of soil, making the soil hydrophobic.
48:
The structure of a hydrophobic sand particle versus an unaffected soil particle. The hydrophobic soil particle is coated in a wax-like lipid compound with a hydrophilic head is attached to the individual particle and the hydrophobic tail is surrounding the outside of the particle. This hydrophobic
136:
In an agricultural setting, hydrophobic soil is a large constraint on crop yields. For example, in
Australia, there have been documented reports of up to 80% loss in production due to soil water repellency. This is due to low rates of seed germination in soils as well as low plant available water
128:
Hydrophobic soils and their aversion to water have consequences on plant water availability, plant-available nutrients, hydrology, and geomorphology of the affected area. By reducing the infiltration rate, runoff generation time is reduced and leads to an increase in the land flow of water during
62:
Soil water repellence is almost always tested with the water droplet penetration time (WDPT) test first because of the simplicity of the test. This test is executed by recording the time it takes for one droplet of water to infiltrate a specific soil, indicating the stability of repellency. Water
145:
Hydrophobic soils have been found on all continents except for
Antarctica. It occurs in dry regions in the United States, southern Australia, and the Mediterranean Basin, and in wet regions including Sweden, the Netherlands, British Columbia, and Columbia. Although it mainly appears in
34:
Other producers of hydrophobic coatings are contamination and industrial spillages along with soil microbial activity. Hydrophobicity can also be seen as a natural soil property that results from the degradation of natural vegetation such as
Eucalyptus that has natural wax properties.
24:
is a soil whose particles repel water. The layer of hydrophobicity is commonly found at or a few centimeters below the surface, parallel to the soil profile. This layer can vary in thickness and abundance and is typically covered by a layer of ash or burned soil.
129:
precipitation or irrigation events. Greater runoff increases erosion, causes uneven wetting patterns in soil, accelerates nutrient leaching reducing soil fertility, develops different flow paths in the region, and increases the risk of contamination in soils.
38:
particles, resulting in water repellence in each particle affected as the hydrophilic head of the lipid attaches itself to the sand particle leaving the hydrophobic tail shielding the outside of the particle. This can be seen in Figure 1 below.
462:
Ruthrof, Katinka X.; Hopkins, Anna J. M.; Danks, Melissa; O’Hara, Graham; Bell, Richard; Henry, David; Standish, Rachel; Tibbett, Mark; Howieson, John; Burgess, Treena; Harper, Richard (October 2019).
49:
tail shields any water from being absorbed by soil particles when many are affected. The unaffected sand particle does not have this coating meaning that water can infiltrate through the sandy soil.
525:
761:
1038:
377:
744:
1022:
526:
https://www.irrigation.org/IA/FileUploads/IA/Resources/TechnicalPapers/2002/AdvancesInUnderstandingAndManagingWaterRepellentSoils.pdf
1027:
1032:
41:
1043:
304:"A multivariate framework for interpreting the effects of soil properties, soil management and landuse on water repellency"
592:
1063:
1048:
1058:
234:
McHale, Glen; Shirtcliffe, Neil J.; Newton, Michael I.; Pyatt, F. Brian; Doerr, Stefan H. (29 January 2007).
1053:
1016:
737:
1354:
1330:
684:
546:
407:
303:
181:
667:
1184:
692:
621:
554:
475:
419:
311:
247:
189:
753:
116:
Characterizing the degree of hydrophobicity in soils based on the water droplet penetration test.
1349:
1304:
937:
730:
645:
499:
335:
271:
406:
Jordán, Antonio; Zavala, Lorena M.; Mataix-Solera, Jorge; Doerr, Stefan H. (1 September 2013).
1219:
708:
685:"The erosional impact of soil hydrophobicity: current problems and future research directions"
637:
570:
491:
435:
373:
327:
263:
205:
700:
629:
562:
483:
427:
365:
319:
255:
197:
1289:
1274:
1134:
182:"The role of fire and soil heating on water repellency in wildland environments: a review"
696:
625:
609:
558:
479:
423:
357:
315:
302:
Harper, R.J.; McKissock, I.; Gilkes, R.J.; Carter, D.J.; Blackwell, P.S. (29 May 2000).
251:
193:
163:
soil because they account for approximately 35% of the near-surface volume of the soil.
1264:
1209:
369:
235:
704:
593:
https://www.daf.qld.gov.au/__data/assets/pdf_file/0016/53044/Soil-Water-Repellency.pdf
566:
463:
323:
201:
1343:
1309:
1194:
633:
503:
339:
649:
275:
1294:
1239:
610:"Assessing Soil Water Repellency Using the Molarity of Ethanol Droplet (Med) Test"
431:
1299:
1279:
1199:
1179:
1159:
1149:
1144:
487:
1284:
1234:
1189:
1174:
1139:
1109:
975:
882:
847:
822:
712:
641:
574:
495:
439:
408:"Soil water repellency: Origin, assessment and geomorphological consequences"
331:
267:
209:
1269:
1214:
1154:
917:
912:
902:
837:
807:
787:
1254:
1169:
1124:
1000:
980:
970:
955:
927:
922:
907:
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872:
852:
842:
827:
812:
802:
797:
792:
1204:
1164:
1129:
1119:
1114:
1104:
1099:
995:
965:
960:
950:
945:
897:
892:
867:
862:
857:
832:
817:
782:
777:
772:
722:
259:
1314:
1249:
990:
985:
887:
668:
https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_051899.pdf
1229:
40:
1259:
1094:
1089:
1084:
1079:
726:
1244:
520:
Advances in understanding and managing water repellent soils.
236:"Self-organization of hydrophobic soil and granular surfaces"
547:"Approaches to characterize the degree of water repellency"
683:
Shakesby, R.A.; Doerr, S.H.; Walsh, R.P.D. (29 May 2000).
545:
Letey, J.; Carrillo, M.L.K; Pang, X.P (29 May 2000).
464:"Rethinking soil water repellency and its management"
1072:
1009:
936:
760:
608:Roy, Julie L.; McGill, William B. (February 2002).
589:Queensland Department of Agriculture and Fisheries
358:"Hydrophobic compounds in sands from New Zealand"
662:Soil Quality Resource Concerns: Hydrophobicity.
738:
141:Locations and appearance of hydrophobic soils
8:
745:
731:
723:
68:
172:
1039:Canadian system of soil classification
678:
676:
603:
601:
159:that triggers soil water repellency.
7:
540:
538:
536:
534:
457:
455:
453:
451:
449:
401:
399:
397:
395:
356:Horne, D.J.; McIntosh, J.C. (2003),
351:
349:
297:
295:
293:
291:
289:
287:
285:
229:
227:
225:
223:
221:
219:
124:Effect on agriculture and ecosystems
587:Poulter, R. Soil Water Repellency.
1023:Unified Soil Classification System
370:10.1016/b978-0-444-51269-7.50005-9
72:Penetration time of water droplet
14:
1028:AASHTO Soil Classification System
1326:
1325:
634:10.1097/00010694-200202000-00001
16:Soil whose particles repel water
1044:Australian Soil Classification
1035:(French classification system)
1:
705:10.1016/S0022-1694(00)00193-1
567:10.1016/S0022-1694(00)00183-9
324:10.1016/S0022-1694(00)00209-2
202:10.1016/S0022-1694(00)00194-3
432:10.1016/j.catena.2013.05.005
364:, Elsevier, pp. 25–35,
83:Soil is not water repellent
1064:List of vineyard soil types
670:. (Accessed: 27 April 2021)
595:. (Accessed: 13 April 2021)
528:. (Accessed: 14 April 2021)
180:Debano, L.F (29 May 2000).
150:Hydrophobic soil management
107:Soil is severely repellent
91:Soil is slightly repellent
1371:
1049:Polish Soil Classification
691:. 231–232 (1–4): 178–191.
488:10.1007/s11258-019-00967-4
310:. 231–232 (1–4): 371–383.
188:. 231–232 (1–4): 195–206.
1323:
1073:Non-systematic soil types
1059:List of U.S. state soils
553:. 231–232 (1–4): 61–65.
99:Soil is water repellent
1054:1938 USDA soil taxonomy
1033:Référentiel pédologique
1017:FAO soil classification
240:Applied Physics Letters
29:Formation and structure
88:5 seconds to 1 minute
58:Hydrophobicity testing
50:
362:Soil Water Repellency
104:More than 10 minutes
66:Results of the WDPT:
44:
1185:Calcareous grassland
762:World Reference Base
689:Journal of Hydrology
551:Journal of Hydrology
308:Journal of Hydrology
186:Journal of Hydrology
80:Less than 5 seconds
754:Soil classification
697:2000JHyd..231..178S
626:2002SoilS.167...83R
559:2000JHyd..231...61L
480:2019PlEco.220..977R
424:2013Caten.108....1J
316:2000JHyd..231..371H
252:2007ApPhL..90e4110M
194:2000JHyd..231..195D
938:USDA soil taxonomy
764:for Soil Resources
51:
1337:
1336:
379:978-0-444-51269-7
260:10.1063/1.2435594
111:
110:
1362:
1329:
1328:
1225:Hydrophobic soil
747:
740:
733:
724:
717:
716:
680:
671:
660:
654:
653:
605:
596:
585:
579:
578:
542:
529:
514:
508:
507:
459:
444:
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403:
390:
389:
388:
386:
353:
344:
343:
299:
280:
279:
231:
214:
213:
177:
96:1 to 10 minutes
69:
22:Hydrophobic soil
1370:
1369:
1365:
1364:
1363:
1361:
1360:
1359:
1340:
1339:
1338:
1333:
1319:
1290:Subaqueous soil
1275:Serpentine soil
1135:Parent material
1068:
1005:
932:
763:
756:
751:
721:
720:
682:
681:
674:
661:
657:
607:
606:
599:
586:
582:
544:
543:
532:
515:
511:
474:(10): 977–984.
461:
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405:
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393:
384:
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355:
354:
347:
301:
300:
283:
233:
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217:
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75:Classification
60:
31:
17:
12:
11:
5:
1368:
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1352:
1342:
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1335:
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1318:
1317:
1312:
1307:
1302:
1297:
1292:
1287:
1282:
1277:
1272:
1267:
1265:Prime farmland
1262:
1257:
1252:
1247:
1242:
1237:
1232:
1227:
1222:
1220:Fuller's earth
1217:
1212:
1210:Expansive clay
1207:
1202:
1197:
1192:
1187:
1182:
1177:
1172:
1167:
1162:
1157:
1152:
1147:
1142:
1137:
1132:
1127:
1122:
1117:
1112:
1107:
1102:
1097:
1092:
1087:
1082:
1076:
1074:
1070:
1069:
1067:
1066:
1061:
1056:
1051:
1046:
1041:
1036:
1030:
1025:
1020:
1013:
1011:
1007:
1006:
1004:
1003:
998:
993:
988:
983:
978:
973:
968:
963:
958:
953:
948:
942:
940:
934:
933:
931:
930:
925:
920:
915:
910:
905:
900:
895:
890:
885:
880:
875:
870:
865:
860:
855:
850:
845:
840:
835:
830:
825:
820:
815:
810:
805:
800:
795:
790:
785:
780:
775:
769:
767:
758:
757:
752:
750:
749:
742:
735:
727:
719:
718:
672:
666:Available at:
655:
597:
591:Available at:
580:
530:
524:Available at:
516:Kostka, S. J.
509:
445:
391:
378:
345:
281:
215:
171:
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165:
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142:
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125:
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109:
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100:
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81:
77:
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73:
59:
56:
30:
27:
15:
13:
10:
9:
6:
4:
3:
2:
1367:
1356:
1355:Types of soil
1353:
1351:
1348:
1347:
1345:
1332:
1331:Types of soil
1322:
1316:
1313:
1311:
1310:Tropical peat
1308:
1306:
1303:
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1298:
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1293:
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1208:
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1201:
1198:
1196:
1195:Dry quicksand
1193:
1191:
1188:
1186:
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1178:
1176:
1173:
1171:
1168:
1166:
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1128:
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1021:
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1010:Other systems
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1002:
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481:
477:
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469:
468:Plant Ecology
465:
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246:(5): 054110.
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64:
57:
55:
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43:
39:
35:
28:
26:
23:
19:
1240:Martian soil
1224:
688:
663:
658:
620:(2): 83–97.
617:
614:Soil Science
613:
588:
583:
550:
521:
517:
512:
471:
467:
415:
411:
383:, retrieved
361:
307:
243:
239:
185:
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144:
135:
131:
127:
118:
113:
112:
65:
61:
52:
45:
36:
32:
21:
20:
18:
1305:Terra rossa
1300:Terra preta
1280:Spodic soil
1200:Duplex soil
1180:Brown earth
1160:Alkali soil
1150:Rhizosphere
1145:Laimosphere
1019:(1974–1998)
976:Inceptisols
883:Plinthosols
848:Kastanozems
1344:Categories
1285:Stagnogley
1235:Lunar soil
1190:Dark earth
1175:Brickearth
1140:Pedosphere
1110:Soil crust
918:Technosols
903:Solonchaks
823:Ferralsols
788:Anthrosols
522:Irrigation
167:References
1350:Hydrology
1270:Quicksand
1215:Fill dirt
1155:Bulk soil
1001:Vertisols
991:Spodosols
981:Mollisols
971:Histosols
956:Aridisols
928:Vertisols
923:Umbrisols
913:Stagnosol
878:Planosols
873:Phaeozems
853:Leptosols
838:Gypsisols
828:Fluvisols
808:Chernozem
803:Cambisols
798:Calcisols
793:Arenosols
713:0022-1694
642:0038-075X
575:0022-1694
504:202718051
496:1385-0237
440:0341-8162
340:128891936
332:0022-1694
268:0003-6951
210:0022-1694
46:Figure 1:
1255:Paleosol
1170:Blue goo
1125:Gypcrust
996:Ultisols
966:Gelisols
961:Entisols
951:Andisols
946:Alfisols
908:Solonetz
898:Retisols
893:Regosols
868:Nitisols
863:Luvisols
858:Lixisols
843:Histosol
833:Gleysols
818:Durisols
813:Cryosols
783:Andosols
773:Acrisols
650:96024286
385:27 April
276:55856070
137:levels.
114:Table 1:
1205:Eluvium
1165:Bay mud
1130:Caliche
1120:Hardpan
1115:Claypan
1105:Subsoil
1100:Topsoil
986:Oxisols
888:Podzols
778:Alisols
766:(1998–)
693:Bibcode
622:Bibcode
555:Bibcode
476:Bibcode
420:Bibcode
418:: 1–5.
312:Bibcode
248:Bibcode
190:Bibcode
1315:Yedoma
1250:Muskeg
711:
648:
640:
573:
518:et al.
502:
494:
438:
412:CATENA
376:
338:
330:
274:
266:
208:
1295:Takir
1230:Loess
646:S2CID
500:S2CID
336:S2CID
272:S2CID
1260:Peat
1095:Loam
1090:Clay
1085:Silt
1080:Sand
709:ISSN
664:USDA
638:ISSN
571:ISSN
492:ISSN
436:ISSN
387:2021
374:ISBN
328:ISSN
264:ISSN
206:ISSN
1245:Mud
701:doi
630:doi
618:167
563:doi
484:doi
472:220
428:doi
416:108
366:doi
320:doi
256:doi
198:doi
1346::
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470:.
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410:.
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360:,
348:^
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326:.
318:.
306:.
284:^
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262:.
254:.
244:90
242:.
238:.
218:^
204:.
196:.
184:.
746:e
739:t
732:v
715:.
703::
695::
652:.
632::
624::
577:.
565::
557::
506:.
486::
478::
442:.
430::
422::
368::
342:.
322::
314::
278:.
258::
250::
212:.
200::
192::
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