Rainfed farming in eastern Sudan depends on rainfall that occurs within a short and uneven season. In the cracking Vertisols of Gedaref, soil moisture after wetting can decline quickly, especially when the surface remains exposed. This study examined whether observed soil moisture differed among sesame straw mulch rates after a standardized wetting event in an uncropped Vertisol containing 76% clay, 14% sand, and 10% silt. The field experiment was arranged in a randomized complete block design with three replications and five mulch rates: 0, 1.39, 2.78, 4.17, and 5.56 t ha？1, equivalent to 0, 0.5, 1.0, 1.5, and 2.0 kg per 3.6 m2 plot. Each plot received 100 L of water, equivalent to 27.78 mm. Mulch was applied four days after wetting, and soil moisture was then measured weekly for eight weeks at 0 - 30 and 30 - 60 cm depths. No soil-moisture measurement was taken before mulch application. A repeated-measures linear mixed-effects model showed that soil moisture increased by 0.592 percentage points for each additional t ha？1 of sesame straw mulch, while it declined by 0.482 percentage points per week. The mulch treatment × sampling week interaction was not significant (F = 0.33, p > 0.99), so treatment-specific slopes were treated only as descriptive summaries. Across depths and weeks, mean soil moisture was 23.27% under the 5.56 t ha？1 treatment and 19.69% in the control, giving an observed difference of 18.2%. The results show that observed soil moisture differed among sesame straw mulch rates after a standardized wetting event under uncropped conditions. Evaporation, soil cracking, crop emergence, and yield were not measured. The findings should be treated as preliminary field dry-down evidence and tested under cropped conditions before field recommendations are made.
References
[1]
Blokhuis, W.A. (1993) Vertisols in the Central Clay Plain of the Sudan. Wageningen Agricultural University.
[2]
Elias, E.A., Salih, A.A. and Alaily, F. (2001) Cracking Patterns in the Vertisols of the Sudan Gezira at the End of Dry Season. International Agrophysics, 15, 151-155.
[3]
Bronswijk, J.J.B. (1988) Modeling of Water Balance, Cracking and Subsidence of Clay Soils. Journal of Hydrology, 97, 199-212. https://doi.org/10.1016/0022-1694(88)90115-1
[4]
Dinka, T.M. and Lascano, R.J. (2012) Review Paper: Challenges and Limitations in Studying the Shrink-Swell and Crack Dynamics of Vertisol Soils. Open Journal of Soil Science, 2, 82-90. https://doi.org/10.4236/ojss.2012.22012
[5]
Ritchie, J.T. (1972) Model for Predicting Evaporation from a Row Crop with Incomplete Cover. Water Resources Research, 8, 1204-1213. https://doi.org/10.1029/wr008i005p01204
[6]
Lal, R. (1974) Soil Temperature, Soil Moisture and Maize Yield from Mulched and Unmulched Tropical Soils. Plant and Soil, 40, 129-143. https://doi.org/10.1007/bf00011415
[7]
Brutsaert, W. (1982) Evaporation into the Atmosphere: Theory, History and Applications. D. Reidel Publishing Company, Dordrecht.
[8]
Allen, R.G., Pereira, L.S., Raes, D. and Smith, M. (1998) Crop Evapotranspiration: Guidelines for Computing Crop Water Requirements. FAO Irrigation and Drainage Paper No. 56, FAO, Rome.
[9]
Hillel, D. (1998) Environmental Soil Physics. Academic Press.
[10]
Kader, M.A., Senge, M., Mojid, M.A. and Ito, K. (2017) Recent Advances in Mulching Materials and Methods for Modifying Soil Environment. SoilandTillageResearch, 168, 155-166. https://doi.org/10.1016/j.still.2017.01.001
[11]
Kodikara, J. and Costa, S. (2013) Desiccation Cracking in Clayey Soils: Mechanisms and Modelling. In: Laloui, L. and Ferrari, A., Multiphysical Testing of Soils and Shales, Springer, 21-32.
[12]
Oliver, J.E. (1980) Monthly Precipitation Distribution: A Comparative Index. The Professional Geographer, 32, 300-309. https://doi.org/10.1111/j.0033-0124.1980.00300.x
[13]
de Luis, M., González-Hidalgo, J.C., Brunetti, M. and Longares, L.A. (2011) Precipitation Concentration Changes in Spain 1946–2005. Natural Hazards and Earth System Sciences, 11, 1259-1265. https://doi.org/10.5194/nhess-11-1259-2011
Sen, P.K. (1968) Estimates of the Regression Coefficient Based on Kendall’s Tau. Journal of the American Statistical Association, 63, 1379-1389. https://doi.org/10.1080/01621459.1968.10480934
[16]
Kendall, M.G. (1975) Rank Correlation Methods. 4th Edition, Charles Griffin.
[17]
Saxton, K.E. and Rawls, W.J. (2006) Soil Water Characteristic Estimates by Texture and Organic Matter for Hydrologic Solutions. SoilScienceSocietyofAmericaJournal, 70, 1569-1578. https://doi.org/10.2136/sssaj2005.0117
[18]
R Core Team (2026) R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna. https://doi.org/10.32614/R.manuals
[19]
Bates, D., M？chler, M., Bolker, B. and Walker, S. (2015) Fitting Linear Mixed-Effects Models Using lme4. Journal of Statistical Software, 67, 1-48. https://doi.org/10.18637/jss.v067.i01
[20]
Zribi, W., Aragüés, R., Medina, E. and Faci, J.M. (2015) Efficiency of Inorganic and Organic Mulching Materials for Soil Evaporation Control. Soil and Tillage Research, 148, 40-45. https://doi.org/10.1016/j.still.2014.12.003
[21]
Li, M., Ali, S., Hussain, S.A., Khan, A. and Chen, Y. (2024) Diverse Tillage Practices with Straw Mulched Management Strategies to Improve Water Use Efficiency and Maize Productivity under a Dryland Farming System. Heliyon, 10, e29839. https://doi.org/10.1016/j.heliyon.2024.e29839
[22]
Song, W., Han, F., Bao, Z., Chai, Y., Wang, L., Huang, C., et al. (2024) Mulching Practices Improve Soil Moisture and Enzyme Activity in Drylands, Increasing Potato Yield. Agronomy, 14, Article 1077. https://doi.org/10.3390/agronomy14051077
[23]
Demo, A.H. and Asefa Bogale, G. (2024) Enhancing Crop Yield and Conserving Soil Moisture through Mulching Practices in Dryland Agriculture. Frontiers in Agronomy, 6, Article 1361697. https://doi.org/10.3389/fagro.2024.1361697
[24]
Wilding, L.P. and Tessier, D. (1988) Genesis of Vertisols: Shrink-Swell Phenomena. In: Wilding, L.P. and Puentes, R., Vertisols: Their Distribution, Properties, Classification and Management, Texas A & M University Printing Center, 55-81.
