Editing Water table (section)

==Effects on crop yield==
[[File: Rudd PartReg.png|thumb|upright=1.4|A plot of sugarcane yield versus depth of water table in Australia. The critical depth is 0.6&nbsp;m.<ref>Rudd, A.V. and C.W Chardon 1977. ''The effects of drainage on cane yields as measured by water table height in the Machnade Mill area.'' In: Proceedings of the 44th Conference of the Queensland Society of Sugar Cane Technology, Australia.</ref><ref>[https://www.waterlog.info/partreg.htm Software for partial regression with horizontal segment]</ref>]]

Most crops need a water table at a minimum depth.<ref>''Crop Yield versus Depth of the Ground Water Table, Statistical Analysis of Data Measured in Farm Lands Aiming at the Formulation of Drainage Needs.'' International Journal of Agricultural Science, 6, 174–187. Online: [https://www.iaras.org/iaras/filedownloads/ijas/2021/014-0023(2021).pdf] or [https://www.waterlog.info/pdf/Crop%20yield%20and%20depth%20of%20water%20table.pdf]</ref> For some important food and fiber crops a classification was made<ref>Nijland, H.J. and S. El Guindy 1984.''Crop yields, soil salinity and water table depth in the Nile Delta''. In: ILRI Annual Report 1983, Wageningen, The Netherlands, pp. 19–29. Online: [https://www.waterlog.info/pdf/egypt.pdf]</ref> because at shallower depths the crop suffers a yield decline.<ref>K.J.Lenselink et al. ''Crop tolerance to shallow water tables''. Online: [https://www.waterlog.info/cropwat.htm]</ref>

{| class="wikitable" 
! Crop and location || DWT tolerance  || Classification || Explanation 
|-
| Wheat, Nile Delta, Egypt  || 45 || Very tolerant || Resists shallow water tables
|-
| Sugar cane, Australia     || 60 || Tolerant || The water table should be deeper than 60&nbsp;cm
|-
| Banana, Surinam           || 70 || Slightly sensitive || Yield declines at water tables <&nbsp;70&nbsp;cm deep
|-
| Cotton, Nile Delta        || 90 || Sensitive || Cotton needs dry feet, water table should be deep
|}
:(where DWT = depth to water table in centimetres)