Cotton Growth and Early Season Irrigation
2011 is shaping up to be one of the more challenging years we have faced in some time. While no year can be considered normal, difficult weather conditions have tested the mettle of many this year. Flooding, delaying planting, and re-plants have all been dealt with this year as well as record breaking heat and isolated hail storms over the past couple of weeks. Several questions have come in this week regarding irrigating small cotton. Generally, young cotton does not require large amounts of moisture for adequate growth and development. As such, in most years there is enough moisture in the soil profile to maintain growth until periods of higher water use arrive, which is typically in the weeks leading up to bloom. However, soil moisture in several areas of Mississippi is lacking to the point that cotton growth and development is suffering. In addition to restricted growth, many growers are also irrigating in an attempt to incorporate nitrogen and preemergence herbicides into the soil profile. While irrigation usually does not do as good of a job incorporating nitrogen and herbicides as rainfall, it should provide some benefit compared to the alternative (little to no rainfall predicted for next 10-14 days).
For those who have cotton that is suffering from extending periods of drought, irrigation at this point in time may prove beneficial. However, it is important to keep in mind that once we start the irrigation cycle, it must be maintained. Do not begin irrigating now and then delay subsequent irrigation applications until later in the season because the plants have began to grow once again. As indicated above, small cotton does not have the water requirements as older cotton. As such, irrigating young cotton every 10 days would preferred in situations where blooming cotton is normally irrigated every 7 days. As is the case with most things, timing between irrigation applications should be adjusted based on weather conditions, soil type, and crop growth stage.