Deciding when to cease irrigation is likely one of the key selections in cotton manufacturing. On this article we clarify the consequences of terminating irrigation too early or too late, focus on the findings of latest analysis tasks from Oklahoma and the area, and clarify various factors that have to be thought of when deciding to terminate cotton irrigation.
Stopping irrigation too early can lead to yield loss, particularly if soil moisture is just not enough to help boll filling after irrigation termination. In a analysis mission that was carried out from 2015 to 2017 at OSU’s Southwest Analysis and Extension Heart close to Altus, the consequences of three irrigation termination dates on cotton yield and fiber high quality had been studied.
The termination dates had been: 1) finish of August (normal termination date), 2) one week earlier, and 3) two weeks earlier (mid-August).
Terminating mid-August resulted in additional water conservation. On common, seasonal water use was 28% smaller in comparison with end-of-August termination. This can be useful for growers throughout the irrigation district as extra water might be saved within the reservoir for the following irrigation season.
Terminating irrigation one week later than mid-August resulted in 16% water financial savings. 28% saving in irrigation software would translate to about 14,000 acre-feet of water in a mean 12 months within the district. Regardless of water financial savings, cotton lint yield was negatively impacted by early termination.
When averaged over the three years (2015-2017), lint yield for end-of-August termination was 1,448 lb/ac, bigger than the common yield for terminating one week earlier (1,221 lb/ac) and two weeks earlier in mid-August (1,138 lb/ac).
Common micronaire decreased from 3.89 to three.65 and common uniformity declined from 82.8% to 81.7% when terminated 2 weeks sooner than the top of August One main commentary was that the impression of earlier termination was extremely variable from 12 months to 12 months relying on the late-season rainfall and soil moisture availability.
In years that had been characterised with dry late season, ending irrigations even one week earlier had a considerable impact on cotton efficiency. In distinction, irrigation might be terminated two weeks early with none impression if well timed rainfalls replenished soil moisture in direction of the top of the rising season.
The outcomes discovered within the OSU examine was just like a examine by Texas A&M AgriLife that reported one of the best time of irrigation termination to be the primary week of September in regular years and the final week of August in moist years for the Texas Panhandle area.
Stopping irrigation too late can have adverse results on yield and fiber high quality by rising pest and illness strain and resulting in hardlock or boll rot. That is particularly the case for pivot irrigation as cover will get moist throughout water software and should keep moist for a number of hours relying on climate circumstances.
One other problem attributable to terminating too late, particularly this 12 months that we’re nonetheless behind in phrases of crop progress or maturity, is fueling extreme late-season vegetative development. Lastly, irrigating too late can cut back the efficacy of defoliation.
Crop improvement have to be thought of in deciding when to terminate irrigations. A common suggestion for furrow irrigation is to cease irrigation at first crack boll if root zone moisture is enough. Heart pivot and drip techniques might have to go longer than first crack boll (for instance 10% open bolls) as a smaller quantity of water is utilized by these techniques in every occasion in comparison with deep, heavy irrigations of furrow techniques.
Some earlier research have really helpful irrigation termination to be determined based mostly on rising diploma days (warmth models) collected after cutout (NAWF=5). For cotton, diploma days are sometimes estimated based mostly on 60˚F as the edge temperature and therefore diploma days are known as DD60’s.
Crop improvement is immediately associated to DD60’s. A common suggestion is to terminate irrigation at 350 DD60’s previous cutout. In a examine in west Texas, no profit in yield and fiber high quality
was noticed for irrigation termination later than 400 DD60’s previous cutout underneath subsurface drip irrigation.
Many elements play a job in figuring out one of the best time to terminate cotton irrigation, making this choice extremely variable from subject to subject and 12 months to 12 months. Right here we now have summarized a few of the primary elements that have to be thought of.
● Crop improvement: some earlier research within the area have really helpful termination based mostly on boll opening (first crack boll for furrow irrigation and 10% open boll for pivot). Different research have used 350-450 DD60’s after reaching cutout.
● Root zone soil moisture: late-season water availability within the root zone has a major impression on cotton yield and fiber high quality. If all different elements point out irrigation ought to be terminated however the soil moisture is just not enough and no rain is in forecast, irrigation ought to proceed a bit longer to keep away from yield losses.
● Soil kind: deep clay soils can maintain extra water and thus take extra benefit of late-season rains, particularly if the basis system is deep and wholesome. Sandy soils or soils with limiting layers (for instance shallow bedrock) will maintain much less water and might have extra irrigation.
● Irrigation kind: Furrow techniques apply giant quantities of water and might soak the whole root zone throughout the sphere. Irrigation might be terminated earlier for these techniques. Subsurface drip techniques apply the smallest quantities of water however at a lot increased frequency. As well as, they sometimes don’t moist the whole subject and should have crop roots which are concentrated close to drip tapes. They might have to run later particularly underneath drier circumstances. Overhead sprinklers moist the cover and might trigger boll rot if they’re terminated late.
