Abstract
Highlights Crop coefficients (K cb ) were calculated using Normalized Difference Vegetative Indices (NDVI) and compared to the FAO-56 method. Cotton yields using NDVI-K cb based irrigation scheduling to a uniform checkbook irrigation were compared. Irrigated cotton yields were not significantly different between irrigation methods but were significantly higher in years requiring higher volumes of irrigation water. Cotton fiber quality was not significantly different for the two irrigation methods or plant populations. Abstract. Irrigation timing is crucial for achieving high cotton yields and lint quality. This irrigation timing is more challenging in the southeastern U.S. Coastal Plain region due to its spatial variable sandy soils with low water and nutrient holding capacities and rainfall variability during the growing season. To address these challenges, we conducted a 2-year (2017 and 2018) study evaluating two irrigation scheduling methods under a variable rate irrigation system. The two irrigation methods were: (1) a uniform irrigation management based on weekly crop water usage, and (2) spatial crop coefficients derived from normalized difference vegetative indices (NDVI). We compared cotton yields and water use efficiency using the two irrigation scheduling methods at two different planting densities. The two plant populations were 5 and 11.5 plants m 2 to provide different NDVI readings and water requirements. In 2017, there were no significant differences in cotton yields due to the adequate rainfall during the growing season that required only three irrigations events. The mean irrigation depth for the NDVI method was significantly lower than the uniform method (56 and 64 mm, respectively, LSD = 4.2). In 2018, there was lower rainfall during the growing season requiring eight irrigation events and the cotton yields in the two irrigation treatments were significantly higher than the rainfed treatment. Irrigation depths in 2018 were not significantly different for the two irrigation methods. Water use efficiencies were not significantly different for the two irrigation methods. The planting density had little impact on the cotton yields, irrigation depth, water use efficiency, or cotton fiber quality. These results indicate that the NDVI-derived crop coefficient values were as effective in prescribing irrigation applications as the uniform irrigation method for irrigation management. The NDVI-derived crop coefficient irrigation method appears to be a useful tool for managing irrigation and developing irrigation prescriptions. Keywords: Cotton, Irrigation scheduling, Normalized difference vegetation indices, Variable rate irrigation
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Claims 9
Claim · model-written summary
Irrigated cotton yields did not differ significantly between the NDVI-based and uniform checkbook irrigation methods.
- Taxon
- cotton
Gossypium hirsutume0 - Treatment
- irrigation methodse0
- Outcome
- cotton yieldse0
- Direction
- not significantly differente0
- Comparator
- uniform checkbook irrigatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Irrigated cotton yields were not significantly different between irrigation methods”
e1“Cotton yields using NDVI-K cb based irrigation scheduling to a uniform checkbook irrigation were compared”
Claim · model-written summary
Cotton fiber quality did not differ significantly between the two irrigation methods.
- Taxon
- CottonGossypium hirsutume0
- Treatment
- the two irrigation methodse0
- Outcome
- Cotton fiber qualitye0
- Direction
- not significantly differente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cotton fiber quality was not significantly different for the two irrigation methods or plant populations”
Claim · model-written summary
Cotton fiber quality did not differ significantly between the two plant populations.
- Taxon
- CottonGossypium hirsutume0
- Treatment
- plant populationse0
- Outcome
- Cotton fiber qualitye0
- Direction
- not significantly differente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cotton fiber quality was not significantly different for the two irrigation methods or plant populations”
Claim · model-written summary
In 2017 the mean irrigation depth was significantly lower with the NDVI method than with the uniform method (56 versus 64 mm, LSD = 4.2).
- Taxon
- CottonGossypium hirsutumt0
- Treatment
- NDVI methode0
- Outcome
- mean irrigation depthe0
- Direction
- significantly lowere0
- Value
- 56 and 64 mme0
- Qualifier
- LSD = 4.2e0
- Comparator
- uniform methode0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The mean irrigation depth for the NDVI method was significantly lower than the uniform method (56 and 64 mm, respectively, LSD = 4.2)”
t0“Cotton”
Claim · model-written summary
In 2018 cotton yields in the two irrigation treatments were significantly higher than in the rainfed treatment.
- Taxon
- cottonGossypium hirsutume0
- Treatment
- the two irrigation treatmentse0
- Outcome
- cotton yieldse0
- Direction
- significantly highere0
- Comparator
- the rainfed treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the cotton yields in the two irrigation treatments were significantly higher than the rainfed treatment”
Claim · model-written summary
Irrigation depths in 2018 did not differ significantly between the two irrigation methods.
- Taxon
- CottonGossypium hirsutumt0
- Treatment
- the two irrigation methodse0
- Outcome
- Irrigation depthse0
- Direction
- not significantly differente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Irrigation depths in 2018 were not significantly different for the two irrigation methods”
t0“Cotton”
Claim · model-written summary
Water use efficiencies did not differ significantly between the two irrigation methods.
- Taxon
- CottonGossypium hirsutumt0
- Treatment
- the two irrigation methodse0
- Outcome
- Water use efficienciese0
- Direction
- not significantly differente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water use efficiencies were not significantly different for the two irrigation methods”
t0“Cotton”
Claim · model-written summary
Planting density had little impact on cotton yields, irrigation depth or water use efficiency.
- Taxon
- cottonGossypium hirsutume0
- Treatment
- planting densitye0
- Outcome
- cotton yields, irrigation depth, water use efficiencye0
- Direction
- little impacte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The planting density had little impact on the cotton yields, irrigation depth, water use efficiency, or cotton fiber quality”
Claim · model-written summary
The NDVI-derived crop coefficient values were as effective as the uniform irrigation method in prescribing irrigation applications.
Verbatim
e0“NDVI-derived crop coefficient values were as effective in prescribing irrigation applications as the uniform irrigation method for irrigation management”
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