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Effect of timing of a deficit-irrigation allocation on corn evapotranspiration, yield, water use efficiency and dry mass

Payero, J.O. and Tarkalson, D.D. and Irmak, S. and Davison, D. and Petersen, J.L. (2009) Effect of timing of a deficit-irrigation allocation on corn evapotranspiration, yield, water use efficiency and dry mass. Agricultural Water Management. 96:1387-1397.

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Water regulations have decreased irrigation water supplies in Nebraska and some other areas of the USA
Great Plains. When available water is not enough to meet crop water requirements during the entire
growing cycle, it becomes critical to know the proper irrigation timing that would maximize yields and
profits. This study evaluated the effect of timing of a deficit-irrigation allocation (150 mm) on crop
evapotranspiration (ETc), yield, water use efficiency (WUE = yield/ETc), irrigation water use efficiency
(IWUE = yield/irrigation), and dry mass (DM) of corn (Zea mays L.) irrigated with subsurface drip
irrigation in the semiarid climate of North Platte, NE. During 2005 and 2006, a total of sixteen irrigation
treatments (eight each year) were evaluated, which received different percentages of the water
allocation during July, August, and September. During both years, all treatments resulted in no crop
stress during the vegetative period and stress during the reproductive stages, which affected ETc, DM,
yield, WUE and IWUE. Among treatments, ETc varied by 7.2 and 18.8%; yield by 17 and 33%; WUE by 12
and 22%, and IWUE by 18 and 33% in 2005 and 2006, respectively. Yield and WUE both increased linearly
with ETc and with ETc/ETp (ETp = seasonal ETc with no water stress), and WUE increased linearly with
yield. The yield response factor (ky) averaged 1.50 over the two seasons. Irrigation timing affected the
DMof the plant, grain, and cob, but not that of the stover. It also affected the percent of DM partitioned to
the grain (harvest index), which increased linearly with ETc and averaged 56.2% over the two seasons,
but did not affect the percent allocated to the cob or stover. Irrigation applied in July had the highest
positive coefficient of determination (R2) with yield. This high positive correlation decreased
considerably for irrigation applied in August, and became negative for irrigation applied in September.
The best positive correlation between the soil water deficit factor (Ks) and yield occurred during weeks
12–14 from crop emergence, during the ‘‘milk’’ and ‘‘dough’’ growth stages. Yield was poorly correlated
to stress during weeks 15 and 16, and the correlation became negative after week 17. Dividing the
150 mm allocation about evenly among July, August and September was a good strategy resulting in the
highest yields in 2005, but not in 2006. Applying a larger proportion of the allocation in July was a good
strategy during both years, and the opposite resulted when applying a large proportion of the allocation
in September. The different results obtained between years indicate that flexible irrigation scheduling
techniques should be adopted, rather than relying on fixed timing strategies.

Item Type: Article
NWISRL Publication Number: 1305
Subjects: Soil
Irrigation > Drip irrigation
Depositing User: Users 6 not found.
Date Deposited: 30 Nov 2009 21:16
Last Modified: 17 Oct 2016 16:29
Item ID: 1328