1. COMPARISON OF WATER USE AND CROP WATER USE EFFICIENCY OF MAIZE,
SORGHUM, AND SOYBEAN IN NEBRASKA
J.M. Rees*1, S. Irmak2, and D. Andersen3.
1Extension Educator, University of Nebraska-Lincoln
2Soil & Water Resources & Irrigation Engineer, UNL Dept. of Biological Systems Engineering
3Water Resources Specialist, Little Blue Natural Resources District, Davenport, NE
Figure 1. Seasonal Crop Water Use (ET) for Maize, Soybean,
ABSTRACT: RESULTS/DISCUSSION: and Sorghum in 2009 and 2010 from emergence to
Water is a crucial resource for agricultural production. As the availability of General soil water balance equation was used to quantify seasonal crop water use and water use efficiency: physiological maturity
freshwater resources is decreasing in parts of Nebraska and the world, ETc = (TSWi - TSWe) + rainfall – RO – DP 26
newer hybrids and varieties have been developed for handling stresses like 24
where:
water-limited conditions. While the trend of losing rainfed sorghum acres to ETc = crop evapotranspiration (in) 22
maize acres continues, data lack in terms of water use efficiency between TSWi = initial available soil water at the beginning of season (in) 20
maize, sorghum, and soybean. Field studies were conducted in two rainfed TSWe = available soil water at the full maturity (in) 14.5” 23.3” 14.0” 22.0” 13.7” 21.3”
18
Crop water use (in)
fields in South Central Nebraska to determine crop water use efficiency of RO = Runoff (assumed zero)
16
these three crops over several years. Watermark granular matrix sensors DP = Deep percolation (assumed zero)
14
measured soil water status every 1 ft up to 4 ft for the entire growing season Evapotranspiration of maize, soybean, and sorghum in 2009 was: 14.5”, 14.0”, and 13.7” respectively with 12
and a general soil water balance equation was used to quantify seasonal 10.1” of rainfall during the growing season (Figures 1 and 2). 10
crop water use and water use efficiency. In 2009, the evapotranspiration Evapotranspiration of maize, soybean, and sorghum in 2010 was: 23.3”, 22.0”, and 21.3” respectively with 8
(ET) of maize, soybean, and sorghum was 14.5, 14.0, and 13.7 inches and 16.4” of rainfall during the growing season (Figures 1 and 3). 6
in 2010, 23.3, 22.0, and 21.3 inches, respectively. By accounting the final
All crops both years followed the same trend with maize using more water than soybean and sorghum each 4
grain yields, the overall crop water use efficiency of maize was 6.7 bu/inch in 2
2009 and 4.3 bu/inch in 2010; for soybean it was 2.4 bu/inch in 2009 and 2.0 year (Figure 1).
0
bu/inch in 2010; and for sorghum it was 5.6 bu/inch in 2009 and 5.5 bu/inch Crop Water Use Efficiency (CWUE) was determined by dividing the final yield/ET for each crop each year. Maize 2009 Maize 2010 Soy 2009 Soy 2010 Sorg 2009 Sorg 2010
in 2010. Rainfed maize was most efficient in the drier year of 2009. Sorghum had the most consistent CWUE between 2009 and 2010. All CWUE can be viewed in Table 2.
However, sorghum was the most consistent water use-efficient crop 2009 was a dry summer in this area of Nebraska. All crops rooted down utilizing moisture out of the 4 th foot soil
between the two years of varying environmental conditions with rainfall moisture profile removing 5” on average from the total moisture profile (Figure 2). Herbicide did not receive
received from crop emergence to physiological maturity of 10.1 inches in Table 2. ET, Yield, and Crop Water Use Efficiency of Maize,
rainfall for activation. Grass pressure and nitrogen deficiency may have contributed to low sorghum yield in 2009. Soybean, and Sorghum in 2009 and 2010.
2009 and 16.4 inches in 2010.
2010 was a very wet May and June followed by a dry summer and fall. Maize and soybean only depleted 2.5”
out of the total moisture profile while sorghum depleted 3.0” (Figure 3). Maize shut down early in August due to Crop 2009 2009 2009 2010 2010 2010
environmental stresses while sorghum was flowering during the one substantial rain received in August. Etc Yield CWUE Etc Yield CWUE
(in) (bu) (bu/in) (in) (bu/ac) (bu/in)
OBJECTIVE:
Determine the crop water use efficiency of new maize,
sorghum, and soybean hybrids and varieties. Maize 14.5 97.5 6.7 23.3 101.2 4.3
Soybean 14 33.4 2.4 22.0 44.0 2.0
Table 1. Agronomic Practices for Each Field Site in 2009 and 2010. Sorghum 13.7 77.4 5.6 21.3 118.0 5.5
Practice Performed Lawrence, NE 2009 Lawrence, NE 2010
Planting Date and Rate May 7 at 20,000 seeds/acre May 7 at 20,000 seeds/acre
Maize Hybrid Pioneer 33T57 Pioneer 33T57 Figure 2 (2009) and Figure 3 (2010) Total Soil Water Depletion
Planting Date and Rate May 8 at 135,000 seeds/acre May 7 at 135,000 seeds/acre for Maize, Soybean, and Sorghum vs. Cumulative Rainfall.
Soybean Variety Pioneer 92M61 Pioneer 92M61
Planting Date and Rate May 19 at 65,000 seeds/acre May 28 at 65,000 seeds/acre 12.0 12
Sorghum Variety Pioneer 85Y40 Pioneer 85Y40
11.0
Total soil water in the top 4 ft (in)
Row Spacing and No. Rows 12 rows, 30” spacing 12 rows, 30” spacing
10.0 10
Previous Crop Sorghum Sorghum Rainfall (in.)
9.0
Cumulative Rainfall (in.)
Tillage Practice No-till No-till
8.0 Maize 8
Fertilizer Dry blend 90-40-0 as per soil test for 100 bu/ac 100 lbs urea + Nserve as per soil test for 7.0
sorghum 100 bu/ac sorghum Soybean
6.0 6
Soil Moisture Equipment May 22: Maize and Soybean May 18: Maize and Soybean Sorghum
MATERIALS/METHODS: Installation June 12: Sorghum June 4: Sorghum 5.0
Cumulative
4.0 4
Study was conducted via on-farm research. A farmer with Herbicide *Pre-plant application of Dual II Magnum and *Pre-plant Glyphosate burndown. Rainfall (in)
Glyphosate over entire plot. *Split Lumax application to sorghum pre- 3.0
rainfed fields was identified to cooperate with this study. *Glyphosate application to maize and soybean. plant and at planting. 2.0 2
The field location changed each year. All agronomic *Rescue treatment of Paramount and Atrazine for *One post application of Glyphosate to maize 1.0
practices can be viewed in Table 1. grass control in sorghum. and soybean.
0.0 0
*2nd Glyphosate application to maize and soybean. Date
A three crop randomized complete block design was Full Maturity Date Soybean: September 15 Maize: October 5 Soybean: August 30 Maize: September 12
21-May-09 15-Jun-09 10-Jul-09 4-Aug-09 29-Aug-09 23-Sep-09 18-Oct-09
implemented for this study. Sorghum: October 6 Sorghum: October 4 12.0 18
Watermark granular matrix sensors were installed after crop 16
10.0
emergence in each plot. These sensors measured soil
water status every 1 ft up to 4 ft. Data was collected every CONCLUSIONS: 14
Total soil water (in/4 ft)
Rainfed maize was the most water use efficient crop in the drier year of 2009,
Cumulative rainfall (in)
8.0 12
hour during the growing season for each crop plot.
Each plot was checked once/week during the growing most likely because of deep rooting depth. Maize roots failed to root down in 6.0 Rain (in)
10
season to ensure all equipment was working. Field notes 2010 due to the wet spring which may have inhibited CWUE in 2010. Maize tot. water (in) 8
regarding weed/disease pressure and crop condition were Sorghum was the most consistent water-use efficient crop from 2009-2010. 4.0 Soybean tot. water (in) 6
Sorghum tot. water (in)
taken. One more year of research will be conducted to make further conclusions and 4
Cum. Rainfall (in)
Data was collected and summarized at the end of the solidify results.
2.0
2
growing season.
Results were presented at winter meetings, field days, and 0.0
22-May-10 11-Jun-10 1-Jul-10 21-Jul-10 10-Aug-10 30-Aug-10 19-Sep-10
0
9-Oct-10
This research was sponsored by a grant from the Nebraska Grain Sorghum Board. A special thanks to John
http://cropwatch.unl.edu. Dolnicek, the cooperating farmer on this study. Date