Maize Irrigation Study, 1984, Georgia Coastal Plain

Yield Comparisons:
Study:

Research Objective: Determine the effects of soil moisture pattern on corn yield and on stalk and root diseases.
Treatments:
 1.Lambert model irrigation - when predicted water content (pwc) falls below allowable depletion (ad) ad model 50-30% refill 100% drained upper limit (dul)
 2.Same as above except ad model 70-55% refill 100% dul
 3.Same as above except ad model 70-55% refill 75% dul
 4.Original Lambert model ad 60% refill 90% dul root depth as measured
 5.Vary except grainfill stage
 6.Dry down during vegetative (subsoil dewatering)
 7.Control - Vary full season
 8.Irrigate 80% of pan every three days
 9.Two irrigations - one weeks pretassel, two weeks later (third optional if no rainfall)
 10.No irrigation

Basic Crop Management: PLANTED - 20 Mar 1984 (placed 5-7.5 cm deep); HARVEST - 10 Jul 1984 (2-row grain combine); TILLAGE - Moldboard Plow (30 cm deep plus smoothing and bed shaping), wheel traffic controlled at 1.2 m centers; FERTILIZATION - Typical Extension Recommended Rate; WEED & PEST CONTROL: Typical Extension Recommendations.
Chronological Treatment and Observation Details

Observations and data sets for individual treatments (crop years) follow:
Treatment 1:
 Lambert model irrigation - when predicted water content (pwc) falls below allowable depletion (ad) ad model 50-30% refill 100% drained upper limit (dul)
  • Irrigation Dates and Amounts: Text Format;
  • Phenology: Emergence - 30 Mar 1984; Pollination (R2) - 31 May 1984; Maturity (Black layer) - 28 Jun 1984
  • Stand Count:
  • Soil Water Pressure Observations: Tensiometer & Gypsum Block
  • Yield Corn Grain, 15.5% moisture, T/ha: 8.78 Text File
Treatment 2:
 Same as above except ad model 70-55% refill 100% dul
  • Irrigation Dates and Amounts: Text Format;
  • Phenology: Emergence - 30 Mar 1984; Pollination (R2) - 31 May 1984; Maturity (Black layer) - 28 Jun 1984
  • Stand Count:
  • Soil Water Pressure Observations: Tensiometer & Gypsum Block
  • Yield Corn Grain, 15.5% moisture, T/ha: 7.98 Text File
Treatment 3:
 Same as above except ad model 70-55% refill 75% dul
  • Irrigation Dates and Amounts: Text Format;
  • Phenology: Emergence - 30 Mar 1984; Pollination (R2) - 31 May 1984; Maturity (Black layer) - 28 Jun 1984
  • Stand Count:
  • Soil Water Pressure Observations: Tensiometer & Gypsum Block
  • Yield Corn Grain, 15.5% moisture, T/ha: 9.29 Text File
Treatment 4:
 Original Lambert model ad 60% refill 90% dul root depth as measured
  • Irrigation Dates and Amounts: Text Format;
  • Phenology: Emergence - 30 Mar 1984; Pollination (R2) - 31 May 1984; Maturity (Black layer) - 28 Jun 1984
  • Stand Count:
  • Soil Water Pressure Observations: Tensiometer & Gypsum Block
  • Yield Corn Grain, 15.5% moisture, T/ha: 10.58 Text File
Treatment 5:
 Vary except grainfill stage
  • Irrigation Dates and Amounts: Text Format;
  • Phenology: Emergence - 30 Mar 1984; Pollination (R2) - 31 May 1984; Maturity (Black layer) - 28 Jun 1984
  • Stand Count:
  • Soil Water Pressure Observations: Tensiometer & Gypsum Block
  • Yield Corn Grain, 15.5% moisture, T/ha: 6.61 Text File
Treatment 6:
 Dry down during vegetative (subsoil dewatering)
  • Irrigation Dates and Amounts: Text Format;
  • Phenology: Emergence - 30 Mar 1984; Pollination (R2) - 31 May 1984; Maturity (Black layer) - 28 Jun 1984
  • Stand Count:
  • Soil Water Pressure Observations: Tensiometer & Gypsum Block
  • Yield Corn Grain, 15.5% moisture, T/ha: Average - 8.57; Individual plots - 9.22, 7.92 Text File
Treatment 7:
 Control - Vary full season
  • Irrigation Dates and Amounts: Text Format;
  • Phenology: Emergence - 30 Mar 1984; Pollination (R2) - 31 May 1984; Maturity (Black layer) - 28 Jun 1984
  • Stand Count:
  • Soil Water Pressure Observations: Tensiometer & Gypsum Block
  • Yield Corn Grain, 15.5% moisture, T/ha: Average - 10.30; Individual plots - 9.49, 11.11 Text File
Treatment 8:
 Irrigate 80% of pan every three days
  • Irrigation Dates and Amounts: Text Format;
  • Phenology: Emergence - 30 Mar 1984; Pollination (R2) - 31 May 1984; Maturity (Black layer) - 28 Jun 1984
  • Stand Count:
  • Soil Water Pressure Observations: Tensiometer & Gypsum Block
  • Yield Corn Grain, 15.5% moisture, T/ha: 10.41 Text File
Treatment 9:
 Two irrigations - one week pretassel, two weeks later (third optional if no rainfall)
  • Irrigation Dates and Amounts: Text Format;
  • Phenology: Emergence - 30 Mar 1984; Pollination (R2) - 31 May 1984; Maturity (Black layer) - 28 Jun 1984
  • Stand Count:
  • Soil Water Pressure Observations: Tensiometer & Gypsum Block
  • Yield Corn Grain, 15.5% moisture, T/ha: Average - 3.80; Individual plots - 0.82, 6.77 Text File
Treatment 10:
 No irrigation
  • Irrigation Dates and Amounts: Text Format;
  • Phenology: Emergence - 30 Mar 1984; Pollination (R2) - 31 May 1984; Maturity (Black layer) - 28 Jun 1984
  • Stand Count:
  • Soil Water Pressure Observations: Tensiometer & Gypsum Block
  • Yield Corn Grain, 15.5% moisture, T/ha: Average - 2.63; Individual plots - 0.80, 4.45 Text File
For more information on the study and its interpretation contact:
Dr. Jim Hook Professor, Soil and Water Management
Crop and Soil Sciences Department and NESPAL
The University of Georgia, College of Agricultural and Environmental Sciences
P.O. Box 748, Tifton, GA 31793-0748
e-mail: jimhook@tifton.cpes.peachnet.edu

Page developed by James E. Hook, Amanda Richards, and Linsey Forlow.
Last Modified on 29 June 2000.