VRI - Corn Product Response to Irrigation and Population - Bruning, NE

Trial Overview

  • With the increase in limited irrigation due to reductions in pumping capacity or restrictions on the amount of water producers are able to pump over a certain period of time, it is imperative that Monsanto tests products under varying irrigation rates to supply better corn product recommendations by irrigation level.

Research Objective

  • The objective of this study was to determine the yield response of key DEKALB® brand corn products for the region based on planting population and irrigation amount.
Soil Type
Previous Crop
Tillage Type
Planting Date
Harvest Date
Potential Yield
Planting Rate
Bruning, NE
Silt loam
No tillage
300 bu/acre
24K, 30K, 36K, and 42K

Site Notes:

Eleven DEKALB® brand corn products were planted at 24K, 30K, 36K, and 42K (K = 1,000) seeds/acre (s/a) under 100% full irrigation (100% FI) and 50% of full irrigation (50% FI).Corn products and planting rates were replicated two times under the 100% FI and 50% FI treatments.The trial was irrigated with a center pivot system with drop nozzles placed just above the crop canopy.At planting, the site had approximately 6 inches of plant available water in the top 3 feet of the soil profile. A wet May was followed by below normal precipitation in June and July. Monthly rainfall totals were: 6.2 inches in May, 1.3 inches in June, 1.4 inches in July, and 2.9 inches in August. Weed control was excellent, 200 lbs. of actual N was side-dressed at the V2 stage, and very little lodging was observed prior to harvest.The amount of irrigation applied per pass was 0.8 inch for the 100% FI treatment (totaling 8.4 inches) and 0.4 inch for the 50% FI treatment.



Understanding the Results

  • Averaged across all products and planting populations, yields were 16 bu/acre higher for the 100% FI treatment than the 50% FI treatment.
  • Yield response to increasing irrigation was as high as 50 bu/acre (DKC63-21RIB and DKC66-74RIB brand blends) averaged across all populations. Several products showed a lower response to increasing irrigation (i.e. DKC63-55RIB brand blend).
  • Increasing plant density from 24K to 30K seeds/acre provided the largest yield increase for most products. The average yield response across products was 19 bu/acre at 50% FI and 37 bu/acre at 100% FI.
  • The yield response by increasing plant density from 30K to 36K seeds/acre was much less, averaging 14 bu/acre at 50% FI, and only 6 bu/acre at 100% FI. DKC64-34RIB, DKC66-74RIB, DKC68-26RIB, and DKC70-27RIB brand blends had the greatest response to this increase in plant density.
  • Increasing plant density from 36K to 42K seeds/acre had mixed results. At 50% FI, only DKC63-21RIB, DKC63-55RIB, and DKC60-67RIB brand blends showed more than a 10 bu/acre increase. Most products had little or no response to this increase in plant density. However, at 100% FI, DKC55-84RIB, DKC60-67RIB, DKC63-60RIB, and DKC66-74RIB brand blends all had 24+ bu/acre increases.

What Does This Mean for Your Farm

  • Farmers should carefully consider corn product selection and planting rate based on the irrigation capabilities in each field to help maximize their return.
  • While yield typically increases with increased irrigation, farmers should weigh the cost of applying extra water against the potential profits from increased yield, especially when yield-limiting conditions occur.
  • These data suggest that the planting population should be at least 30K seeds/acre, even at reduced irrigation levels, as there was a consistent yield and profit penalty with under-planting, regardless of product selection.
  • Monsanto intends to continue these trials to evaluate corn product response to irrigation level and planting population under changing environmental conditions for the 2018 season. Readers should keep in mind that these results are from one location only, and should look at multiple site results before drawing conclusions.