Johnathon D. Holman

Response of Drought Tolerant and Conventional Corn to Limited Irrigation

Summary With declining water levels in the Ogallala aquifer, many wells cannot supply peak irrigation water needs for corn. Emerging drought-tolerant (DT) corn hybrids could help farmers maintain yield with limited capacity wells. A knowledge gap exists com-paring transgenic DT and conventional corn hybrids in yield response to water level. The purpose of this study was to compare yield, yield components, water productivity, and irrigation water use efficiency response of DT corn with cspB (DKC 6267 DGVT-2PRO) transgene trait and conventional corn hybrid (DKC 62-98 VT2PRO) with similar maturity to full and limited irrigation. Preliminary results from the 2014 grow-ing season indicate the effect of irrigation level on corn yield was significant ( P-val-ue<0.001) . The effect of the cspB transgene trait in the DT hybrid did not affect yield ( P-value=0.32) , and there was no effect of the interaction between irrigation level and corn hybrid on yield ( P-value=0.82) . The effect of irrigation and hybrid on 100 kernel weight was significant, with

Soil Nutrients Status after Fifty Years of Tillage and Nitrogen Fertilization

ABSTRACT Long-term studies are valuable in assessing the impact of crop management practices on soil sustainability and function. This study used two calculation scenarios, fixed depth and Equivalent Soil Mass (ESM) to assess (i) soil nutrient status and (ii) soil organic carbon (SOC) after 50 years of nitrogen (N) fertilizer application rates (0, 22, 45, and 67 kg N ha−1) and tillage [clean tillage (CT), reduced tillage (RT), and no-tillage (NT)] in a dryland winter wheat-sorghum-fallow cropping system. The soil organic matter (SOM) content increased by 33% with NT and RT compared with CT. The SOC at 0–30 cm was 39% greater than 30–60 cm depth with both fixed depth and ESM calculations. Soil nutrient specifically soil calcium (Ca), magnesium (Mg), and phosphorus (P) associated with N rates were no different than the control. Crop nutrient removal may eventually reduce soil nutrient contents with only N application. Nutrient addition specifically P should be considered in the future.

Seeding Rate for Dryland Wheat

Four winter wheat varieties (PlainsGold Byrd, Limagrain T158, Syngenta TAM 111, and WestBred Winterhawk) were planted at five seeding rates (30, 45, 60, 75, and 90 lb/a) in the fall of 2014, 2015, and 2016 at Colby, Garden City, and Tribune, KS. The objective of the study is to identify appropriate seeding rates for dryland winter wheat in western Kansas. Averaged across varieties, a seeding rate of 60 lb/a seemed to be adequate at all locations in 2015. However, with higher yields in 2016, a higher seeding rate (75 lb/a) was beneficial. Although yields were less in 2017 than 2016, a seeding rate of 75 lb/a generally produced the highest yields. The wheat variety T158 was the highest yielding (or in the highest group) at all locations in 2015. Other varieties may have been affected by differential response to stripe rust and winter injury resulting in lower yields. In 2016, the highest yielding variety varied by location. TAM 114 was in the highest yielding variety at each location in 2017. Variety selection and growing season appears to have more effect on wheat yields than seeding rate.

Teff Grass Response to Nitrogen Fertilization

Teff, a warm season annual grass native to Africa, is gaining popularity as a forage crop in the United States. Little information regarding nitrogen fertilization is available for teff grass production. This field experiment was conducted to evaluate teff grass response to varying nitrogen fertilization rates under dryland conditions. There was no yield response to increasing nitrogen rate or nitrogen source applied.

Determining Profitable Annual Forage Rotations

Producers are interested in growing forages, yet the southwest region of Kansas lacks proven recommended crop rotations such as those for grain crops. Forage production is important to the region’s livestock and dairy industries and is becoming increasingly important as irrigation well capacity declines. Forages require less water than grain crops and may allow for increased cropping intensity and opportunistic cropping. A study was initiated in 2013 comparing several 1-, 3-, and 4-year forage rotations with no-till and minimum-till (mintill). Data presented are from 2013 through 2014. Winter triticale yields were not affected by tillage in 2013 but were increased by tillage in 2014. Double-crop forage sorghum yielded 30% of full-season forage sorghum in 2013, which was a drought year, but across years yielded 70% of full-season sorghum. Oats failed to make a crop during the drought year and do not appear to be as drought tolerant as spring triticale or forage sorghum. Subsequent years will be used to compare forage rotations and profitability.

Fallow Replacement Crop (Cover Crops, Annual Forages, and Short-Season Grain Crops) Effects on Available Soil Water

Producers are interested in growing cover crops and reducing fallow. Limited information is available on growing crops in place of fallow in the semiarid Great Plains. Between 2012 and 2015, spring cover, annual forage, and grain crops were grown in place of fallow in a no-till wheat-grain sorghum-fallow (WSF) rotation in southwest Kansas. Growing a cover, hay, or grain crop in place of fallow reduced the amount of stored soil moisture at wheat planting. On average, cover crops stored slightly more moisture than hay crops, but this soil moisture difference did not affect wheat yields. Soil moisture after grain crops was less than after cover or hay crops, and this difference resulted in reduced wheat yields. These results do not support claims that cover crops increase soil moisture compared to fallow. Soil moisture storage from fallow crop termination to wheat planting was greatest among those treatments that were most dry at termination and produced the most aboveground biomass. On average, cover crops had a 28% precipitation storage efficiency (PSE) and hay crops had a 22% PSE between termination and wheat planting. Fallow during the full-fallow period (sorghum harvest to wheat planting) had an 18% PSE. Crops grown in place of fallow must compensate for the expense of growing the crop plus the reduction in soil moisture for the next crop.

Volunteer corn in fallow

Introduction Volunteer corn is a common weed in the fallow phase of wheat-corn-fallow in western Kansas and the west central Great Plains. No-till increases precipitation storage, reduces soil erosion, and often increases crop yields when compared to conventional-till. As a result, many producers have adopted no-till cropping systems that use glyphosate extensively for weed control in fallow. Because most of the corn grown is herbicide-tolerant, volunteer corn in fallow may not be controlled with glyphosate. Failing to control weeds in fallow can reduce soil moisture storage and subsequent crop yield.