James L. Petersen

Crop Residue Cover Effects on Evaporation, Soil Water Content, and Yield of Deficit-Irrigated Corn in West-Central Nebraska

Competition for water is becoming more intense in many parts of the U.S., including west-central Nebraska. It is believed that reduced tillage, with more crop residue on the soil surface, conserves water, but the magnitude of water conservation is not clear. A study was initiated on the effect of residue on soil water content and corn yield at North Platte, Nebraska. The experiment was conducted in 2007 and 2008 on plots planted to field corn (Zea mays L.). In 2005 and 2006, soybean was grown on these plots. There were two treatments: residue-covered soil and bare soil. Bare-soil plots were created in April 2007. The residue plots were left untreated. In April 2008, bare-soil plots were recreated on the same plots as in 2007. The experiment consisted of eight plots (two treatments with four replications each). Each plot was 12.2 m × 12.2 m. During the growing season, soil water content was measured several times in each of the plots at six depths, down to a depth of 1.68 m, using a neutron probe. The corn crop was sprinkler-irrigated but purposely water-stressed, so that any water conservation in the residue-covered plots might translate into higher yields. In 2007, mean corn yield was 12.4 Mg ha-1 in the residue-covered plots, which was significantly (p = 0.0036) greater than the 10.8 Mg ha-1 in the bare-soil plots. Other research has shown that it takes 65 to 100 mm of irrigation water to grow this extra 1.6 Mg ha-1, which may be considered water conservation due to the residue. In 2008, the residue-covered soil held approximately 60 mm more water in the top 1.83 m compared to the bare soil toward the end of the growing season. In addition, mean corn yield was 11.7 Mg ha-1 in the residue-covered plots, which was significantly (p = 0.0165) greater than the 10.6 Mg ha-1 in the bare-soil plots. It would take 30 to 65 mm of irrigation water to produce this additional 1.1 Mg ha-1 of grain yield. Thus, the total amount of water conservation due to the residue was 90 to 125 mm in 2008. Water conservation of such a magnitude will help irrigators to reduce pumping cost. With deficit irrigation, water saved by evaporation is used for transpiration and greater yield, which may have even greater economic benefits. In addition, with these kinds of water conservation, more water would be available for competing needs.

Fertilizer and crop management practices for improving maize yields on high pH soils

Abstract In Nebraska, nearly 0.4 million hectares (ha) of maize (Zea mays L.) are subjected to varying degrees of iron (Fe) chlorosis from high pH soil. A factorial design with two maize varieties (tolerant and non‐tolerant) and seed row applied Fe treatments with four replications was used on three soil areas of Cozad silt loam with pHs of 8.6, 8.2, and 7.7. Iron treatments included a check, seed row applied FeSO4•7H2O, FeEDDHA, dried granular FeSO4‐polyacrylamide gel and foliar sprays of 1.5% FeSO4•7H2O. Chlorophyll meter readings at V8 and V10 separated treatment effects on the pH 8.6 site and were highly correlated with yield. In 1993, all Fe treatments on the pH 8.6 site produced significant yield increases on both varieties except the foliar treatment and FeEDDHA on the non‐tolerant hybrid. The FeSO4‐polyacrylamide gel was especially effective, but was not available in 1994. Most Fe treatments significantly increased yields on the pH 8.2 and 8.6 sites, but not the pH 7.7 site. In 1994, most Fe treat...

Genetic improvement of corn for tolerance to high pH soils

Abstract Iron deficiency chlorosis (FeDC) is a major problem for many crop and ornamental plants in Nebraska. The most severe conditions are in river valleys where soil pH may range from pH 5.0 or less, to areas with pH values over 10. The problem of FeDC in various degrees affects nearly 500,000 ha of corn (Zea mays L.) in Nebraska. On a global scale, millions of hectares are affected. Soils in most fields are not homogeneous, thus high pH areas, where crop chlorosis prevails, are intermixed with areas of excellent soils that are capable of producing high yields. Corn breeding germplasms and experimental and commercial corn hybrids were grown on four sites of Cozad silt loam, saline‐sodic (Typic Haplustolls) with pH ranges from 7.4 to 8.6. Marked differences in response to the pH 8.6 site resulted in no surviving plants in some genotypes to relatively normal appearing growth in others. No hybrids were found that yielded as well on the pH 8.6 soils as they did on better soils. However, several that did be...

Effect of Nitrogen Application Timing on Corn Production Using Subsurface Drip Irrigation

The use of subsurface drip irrigation (SDI) in row-crop agriculture is increasing because of potential increases in water and nutrient use efficiency. Research-based information is needed to manage N applications through SDI systems in field corn (Zea mays L.) production. This study was conducted to assess the effect of different in-season SDI system N application timings on corn production and residual soil NO3-N at the University of Nebraska-Lincoln West Central Research and Extension Center in North Platte, Neb, on a Cozad silt loam (fine-silty, mixed, mesic Fluventic Haplustoll). We evaluated the effect of three N application timing methods (varying percentages of the total N rate [48% of total N] applied at the V10, VT, and R3 growth stages, in addition to uniform N applications [52% of total N] over all treatments at preplant, planting, and V14 growth stage) at two N application rates (University of Nebraska-Lincoln [UNL] recommended rate and the UNL rate minus 20%) on corn grain and biomass yield and end-of-study distribution of residual soil NO3-N. In 2006, there were no significant differences in corn grain yields between the two N application rates. In 2007, the grain yield under the UNL recommended N rate was significantly higher (190 kg ha−1) than the UNL-minus-20% N rate. The average grain yield for this study was close to the predicted yields (based on average 5-year historic yields + a 5% yield increase), indicating that corn production under SDI is satisfactory. In 2006 and 2007, grain yield and biomass production for the N application timing treatments were not significantly different (P > 0.05). The application of 13% of the total N at as late as R3 did not result in decreased yields. The lack of response to different N application timing treatments indicates that there is flexibility in N application timing for corn production under SDI. The distribution of NO3-N in the 0- to 0.9-m and 0.9- to 1.8-m soil profiles was not significantly different among all the treatments.

Effects of Crop Residue Removal on Soil Water Content and Yield of Deficit-Irrigated Soybean

Reduced tillage, with more crop residue remaining on the soil surface, is believed to conserve water, especially in arid and semi-arid climates. However, the magnitude of water conservation is not clear. An experiment was conducted to study the effect of crop residue removal on soil water content, soil quality, and crop yield at North Platte, Nebraska. The same field plots were planted to soybean (Glycine max) in 2009 and 2010. There were two treatments: residue-covered soil and bare soil. Residue (mostly corn residue in 2009 and mostly soybean residue in 2010) was removed every spring from the same plots using a flail chopper and subsequent hand-raking. The experiment consisted of eight, 12.2 m × 12.2 m, plots (two treatments with four replications each). Soybeans were sprinkler-irrigated, but purposely water-stressed, so that any water conservation in the residue-covered plots might translate into higher yields. After four years of residue removal, soil organic matter content and soil residual nitrate nitrogen were significantly smaller, and soil pH was significantly greater, in the bare-soil plots compared to the residue-covered plots. The residue-covered soil held approximately 90 mm more water in the top 1.83 m compared to the bare soil near the end of the 2009 growing season. In addition, mean soybean yield was 4.5 Mg ha-1 in the residue-covered plots, compared to 3.9 Mg ha-1 in the bare-soil plots. Using two crop production functions, it is estimated that between 74 and 91 mm of irrigation water would have been required to produce this extra 0.6 Mg ha-1. In 2010, mean soybean yield was 3.8 Mg ha-1 in the residue-covered plots, compared to 3.3 Mg ha-1 in the bare-soil plots. Between 64 and 79 mm of irrigation water would have been required to produce this extra 0.5 Mg ha-1. In both years, several processes may have contributed to the differences observed: (1) greater evaporation of water from the soil in the bare-soil treatment, and (2) greater transpiration by plants in the bare-soil treatment in the beginning of the growing season as a result of more vegetative growth due to higher soil temperatures in the bare-soil treatment.

Use of Fly Ash as a Liming Material of Corn and Soybean Production on an Acidic Sandy Soil

Fly ash (FA) produced from subbituminous coal combustion can potentially serve as a lime material for crop production in acidic soils. A five-year study was conducted to determine if FA was an effective liming material in an acid sandy soil under corn and soybean grain production. Fly ash and pelletized lime (PL) were surface applied at rates ranging from 3,200 to 6,400 and 1,416 to 5,658 kg/ha (0.5 to 2 times the recommended rate) at two sites near Brunswick, NE, respectively. At Site A, lime source additions increased soil pH by 0.7 units and decreased soil exchangeable Al by 7.3 mg/kg to a depth of 20 cm. Lime applications resulted in pH increase during the first year (2004) at the 0 to 10-cm depth, and in 2007 at the 10 to 20-cm depth. At Site B, soil pH data suggested that one or more past lime applications may have occurred. Corn and soybean grain yields were not different during each year between the control and lime source treatments at both sites. This lack of difference was likely due to soluble Al concentrations not being great enough to affect grain yield. Fly ash did not negatively affect grain yields in this study. Boron concentration (400 mg/kg) in FA were likely too low to adversely affect yields. The FA applied at rates in this study, increased pH comparable to PL and is an appropriate liming material.

Effect of Amount and Timing of Subsurface Drip Irrigation on Corn Production

Subsurface drip irrigation (SDI) has the potential of being a more efficient irrigation system compared to systems such as center pivot and furrow irrigation. The objective of this study was to determine the effect of the amount and timing of irrigation, using SDI, on corn (Zea mays) production. A field study was conducted at North Platte, Nebraska in 2007 and 2008, using two SDI systems. The study was replicated eight times on the older SDI system (SDI1) and four times on the newer SDI system (SDI2). On SDI1, there were nine treatments to impose different irrigation regimes, ranging from dryland to fully irrigated. Five of the nine treatments allowed water stress only after tasseling and silking. On SDI2, there were eight treatments that were very similar to the nine on SDI1.

Effect of Crop Residue on Soil Water Content and Yield of Sprinkler-irrigated Corn

Competition for water is becoming more intense in many parts of the USA, including west-central Nebraska. It is believed that reduced tillage with increased crop residue conserves water, but the magnitude of water savings is not clear. In 2007, a study was initiated on the effect of residue on soil water content and crop yield at North Platte, Nebraska. The experiment was conducted on a set of plots planted to field corn (Zea mays). There were two treatments: residue-covered soil and bare soil. Bare-soil plots were created by using a dethatcher and subsequent hand-raking, removing most of the residue. The residue plots were left untreated. The residue was mostly from previous no-till soybean crops. Residue mass and cover were measured twice: at the beginning (June) and at the end (October) of the growing season. The experiment consisted of eight plots (two treatments times four replications). Each plot was 12.2 m (40 ft) by 12.2 m. During the growing season, soil water content was measured seven times in each of the plots at six depths using a neutron probe (CPN Hydroprobe).

Corn Water Use and Yield for Various Limited Irrigation Treatments

With limited water resources, it becomes more critical to know how much and when to irrigate. The objective of this study was to determine the effect of the amount and timing of irrigation on corn (Zea mays L.) yield using subsurface drip irrigation (SDI). A field study was conducted at North Platte, Nebraska in 2007 - 2009, using two SDI systems. The study was replicated eight times on the older SDI system (SDI1) and four times on the newer SDI system (SDI2). On SDI1, there were nine treatments to impose different irrigation regimes, ranging from dryland to fully irrigated. Five of the nine treatments allowed for various degrees of water stress, but only after tasseling and silking. On SDI2, there were eight treatments that were very similar to those on SDI1.

Effect of Crop Residue on Soil Water Content and Yield of Deficit-Irrigated Corn and Soybean

It is believed that reduced tillage, with more crop residue on the soil surface, conserves water, especially in arid and semi-arid climates. However, the magnitude of water conservation is not clear. In 2007, a study was initiated on the effect of residue on soil water content and crop yield at North Platte, Nebraska. The experiment was conducted on plots planted to field corn (Zea mays L.) in 2007 and 2008, and soybean (Glycine max) in 2009. There were two treatments: residue-covered soil and bare soil. Bare-soil plots were created in April 2007 by using a dethatcher and subsequent hand-raking. In April 2008 and 2009, bare-soil plots were recreated on the same plots as in 2007. The experiment consisted of eight plots (two treatments with four replications each). Each plot was 12.2 m by 12.2 m. The crop was sprinkler-irrigated, but purposely water-stressed, so that any water conservation in the residue-covered plots might translate into higher yields.