George Rehm

Impact of banded potassium for corn and soybean production in a ridge‐till planting system

Abstract Potassium (K) deficiency symptoms in corn (Zea mays L.) grown in the ridge‐till planting system were a major concern for producers who used this planting system. The purpose of this study was to develop management practices for use of K fertilizer in the ridge‐till planting system. The study was conducted on a farm in southwestern Minnesota where the ridge‐till planting system had been used for several years. The first year was devoted to an evaluation of rate of K (0, 37, 74, and 148 kg K/ha) applied in a band in the center of the ridge on growth and yield of three corn hybrids. Frequency of K application was evaluated for soybean [Glycine max L. (Merril)] production in the second year and corn in the third year of the study. The response to K use and the K rate x hybrid interaction were significant. Residual effects of banded K were evident with both corn and soybeans if rates of 74 kg K/ha or higher were used. The data collected show that use of banded K is important for corn and soybean produ...

Evaluation of some soil and plant analysis procedures as predictors of the need for sulfur for corn production

Abstract The objective of this study was to evaluate the usefulness of measures of mineralized sulfur (S), soil sulfate‐sulfur (SO4‐S), concentration of S in plant tissue, and the N: S ratio in plant tissue as predictors of the need for S in a fertilizer program for corn (Zea mays L.). Data to evaluate the use of plant analysis for S as a predictor were obtained from ten sites where various rates of N and S were applied to corn. Regression analysis was used to relate the S concentration in the ear leaf tissue as well as the N: S ratio in the same tissue to relative yield when the rate of applied N was held constant at a rate of 168 kg/ha. These measures of S in plant tissue were not significantly related to relative yield at sites where there was no response to fertilizer S as well as sites where added S increased yield. Data from the same sites were used to assess the ability of soil tests to predict the need for fertilizer S. A measurement of extractable SO4‐S in the surface soil (0–15 cm) was not relia...

Timing sulfur applications for corn (Zea mays L.) production on irrigated sandy soil

Abstract The importance of sulfur (S) for corn (Zea mays L.) production on sandy soils has been noted for a number of years. Yet, there has been no extensive evaluation of the timing of S applications on corn production in these specific situations. This study was conducted for the purpose of measuring the effect of split applications of fertilizer S on com grown on irrigated sandy soils. The study was conducted in 1985 and 1986. Fourrâtes of fertilizer S (0, 6.5, 13, and 26 kg/ha) were combined with six times of application schemes in a randomized complete block design with four replications. Granular gypsum was used as the source of S. Corn responded to the use of fertilizer S in 1986 only. Time of application had no significant effect on yield in either year. There were no advantages to the use of split applications. The S concentration in the ear leaf tissue at silking was affected by both rate and time of S application at each experimental site. The current recommendation is to apply fertilizer S, wh...

Response of Hard Red Spring Wheat to Copper Fertilization

To achieve optimum production of hard red spring wheat, growers should know if use of copper (Cu) in a fertilizer program is necessary. For this study, copper was broadcast and incorporated before planting in the sulfate or chelate form to supply both 6.7 and 13.4 kg Cu ha−1 at six sites. The soils at the majority of the sites had a loamy fine sand texture with low organic‐matter content. Application of Cu increased grain yield at one site. Grain yield response, however, could not be predicted by amount of Cu extracted from soil by the diethylenetriaminepentaacetic acid (DTPA) procedure. Concentrations of Cu in whole plant tissue did not match those reported in the literature. The results of this study do not support the addition of Cu to a fertilizer program for production of hard red spring wheat on mineral soils in the northern Great Plains.

Effect of Soil Sample Density on Nitrogen Application Maps and Sugar Beet Root Yield and Quality

Abstract Production of high‐quality sugar beets requires precise nitrogen (N) fertilizer management with N recommendations based on a measurement of residual nitrate‐N to 120 cm (4 ft) soil depth. The objective of this study was to determine the agronomic and economic aspects of using different grid cell sizes for sampling soil nitrate‐N. A 5‐ha field (12.4 acre) was soil sampled for nitrate‐N using 18.3×18.3 m grid cells in 1997 and 1998. Nitrogen application maps for four different grid cell sizes 18.3×18.3 m (60×60 ft), 54.9×54.9 m (180×180 ft), 91.4×91.4 m (300×300 ft), and 128×128 m (420×420 ft) were developed from these soil samples and compared with a conventional average for each field. The five nitrogen fertilizer treatments adjusted for grid cell size were applied with a fertilizer truck equipped with a variable rate applicator in two replicates of 274‐m long strips. Sugar beet quality was determined on root samples taken immediately before root harvest on a 18.3×18.3 grid. Root yield was determined with a conventional harvester equipped with a yield monitor. The nitrogen fertilizer application maps derived from the 54.9×54.9 m, 91.4×91.4 m, and 128×128 m soil sampling grids were similar in 1997. The application map derived from 18.3×18.3 m grid cell size was different from the application maps derived from larger grid cell sizes. Although there were differences in N application maps, there were no differences in root yield, root quality, or recoverable sucrose among grid cell sizes or constant rate applications in either 1997 or 1998.