Albert L. Sims

Survival and Inoculum Production of Gibberella zeae in Wheat Residue

Survival and inoculum production of Gibberella zeae (Schwein.) Petch (anamorph Fusarium graminearum (Schwabe)), the causal agent of Fusarium head blight of wheat and barley, was related to the rate of wheat (Triticum aestivum L.) residue decomposition. Infested wheat residue, comprising intact nodes, internodes, and leaf sheaths, was placed in fiberglass mesh bags on the soil surface and at 7.5- to 10-cm and 15- to 20-cm depths in chisel-plowed plots and 15 to 20 cm deep in moldboard-plowed plots in October 1997. Residue was sampled monthly from April through November during 1998 and every 2 months through April to October 1999. Buried residue decomposed faster than residue placed on the soil surface. Less than 2% of the dry-matter residue remained in buried treatments after 24 months in the field, while 25% of the residue remained in the soil-surface treatment. Survival of G. zeae on node tissues was inversely related to the residue decomposition rate. Surface residue provided a substrate for G. zeae for a longer period of time than buried residue. Twenty-four months after the initiation of the trial, the level of colonization of nodes in buried residue was half the level of colonization of residue on the soil surface. Colonization of node tissues by G. zeae decreased over time, but increased for other Fusarium spp. Ascospores of G. zeae were still produced on residue pieces after 23 months, and these spores were capable of inducing disease. Data from this research may assist in developing effective management strategies for residues infested with G. zeae.

Zinc in wheat grain as affected by nitrogen fertilization and available soil zinc

Abstract Greenhouse and field experiments were conducted to determine the influence of nitrogen (N) fertilization and DTPA‐extractable soil zinc (Zn) on Zn concentration in wheat (Triticum aestivum L., cv. Pioneer 2375) grain. Application of zinc sulfate (ZnSO4) in the range of 0 to 8 mg Zn kg‐1 increased linearly DTPA‐extractable Zn in an incubated calcareous soil from 0.3 to 5.0 mg kg‐1. Application of these rates of ZnSO4 to the same soil under greenhouse conditions increased Zn concentration of wheat grain from 26 to 101 mg kg‐1. The influence of 134 kg urea‐N ha‐1 on Zn concentration in wheat grain at eight field sites, with DTPA‐extractable soil Zn levels ranging from 0.3 to 4.9 mg kg‐1, was studied. Nitrogen fertilizer increased wheat‐grain yields in four of the eight experiments but had little effect on grain‐Zn concentration. Grain‐Zn concentration ranged from 31 to 45 mg kg‐1 in N‐fertilized plots at the various sites and was related (r=0.74*) to DTPA‐extractable soil Zn.

Content and Potential Availability of Selected Nutrients in Field‐Applied Sugar Beet Factory Lime

Factory lime generated during sugar beet processing contains phosphorus (P). Factory lime collected from seven sugar beet factories in North Dakota and Minnesota had P concentrations ranging from 3470 to 7043 mg P kg−1. Soil collected from two field trials one and two growing seasons after factory lime application was analyzed for pH changes and soil‐test P (STP). At one site, soil pH increased after both growing seasons, as did STP, indicating a continued release of P as the factory lime dissolved and reacted with the soil. At the second site, increased soil pH and STP were evident after one growing season, but a few months later the pH had no further change and STP decreased. The data suggest factory lime has the potential to supply P to a growing crop, but actual proportion of P available from the factory lime could not be quantified from these experiments.

Spring wheat response to fertilizer nitrogen following a sugar beet crop varying in canopy color

Experiments were conducted in the Red River Valley (RRV) of Minnesota to determine the responses of hard red spring wheat (Triticum aerstivum L.) to fertilizer N after a sugar beet (Beta vulgaris L.) crop that varied spatially in canopy color and N content. A color aerial photograph was acquired of the sugar beet field just prior to root harvest, and six sites were selected that varied in sugar beet canopy color, three each of green and yellow canopy sites. The three green sugar beet canopies returned 369, 265, and 266 kg N ha−1 to the soil while the three yellow sugar beet canopies returned 124, 71, and 73 kg N ha−1 to the soil. Spring wheat response to fall-applied urea-N fertilizer (0, 45, 90, 135, and 180 kg N ha−1) was determined the following year at each of the above antecedent canopy sites. Soil NO3-N in the top 0.6 m of soil varied among the locations with a range of 35 to 407 kg NO3-N ha−1 at the green canopy sites and 12 to 23 kg NO3-N ha−1 at the yellow canopy sites. Application of fertilizer N according to traditional recommendation methods would have resulted in fertilizer applications at all three yellow canopy sites and two of the three green canopy sites. At the antecedent green sugar beet canopy sites, fertilizer N had little or no effect on spring wheat grain yields, grain N concentration, anthesis dry matter, and anthesis N content. In contrast, fertilizer N increased all four parameters at the antecedent yellow sugar beet canopy sites. The data indicate that fertilizer N management can be improved by using remote sensing to delineate management zones according to antecedent sugar beet canopy color.

Evaluation of methods to determine residual soil nitrate zones across the northern Great Plains of the USA

A four-year study was conducted from 2000 to 2004 at eight field sites in Montana, North Dakota and western Minnesota. Five of these sites were in North Dakota, two were in Montana and one was in Minnesota. The sites were diverse in their cropping systems. The objectives of the study were to (1) evaluate data from aerial photographs, satellite images, topographic maps, soil electrical conductivity (ECa) sensors and several years of yield to delineate field zones to represent residual soil nitrate and (2) determine whether the use of data from several such sources or from a single source is better to delineate nitrogen management zones by a weighted method of classification. Despite differences in climate and cropping, there were similarities in the effectiveness of delineation tools for developing meaningful residual soil nitrate zones. Topographic information was usually weighted the most because it produced zones that were more correlated to actual soil residual nitrate than any other source of data at all locations. The soil ECa sensor created better correlated zones at Minot, Williston and Oakes than at most eastern sites. Yield data for an individual year were sometimes useful, but a yield frequency map that combined several years of standardized yield data was more useful. Satellite imagery was better than aerial photographs at most locations. Topography, satellite imagery, yield frequency maps and soil ECa are useful data for delineating nutrient management zones across the region. Use of two or more sources of data resulted in zones with a stronger correlation with soil nitrate.

Influence of rate and placement of phosphate fertilizer on growth and yield of hard red spring wheat in diverse tillage systems

Management of P is a major issue for crop producers who grow hard red spring wheat (Triticum aestrivum, L.) with conservation tillage. Compared to the use of the moldboard plow, tillage that leaves crop residue on the soil surface can cause changes in soil chemical, biological, and physical properties. These changes may affect management practices for fertilizer P. Two studies were conducted to evaluate the impact of rate and placement of fertilizer P on hard red spring wheat production in various tillage systems. In one study, P rates of 0, 5.5, 11.0, 16.5, and 22.0 kg ha−1 were: (1) broadcast and incorporated, or (2) applied in a subsurface band prior to tillage, or placed with the seed at planting. The chisel plow was used for primary tillage in this study. In a separate study, P rates of 0, 20, 40, and 60 kg ha−1 were: (1) broadcast and incorporated, (2) applied in a subsurface band, or (3) applied with the seed at planting. These P rates and placements were used in a moldboard plow, chisel plow, and no-till planting system. There was a positive response to rate of fertilizer P used in both studies, with a higher rate needed for optimum yield when soil test levels for P were in the low rather than the medium range. Tillage system had an effect on yield with no-till < chisel plow < moldboard plow. There was no interaction between: (1) tillage system and rate of P applied, (2) tillage system and P placement, and (3) rate and placement of P fertilizer. The data collected from these studies lead to the conclusion that the recommended rate of fertilizer P should not be adjusted for either method of placement or tillage system.

Remote sensing of sugarbeet canopies for improved nitrogen fertilizer recommendations for a subsequent wheat crop.

Abstract Return to soil of high N, green sugarbeet (Beta vulgaris L.) tops, but not the return of low N, yellow to yellow‐green tops, reduces the magnitude of N‐fertilizer responses for the following crop. Twelve N fertilizer trials with spring wheat (Triticum aestivum L.) were established at sites with late‐season ‘green’ (8 sites) or ‘yellow’ (4 sites) sugarbeet canopies the previous year. Late‐season, aerial color photographs of sugarbeet fields and global positioning system (GPS) technology were used to locate the experimental sites. Based on the soil NO3‐N test customarily used in the Northern Grain Plains, N fertilizer responses were expected at 11 of the 12 sites. However, no significant grain‐yield responses were obtained at the eight antecedent ‘green’ sugarbeet sites. Expected yield and grain‐N responses were obtained at the four antecedent ‘yellow’ sites. In contrast to the usual soil NO3‐test, remote sensing of the previous sugarbeet crop resulted in successful prediction of N‐fertilizer responses at all 12 experimental sites. Application of N fertilizer at the ‘green’ canopy sites increased the likelihood that excess soil NO3‐N would be present after the wheat harvest. A precision farming technique, involving remote sensing of late‐season sugarbeet canopies, use of GPS technology, and use of variable rate N‐fertilizer application is recommended for a wheat crop following sugarbeet.

Neural network models for soil nitrate prediction using imagery and non-imagery information

Ten satellite imagery and four non-imagery data were used to develop soil nitrate prediction models using neural network architectures i.e. Backpropagation, Modular and Radial basis function. Back propagation model yielded an average prediction accuracy of 67.92% with a root mean square error of 0.87. Radial basis function model, on the other hand, predicted with an average prediction accuracy of 90.04%. The modular neural network predicted with average prediction accuracy of 77.12%, correlation coefficient of 0.62 and RMSEP of 0.51. The modular neural network based prediction model, showed overall highest performance than BPNN and RBFN models.