Wheat yield and grain protein variation within an undulating soil landscape

Abstract

Wheat yield and grain protein variation within an undulating soil landscape. Can. J. Soil Sci. 81: 459-467. The objective of this study was to compare landform element complexes (LEC) and soil series as discrete management units for variable rate N fertilizer application. Crop response attributes including grain yield, and grain protein concentration were studied in ten intensively sampled transects in an undulating glacial till soil-landscape near Miniota, Manitoba. In 1997, a year with growing season precipitation 37% below average, median grain yield tended to increase with both N fertilizer and with convergent character in the landscape (upper < mid < lower). Varcoe soils, located predominantly within the lower LEC, were generally more productive than Newdale soils. Grain protein concentration increased with N fertilizer, but tended to decrease with convergent character in the landscape (upper > mid > lower), and was lowest in the Varcoe series. In 1998, growing season precipitation was 62% above average. Grain yield responses to N fertilizer were greater, due in part to declining N fertility in the check and 45 kg ha -1 treatments. Trends among LEC were opposite to those in 1997, as median grain yield estimates tended to decrease with convergent character in the landscape (upper > mid > lower). Grain yield was modeled as a function of estimated plant-available N supply within each LEC and soil series. Modeled 1997 grain yield maxima were 2077, 2261 and 2485 kg ha -1 in the upper, mid and lower LEC. Estimated plant-available N supply at the yield maxima were 89, 130 and 130 kg N ha -1 , respectively. In 1998, the relative order of modeled maxima among LEC was reversed. Grain yield of 2501, 2355 and 2227 kg ha -1 were predicted in the upper, mid and lower LEC. Estimated plant-available N supply at the yield maxima were 146, 142 and 154 kg N ha -1 , correspondingly. In 1997, plateau yields were 2379, 2495 and 2325 kg ha -1 for Newdale, Varcoe and Angusville series, respectively, where the Varcoe series responded most strongly to estimated plant-available N supply. The corresponding estimated plant-available N supply values at the modeled maxima were 195, 139 and 110 kg ha -1 . In 1998, plateau yields were 2343, 2253 and 2285 kg ha -1 for Newdale, Varcoe and Angusville series, respectively. The corresponding estimated plant-available N supply values at the modeled maxima were 136, 148 and 155 kg ha -1 . Successful variablerate fertilization by LEC or soil series will require long-term empirical study to establish risk-based grain yield-N relationships, and to determine if an economic advantage over conventional fertilization practices exists. . L'étude devait comparer l'utilité des complexes d'éléments topographiques (CET) et des séries de sols en tant qu'unités agronomiques discrètes permettant de déterminer la quantité d'engrais à appliquer dans le cadre d'un régime de fertilisation azotée variable. Les auteurs ont examiné divers attributs de la réaction des cultures, dont le rendement grainier et la concentr...

Soil nitrogen dynamics as affected by landscape position and nitrogen fertilizer

“…Crop productivity and N uptake can vary with positions within a landscape, particularly on the rolling plains and hummocky landforms of prairie landscapes (Fiez et al 1994(Fiez et al , 1995Walley et al 2001). Manning et al (2001b) found that, for a growing season with precipitation 62% higher than average, wheat yield and N uptake were significantly less at lower slope than at upper slope positions when N fertilizer was applied at 45 and 90 kg N ha -1 . However, the opposite trend in wheat yield was observed in another year with growing season precipitation 37% below average.…”

Can Landform Stratification Improve Our Understanding of Crop Yield Variability?

“…Fiez et al (1994) observed the highest grain protein at shoulder positions, whereas the lowest was observed at north exposed backslope positions. Manning et al (2001) observed the lowest protein content for wheat at F positions and attributed that to the greater biomass production at that landform together with a dilution effect. One possible explanation of such a difference between results at our field site and the literature might be differences in the availability of soil nitrogen to the plants (Jowkin and Schoenau, 1998), or attributed to late season moisture stress (Fiez et al, 1994).…”

“…If data showed no normal distributions, the Kruskal-Wallis test was applied. Generally an a=0.2 was used (Manning et al, 2001).…”

Effect of nitrogen fertilization and topography on soft red winter wheat yield and protein content in two Ontario landscapes

“…Mean grain protein concentrations were significantly different with respect to slope position and increased from the lower to the upper slope position at each site (Table 6). Manning et al (2001b) also found that grain protein concentration increased upslope and suggested it was likely due to proportionally less yield produced. An upper slope position would be expected to have relatively lower levels of plant available water, which may cause lower total grain and protein yields.…”

“…This increased biomass production has in turn resulted in greater SOC content, which contributes to a greater available water content in the soil, potentially mineralizable N, and soil profile development. Lower yields and available moisture on the upper slope position generally result in higher grain protein concentrations in winter wheat (Mulla et al 1992;Manning et al 2001b). Thus, the use of topography to aid in the delineation of N management units is appealing as it would identify some of the more significant changes in soil characteristics in a field, as well as being a method of delineation to which producers can readily relate from a crop production viewpoint.…”