Nutrient uptake of hybrid poplar in competition with weeds using the soil supply and nutrient demand (SSAND) model

Abstract

. 2009. Nutrient uptake of hybrid poplar in competition with weeds using the soil supply and nutrient demand (SSAND) model. Can. J. Soil Sci. 89: 197Á207. Mechanistic nutrient uptake models can help gain a quantitative understanding of nutrient uptake by plants under weed-competing conditions. The objectives of this study were to check the applicability of the soil supply and nutrient demand (SSAND) model to predict N, P and K uptake by hybrid poplar (Populus deltoides )Populus)petrowskyana var. Walker) grown with and without competition with dandelion (Taraxacum officinale) and quackgrass (Elymus repens) in a controlled environment, and to determine if incorporating N mineralization into the model would improve N uptake predictions. Simulation results showed that N uptake was underestimated for hybrid poplar by 58 to 73%, depending upon soil type and weed treatment. Incorporation of N mineralization as a model input improved the hybrid poplar N uptake predictions by 24 and 67% in the pasture and alfalfa soil, respectively, when grown without weeds. The SSAND model underestimated P uptake by 84 to 89% and overestimated K uptake by 28 to 59% for hybrid poplar depending upon the soil type and weed treatment. Results from this study illustrate that modeling competition between two species in a controlled environment study is a complex process and that further work is required to understand the underlying processes controlling nutrient supply and uptake in these systems.

Modeling nitrogen uptake for hybrid poplar with and without weed competition

“…Therefore, these results are encouraging given the existing variability in the field, although the model only worked for hybrid poplar N predictions under a single plant species scenario. On the other side, under a two plant species scenario, N uptake predictions were greatly underestimated by both hybrid poplar and weed species and similar results were observed under controlled growth chamber conditions (Kabba et al, 2009). This suggests that many interactive processes occurring at the ecosystem level, particularly under a weed competing environment, may affect the supply of N in the soil and N uptake at the root surface.…”

“…Kabba et al (2009) observed underestimation of N uptake by hybrid poplar under controlled condition for a one plant species' scenario and the underestimation was improved after incorporating N mineralization; however, predictions for the field matched up to the observed N uptake only for the pasture soil and still underestimated N uptake for the alfalfa soil. Therefore, these results are encouraging given the existing variability in the field, although the model only worked for hybrid poplar N predictions under a single plant species scenario.…”

Acquisition of phosphorus and other poorly mobile nutrients by roots. Where do plant nutrition models fail?

“…In perennial plant species, in spite of the evidence for changes in root physiological properties (Escamilla and Comerford 2000; Kelly et al 2001), most studies used similar models as those developed for annual plants to simulate nutrient acquisition (Cropper and Comerford 2005;Gregory 2006;Kabba et al 2009;Kelly et al 1992;Lin and Kelly 2010). To satisfy the hypothesis of stability of plant physiological properties, most of these works on perennial plant species were conducted in controlled conditions, i.e.…”

Juvenile growth of hybrid poplars on acidic boreal soil determined by environmental effects of soil preparation, vegetation control, and fertilization

“…The impact of MSP on soil fertility is more variable, sometimes improving nutrient mobilization (Ross and Malcolm, 1982) and on other occasions reducing it (Messier et al, 1995;Yildiz et al, 2010), notably due to soil organic matter removal (Arocena, 2000;GartziaBengoetxea et al, 2009). Given that hybrid poplars have high needs for resources, they are also known to be particularly sensitive to competition (Stanturf et al, 2001;Kabba et al, 2007Kabba et al, , 2009. Competition control generally has positive effects on early development of seedlings because the first few years are the most critical for survival (Morris et al, 1993;Löf, 2000;Harrington, 2006).…”