Monitoring, Analysis and Modeling of Yield and Quality Dynamics of Lolium perenne Varieties for Biogas Production

Abstract

The overall aim of this project is to increase the biogas production of perennial ryegrass (Lolium perenne) by model-based optimization of the harvesting date. In a preliminary step it was analyzed statistically, whether the harvesting date influences yield and quality of L. perenne varieties. In a second step a model for yield and quality development of the varieties was set up and parameterized.In the first step 20 varieties of L. perenne differing in maturing times were cultivated at five sites in Germany and the Netherlands. Two harvesting treatments were applied: consistent harvest (H c ), where all varieties were harvested at the same time, as it is common practice, and differentiated harvest (H d In the second step, a logistic growth model for yield and quality development was set up, which also includes the most important environmental conditions, such as temperature and soil moisture. For model parameterization, eight L. perenne varieties with different maturing times were cultivated at four locations in Germany and harvested in time series. Yield and quality of L. perenne and environmental conditions were monitored. The model fitted well to both, yield and quality data of L. perenne varieties at all sites. The differences in yield and quality development were reflected by the model through differences in rates of growth and temperature coefficients: Early varieties had lower rates of growth and temperature coefficients than late varieties.It can be concluded, that this model can help to characterize L. perenne varieties and determine the optimal date of harvest for an increased biogas production.

Independent role of belowground organisms and plant cultivar diversity in legume-grass communities

“…Intraspecific diversity can refer to a number of hierarchical levels of diversity such as the richness of genotypes or subspecies; in our study higher cultivar diversity was used as a proxy for higher intraspecific diversity. Furthermore, several investigations about perennial grass and legume cultivars have been reporting consistent differences in traits including canopy structure, nutritional quality or resistance to fungal diseases among different cultivars (Gilliland et al, 2002;Smit et al, 2005;Jacob et al, 2010;Swieter et al, 2014).…”

Modeling the Daily Dynamics of Grass Growth of Several Species According to Their Functional Type, Based on Soil Water and Nitrogen Dynamics: Gras-Sim Model Definition, Parametrization and Evaluation

“…Several models already address the grass growth dynamics. Most of them simulate monospecific or speciesdominated grasslands, in particular that of the perennial ryegrass (Lolium perenne), under cutting conditions [15][16][17] or grazing by taking into account the impact of the grazing process on the sward [18][19][20][21].…”