Tommaso Maggiore

Parameterization of a crop growth and development simulation model at sub-model components level. An example for winter wheat (Triticum aestivum L.)

Abstract Dynamic simulation models are frequently used for assessing agronomic and environmental effects of different management practices, under various pedo-climatic conditions. CropSyst is a suitable cropping systems simulation model for such applications. However, available CropSyst crop parameters for winter wheat, one of the most important cereals in the world, are limited. In this work we show that it is possible to parameterize separate sub-model components by using existing experimental data and literature. The experiments, carried out in northern Italy between 1986 and 2001, quantified the dynamics of aboveground biomass (AGB), plant nitrogen (N) concentration (PNC) and N uptake (UPTK) by means of periodical measurements. The relative root mean square error (calculated by dividing the root mean square error by the average of observations) obtained after model calibration and validation on an independent data set was, respectively, in the range 9–30% and 17–32% for AGB, 10% and 6–40% for PNC, 8–28% and 9–24% for UPTK. AGB was frequently underestimated. Despite the limited accuracy of simulations, we argue that calibrated crop parameters are adequate for scenario analysis as most differences between years and fertilization levels were reproduced by the model and final AGB and cumulative UPTK were also correctly simulated.

Biogas from dedicated energy crops in Northern Italy: electric energy generation costs

Agricultural anaerobic digestion facilities are increasing in many EU member States and biomass supply is sometimes an issue. Dedicated energy crops (DEC) (mainly Maize, Triticale and Sorghum) are often used to integrate other substrates, such as agricultural residues, manure and organic waste. However, DEC production includes onerous agricultural operations (soil preparation, harvest, transport and storage) and may result in high unit costs (UC) of electric energy (EE, € kWhe−1), compared to other renewable sources. In this work, seven different types of DEC (4 different combinations of crop successions) were cultivated in 30 different parcels, distributed along the Po Valley (northern Italy), using different varieties of seeds for each crop type. All agricultural operations were accounted for their costs (988–3346 € ha−1). Biomass production was measured and reported as average of different parcels for each type of crop (31.2–187 Mg ha−1). Biomass dry matter content and biogas potential were measured on representative samples and the EE obtainable was calculated (7.9–35.3 MWhe ha−1), by assuming conservative factors (CH4 contents in biogas and electric generation yields). The costs of ensiled biomass sensibly varied (13.8–40 € Mg−1) among crop solutions, as well as the same UC of EE (0.068–0.150 € kWhe−1). These costs were considered together with typical plant management and investment costs (plant size: 0.5–1 MWe): total UC of EE generation through anaerobic digestion (considering 100% DEC) varied in a relatively wide range (0.143–0.279 € kWhe−1). When the biomass mix is ‘blended’ with low‐cost residues or organic waste, this range could be lowered to 0.096–187 € kWhe−1. Only this strategy and strong efforts in reducing technological investment/management costs can candidate biogas‐based EE as a really competitive renewable alternative to traditional sources, in the next future.

Spatial interpolation of soil physical properties for irrigation planning. A simulation study in northern Italy

Abstract To calculate water balances at a regional scale, a frequently adopted approach (choropleth mapping) consists of using soil profile observations to identify ‘homogeneous areas’, to which simulation models are applied. However, spatial variability of soil properties within ‘homogeneous areas’ is a potential source of error, if the relationship between model inputs and model outputs is not linear. The aim of this work is to assess the feasibility of using spatially variable soil information for providing more detailed inputs to simulation models and to evaluate its effects on calculated irrigation water requirements. Point observations of soil properties in the topsoil layer were collected in a plain area near Milano (northern Italy). Particle size distribution was determined on 154 samples. The cropping systems simulation model cropsyst was applied at the study area by using four different sets of soil input data: the first one was derived from the soil map (1 datum per soil mapping unit), the other three were obtained by the use of geostatistical procedures applied to point observations (several data per soil mapping unit). The results of cropsyst s multi-year simulation for grain-maize were used to calculate the amount of grain biomass produced, actual crop evapotranspiration (ET), irrigation water needed and soil water drainage (SWD) for each soil unit (SU), their standard deviation (S.D.) in time and their S.D. in space within each SU. A clear spatial structure could be identified for all georeferenced model inputs and for model outputs related to crop growth (yield, ET). Simulated values for grain yield (GY), actual ET, irrigation water applied (IWA) and SWD were very similar for choropleth mapping and for geostatistics-based procedures. The S.D. in time was low for variables related to crop growth and was increasing for IWA and SWD. For all simulated variables the S.D. in space was always very low. In general, the spatial variability of model results was much lower than the spatial variability of model inputs: this smoothing effect was due to the application of kriging, pedotransfer functions (PTF) and simulation modeling. These results suggest that for evaluating water management scenarios at this scale, when hydrological properties are not measured, georeferenced soil data are available only for topsoil, and variability of soil particle distribution within SUs is not too high, the choropleth mapping method can be successfully used.

Evaluation of Triticale as a Forage Plant through the Analysis of the Cinetic of some Qualitative Parameters from Stem Elongation to Maturity.

For two years a field experiment has been carried out at S.Angelo Lodigiano (Milano-Italy) with Mizar and Rigel, two common triticale varieties, grown in plots replicated four times in a randomized complete block design. Plants from each plot were sampled from stem elongation to earing every ten days, from earing to waxy maturity every three days, and from the latter to full maturity every ten days. After having measured the water content of each sample, those parameters characterizing the quality of the forage (Raw Protein, NDF, ADF, ADL, Ash) and estimating its nutritional value (MFU kg-1) were analyzed.