Pasquale Garofalo

Durum wheat (Triticum durum Desf.) in rotation with faba bean (Vicia faba var. minor L.): long-term simulation case study

The aim of this work was to applythe CropSyst simulation model toevaluate theeffect of faba bean cultivation as a break crop in the continuous durum wheat cropping system in southern Italy. The model was previously calibrated and validated for durum wheat and faba bean on data derived from experiments carried out in southern Italy (for different years and treatments), comparing observed and simulated crop growth, yield, soil water, and nitrogen output variables. The validation showed good agreement between simulated and observed values for cumulative above-ground biomass, greenareaindex,andsoilwatercontentforbothcropsandgrainyieldfordurumwheat;anegativecorrelationforgrainyieldin fababeanwasobservedduetoareductioninharvestindexinthewell-wateredcrop,whichthemodeldoesnotsimulatewell. Subsequently, a long-term analysis was carried out to study the effects on durum wheat of introducing a legume crop in rotation with the cereal in 2 and 3-year sequences. Along-termsimulation,basedon53yearsofdailymeasuredweatherdata,showedthatfababean,duetoalowerlevelof transpiratedwater(onaverage247mmfordurumwheatand197mmforfababean),allowedforgreatersoilwateravailability atdurumwheatsowingforthecerealwheninrotationwithalegumecrop(onaverage,+84mm/mfordurumwheatfollowing thefababean),withpositiveeffectsfornitrogenuptake,above-groundbiomass,andgrainyieldofwheat.Theyieldincrease of wheat when following a faba bean crop was on average +12%, but this effect was amplified in drier years (up to 135%). Inconclusion,thecasestudyofferedthepotentialtoconfirmthepositiveresultspreviouslyobtainedinlong/medium-term field experiments on the introduction of faba bean in rotation with durum wheat, as well as reduction in the chemical application of nitrogen.

Radiation-use efficiency of irrigated biomass sorghum in a Mediterranean environment

Mathematicalcropsimulationmodelsareusefultoolsinpredictingthepotentialyieldof fieldcropsinaspecific environment. The main driving parameter used to estimate biomass accumulation in most of these models is radiation-use efficiency(RUE).Biomasssorghum(SorghumbicolorL.Moench)isacropthatcanbeusedforenergyproduction(thermal and bioethanol chains) and a knowledge of its RUE in different water supply conditions can help to improve model simulations and evaluate crop diffusion. A 3-year field experiment was carried out in Southern Italy where sorghum was submitted to four irrigated regimes based on actual crop evapotranspiration (ETc). In the first year ETc was measured with weighted lysimeters, while in the other 2 years it was estimated by means of estimated crop coefficient (Kc) and the reference evapotranspiration ET0. The RUE, calculated as the slope of the first-order equation between dry biomass and intercepted photosynthetically active radiation along a crop cycle, showed an average of 2.91 � 0.54gMJ -1 , even if the RUE proved to be closely correlatedwithcropwaterconsumption.Thelatterrangedbetween891and454mmandtheRUEincreased4.2mgMJ -1 per mm of water used. A high crop interception of solar radiation was observed in sorghum, reaching its maximum efficiency 40 days after sowing. To obtain high yielding yield biomass sorghum requires a large supply of water, as confirmed by the Kc calculated during the crop cycle, which resulted higher (especially in the development and middle stages) when compared with those reported in the FAO 56 Paper. The obtained RUE values also confirmed a high efficiency in biomass production of this crop, allowing for the introduction of biomass sorghum in the cropping systems of Mediterranean environments as an alternative crop for energy purposes, but with adequate irrigation water supply.

Irrigation and nitrogen fertilization treatments on productive and qualitative traits of broad bean (Vicia faba var. minor L.) in a Mediterranean environment

Broad bean (Vicia faba var. minor L.) is a legume crop cultivated in the Mediterranean area for animal feeding and green manure purposes. The crop has an important role on the sustainability of the cropping systems for its ability to fix nitrogen and for the effects on soil structure, weed competition, nitrate leaching and pest control. This research, carried out in Central Italy, investigated the effect of the irrigation and nitrogen fertilization on productive traits of broad bean (biomass, seed yield, seed weight, harvest index, protein yield), seed chemical composition (nitrogen, phosphorus, potassium, trypsin inhibitors, tannin polyphenols, total polyphenols), water and nitrogen budgets (ETc, WUE, plant N content, N fixed, soil N uptake). The yearly variability was the factor that greatly influenced the crop performances in term of total biomass (13.6 t ha-1, on average), yield (3.53 t ha-1, on average) and protein yield (841 kg ha-1, on average). Evapotranspiration was affected by the water availability (rainfall and irrigation), and water use efficiency for the biomass (31.68 g kg -1, on average) and yield (8.36 g kg -1, on average) were quite stable among water and nitrogen treatments. Anti-nutritional factors in the seed remained similar for all experimental treatments and below the threshold levels for animal feeding purposes.