YIELD, QUALITY AND SOIL ORGANIC CARBON DYNAMICS OF FOOD AND ENERGY CROP ROTATIONS FOR ADVANCED BIOFUELS PRODUCTION

The cultivation of a sequence of food and energy crop has the potential to strengthen the crop rotation effect without reducing food land. Sunn hemp (Crotalaria juncea L.), biomass sorghum (Sorghum bicolor x sudangrass), kenaf (Hibiscus cannabinus L.), and industrial hemp (Cannabis sativa L.) are annual high yielding lignocellulosic crops with great potential for advanced biofuels. The objective of the present study was to assess the biomass and grain yield, compare the grain quality and identify the SOC changes over six-years of the following rotations: i) maize - fallow - wheat - maize (C); ii) maize - sunn hemp - wheat + sunn hemp - maize (R1); iii) maize - fiber sorghum - wheat + sunn hemp - maize (R2); iv) maize - kenaf - wheat + sunn hemp - maize (R3); v) maize - industrial hemp - wheat + sunn hemp - maize (R4). At the end of the cropping systems the intensified rotation increased the biomass yield by 64, 147, 66, and 90 % for R1, R2, R3, and R4, respectively compared with control. Wheat grain yield decreased by 32 % in R2, compared with R4 and C. Wheat grain quality resulted with higher protein in C and R4 (+8 %) compared with R2 and R3. The SOC stock from 2016 to 2021 increased by 7 %, regardless of the rotation.