Sustainability in cereal crop production in mediterranean environments

Abstract

The continuous increase of the world population (a growth of about one-third is expected by 2050), together with an even larger increase in food demand (especially in emerging countries), will lead in the next 30 years to the necessity to produce 70% more food. To keep the pace with food demand, global cereal production would need to increase by 40% overall, or by some 900 million tons between the present and 2050. Single countries can either increase production or increase net imports or a combination of both. This new global emergency involves researchers, farmers, politicians, the agro-food industry, and all stakeholders, and the new challenge can be summarized as follows: to produce more, but in a sustainable way. The goal of "sustainable intensification" constitutes one of the priorities for the research in agriculture and one of the cornerstones of the new Common Agricultural Policy. In this context, all the techniques designed to maximize production through the more efficient use of resources are in line with the objectives of sustaining production with minimal impact. In Mediterranean environments, cereal crops are grown mainly in the semiarid and subhumid areas. In arid and semiarid areas dryland farming, techniques are of renewed interest in the view of sustainability. They are aimed to increase water accumulation in the soil, reduce runoff and soil evaporation losses, choose species and varieties able to make better use of rainwater, and rationalize fertilization plans, sowing dates, and weed and pest control. Fertilization plans should be based on well-defined principles of plant nutrition, soil chemistry, and chemistry of the fertilizer elements. Starting from the calculation of nutrient crop uptake (based on the actually obtainable yield), dose calculation must be corrected by considering the relationship between the availability of the trace elements in soil and the main physical and chemical parameters of the soil (pH, organic matter content, mineralization rate, C/N, ratio of solubilization of phosphorus, active lime content, presence of antagonist ions, etc.). The choice of traditional, minimum, or no-tillage is one of the most controversial aspects of agricultural research; much depends on soil texture, crop type (depending mainly on the characteristics of the root), rainfall regime (mainly intensity), long-period tillage plan, structural stability of the soil (in function of the organic matter content), and all other variables and their interaction. In any case, minimum tillage and sod seeding are generally less expensive and evidence points to a lower production of CO2 with respect to traditional tillage. Weed and pest control is also a critical point for the sustainability of cereal production: sustainability in control strategies involves minimizing the use of chemicals while safeguarding yields. To this end, priority should be given to preventive and nonchemical agronomic measures, while chemical means should be used only when the level of weeds and pests exceeds the threshold of economic damage. Finally, precision farming is one of the most powerful tools for the sustainability of cereal crop production. This technique helps the farmers in their decisions, taking into account the local variability of physical, chemical, and biological properties of the soil, as well as the timing of input application. With this management strategy, input of resources is balanced and optimized in order to increase yields and reduce interventions and costs; the environmental impact is significantly reduced, as well as the amount of resources used for the production.