Sustainable Food Security: Crop Production

Introduction

This first week we are setting the scene for the global food situation today and projected demand and supply options tomorrow. Covering the four pillars of global food systems, we will zoom in on availability issues, and more in particular on crop production, as central theme of this course. Photosynthesis plays a key role in this process, turning solar light into food, which fuels mankind. Analogously to physical principles applied in building houses, you'll be acquainted to the bio-physical principles in growing crops.

Potential production

Potential production is the simplest representation of crop growth, defined by the crop's genetic potential and the ambient growth factors radiation, temperature and carbon dioxide concentration in the air. Under perfect crop management, with no limitation of water and nutrients, and a weed, pathogen and pest free environment, crops reach their potential production. This week focuses on the conversion of carbon dioxide into plant biomass as powered by solar radiation, with temperature as modifying factor. Based on variation in solar radiation and temperature around the globe, you'll be able to calculate potential crop yields for different locations.

Water limited production

In the process of fixing carbon dioxide from the air into biomass, crops inevitably lose water by transpiration. When transpired water from the leaf surface is not adequately replenished through water uptake by the roots, crop production becomes water-limited, resulting in lower yields. Accounting for the evaporative demand of the air and water availability to the crop, water-limited production can be assessed. Conversely, to reach potential yield, you may determine the amount of water required through irrigation, as a yield increasing measure.

Nutrient limited production

In addition to water, nutrients are essential to crop production to support physiological processes, like photosynthesis. Various nutrients are absorbed from the soil by the roots. When nutrient availability falls short, production becomes nutrient-limited. In that situation nutrient application by manure or artificial fertilizers is a yield increasing measure..

Actual production

Actual crop production refers a situation where production is further reduced by effects of weed, pests (insects, mites, nematodes, rodents, and birds), diseases (fungi, bacteria, viruses) and/or pollutants. This introduces an extra level of complexity in plant production. In spite of intensive crop protection measures in some parts of the world, the actual production is the common production situation for the majority of the world's agricultural production systems. We will look at how weeds, and pests and diseases affect crop yields and what measures can be taken to prevent losses.

Synthesis

Having tackled the three distinguished production situations separately in the previous weeks, we now come back to complete the diagram reflecting the 'principles of production ecology'. Hopefully, it means more to you now and you can use it in analysing the impact of genetics, environment and management on crop yields, as will be discussed in this synopsis.