Closing Yield Gaps?

What is a yield gap?  A recent article from the journal Nature states that closing the yield gap provides hope for feeding the global population in the future.

Maize yields- with and without fertilizer

A yield gap is used to describe the huge gap between crop yields obtained by successful farmers and those achieved by the average farmers.

Another term frequently used is ecological intensification.  This is the concept of closing this yield gap while minimizing the impacts of food production on soil degradation, water pollution, and wasting resources.  This concepts emphasizes intelligent food production that saves inputs and protects the environment (sustainable intensification).
  
A recent Nature article discusses the promise of this concept:

 Closing yield gaps through nutrient and water management

Nathaniel D. Mueller, J. S. Gerber, M. J., D. K. Ray, N. R. & J. A. Foley (2012)

The authors report that it is possible to feed the whole world by 2050, even as population jumps by 2 billion to reach 9 billion and food demand will double from the present because of better living standards.

Preparing field for rice planting

The researchers from McGill University in Montreal, Canada, and the University of Minnesota, US, gathered data from 157 countries and found that most of them suffered from a serious 'yield gap'. 

They found that global yield variability is heavily controlled by fertilizer use, irrigation and climate. Large production increases (45% to 70% for most crops) are possible from closing yield gaps to 100% of attainable yields, and the changes to management practices that are needed to close yield gaps vary considerably by region and current intensity. 

They conclude that meeting the food security and sustainability challenges of the coming decades is possible, but will require considerable changes in nutrient and water management.

Their focus on yield gaps helps us identify what plant nutrition and water availability factors are limiting global food production, but the contribution of improved genetics will also play a role.  Providing the necessary fertilizer to the areas where it is needed has proven to be a challenge.  There are considerable opportunities to improve irrigation efficiency, but there are physical limitations to global water availability.  

Closing the yield gap requires localized information on what is holding back productivity.  Gathering the necessary information is the first step.  Implementing that information through appropriate technology has generally proven to be a formidable barrier.

Soil productivity must be maintained

The International Plant Nutrition Institute has been active in identifying how soil fertility holds back the yields of major food crops (Agri-stats).  Another international group has launched the Global Yield Gap and Water Productivity Atlas to identify areas where yield gaps can be narrowed (www.yieldgap.org)