The wheat gap
Exploiting the yield gap for sustainable intensification of winter wheat production
Experimental plots at Bjertorp in Västergötland. Photo: Bo Stenberg.
This project is examining whether it is possible to increase the yield of wheat, in order to increase global access to food and simultaneously decrease the environmental impact of cultivation measures. Wheat is one of the most important food crops in the world, but wheat yields in Europe have stagnated and the yield gap, i.e. the difference between potential and actual yield, needs to be decreased if production levels are to be raised. Moreover, the yield trend in Sweden has been worse than in most other countries in Western Europe.
The aim of this project is to increase wheat yields while also decreasing the risk of a greater environmental impact. The project is based on three-year field trials with winter wheat at four sites and on computer simulations.
Through these approaches, the researchers can investigate the difference between the normal yield obtained by farmers and the potential yield under perfect conditions, when the crop is not subjected to water or nutrient deficiency or any other negative impact, e.g. diseases. With knowledge of the reasons behind the yield gap, farmers should be able to increase their yield.
Different measures for increasing yield are often combined with increased nitrogen fertilisation in order to achieve an effect, but this increases the risk of an environmental impact of cultivation, e.g. leaching. This is where precision agriculture can be a solution, since with the help of different forms of technology it is possible to fertilise more precisely according to crop and soil requirements in different parts of the field.
Experimental plots. Photo: Bo Stenberg.
Bo Stenberg inserting moisture probes into one of the experimental plots in the project. Photo: Lena Engström.
Facts on the methodThe field trials comprise the following treatments:
• Zero nitrogen – normal cropping practices for the area, but without nitrogen fertilisation
• Normal – normal cropping practices throughout
• Plus nitrogen – cropping practices, but with overoptimal nitrogen fertilisation
• Plus nutrients – normal cropping practices, but with overoptimal PK+micronutrients
• Plus pesticides – normal cropping practices, but with overoptimal use of pesticides
These treatments will be applied in all possible combinations.
The aim of the field trials is to determine the potential yield under specified climate and soil conditions, observe the yield decreases that arise owing to the resulting water and nutrient deficit or disease attacks and explain the yield differences with the help of crop models.
The input used in the crop models will be soil parameters, crop, degree of mineralisation of the organic material, how effectively the crop utilises solar radiation etc. The model will be adjusted relative to the actual status of the crop with the help of N sensors that make optimal measurements of the actual nitrogen concentration in the crop. The models will be used e.g. for explaining differences between potential and actual yield, converting the results to regional level and adjusting the nitrogen fertilisation rate based on variations within the field.
FACTS ON THE PROJECT
Name: Bo Stenberg, SLU Uppsala
Funding: SEK 8,4 million
Project period: 2014-2018
Find out more about Bo