Senthold Asseng, Jose R. Guarin, Mahadev Raman, Oscar Monje, Gregory Kiss, Dickson D. Despommier, Forrest M. Meggers, and Paul P. G. Gauthier

PNAS August 11, 2020 117 (32) 19131-19135

Significance

Wheat is the most important food crop worldwide, grown across millions of hectares. Wheat yields in the field are usually low and vary with weather, soil, and crop management practices. We show that yields for wheat grown in indoor vertical farms under optimized growing conditions would be several hundred times higher than yields in the field due to higher yields, several harvests per year, and vertically stacked layers. Wheat grown indoors would use less land than field-grown wheat, be independent of climate, reuse most water, exclude pests and diseases, and have no nutrient losses to the environment. However, given the high energy costs for artificial lighting and capital costs, it is unlikely to be economically competitive with current market prices.

Abstract

Scaling current cereal production to a growing global population will be a challenge. Wheat supplies approximately one-fifth of the calories and protein for human diets. Vertical farming is a possible promising option for increasing future wheat production. Here we show that wheat grown on a single hectare of land in a 10-layer indoor vertical facility could produce from 700 ± 40 t/ha (measured) to a maximum of 1,940 ± 230 t/ha (estimated) of grain annually under optimized temperature, intensive artificial light, high CO₂ levels, and a maximum attainable harvest index. Such yields would be 220 to 600 times the current world average annual wheat yield of 3.2 t/ha. Independent of climate, season, and region, indoor wheat farming could be environmentally superior, as less land area is needed along with reuse of most water, minimal use of pesticides and herbicides, and no nutrient losses. Although it is unlikely that indoor wheat farming will be economically competitive with current market prices in the near future, it could play an essential role in hedging against future climate or other unexpected disruptions to the food system. Nevertheless, maximum production potential remains to be confirmed experimentally, and further technological innovations are needed to reduce capital and energy costs in such facilities.

See https://www.pnas.org/content/117/32/19131

Figure 2: Annual field and indoor wheat yields. Observed wheat yields from the field (gray bars) and an indoor controlled environment pilot experiment (blue bar), and simulated mean yields from two crop models for wheat cultivars with a low harvest index (green bar) and a theoretical high harvest index (red bar) grown in an indoor controlled environment. Error bars show SEM for the field, SD of the indoor experiment, and ± the mean of the 10th and 90th percentiles of the indoor simulations. Yields are shown at 11% grain moisture. ¹10-y average yield, 2008–2017 (2). ²Guinness World Record, 2017 (14). ³Observed 70-d season indoor experiment with 20 h of 1,400 μmol/m²/s light daily (50 MJ/m²/d) and 330 ppm atmospheric CO₂ concentration, scaled up to 1 ha and multiplied by 5 harvests/y (13). ⁴Simulated 1-ha indoor experiment using the DSSAT-NWheat and SIMPLE models with 70-d seasons and 5 harvests/y with constant light and 1,200 ppm atmospheric CO₂. The average of simulations with 1,800, 1,900, and 2,000 μmol/m²/s light (77, 81, and 86 MJ/m²/d, respectively) and ±10% RUE is shown. ⁵Simulated 1-ha indoor experiment using the DSSAT-NWheat and SIMPLE models with 70-d seasons and 5 harvests/y with constant light, 1,200 ppm atmospheric CO₂ and a theoretical harvest index of 0.64 (24). The average of simulations with 1,800, 1,900, and 2,000 μmol/m²/s light (77, 81, and 86 MJ/m²/d, respectively) and ±10% RUE is shown.