Indices of crop water stress from UAV images precisely map residual nitrogen

The risk of nutrient losses in production of vegetables and early potatoes under irrigation is increased by significant spatial variability of soil water capacity and infiltration rate of fields. The impact of water stress on not irrigated crops, occasionally grown on the vegetable fields, was proved to precisely map the soil conditions in a scale of less than one meter. Nitrogen balance, the amount of N not exported in yield was tightly related to soil conditions and the stress indices derived from airborne images data (r = 0.80-0.90).

Vegetable production, including early potatoes, is known for low nitrogen utilization efficiency and higher residual mineral N left after harvest (Haberle et al. 2018). The risk of N nitrate leaching is increased by irrigation and high soil spatial variability of fields situated often near rivers. In the Czech Republic these regions are also utilized for the accumulation and extraction of drinking water (Bruthans et al. 2018). In the study the impact of water stress on not irrigated crops, occasionally included to vegetable crop rotations was used. Previously, we showed that soil texture and calculated water capacity variability had a tight relationship with water stress impacts (including 13C discrimination) on the crops grown in the fields (Haberle et al. 2018).