Climate change is affecting the water cycle across the globe, and temporal variation of rainfall has increased considerably. The distribution of rainfall has become more irregular over time, and flood and drought events have increased in frequency. This unbalanced variability in rainfall is principally negative for the growth of crops.
Temporal variation in rainfall can also influence when crop fertilizer is applied, further restricting crop demand and fertilizer supply syncing.
Furthermore, intensified temporal variability of rainfall leads to an asynchronous between nitrogen (N) supply and demand. As a result, more reactive nitrogen losses, including gaseous emissions, and leaching loss, occur, triggering greenhouse gas emissions, air pollution, water pollution, and other human health and ecological environment effects.
Prof. Peter M. Vitousek from Stanford University and his team replicated the crop productivity based on soil temperature and moisture, and biologically available N and P from all sources (atmospheric deposition, fertilizer, and mineralization of N and P from soil organic N and P), to evaluate how temporal variation in precipitation impacts crop harvest and nitrogen losses.
Data from the model demonstrate that the suitable amount of fertilizer application (20 and 100 units of P and N, respectively) and the suitable timing of addition can result in a higher retrieval of N in harvested material of 53.6 and a lower N loss of 60.8, which is a suggested best practice for numerous field crops.
The intensified variability of rainfall has the probability of yielding extreme precipitation and a more irregular dispersal of water resources, with many opposing effects on agricultural production. The team found that surges in temporal variation in rainfall caused decreasing yields and increasingly larger losses of reactive N.
These losses are expected to be predominantly vital for P since the relative immobility of P results in large pools of fertilizer-derived P to amass in surface soils, where they are susceptible to losses via soil erosion and runoff.
Temporal variations in rainfall worldwide will be more intense with anthropogenic climate change, which will decrease yields and surge nitrogen losses.
The team hopes to investigate solutions that could resolve this climate risk. However, modifying fertilizer application amounts (~30%) based on soil moisture content will decrease reactive N losses (~50%) but does not boost crop yields.
In rain-fed agricultural biomes, climate-change-triggered increases in temporal variation in rainfall will make it hard to support cropping systems that are high yielding as well as have small human-health and environmental footprints. Briefly, it appears likely that mankind will have to deal with growing challenges to food security with the continuous improvement in rainfall variability.
The atmosphere is a very delicate and complicated system. As the greenhouse gases released by humans amass in the atmosphere, they may ultimately cause extreme weather events like rainstorms.
Effort is required worldwide to decrease emission and achieve carbon neutrality as soon as possible so that the future of the Earth's climate can be changed.
Vitousek, P. M., et al. (2022) Climate-Change-Induced Temporal Variation in Precipitation Increases Nitrogen Losses from Intensive Cropping Systems: Analysis with a Toy Model. Frontiers of Agricultural Science and Engineering. doi.org/10.15302/J-FASE-2022452.