Crop response to P fertilizer omission under a changing climate-Experimental and modeling results over 115 years of a long-term fertilizer experiment

Phosphorus (P) is an essential plant nutrient. However, our understanding of the complex interactions between soil P availability, environment, management and crop growth is still limited. We used unique historic and recent soil and crop data spanning more than a century combined with a process-based crop model to analyze the impact of P fertilizer omission and P fertilization on the biomass production of five crops. The long-term field experiment at Dikopshof, Germany, was established in 1904 with a 5-year crop rotation of sugar beet, winter wheat, winter rye, clover and oat/potato (potato replaced oat in 1953) on a fertile Luvisol. Averaged over the period from 1906 to 2018, the yield loss due to P omission was low for winter wheat and winter rye (7-8 %). In contrast, yield losses for sugar beet, clover and potato were relatively high (15-24 %). The yield loss from P fertilizer omission in comparison to the reference treatment (rotation mean excluding oat/potato) increased until the middle of the last century from 7% to 18 %, but subsequently decreased to 13 %. Trend and correlation analyses suggest that this decrease was related to an increase in air temperatures in especial during spring and a lower yield loss under P omission. Crop model simulations showed decreasing topsoil organic carbon concentrations after the 1930ies as manure was discontinued in 1942 but also due to increasing air temperatures. The increase in plant-available topsoil P concentrations during the last decades was one of the main factors offsetting yield losses despite P fertilizer omission. Our study suggests that climate change and, in particular, a marked increase in temperature since the middle of the last century most likely influenced soil P dynamics with a significant impact on crop production.

Automated summary

This study examined the impact of phosphorus fertilizer omission and fertilization on biomass production of different crops using historic and recent soil/crop data along with a crop model. Results showed that phosphorus omission had varying effects on different crops, with lower yield losses for winter wheat and winter rye compared to sugar beet, clover, and potato. The decrease in yield loss over time was attributed to factors such as increasing air temperatures and changes in soil phosphorus dynamics.